Re: Toolchain with ldc and AArch64 OSX
On Saturday, 24 June 2023 at 15:16:37 UTC, Cecil Ward wrote: I have LDC running on an ARM Mac. If anyone else out there is an LDC or GDC user, could you knock up a quick shell program to compile and link a .d file to produce an executable ? found the linker but these tools are all new to me and a bit of help would save me a lot of trial and error and frustration as I try to find docs. GDC would be great too. I have managed to achieve this before on a Raspberry Pi AArch64 Linux Debian where the compiler can link and generate an executable just in integrated fashion in the one command. The OSX tools seem rather different however. I’m going to try installing GDC on the Mac next, have got that running on the Pi too successfully. I have ldc installed (from `brew`) on my (also arm) Mac, it works fine, or do you specifically want to work out which linker to invoke manually and so on? I'm not sure if gdc is currently easy to obtain on arm macs. I think it should work fine but some packages hadn't enabled arm support on macos yet, last time *I* checked at least.
Re: How to get the body of a function/asm statement in hexadecimal
On Sunday, 29 January 2023 at 21:45:11 UTC, Ruby the Roobster
wrote:
I'm trying to do something like
```d
void main()
{
auto d =
*d.writeln;
}
void c()
{
}
```
In an attempt to get the hexadecimal representation of the
machine code of a function. Of course, function pointers
cannot be dereferenced. What do?
Furthermore, I would like to be able to do the same for an
`asm` statement.
The function pointer can be casted to a pointer type. It is worth
saying, however, that it is not trivial to find where the *end*
of a function is. In X86 it's not even trivial to find the end of
an instruction!
If you'd just like the bytes for inspection, you could use a tool
like objdump. For more complicated situations you will need to
use a hack to tell you where the end of a function is.
Re: Solving optimization problems with D
On Sunday, 1 January 2023 at 21:11:06 UTC, Ogi wrote: I’ve read this [series if articles](https://www.gamedeveloper.com/design/decision-modeling-and-optimization-in-game-design-part-1-introduction) about using Excel Solver for all kinds of optimization problems. This is very neat, but of course, I would prefer to write models with code instead, preferably in D. I glanced at mir-optim but it requires knowledge of advanced math. Is there something more approachable for a layperson? What do you want to optimize? Optimization in general requires reasonably advanced mathematics, whereas a single problem can be simplified.
Re: Can we ease WASM in D ?
On Wednesday, 16 November 2022 at 23:00:40 UTC, Adam D Ruppe wrote: On Wednesday, 16 November 2022 at 22:51:31 UTC, bioinfornatics wrote: [...] It would be pretty cool if you could just mark `@wasm` on a function and have it magically convert... the dcompute thing i *think* does something like this. but im not sure. [...] What I've done before (including the webassembly.arsdnet.net website) is have the server call the compiler as-needed when requesting the file, which makes it feel pretty transparent. You might want to do that too, it'd be on the file level instead of on the function level but it works. This is what it does, albeit with a pretty wacky pipeline because GPUs be crazy.
Re: dmd as a library
On Tuesday, 8 November 2022 at 00:05:18 UTC, vushu wrote: Any where to find learning material for using dmd as a library? thanks. What do you want to do with it.
Re: how to benchmark pure functions?
On Thursday, 27 October 2022 at 18:41:36 UTC, Dennis wrote:
On Thursday, 27 October 2022 at 17:17:01 UTC, ab wrote:
How can I prevent the compiler from removing the code I want
to measure?
With many C compilers, you can use volatile assembly blocks for
that. With LDC -O3, a regular assembly block also does the
trick currently:
```D
void main()
{
import std.datetime.stopwatch;
import std.stdio: write, writeln, writef, writefln;
import std.conv : to;
void f0() {}
void f1()
{
foreach(i; 0..4_000_000)
{
// nothing, loop gets optimized out
}
}
void f2()
{
foreach(i; 0..4_000_000)
{
// defeat optimizations
asm @safe pure nothrow @nogc {}
}
}
auto r = benchmark!(f0, f1, f2)(1);
writeln(r[0]); // 4 μs
writeln(r[1]); // 4 μs
writeln(r[2]); // 1 ms
}
```
I recommend a volatile data dependency rather than injecting
volatile ASM into code FYI i.e. don't modify the pure function
but rather make sure the result is actually used in the eyes of
the compiler.
Re: vectorization of a simple loop -- not in DMD?
On Thursday, 14 July 2022 at 13:00:24 UTC, ryuukk_ wrote: On Thursday, 14 July 2022 at 05:30:58 UTC, Siarhei Siamashka wrote: On Tuesday, 12 July 2022 at 13:23:36 UTC, ryuukk_ wrote: I wonder if DMD/LDC/GDC have built in tools to profile and track performance Linux has a decent system wide profiler: https://perf.wiki.kernel.org/index.php/Main_Page And there are other useful tools, such as callgrind. To take advantage of all these tools, DMD/LDC/GDC only need to provide debugging symbols in the generated binaries, which they already do. Profiling applications to identify performance bottlenecks is very easy nowadays. I am not talking about linux, and i am not talking about 3rd party tools I am talking about the developers of DMD/LDC/GDC, do they profile the compilers, do they provide ways to monitor/track performance? do they benchmark specific parts of the compilers? I am not talking about the output of valgrind Zig also has: https://ziglang.org/perf/ (very slow to load) Having such thing is more useful than being able to plug valgrind god knows how into the compiler and try to decipher what does what and what results correspond to what internally, and what about a graph over time to catch regressions? DMD is very fast at compiling code, so i guess Walter doing enough work to monitor all of that LDC on the other hand.. they'd benefit a lot by having such thing in place Running valgrind on the compiler is completely trivial. Builtin profilers are often terrible. LDC and GDC and dmd all have instrumenting profilers builtin, of varying quality. gprof in particular is somewhat infamous. dmd isn't particularly fast, it does a lot of unnecessary work. LDC is slow because LLVM is slow. We need a graph over time, yes.
Re: vectorization of a simple loop -- not in DMD?
On Monday, 11 July 2022 at 18:15:16 UTC, Ivan Kazmenko wrote:
Hi.
I'm looking at the compiler output of DMD (-O -release), LDC
(-O -release), and GDC (-O3) for a simple array operation:
```
void add1 (int [] a)
{
foreach (i; 0..a.length)
a[i] += 1;
}
```
Here are the outputs: https://godbolt.org/z/GcznbjEaf
From what I gather at the view linked above, DMD does not use
XMM registers for speedup, and does not unroll the loop either.
Switching between 32bit and 64bit doesn't help either.
However, I recall in the past it was capable of at least some
of these optimizations. So, how do I enable them for such a
function?
Ivan Kazmenko.
How long ago is the past? The godbolt.org dmd is quite old.
The dmd backend is ancient, it isn't really capable of these
kinds of loop optimizations.
Re: Is there any implementation of a 128bit integer?
On Monday, 11 July 2022 at 00:19:23 UTC, Era Scarecrow wrote: On Friday, 8 July 2022 at 15:32:44 UTC, Rob T wrote: [...] There was a discussion on this not long ago. Walter tried implementing it recently too, though I'm guessing he gave up. [...] Note that you're replying to a message containing a link to the implementation that is in the standard library today.
Re: Enforce not null at compile time?
On Monday, 20 June 2022 at 17:48:48 UTC, Antonio wrote: Is there any way to specify that a variable, member or parameter can't be null? You can use an invariant if it's a member of an aggregate but be warned that these are only checked at the boundaries of public member functions.
Re: How to map machine instctions in memory and execute them? (Aka, how to create a loader)
On Monday, 6 June 2022 at 15:13:45 UTC, rempas wrote: I tried to find anything that will show code but I wasn't able to find anything expect for an answer on stackoverflow. I would find a lot of theory but no practical code that works. What I want to do is allocate memory (with execution mapping), add the machine instructions and then allocate another memory block for the data and finally, execute the block of memory that contains the code. So something like what the OS loader does when reading an executable. I have come with the following code: [...] If you know the instructions ahead of time LDC and GDC will both let you put a function in it's own section, and you can then use some linker magic to get pointers to the beginning and end of that section.
Re: want to confirm: gc will not free a non-gc-allocated field of a gc-allocated object?
On Tuesday, 7 June 2022 at 09:12:25 UTC, ag0aep6g wrote: On 07.06.22 11:00, max haughton wrote: On Tuesday, 7 June 2022 at 08:56:29 UTC, ag0aep6g wrote: [...] That wasn't mw's question. I also answered this in my original one IIRC. You didn't. Ok I must have assumed it was obvious it wouldn't free it.
Re: want to confirm: gc will not free a non-gc-allocated field of a gc-allocated object?
On Tuesday, 7 June 2022 at 08:56:29 UTC, ag0aep6g wrote: On 07.06.22 03:02, max haughton wrote: I'm talking about the data in the array. void[] might contain pointers, float[] does not so it won't be scanned. That wasn't mw's question. I also answered this in my original one IIRC. There's nothing too free because the GC didn't allocate it. Every allocator needs to either have a GC or a fast way to free memory which includes checking whether it owns memory in the first place. annoyingly you can't express this in the malloc/free pattern very well at all. One of the many gifts C has given the world.
Re: want to confirm: gc will not free a non-gc-allocated field of a gc-allocated object?
On Tuesday, 7 June 2022 at 00:40:56 UTC, ag0aep6g wrote:
On 07.06.22 00:22, max haughton wrote:
float[] doesn't contain pointers, so the GC won't do anything
to or with it.
wat
float[] is a pointer (plus a length). The GC will deal with it
like any other pointer.
I'm talking about the data in the array.
void[] might contain pointers, float[] does not so it won't be
scanned. Or at least shouldn't be...
This is why you shouldn't use void[] for everything if you can
help it.
```
void main()
{
import std.stdio;
auto voidArray = typeid(void[]);
auto floatArray = typeid(float[]);
writeln(voidArray.next.flags() & 1 );
writeln(floatArray.next.flags() & 1);
}
```
Re: want to confirm: gc will not free a non-gc-allocated field of a gc-allocated object?
On Monday, 6 June 2022 at 22:18:08 UTC, mw wrote:
Hi,
Suppose I have this code:
```
class GCAllocated {
float[] data;
this() {
// non-gc-allocated field
this.data = cast(float[])(core.stdc.stdlib.malloc(nBytes)[0
.. nBytes]);
}
}
void foo() {
auto obj = new GCAllocated(); // gc-allocated owning object
...
}
```
So when `obj` is cleanup by the GC, obj.data won't be freed by
the GC: because the `data` is non-gc-allocated (and it's
allocated on the non-gc heap), the GC scanner will just skip
that field during a collection scan. Is this understanding
correct?
I need this behavior for a special purpose, so I want to
confirm it.
Thanks.
float[] doesn't contain pointers, so the GC won't do anything to
or with it.
Re: What are (were) the most difficult parts of D?
On Sunday, 22 May 2022 at 20:05:33 UTC, Chris Piker wrote: On Sunday, 22 May 2022 at 19:33:21 UTC, rikki cattermole wrote: I should probably jump back to another thread, but maybe one more reply isn't too much off topic discussion... [...] https://github.com/gcc-mirror/gcc/tree/master/gcc/testsuite Look for folders starting with gdc. There is no analogue for buildkite as per se.
Re: What are (were) the most difficult parts of D?
On Saturday, 21 May 2022 at 19:00:04 UTC, Johan wrote: On Tuesday, 17 May 2022 at 06:28:10 UTC, cc wrote: On Monday, 16 May 2022 at 15:08:15 UTC, H. S. Teoh wrote: [...] According to the dlang.org wiki entry for LDC: [...] So I'm not touching it for now. Lol, what? Don't misquote the wiki about LDC. If you can run DMD on your architecture, LDC has full support too. The "lacking druntime/phobos support" is about architectures that are _not_ x86, x86_64, ARM, AArch64, PowerPC, MIPS, WebAssembly. DMD supports only a subset of what LDC (and GDC) support. -Johan Forget target support, ldc *runs* on more architectures than dmd because it doesn't insist on using x87 all the time.
Re: What are (were) the most difficult parts of D?
On Wednesday, 11 May 2022 at 05:41:35 UTC, Ali Çehreli wrote: What are you stuck at? What was the most difficult features to understand? etc. To make it more meaningful, what is your experience with other languages? Ali Learning D is almost a complete blur in my memory but I distinctly remember not really understanding is expressions well into even fiddling around with them inside the compiler.
Re: What are (were) the most difficult parts of D?
On Friday, 13 May 2022 at 21:07:12 UTC, Christopher Katko wrote:
Is there any way we can get numbered errors like C++ /
Microsoft have?
E2040 Declaration terminated incorrectly
Because then we could easily have a wiki for common error cases
with code snippets of it occurring, and a fix for it. Common
triggers of this error vs the proper code.
And a neat feature that Allegro.cc does, it automatically scans
forum posts for usages of Allegro functions (e.g.
al_draw_bitmap() man page will include links to posts that ask
about al_draw_bitmap and has a Yes/No question next to it "was
this a helpful post" so you can remove bad matches). Here it
would be even easier than matching random questions because
error codes are specific string literals ("E2040") and not some
sort of regex attempt to match someone asking a question about
'R[][][] datatypes' or something like that.
Here is an example:
https://www.allegro.cc/manual/5/al_draw_bitmap
and an C++ error page:
https://docwiki.embarcadero.com/RADStudio/Sydney/en/E2040_Declaration_terminated_incorrectly_(C%2B%2B)
We discussed this a while ago in a foundation meeting. The
details didn't really get hashed out but I think we can
definitely try it.
I have a PR which alters the error message you get if you do
```d
void main()
{
func() == 43;
}
```
This is an example of an error message which could be
counterintuitive to a new D programmer, e.g. maybe they thought
it would act like an assert or whatever, so we can link to a some
html somewhere on dlang.org
Re: Best Practice to manage large projects with dub?
On Friday, 13 May 2022 at 17:51:55 UTC, Ozan Süel wrote: Hi My situation: I'm working on and with many projects based on many libraries. I know how to handle these in Git, GitHub and Dub. But what would be the Best Practice in current dub? Let's say, we have many apps (1 app = 1 package), which use several libs (Every app has his own set of used libs, some are overlapping with other apps), every lib requires new libs to work (some are overlapping),and so on. Let's say we want to have 10 apps and need in sum 100 packages with every possible combinations. One way would be, to pump the dub package manager with 100 new packages for building only 10 apps. I would like to avoid fill the dub database with small packages it. An deprecated way is to combine dub with github, which still works fine to me. What would be good way to manage many small libs to build few big apps? Maybe the solution is around the corner, but better to ask the experts. Thanks in advance Greetings, Ozan I would highly recommend keeping these small libs in a common repository (a monorepo if you will) but in a manner that only what is needed is required. Lots of projects/repositories/dub.jsons == pain
Re: What's a good way to disassemble Phobos?
On Saturday, 30 April 2022 at 18:18:02 UTC, Dukc wrote: I have figured out that my development build of Phobos is for some reason including instances of `__cmp` and `dstrcmp` templates from DRuntime in the Phobos binary. Since `-betterC` client code does not link Phobos in, it fails if it tries to use those functions. The problem: how do I track down what includes those functions in the Phobos binary? The -vasm switch of DMD gives a neat output, but I can get it to only show the disassembly of files I'm compiling (not already combined files), and before the linking phase. So no info where the function calls point to. I also tried ndisasm. It can disassemble already compiled binaries, but it's output is utter trash. It can't even figure where a function begins or ends, let alone displaying their name. Instead it displays just a sea of `add` instructions for the areas between the functions. I'm looking for something where I could search for the call to the DRuntime functions in question, from an already combined .o or .a. What do you suggest? I'm on Linux. If they are templates then try compiling whatever is causing them with `-vtemplates=list-instances`. If you can't recompile then you may be stuck grepping whatever disassembler output works. The sea of add instructions is padding, lookup what `addBYTE PTR [rax],al` assembles to. vasm isn't a good disassembler for anything other than debugging the compiler, all the jumps and relocations aren't resolved.
Re: stack frame & dangling pointer weirdness
On Thursday, 21 April 2022 at 05:49:12 UTC, Alain De Vos wrote:
Following program:
```
import std.stdio;
void main() @trusted
{
int *p=null;
void myfun(){
int x=2;
p=
writeln(p);
writeln(x);
}
myfun();
*p=16;
writeln(p);
writeln(*p);
}
```
outputs :
7FFFDFAC
2
7FFFDFAC
32767
I don't understand why. Would it be possible to explain ?
When you pass a pointer to writeln conceptually it gets copied,
the address that is, but the memory the address points to is in
no man's land because it was in an old stack frame.
As such, this memory gets "overwritten" (at this point it's
invalid anyway) when you call writeln, so when you dereference it
you get something from the old stack of writeln rather than 16.
Re: Do I have to pass parameters with ref explicitly?
On Sunday, 17 April 2022 at 03:00:28 UTC, Elfstone wrote:
I'm reading some d-sources, and it looks like they pass big
structs by value.
Such as:
Matrix4x4f opBinary(string op)(Matrix4x4f rhs) { ... }
I came from a C++ background, and I would have written:
Matrix4x4f opBinary(string op)(const ref Matrix4x4f rhs) {
... }
I haven't found anything in the docs yet. Will the d-compiler
optimize them into virtually the same? Can someone give me a
reference?
It's the same as C++.
Re: Source code for vibe.d listenTCP()
On Saturday, 26 February 2022 at 22:25:46 UTC, Chris Piker wrote: Hi D I'm trying out the vibe.d framework for the first time and it looks like many of the functions mutate some hidden global state. Take for example `listenTCP`. To help me build a mental picuture of the framework I'd like to see what global state is mutated, but for the life of me I can't even find the source code to listenTCP(). The obvious method of: ```bash git clone g...@github.com:vibe-d/vibe.d.git cd vibe.d grep -R -n listenTCP ``` returns many instances where listenTCP is used, but none that look like a definition. It's quite possible I just overlooked it, or maybe it's implemented as a mixin or something weird like that. Anyway if someone can just help me find the source code to listenTCP inside vibe.d I'd be grateful. Thanks for your time, https://dlang.org/spec/traits.html#getLocation can be a bruteforce approach to this question when dealing with a new codebase.
Re: How to get instance member value from getSymbolsByUDA
On Saturday, 26 February 2022 at 17:06:06 UTC, Remi Thebault wrote: On Saturday, 26 February 2022 at 12:01:14 UTC, max haughton wrote: Getting the UDAs from inside a symbol must be done via a recursive procedure in the same manner one would identify the aforementioned symbol i.e. you have to go through the fields looking for UDAs *then* use getUDAs. This is because UDAs cannot convey information without their context, so the trait doesn't look recursively. I don't need to get access to the UDA value, I need the value of the field decorated with UDA. Finally I can get access to the member using `__traits(getMember, req, paramSymbols[0].stringof)`. I see, my apologies. FYI if possible you should avoid using stringof because it's basically only intended for debugging so isn't always consistent - this is what __traits(identifier) is for
Re: How to get instance member value from getSymbolsByUDA
On Saturday, 26 February 2022 at 11:38:16 UTC, Remi Thebault wrote: On Saturday, 26 February 2022 at 11:26:54 UTC, max haughton wrote: On Saturday, 26 February 2022 at 10:39:18 UTC, Remi Thebault wrote: Hi all, I'm trying to establish a REST API by using the type system (used in both client and server code). [...] https://dlang.org/phobos/std_traits.html#getUDAs How do I use `getUDAs` in this context? I have `getUDAs!(req, Param).length == 0`. I think it only works on the struct attributes, not on the fields attributes. Getting the UDAs from inside a symbol must be done via a recursive procedure in the same manner one would identify the aforementioned symbol i.e. you have to go through the fields looking for UDAs *then* use getUDAs. This is because UDAs cannot convey information without their context, so the trait doesn't look recursively.
Re: How to get instance member value from getSymbolsByUDA
On Saturday, 26 February 2022 at 10:39:18 UTC, Remi Thebault wrote: Hi all, I'm trying to establish a REST API by using the type system (used in both client and server code). [...] https://dlang.org/phobos/std_traits.html#getUDAs
Re: stripping binaries from LDC2
On Monday, 7 February 2022 at 14:20:31 UTC, Arjan wrote: On Monday, 7 February 2022 at 13:14:19 UTC, max haughton wrote: On Monday, 7 February 2022 at 12:16:53 UTC, Arjan wrote: In c++ our release builds are build `-O2 -g` and the resulting binaries are stripped with GNU/strip. Is this also possible with LDC2 generated binaries for D code? So build D code with `-O2 -g` and then strip the resulting binary? Why build with debug info if you're going to strip it anyway? The stripped release binaries are going to the client, when a problem occurs get a core dump, using the core dump + the original binary / symbol gives full debug info off site. It is common practice. Then yes, you can do that. D works in basically exactly the same way C++ does in this regard.
Re: stripping binaries from LDC2
On Monday, 7 February 2022 at 12:16:53 UTC, Arjan wrote: In c++ our release builds are build `-O2 -g` and the resulting binaries are stripped with GNU/strip. Is this also possible with LDC2 generated binaries for D code? So build D code with `-O2 -g` and then strip the resulting binary? Why build with debug info if you're going to strip it anyway?
Re: gdc or ldc for faster programs?
On Saturday, 29 January 2022 at 18:28:06 UTC, Ali Çehreli wrote: On 1/29/22 10:04, Salih Dincer wrote: > Could you also try the following code with the same configurations? The program you posted with 2 million random values: ldc 1.9 seconds gdc 2.3 seconds dmd 2.8 seconds I understand such short tests are not definitive but to have a rough idea between two programs, the last version of my program that used sprintf with 2 million numbers takes less time: ldc 0.4 seconds gdc 0.5 seconds dmd 0.5 seconds (And now we know gdc can go about 7% faster with additional command line switches.) Ali You need to be compiling with PGO to test the compilers optimizer to the maximum. Without PGO they have to assume a fairly conservative flow through the code which means things like inlining and register allocation are effectively flying blind.
Re: Is there a way to make a function parameter accept only values that can be checked at compile time?
On Wednesday, 29 December 2021 at 16:51:47 UTC, rempas wrote:
On Wednesday, 29 December 2021 at 16:27:22 UTC, max haughton
wrote:
Inlining + constant propagation. Fancier iterations on those
exist too but 90% of the speedup will come from those since
for it to matter they likely would've been used in first place.
Sounds like black magic? So If I write this:
```
int add(int num, int num2) { return num1 + num2; }
void main() {
int number = add(10, 20);
}
```
The parameters are literals so will D translate this to:
```
int add(int num, int num2) { return num1 + num2; } // Normal one
int add_temp_func() { return 30; } // Created for the function
call in main. No `add` instruction
void main() {
int number = add(10, 20); // Will actually create and call
"add_temp_func"
}
```
Or even better, this:
```
int add(int num, int num2) { return num1 + num2; }
void main() {
int number = add(10, 20); // What we will type and it will
get replaced with the following line
int number = 30; // So it calculates the result at compile
times and doesn't even do a function call
}
```
Is this what D can do? This is what I'm talking about when
saying been able to use values at compile time.
This is handled by the compiler backend. The simplest way it can
do this kind of optimization is by "inlining" the function.
This is done by transplanting the function body into the place
it's used. At this point the compiler simply sees "= 30 + 30"
which it can trivially turn into "= 60" through something called
constant-folding.
The compiler can create new function bodies (like the temp one
you introduce above) but this is a much more niche optimization.
They favour inlining much more aggressively.
I'm tempted to do a YouTube video of a D program being compiled
all the way down the machine code, to show what the compiler does
for you.
Re: Is there a way to make a function parameter accept only values that can be checked at compile time?
On Wednesday, 29 December 2021 at 15:53:38 UTC, rempas wrote: On Wednesday, 29 December 2021 at 11:09:04 UTC, max haughton wrote: If the value is known at compile time the compiler can pretty easily do that for you unless you're really unlucky. How is this even possible? Inlining + constant propagation. Fancier iterations on those exist too but 90% of the speedup will come from those since for it to matter they likely would've been used in first place.
Re: Is there a way to make a function parameter accept only values that can be checked at compile time?
On Wednesday, 29 December 2021 at 08:56:47 UTC, rempas wrote: On Tuesday, 28 December 2021 at 22:26:33 UTC, max haughton wrote: Why do you need this? What's wrong with a normal branch in this case. Runtime performance. I want the value to get checked at compile time and use "static if" with it If the value is known at compile time the compiler can pretty easily do that for you unless you're really unlucky.
Re: Is there a way to make a function parameter accept only values that can be checked at compile time?
On Tuesday, 28 December 2021 at 21:19:29 UTC, rempas wrote:
I would like to know if that's possible. Actually I would like
to do something like the following:
```
extern (C) void main() {
void print_num(int num, comp_time_type int mul) {
static if (is(mul == ten)) {
printf("%d\n", num * 10);
} else static if (is(mul == three)) {
printf("%d\n", num * 3);
} else {
printf("%d\n", num);
}
}
int multi = 211;
print_num(10, 3); // Ok, accept this
print_num(10, multi); // Error, do not accept this
}
```
So I want to have "mul" only accept values that can be
calculate at compile time so I can use it with things like
"static if". Is this possible?
Why do you need this? What's wrong with a normal branch in this
case.
Re: How to print unicode characters (no library)?
On Sunday, 26 December 2021 at 21:22:42 UTC, Adam Ruppe wrote: On Sunday, 26 December 2021 at 20:50:39 UTC, rempas wrote: [...] write just transfers a sequence of bytes. It doesn't know nor care what they represent - that's for the receiving end to figure out. [...] You are mistaken. There's several exceptions, utf-16 can come in pairs, and even utf-32 has multiple "characters" that combine onto one thing on screen. I prefer to think of a string as a little virtual machine that can be run to produce output rather than actually being "characters". Even with plain ascii, consider the backspace "character" - it is more an instruction to go back than it is a thing that is displayed on its own. [...] This is because the *receiving program* treats them as utf-8 and runs it accordingly. Not all terminals will necessarily do this, and programs you pipe to can do it very differently. [...] The [w|d|]string.length function returns the number of elements in there, which is bytes for string, 16 bit elements for wstring (so bytes / 2), or 32 bit elements for dstring (so bytes / 4). This is not necessarily related to the number of characters displayed. [...] yes, it just passes bytes through. It doesn't know they are supposed to be characters... I think that mental model is pretty good actually. Maybe a more specific idea exists, but this virtual machine concept does actually explain to the new programmer to expect dragons - or at least that the days of plain ASCII are long gone (and never happened, e.g. backspace as you say)
Re: First time using Parallel
On Sunday, 26 December 2021 at 06:10:03 UTC, Era Scarecrow wrote:
This is curious. I was up for trying to parallelize my code,
specifically having a block of code calculate some polynomials
(*Related to Reed Solomon stuff*). So I cracked open
std.parallel and looked over how I would manage this all.
To my surprise I found ParallelForEach, which gives the
example of:
```d
foreach(value; taskPool.parallel(range) ){code}
```
Since my code doesn't require any memory management, shared
resources or race conditions (*other than stdout*), I plugged
in an iota and gave it a go. To my amazement no compiling
issues, and all my cores are in heavy use and it's outputting
results!
Now said results are out of order (*and early results are
garbage from stdout*), but I'd included a bitwidth comment so
sorting should be easy.
```d
0x3,/*7*/
0x11, /*9*/
0x9,/*10*/
0x1D, /*8*/
0x5,/*11*/
0x3,/*15*/
0x53, /*12*/
0x1B, /*13*/
0x2B, /*14*/
```
etc etc.
Previously years ago I remember having to make a struct and
then having to pass a function and a bunch of stuff from within
the struct, often breaking and being hard to get to even work
so I didn't hardly touch this stuff. This is making outputting
data MUCH faster and so easily; Well at least on a beefy
computer and not just some chromebook I'm programming on so it
can all be on the go.
So I suppose, is there anything I need to know? About shared
resources or how to wait until all threads are done?
Parallel programming is one of the deepest rabbit holes you can
actually get to use in practice. Your question at the moment
doesn't really have much context to it so it's difficult to
suggest where you should go directly.
I would start by removing the use of stdout in your loop kernel -
I'm not familiar with what you are calculating, but if you can
basically have the (parallel) loop operate from (say) one array
directly into another then you can get extremely good parallel
scaling with almost no effort.
Not using in the actual loop should make the code faster even
without threads because having a function call in the hot code
will mean compilers optimizer will give up on certain
transformations - i.e. do all the work as compactly as possible
then output the data in one step at the end.
Re: Is DMD still not inlining "inline asm"?
On Friday, 12 November 2021 at 11:32:16 UTC, rempas wrote: On Thursday, 11 November 2021 at 19:22:33 UTC, max haughton wrote: There's an attribute to tell it the function is safe to inline. And can't you do that with inline asm? Not always. The attribute is intended for naked asm since inlining could be completely wrong in this case.
Re: Is DMD still not inlining "inline asm"?
On Thursday, 11 November 2021 at 17:29:33 UTC, rempas wrote: On Thursday, 11 November 2021 at 13:22:15 UTC, Basile B. wrote: Yes, this is still the case. A particularity of DMD inliner is that it does its job in the front-end, so inlining asm is totally impossible. Then, even if inlining was done in the backend inlining of asm would not be guaranteed because the byte code is generated at a very late stag, which causes problem with the registry allocator, the preservation of the stack, etc. For example ldc2 does not inline a trival asm func https://godbolt.org/z/1W6r693Tq. As for now, I know no compiler that can do that. What? Not even GCC or Clang? Someone said that LDC2 does it with two ways in the thread I linked There's an attribute to tell it the function is safe to inline.
Re: Better debugging?
On Sunday, 3 October 2021 at 22:21:45 UTC, Tim wrote: Hi all, I am currently using GDB within VScode with the -gc DMD2 compiler switch and my debugging is not amazing. Whenever I inspect a struct/object it just shows me the pointer rather than the object information and strings come up as a gross array of the characters. Does anybody happen to know whether LDB is better or how I can have a nicer debug environment? Thanks in advance Might be something for Iain to weigh in one when it comes to GDC specifically but the non-dmd compilers generate better debug info.
Re: avoid codegen pass
On Saturday, 2 October 2021 at 18:05:06 UTC, Dennis wrote: On Saturday, 2 October 2021 at 16:57:48 UTC, max haughton wrote: Do you have optimizations turned on? i.e. are you compiling with -O by accident? Not needed, it's declared: ```D pragma(inline, true) @property _timezone() @safe const pure nothrow @nogc ``` DMD does inlining in the frontend, and without the `-inline` flag it still inlines functions when requested by `pragma(inline, true)`. That's why you see it logged even without codegen or `-inline`. That's not what causes the long compile time though, `dmd -v` logs passes before doing them, not after, so it's the semantic3 before the inline pass that's taking all the time. I was aware (and am not a fan of) inlining in the frontend, but didn't look at the Phobos code. Honestly dmd shouldn't have an optimizer IMO, it's not fit for purpose anymore, if you want optimizations use GDC or LDC. Inlining doesn't even respect the semantics of the language IIRC
Re: avoid codegen pass
On Saturday, 2 October 2021 at 14:44:16 UTC, Padlev wrote: On Saturday, 2 October 2021 at 13:26:27 UTC, Adam D Ruppe wrote: On Saturday, 2 October 2021 at 13:24:19 UTC, Padlev wrote: -o- how to run only semantic and avoid codegen to have a quicker run? -o- does skip codegen already so why this? it seems to take a long time from the last import xxx semantic3 xxx to reach this inline scan grasshopper inlined std.datetime.systime.SysTime._timezone => std.datetime.systime.SysTime.opAssign!().opAssign inlined std.datetime.systime.SysTime._timezone => std.datetime.systime.SysTime.opAssign!().opAssign can not be avoided? i need only till semantic, no care in inline et cetera Do you have optimizations turned on? i.e. are you compiling with -O by accident?
Re: How use ldc pragmas?
On Friday, 1 October 2021 at 19:23:06 UTC, james.p.leblanc wrote: D-ers, After experimenting with ldc's autovectorization of avx code, it appears there may be counter-intuitiveness to the autovectorization (especially for complex numbers). (My comment may be wrong, so any corrections are quite welcome). [...] Is it sqrt.32 or sqrt.f32? Try the latter, LLVM docs seem to agree.
Re: Development of the foundation of a programming language
On Tuesday, 14 September 2021 at 05:06:01 UTC, Elronnd wrote: On Tuesday, 14 September 2021 at 03:24:45 UTC, max haughton wrote: On Tuesday, 14 September 2021 at 03:19:46 UTC, Elronnd wrote: On Monday, 13 September 2021 at 11:40:10 UTC, max haughton wrote: The dragon book barely mentions SSA for example In fairness, dmd doesn't use SSA either That's not a good thing. No, but if the OP's goal is to contribute to dmd, learning SSA wouldn't be very helpful beyond a general acclimation to compiler arcana. (Unless they wish to add SSA to dmd--a worthy goal, but perhaps not the best thing to start out with.) The backend is not where our efforts should be going. There is way too much work that needs doing above it to motivate working on the backend. The backend's design for the most part is extremely simple just buried under 40 years of code. Besides, there's more to life than dmd, everything else is SSA at least some point in compilation (i.e. GCC isn't SSA all the way down but GIMPLE is).
Re: object.d: Error: module object is in file 'object.d' which cannot be read
On Tuesday, 14 September 2021 at 03:31:17 UTC, Kenneth Dallmann wrote: On Sunday, 27 March 2011 at 10:28:00 UTC, Ishan Thilina wrote: [...] I had the exact same problem, very frustrating. I believe I solved the issue, it was a simple error. When you are installing D, on Windows, it asks you to download MSVC, if it isn't already present. Basically you are missing some form of dependency, which could be different based on which compiler you are using. On my Windows machine I fixed the issue by downloading the Microsoft Visual IDE and then from there I hit a button within that application to download the C compiler, MSVC. After I did that I reinstalled D and it works now. Thank you Please try to avoid resurrecting very old threads if you can.
Re: Development of the foundation of a programming language
On Tuesday, 14 September 2021 at 03:19:46 UTC, Elronnd wrote: On Monday, 13 September 2021 at 11:40:10 UTC, max haughton wrote: The dragon book barely mentions SSA for example In fairness, dmd doesn't use SSA either That's not a good thing.
Re: Development of the foundation of a programming language
On Monday, 13 September 2021 at 04:08:53 UTC, rikki cattermole wrote: On 13/09/2021 3:21 PM, leikang wrote: Are there any recommended books or videos to learn about the principles of compilation? What else should I learn besides the principles of compilation? The classic book on compilers that Walter recommends is the dragon book. https://smile.amazon.com/Compilers-Principles-Techniques-Tools-2nd-dp-0321486811/dp/0321486811 (D Language Foundation is a charity Amazon Smile recognizes). The dragon book is really really showing it's age these days so I would highly recommend getting a copy but not reading it fully. "Engineering a compiler" is much better pedagogically. The dragon book barely mentions SSA for example, although the sections they did properly bother to update towards the end are quite interesting. "Crafting interpreters" is quite good, I recommend it for learning how to actually write a parser without getting bogged down in totally useless theory. Stephen Muchnick's "Advanced Compiler Design and Implementation" is *the* bible for optimizations, but uses a very weird unimplemented language so be careful for bugs. "Optimizing Compilers for Modern Architectures: A Dependence-based Approach" is the only book I'm aware of that actually covers even the beginnings of modern loop optimizations thoroughly. Even this however is still somewhat set back by it being written 20 years ago, the principles are the same but the instinct is not i.e. memory latency is worse, ILP is much better. What all of these books have in common, by the way, is that they were all written at a time when it was assumed that x86 would go the way of the dodo. So there is a somewhat significant deviation from "theory" and practice in some parts as (say) x86 SIMD is quite different from how the authors of the aforementioned book expected the world to go.
Re: Development of the foundation of a programming language
On Monday, 13 September 2021 at 00:53:06 UTC, leikang wrote: I want to contribute to the development of the dlang language, but I feel that I am insufficient, so I want to ask the big guys, can I participate in the development of the Dlang language after learning the principles of compilation? Yes. If you make a PR it should be and will be judged based on the code and only the code, not where or who it came from.
Re: do I incur a penality on compile time if I explicitly declare default behavior ?
On Monday, 21 June 2021 at 04:12:55 UTC, someone wrote:
I mean, coding as following:
```d
int intWhatever = 0; /// default being zero anyway
foreach (classComputer objComputer, objComputers) { ... } ///
explicitly declaring the type instead of letting the compiler
to figure it out
struc Whatever {
public doSomething() { ... } /// explicitly declaring scopes
matching the default ones
}
string[] strWhatever;
if (strWhatever.length > cast(size_t) 1) { ... } /// explicitly
casting for proper types although not required to at all
```
... and the likes; or, besides unnecessary typing, are there
any cons that I should be aware of while using DMD ?
Short answer: No
Longer answer: Still no but it does exercise different code in
the compiler which you could measure if you were mad.
Re: Can't I allocate at descontructor?
On Friday, 5 March 2021 at 20:13:54 UTC, Jack wrote: On Friday, 5 March 2021 at 20:10:39 UTC, Max Haughton wrote: On Friday, 5 March 2021 at 20:03:58 UTC, Jack wrote: On Friday, 5 March 2021 at 09:23:29 UTC, Mike Parker wrote: On Friday, 5 March 2021 at 05:31:38 UTC, Jack wrote: [...] https://dlang.org/blog/2021/03/04/symphony-of-destruction-structs-classes-and-the-gc-part-one/ thanks for such good article. So if the object was allocated on heap, there's no guarantee that the object's destrutor will be called at all? do destrutor allocate at stack are guarantee to be run? Destructors of structs on the stack will always run deterministically. But the ones heap may never run at all, is that right? You can't rely on the garbage collector for deterministic destruction, no.
Re: Can't I allocate at descontructor?
On Friday, 5 March 2021 at 20:03:58 UTC, Jack wrote: On Friday, 5 March 2021 at 09:23:29 UTC, Mike Parker wrote: On Friday, 5 March 2021 at 05:31:38 UTC, Jack wrote: The following code returns a memory error. I did notice it did happens whenever I did a memory allocation. Is this not possible in the descontrutor? if so, why? https://dlang.org/blog/2021/03/04/symphony-of-destruction-structs-classes-and-the-gc-part-one/ thanks for such good article. So if the object was allocated on heap, there's no guarantee that the object's destrutor will be called at all? do destrutor allocate at stack are guarantee to be run? Destructors of structs on the stack will always run deterministically.
Re: dub support for Mac M1?
On Thursday, 4 March 2021 at 22:30:17 UTC, tastyminerals wrote: I got a company MacBook with M1 chip and gradually migrate all the stuff from Linux machine. I got precompiled ldc binary installed without any problem now is the time for dub since I have couple of D projects I use at work and all of them use dub. [...] If someone with an M1 wants to get it working the patch is appreciated but I (for one) don't have one so I can't.
Re: How can I make this work?
On Sunday, 28 February 2021 at 09:18:56 UTC, Rumbu wrote: On Sunday, 28 February 2021 at 09:04:49 UTC, Rumbu wrote: On Sunday, 28 February 2021 at 07:05:27 UTC, Jack wrote: I'm using a windows callback function where the user-defined value is passed thought a LPARAM argument type. I'd like to pass my D array then access it from that callback function. How is the casting from LPARAM to my type array done in that case? for example, I need something like this to work: int[] arr = [1, 2, 3]; long l = cast(long) cast(void*) arr.ptr; int[] a = cast(int[]) cast(void*) l; LPARAM is not long on 32 bits, it's int. Use LPARAM instead of long. And you are passing only the address of the first element this way, loosing the array/slice length. This should work, but keep in mind that you have no warranty that the array stays in memory and it is not garbage collected. int[] arr = [1, 2, 3]; LPARAM l = cast(LPARAM)cast(void*) int[] a = *cast(int[]*)(cast(void*)l); Do the windows APIs expect the length in memory rather than as a parameter? Also Rumbu can you check your email - I may have emailed you on an old email address by accident, but it's about the blog and it will be from mh240@...
Re: Problem Computing Dot Product with mir
On Monday, 22 February 2021 at 07:14:26 UTC, 9il wrote: On Sunday, 21 February 2021 at 16:18:05 UTC, Kyle Ingraham wrote: I am trying to convert sRGB pixel values to XYZ with mir using the following guide: http://www.brucelindbloom.com/index.html?Eqn_RGB_XYZ_Matrix.html [...] mir-glas is deprecated experimental project. It is worth use mir-blas or lubeck instead. There is also naming issue. In the classic BLAS naming dot refers a function that accept two 1D vectors. Deprecated as in formally dead or postponed?
Re: Mixed language projects (D and C++)
On Friday, 19 February 2021 at 10:18:28 UTC, Preetpal wrote: On Friday, 19 February 2021 at 10:01:36 UTC, Max Haughton wrote: On Friday, 19 February 2021 at 09:44:15 UTC, Preetpal wrote: I want to reuse existing C++ code in a new project that I am writing in D and I want to use D in an existing C++ code base (it is not large). I do not anticipate interop being an issue. [...] C++ interop is used every day. The LLVM D compiler, ldc, uses it to talk to LLVM efficiently. There are good resources on it on this very website I am looking for suggestions on what build system to use. I took a look at the LDC project but it looks they are writing their own CMake scripts in the repository itself to add support for D to CMake. I was hoping there might be something that others were using with out of box support for D. I would keep it simple and use the dub pregenerate step to run any old C++ build process then link as usual.
Re: Mixed language projects (D and C++)
On Friday, 19 February 2021 at 09:44:15 UTC, Preetpal wrote: I want to reuse existing C++ code in a new project that I am writing in D and I want to use D in an existing C++ code base (it is not large). I do not anticipate interop being an issue. [...] C++ interop is used every day. The LLVM D compiler, ldc, uses it to talk to LLVM efficiently. There are good resources on it on this very website
Re: Profiling
On Wednesday, 10 February 2021 at 13:31:09 UTC, Guillaume Piolat wrote: On Wednesday, 10 February 2021 at 11:52:51 UTC, JG wrote: [...] Here is what I use for sampling profiler: (On Windows) Build with LDC, x86_64, with dub -b release-debug in order to have debug info. Run your program into: - Intel Amplifier (free with System Studio) - AMD CodeXL (more lightweight, and very good) - Very Sleepy (On Mac) Build with dub -b release-debug Run your program with Instruments.app which you can find in your Xcode.app (On Linux) I don't know. Though most of the time to validate the optimization a comparison program that runs two siilar programs and computer the speed difference can be needed. All Intel tools I'm aware of support (and are free on) Linux. Also, it's just called vTune now and it's been put under the "oneAPI" banner.
Re: GC.addRange in pure function
On Tuesday, 9 February 2021 at 19:53:27 UTC, Temtaime wrote: On Sunday, 7 February 2021 at 14:13:18 UTC, vitamin wrote: Why using 'new' is allowed in pure functions but calling GC.addRange or GC.removeRange isn't allowed? pure is broken. Just don't [use it] [Citation needed]
Re: My simple internet client made in Dlang.
On Thursday, 4 February 2021 at 20:54:15 UTC, Ali Çehreli wrote: On 2/3/21 8:44 AM, Marcone wrote: [...] I think the following would be improvements: >[...] I don't know the protocol but obviously 8192 must be sufficient. [...] Less calls to std.conv can also mean less surface area for exceptions to throw from
Re: Can change vtbl record at runtime ?
On Wednesday, 3 February 2021 at 05:30:37 UTC, Виталий Фадеев
wrote:
Reason:
Reuse component,
bind custom callback without creating new class.
Concept example:
class SaveFilePopup
{
void onSuccess() { /* default operations */ }
}
auto saveFile = new SaveFilePopup();
saveFile.onSuccess = { /* New operations */ }
Delegate:
may be... but, for speed reason, is possible to set the
default code at compile-time ?
class X
{
void delegate() onSuccess = { /* default code */ };
}
Context:
GUI, components, callbacks
Possible to change the vtbl record at runtime ?
Has functional for update vtbl records ?
Do you mean "Can I set onSuccess" at runtime? The virtual tables
are relied upon by the compiler so I wouldn't play with them.
Re: Refactoring tools
On Wednesday, 3 February 2021 at 07:20:06 UTC, Imperatorn wrote: As the title says: 1. Are there any (automated) refactoring tools for D? 2. If not, why? (Is D still too small?) D is also designed to not need as much refactoring as other languages, so even for our size there isn't a huge amount of demand. Previously the actual implementation would've been hard but now we have the compiler working fairly well as a library it's just a question of profitability (be that money, fun, or social kudos).
Re: Minimize GC memory footprint
On Saturday, 30 January 2021 at 16:42:35 UTC, frame wrote: Is there a way to force the GC to re-use memory in already existing pools? I set maxPoolSize:1 to gain pools that can be quicker released after there no longer in use. This already reduces memory usage to 1:3. Sadly the application creates multiple pools that are not necessary in my POV - just fragmented temporary slice data like from format(). What can I do to optimize? I can't tell you much about the inner workings of the GC, but maybe take a look at experimental.allocator and see if anything there can help you (specifically that you understand your program better than the GC)
Re: Why many programmers don't like GC?
On Friday, 15 January 2021 at 21:49:07 UTC, H. S. Teoh wrote: On Fri, Jan 15, 2021 at 09:04:13PM +, welkam via Digitalmars-d-learn wrote: [...] As the joke goes, "you can write assembly code in any language". :-D If you code in a sloppy way, it doesn't matter what language you write in, your program will still suck. No amount of compiler magic will be able to help you. The solution is not to blame this or that, it's to learn how to use what the language offers you effectively. [...] And with D, it's actually easy to do this, because D gives you tools like slices and by-value structs. Having slices backed by the GC is actually a very powerful combination that people seem to overlook: it means you can freely refer to data by slicing the buffer. Strings being slices, as opposed to null-terminated, is a big part of this. In C, you cannot assume anything about how the memory of a buffer is managed (unless you allocated it yourself); as a result, in typical C code strcpy's, strdup's are everywhere. Want a substring? You can't null-terminate the parent string without affecting code that still depends on it; solution? strdup. Want to store a string in some persistent data structure? You can't be sure the pointer will still be valid (or that the contents pointed to won't change); solution? strdup, or strcpy. Want to parse a string into words? Either you modify it in-place (e.g. strtok), invalidating any other references to it, or you have to make new allocations of every segment. GC or no GC, this will not lead to a good place, performance-wise. I could not have written fastcsv if I had to work under the constraints of C's null-terminated strings under manual memory management. Well, I *could*, but it would have taken 10x the amount of effort, and the API would be 5x uglier due to the memory management paraphrenalia required to do this correctly in C. And to support lazy range-based iteration would require a whole new set of API's in C just for that purpose. In D, I can simply take slices of the input -- eliminating a whole bunch of copying. And backed by the GC -- so the code doesn't have to be cluttered with memory management paraphrenalia, but can have a simple, easy-to-use API compatible across a large range of use cases. Lazy iteration comes "for free", no need to introduce an entire new API. It's a win-win. All that's really needed is for people to be willing to drop their C/C++/Java coding habits, and write D the way it's meant to be written: with preference for stack-allocated structs and by-value semantics, using class objects only for more persistent data. Use slices for maximum buffer reuse, avoid needless copying. Use compile-time introspection to generate code statically where possible instead of needlessly recomputing stuff at runtime. Don't fear the GC; embrace it and use it to your advantage. If it becomes a bottleneck, refactor that part of the code. No need to rewrite the entire project the painful way; most of the time GC performance issues are localised and have relatively simple fixes. T I agree that the GC is useful, but it is a serious hindrance on the language not having an alternative other than really bad smart pointers (well written but hard to know their overhead) and malloc and free. I don't mind using the GC for my own stuff, but it's too difficult to avoid it at the moment for the times when it gets in the way. I think the way forward is some robust move semantics and analysis like Rust. I suppose ideally we would have some kind of hidden ARC behind the scenes but I don't know how that would play with structs. One more cynical argument for having a modern alternative is that it's a huge hindrance on the languages "cool"Ness in the next generation of programmers and awareness is everything (most people won't have heard of D)
Re: DConf talk : Exceptions will disappear in the future?
On Tuesday, 5 January 2021 at 19:42:40 UTC, Ola Fosheim Grøstad wrote: On Tuesday, 5 January 2021 at 18:23:25 UTC, sighoya wrote: No error handling model was the HIT and will never be, therefore I would recommend to leave things as they are and to develop alternatives and not to replace existing ones. Or implement C++ exceptions, so that D can catch C++ exceptions transparently (ldc catch clang++ exceptions and gdc catch g++ exceptions). Walter already got quite a lot of the way there on that. There are some PRs on dmd about it but it's not in a state worth documenting yet if it's still there (the tests are still there so I assume it still works)
Re: Get the code of any D-entity as string?
On Friday, 25 December 2020 at 21:25:40 UTC, sighoya wrote: I've read a bit in Dlang traits. It now has the ability to retrieve all method signatures of an overload set. Big plus from me. Is generally possible to get the declaration of a type/module/value as string in traits? I didn't have any concrete use case for it, but it would essentially allow us to reflect over any code (we may have to respect privacy, of course). On top of that, people could write their own token or ast frameworks as library solutions. Further, most of the trait functionality given in the trait library could be simply implemented as a library solution. I don't know D enough to be sure it isn't yet possible. Theoretically, we could read all files in a source folder, but I want also to read declarations from types outside my source folders, e.g. from those located in dyn libs. Not possible although implementing as a __trait would be about 15 lines I think. I think read only AST access in some form would actually be quite nice, if not for dmd's AST being fuckugly (the hierarchy is fine but it's more gcc than clang)
Re: If statements and unused template parameters in Phobos documentation
On Sunday, 20 December 2020 at 13:51:08 UTC, Rekel wrote: I found a lot of the Phobos documentation to contain template arguments and if statements that made no sense to me, for example: ``` uint readf(alias format, A...) ( auto ref A args ) if (isSomeString!(typeof(format))); uint readf(A...) ( scope const(char)[] format, auto ref A args ); ``` https://dlang.org/library/std/stdio/file.readf.html From stdio.readf & stdio.File.readf. I'm assuming this is some kind of template, but often it seems there are more parameters in the first '()' part than are ever given. Am I missing something? Additionally, what is that if statement for? It precedes nothing. The if is a template constraint.
Re: low-latency GC
On Sunday, 6 December 2020 at 11:35:17 UTC, Ola Fosheim Grostad wrote: On Sunday, 6 December 2020 at 11:27:39 UTC, Max Haughton wrote: [...] No, unique doesnt need indirection, neither does ARC, we put the ref count at a negative offset. shared_ptr is a fat pointer with the ref count as a separate object to support existing C libraries, and make weak_ptr easy to implement. But no need for indirection. [...] I think you need a new IR, but it does not have to be used for code gen, it can point back to the ast nodes that represent ARC pointer assignments. One could probably translate the one used in Rust, even. https://gcc.godbolt.org/z/bnbMeY
Re: low-latency GC
On Sunday, 6 December 2020 at 11:07:50 UTC, Ola Fosheim Grostad wrote: On Sunday, 6 December 2020 at 10:44:39 UTC, Max Haughton wrote: On Sunday, 6 December 2020 at 05:29:37 UTC, Ola Fosheim Grostad wrote: It has to be either some kind of heavily customisable small GC (i.e. with our resources the GC cannot please everyone), or arc. The GC as it is just hurts the language. Realistically, we probably need some kind of working group or at least serious discussion to really narrow down where to go in the future. The GC as it is now must go, we need borrowing to work with more than just pointers, etc. The issue is that it can't just be done incrementally, it needs to be specified beforehand. ARC can be done incrementally, we can do it as a library first and use a modified version existing GC for detecting failed borrows at runtime during testing. But all libraries that use owning pointers need ownership to be made explicit. A static borrow checker an ARC optimizer needs a high level IR though. A lot of work though. ARC with a library will have overhead unless the compiler/ABI is changed e.g. unique_ptr in C++ has an indirection. The AST effectively is a high-level IR. Not a good one, but good enough. The system Walter has built shows the means are there in the compiler already. As things are at the moment, the annotations we have for pointers like scope go a long way, but the language doesn't deal with things like borrowing structs (and the contents of structs i.e. making a safe vector) properly yet. That is what needs thinking about.
Re: low-latency GC
On Sunday, 6 December 2020 at 05:29:37 UTC, Ola Fosheim Grostad wrote: On Sunday, 6 December 2020 at 05:16:26 UTC, Bruce Carneal wrote: How difficult would it be to add a, selectable, low-latency GC to dlang? Is it closer to "we cant get there from here" or "no big deal if you already have the low-latency GC in hand"? I've heard Walter mention performance issues (write barriers IIRC). I'm also interested in the GC-flavor performance trade offs but here I'm just asking about feasibility. The only reasonable option for D is single threaded GC or ARC. It has to be either some kind of heavily customisable small GC (i.e. with our resources the GC cannot please everyone), or arc. The GC as it is just hurts the language. Realistically, we probably need some kind of working group or at least serious discussion to really narrow down where to go in the future. The GC as it is now must go, we need borrowing to work with more than just pointers, etc. The issue is that it can't just be done incrementally, it needs to be specified beforehand.
Re: Doubts about the performance of array concatenation
On Wednesday, 2 December 2020 at 00:08:55 UTC, ddcovery wrote: On Tuesday, 1 December 2020 at 23:43:31 UTC, Max Haughton wrote: On Tuesday, 1 December 2020 at 22:49:55 UTC, ddcovery wrote: Yesterday I really shocked when, comparing one algorithm written in javascript and the equivalent in D, javascript performed better!!! [...] Use ldc, rdmd can invoke it for you. DMD's optimizer is not even close to as advanced as a modern JavaScript engine's - that's why we use it for fast build times instead of performance. Impressive performance increase: $ ldc2 -O -release --run sorted.d # D 1.0M: 810 ms 1.5M: 1324 ms 3.0M: 2783 ms 6.0M: 5727 ms Thanks Max I've written a github issue on your repository with flags to get the most out of LLVM.
Re: Dude about ~ array concatenation performance
On Tuesday, 1 December 2020 at 22:49:55 UTC, ddcovery wrote: Yesterday I really shocked when, comparing one algorithm written in javascript and the equivalent in D, javascript performed better!!! [...] Use ldc, rdmd can invoke it for you. DMD's optimizer is not even close to as advanced as a modern JavaScript engine's - that's why we use it for fast build times instead of performance.
Re: How to unit-test a phobos module?
On Wednesday, 25 November 2020 at 21:36:36 UTC, Q. Schroll wrote: On Wednesday, 25 November 2020 at 21:16:15 UTC, Steven Schveighoffer wrote: I typically do: make -f posix.mak std/.test -Steve For some reason, [1] says `make.exe` would be installed by the DMD installer, but I found none. It explicitly says not to use GNU make. (I'm on Windows.) [1] https://wiki.dlang.org/Building_under_Windows The digital mars make is actually distributed with the c compiler. Developing on Windows is such a complete pain e.g. setting it up so it can find the linker and cl. For that reason I currently just do all dmd/phobos/druntime hacking inside WSL because that way I can just press build (dmd has build.d which is cross-platform but druntime and phobos both aren't fun to build on windows unless you've done it recently)
Re: How to construct a tree data structure with differently static nodes types
On Monday, 23 November 2020 at 01:20:04 UTC, data pulverizer
wrote:
Hi all,
I am trying to construct a tree data structure composed of
differently (statically) typed nodes. The basic case is a
binary tree. So you have a node like:
```
struct Node(T)
{
T value;
Node* next;
Node* prev;
}
void main()
{
auto x = Node!(int)(2);
auto y = Node!(double)(3.2);
x.next = //gives error
}
```
Error: cannot implicitly convert expression & y of type
Node!double* to Node!int*
So implicity Node!(T) will produce an object with prev, and
next type Node!(T)*. But once I give them different types:
```
struct Node(T, P, N)
{
T value;
Node!(P...)* prev;
Node!(N...)* next;
}
```
I can no longer specify the types at all, they become
circularly referenced. Would appreciate the solution to this.
Many thanks.
If you want to keep things simple, use OOP (classes).
If you need to use structs, the "sumtype" may be just what you
need (it's a bit more lightweight than std.algebraic in the
standard library). If you want to implement this yourself then
you need to write something called a tagged union.
Re: Request our suggestio: better way to insert data from Array!string[string] into a database table
On Monday, 16 November 2020 at 17:44:08 UTC, Vino wrote: Hi All, Request your suggestion, we have a program which call's an api, the output of the api is parsed using json parser and the result is stored in an array(Array!string[string] data), then these stored result are inserted into MySQL table, for inserting the data into the table we use the below code, this code is a small code which just contains 2 data items (Type,Hostname) and we have similar api's which contains 15-20 data items, hence request your suggestion on is there any better way than the below code, using the below logic the foreach line is will run into multiple lines eg: [...] What are you looking to improve? Do you want to make the code prettier or faster? It doesn't look too bad to my eye although my personal style would be to unpack t and h inside the foreach loop.
Re: presence of function template prevents diagnostic
On Monday, 16 November 2020 at 17:03:32 UTC, Steven Schveighoffer wrote: On 11/14/20 5:44 PM, kdevel wrote: $ dmd -version=X -i foo $ ./foo void A.bar(int s) Is the latter behavior intended or a bug? That seems like a bug. It shouldn't be less ambiguous because you *added* an overload that can also handle it... -Steve It could be technically kosher because of template lookup but I'm not sure if the behaviour is actually specified in the standard. Probably should be a bug.
Re: Why was new(size_t s) { } deprecated in favor of an external allocator?
On Thursday, 15 October 2020 at 06:39:00 UTC, Patrick Schluter wrote: On Wednesday, 14 October 2020 at 20:32:51 UTC, Max Haughton wrote: On Wednesday, 14 October 2020 at 20:27:10 UTC, Jack wrote: What was the reasoning behind this decision? Andrei's std::allocator talk from a few years ago at cppcon covers this (amongst other things) Yes, and what did he say? You seriously don't expect people to search for a random talk from a random event from a random year? It's the first result when you search for "Andrei std::allocator"
Re: Why was new(size_t s) { } deprecated in favor of an external allocator?
On Wednesday, 14 October 2020 at 20:27:10 UTC, Jack wrote: What was the reasoning behind this decision? Andrei's std::allocator talk from a few years ago at cppcon covers this (amongst other things)
Re: Range format specifiers in other languages?
On Sunday, 11 October 2020 at 23:57:31 UTC, Ali Çehreli wrote:
I find D's %( and %) range format specifiers very useful:
import std.stdio;
import std.range;
void main() {
5.iota.writefln!"%(%s, %)"; // Prints 0, 1, 2, 3, 4
}
Are there similar features in other languages?
Thank you,
Ali
I think rust can do something similar with struct pretty
printing. The syntax has curly braces in it but I can't recall it
right now.
Possibly worth showing off (especially given that some people at
first don't even know the templated format string exists)
Re: Taking arguments by value or by reference
On Sunday, 4 October 2020 at 14:26:43 UTC, Anonymouse wrote: On Saturday, 3 October 2020 at 23:47:32 UTC, Max Haughton wrote: The guiding principle to your function parameters should be correctness - if I am passing a big struct around, if I want to take ownership of it I probably want to take it by value but if I want to modify it I should take it by reference (or by pointer but don't overcomplicate, notice in the previous example they lower to the same thing). If I just want to look at it, it should be taken by const ref if possible (D const isn't the same as C++ const, this may catch you out). Const-correctness is a rule to live by especially with an big unwieldy struct. I would avoid the new in for now, but I would go with const ref from what you've described so far. I mostly really only want a read-only view of the struct, and whether a copy was done or not is academic. However, profiling showed (what I interpret as) a lot of copying being done in release builds specifically. https://i.imgur.com/JJzh4Zc.jpg Naturally a situation where I need ref I'd use ref, and in the rare cases where it actually helps to have a mutable copy directly I take it mutable. But if I understand what you're saying, and ignoring --preview=in, you'd recommend I use const ref where I would otherwise use const? Is there some criteria I can go by when making this decision, or does it always reduce to looking at the disassembly? This is skill you only really hone with experience, but it's not too bad once you're used to it. For a big struct, I would just stick to expressing what you want it to *do* rather than how you want it to perform. If you want to take ownership you basically have to take by value, but if you (as you said) want a read only view definitely const ref. If I was reading your code, ref immediately tells me not to think about ownership and const ref immediately tells me you just want to look at the goods. One thing I haven't mentioned so far is that not all types have non-trivial semantics when it comes to passing them around by value, so if you are writing generic code it is often best to avoid these.
Re: Taking arguments by value or by reference
On Saturday, 3 October 2020 at 23:00:46 UTC, Anonymouse wrote: I'm passing structs around (collections of strings) whose .sizeof returns 432. The readme for 2.094.0 includes the following: This release reworks the meaning of in to properly support all those use cases. in parameters will now be passed by reference when optimal, [...] * Otherwise, if the type's size requires it, it will be passed by reference. Currently, types which are over twice the machine word size will be passed by reference, however this is controlled by the backend and can be changed based on the platform's ABI. However, I asked in #d a while ago and was told to always pass by value until it breaks, and only then resort to ref. [18:32:16] at what point should I start passing my structs by ref rather than by value? some are nested in others, so sizeofs range between 120 and 620UL [18:33:43] when you start getting stack overflows [18:39:09] so if I don't need ref for the references, there's no inherent merit to it unless I get in trouble without it? [18:39:20] pretty much [18:40:16] in many cases the copying is merely theoretical and doesn't actually happen when optimized I've so far just been using const parameters. What should I be using? Firstly, the new in semantics are very new and possibly subtly broken (take a look at the current thread in general). Secondly, as to the more specific question of how to pass a big struct around it may be helpful to look at this quick godbolt example (https://d.godbolt.org/z/nPvTWz). Pay attention to the instructions writing to stack memory (or not). A struct that big will be passed around on the stack, whether it gets copied or not depends on the semantics of the struct etc. The guiding principle to your function parameters should be correctness - if I am passing a big struct around, if I want to take ownership of it I probably want to take it by value but if I want to modify it I should take it by reference (or by pointer but don't overcomplicate, notice in the previous example they lower to the same thing). If I just want to look at it, it should be taken by const ref if possible (D const isn't the same as C++ const, this may catch you out). Const-correctness is a rule to live by especially with an big unwieldy struct. I would avoid the new in for now, but I would go with const ref from what you've described so far.
Re: Question about publishing a useful function I have written
On Tuesday, 14 July 2020 at 21:58:49 UTC, Cecil Ward wrote: I have written something which may or may not be novel and I’m wondering about how to distribute it to as many users as possible, hoping others will find it useful. What’s the best way to publish a D routine ? [...] GitHub is the best place to publish code. Does GDC actually use the optimization? I tried something like that before but I couldn't seem to get it to work properly.
Re: Passing iterators into functions
On Thursday, 25 June 2020 at 03:35:00 UTC, repr-man wrote:
I have the code:
int[5] a = [0, 1, 2, 3, 4];
int[5] b = [5, 6, 7, 8, 9];
auto x = chain(a[], b[]).chunks(5);
writeln(x);
It produces a range of slices as is expected: [[0, 1, 2, 3, 4],
[5, 6, 7, 8, 9]]
However, when I define a function as follows and pass in the
result of the chain iterator:
auto func(R)(R r, size_t width)
if(isRandomAccessRange!R)
{
return r.chunks(width);
}
void main()
{
int[5] a = [0, 1, 2, 3, 4];
int[5] b = [5, 6, 7, 8, 9];
auto x = func!(int[])(chain(a[], b[]), 5);
writeln(x);
}
It gives me an error along the lines of:
Error: func!(int[]).func(int[] r, ulong width) is not callable
using argument types (Result, int)
cannot pass argument chain(a[], b[]) of type Result to
parameter int[] r
I was hoping it would return the same result as the first
program.
This seems to have to do with the fact that all iterators
return their own unique type. Could someone help me understand
the reason behind this design and how to remedy my situation?
Chain returns a range not an int[]. You need to either convert
the range to an array via .array or allow the compiler to infer
the type of the parameter of func (You'll need to import
std.range to have the range interface available)
mhh
Re: dmd memory usage
On Monday, 18 November 2019 at 00:20:12 UTC, Steven Schveighoffer wrote: I'm fighting some out of memory problems using DMD and some super-template heavy code. I have ideas on how to improve the situation, but it involves redesigning a large portion of the design. I want to do it incrementally, but I need to see things improving. Is there a straightforward way to figure out how much memory the compiler uses during compilation? I though maybe /usr/bin/time, but I feel like I don't trust the output to be the true max resident size to be what I'm looking for (or that it's 100% accurate). Is there a sure-fire way to have DMD print it's footprint? -Steve Massif is good for this. ms_print will give you a graphical summary, and the data is human and machine readable. The only setback being that massif can make the execution slower however I can't give exact numbers but it can be terrible.
Re: Execute certain Tests?
On Saturday, 2 November 2019 at 17:27:14 UTC, Martin Brezel wrote: Is there a trick to execute only the test, defined in one file? Or the Tests of a certain Module? Or in general: How to avoid to execute all the tests, when running "dub test"? It doesn't has to be dub, though. Not by default, if you know the language well then you can use UDAs to write a fancy test runner in ten minutes, if not then use Attila's unit-threaded (or similar) Max
Re: On D's garbage collection
On Tuesday, 8 October 2019 at 16:28:51 UTC, Marcel wrote: I'm been thinking about using D in conjunction with C11 to develop a set of applications with hard real-time requirements. While initially the goal was to use C++ instead, it has become clear that D's introspection facilities will offer significant advantages. Unfortunately, the project will heavily rely on custom memory allocators written in C, so the presence of garbage collection in the language is a problem. While I'm aware that the nogc attribute exists, I haven't actually seen a way to apply it to a whole project. Is this possible? Do you want to write D code that just doesn't use the GC or the whole runtime? If the former then use @nogc at the entry point of your D code (This means that - say - main cannot call anything non-@nogc and therefore guarantees the program is @nogc), if the latter then use -betterC IMO, if the interface to your memory allocators is stable then just link with them and write the whole thing in D (Interfacing with C is a solved problem but C is just awful compared to the features you get for free in D)
Re: how to definition a non-const pointer that point a const var.
On Saturday, 24 August 2019 at 05:03:43 UTC, Jonathan M Davis wrote: On Friday, August 23, 2019 10:14:56 PM MDT lili via Digitalmars-d-learn wrote: Hi: In C we can definition const int *ncp_to_cv; or int * const cp_to_ncv; How to do this in D. D uses parens to restrict how much of the type is const. const int* - const pointer to const int const(int*) - const pointer to const int const(int)* - mutable pointer to const int Similarly, const(int*)* - mutable pointer to const pointer to const int const(int)** - mutable pointer to mutable pointer to const int D's const is transitive, so it's not possible to have a const pointer to a mutable type. - Jonathan M Davis As to const pointers to mutable types, it can be done in a library (Final in std.typecons). I don't know what the overhead is but I imagine it wraps it in a struct
Re: How should I sort a doubly linked list the D way?
On Tuesday, 13 August 2019 at 18:54:58 UTC, H. S. Teoh wrote: On Tue, Aug 13, 2019 at 11:28:35AM -0700, Ali Çehreli via Digitalmars-d-learn wrote: [...] Summary: Ditch the linked list and put the elements into an array. :) [...] +1. The linked list may have been faster 20 years ago, before the advent of modern CPUs with caching hierarchies and memory access predictors. These days, with CPU multi-level caches and memory access predictors, in-place arrays are often the best option for performance, up to a certain size. In general, avoid indirection where possible, in order to avoid defeating the memory access predictor and reduce the number of cache misses. T I saw a Bjarne Stroustrup talk where he benchmarked that the for n > 1, std::vector was a lot faster than a linked list for all supported operations. I don't know how clever the caching strategies are on a modern processor (Pointer chasing), but to my knowledge the only way of getting a cache efficient linked list would be to effectively have a very contiguous allocator (Which obviously defeats the purpose of using a list in the first place) Found it: https://www.youtube.com/watch?v=YQs6IC-vgmo
Re: Desktop app with vibe.d
On Monday, 12 August 2019 at 10:41:57 UTC, GreatSam4sure wrote: Pls I want to know if it is possible to build desktop app with vibe.d just like nodejs. I am not satisfy with the GUI of Dlang such as dlangui and gtkd. I don't think they have good styling capabilities like HTML and CSS. I will be happy if I can build an app in D with fanciful ui. I will also be happy if you know any other way to build a fanciful ui in D like adobe flex, javafx, etc. vibe.d is a backend framework so unless you ran it and had the user connect via a web browser I don't think so. Honestly, avoid web technology on the desktop like the plague. It's slow and memory hogging.
Re: Question about ubyte x overflow, any safe way?
On Sunday, 4 August 2019 at 18:22:30 UTC, matheus wrote: On Sunday, 4 August 2019 at 18:15:30 UTC, Max Haughton wrote: What do you want to do? If you just want to count to 255 then use a foreach This was just an example, what I'd like in this code is either: Get an error (exception) when overflow or even an warning (Only if "some" flag was active). If you want to prevent overflow you must either use BigInt or wrap ubyte in a struct that doesn't allow overflow Could you please elaborate about this struct wrapping? Do you mean manually check on change? Matheus. Std.experimental.checkedint maybe exactly what you are looking for
Re: Question about ubyte x overflow, any safe way?
On Sunday, 4 August 2019 at 18:12:48 UTC, matheus wrote:
Hi,
The snippet below will produce an "infinite loop" because
obviously "ubyte u" will overflow after 255:
import std.stdio;
void main(){
ubyte u = 250;
for(;u<256;++u){
writeln(u);
}
}
Question: Is there a way (Flag) to prevent this?
Matheus.
What do you want to do? If you just want to count to 255 then use
a foreach
If you want to prevent overflow you must either use BigInt or
wrap ubyte in a struct that doesn't allow overflow
Re: Calling / running / executing .d script from another .d script
On Sunday, 28 July 2019 at 12:56:12 UTC, BoQsc wrote: Right now, I'm thinking what is correct way to run another .d script from a .d script. Do you have any suggestions? You'd need to bring a compiler with you and then build it into a shared library (then dlopen it). To do this you'd need a clear API defined in the file to be compiled, so you can call it. If you want to use druntime in said file you need to use loadLibrary in core instead of dlopen
Re: Is betterC affect to compile time?
On Thursday, 25 July 2019 at 14:20:03 UTC, Ali Çehreli wrote: On 07/25/2019 05:46 AM, Oleg B wrote: On Thursday, 25 July 2019 at 12:34:15 UTC, rikki cattermole wrote: Those restrictions don't stop at runtime. It's vary sad. What reason for such restrictions? It's fundamental idea or temporary implementation? It looks like a bug to me. Ali If the spec is to be believed then it is. I filed a bugzilla, https://issues.dlang.org/show_bug.cgi?id=20086
Re: Is there a way to bypass the file and line into D assert function ?
On Friday, 19 July 2019 at 15:30:25 UTC, Newbie2019 wrote:
for example:
void ASSERT(string fmt, string file = __FILE_FULL_PATH__,
size_t line = __LINE__, T...) (bool c, scope T a) @nogc {
assert(c, string, file, line);
}
but i get this error:
error.d(39): Error: found file when expecting )
error.d(39): Error: found ) when expecting ; following statement
error.d(39): Deprecation: use { } for an empty statement, not ;
I want d to print the error message with some format
information, and show the right file and line for the original
location.
Is it doable ?
Isn't assert a template (file and line) rather than a plain
function call?
Worst comes to worst, you can provide your own _d_assert(?) and
override object.d then just call the C assert
Re: How to use std.windows.registry, there are no documentations.
On Thursday, 11 July 2019 at 08:53:35 UTC, BoQsc wrote: https://dlang.org/phobos/std_windows_registry.html https://github.com/dlang/phobos/blob/master/std/windows/registry.d Can someone provide some examples on how to: set, change, receive something from the Windows registry using Phobos std.windows.registry library? I didn't know that existed, but the source code is documented but not in the style that the doc generated recognizes as far as I can tell.
Re: Memory allocation failed in CT
Is this a 64 or 32 bit compiler? Also could you post the source code if possible? You could try "--DRT-gcopt=profile:1" druntime flag to see if the compiler is running out of memory for real
Re: Memory allocation failed in CT
On Tuesday, 9 July 2019 at 17:48:52 UTC, Andrey wrote: Hello, I have got a problem with compile-time calulations. I have some code generator that should create some long string of code during CT and after generation I mixin it. If I run it normally - in run time - then there is no error and I get expected output - string with size ~ 3.5 MB. If I run it in CT then I recieve an error: [...] I don't understand why... The only operation in my generator is string concatination: _result ~= "some code...". Are you using the -lowmem flag? This enables the GC during compilation i.e. you might be running out of memory (CTFE is not efficient with memory during evaluation)
Re: Why are immutable array literals heap allocated?
On Friday, 5 July 2019 at 16:25:10 UTC, Nick Treleaven wrote: On Thursday, 4 July 2019 at 11:06:36 UTC, Eugene Wissner wrote: static immutable arr = [1, 2]; You have to spell it out that the data is static. Yes, I was wondering why the compiler doesn't statically allocate it automatically as an optimization. LDC might be able to optimize it away but by default its heap allocated, I imagine for thread safety
Re: Transform a function's body into a string for mixing in
On Thursday, 20 June 2019 at 19:09:11 UTC, Emmanuelle wrote: Hello! Is there any trait or Phobos function for transforming a function/delegate/lambda/whatever's body into a string suitable for `mixin(...)`? For example: --- __traits(getBody, (int a, int b) => a + b); // returns "(int a, int b) => a + b" // or maybe just "a + b" --- If not, is there any way to do this _without_ using strings? They are very inconvenient and could hide errors. Thanks! We don't have anything AST-macro ish or a trait as described. The trait isn't impossible to implement but I could imagine it being a nightmare for compile times
Re: DIP 1016 and const ref parameters
On Wednesday, 19 June 2019 at 19:25:59 UTC, Jonathan M Davis wrote: On Wednesday, June 19, 2019 12:28:12 PM MDT XavierAP via Digitalmars-d-learn wrote: [...] The DIPs are here: https://github.com/dlang/DIPs [...] DIP1014 has not been implemented in DMD or druntime yet, AFAIK
Re: How to compile my DMD fork?
On Friday, 14 June 2019 at 18:07:11 UTC, Q. Schroll wrote: Basically the headline. I want to try to implement my DIP. I've already forked DMD from GitHub. Now, what would I have to do in order to get a D compiler with my changes? I have Windows on x86-64 and Visual Studio on my machine. It might just be a quirk of my install (but It happened recently enough ago that it's worth mentioning) but if you get a really cryptic error message about some msbuild dll being missing you need to find the configuration option and manually set it to the dll actually present.
Re: Does slicing have an effect?
On Tuesday, 21 May 2019 at 20:31:58 UTC, Dennis wrote: I was replacing a memcpy with a slice assignment and accidentally used == instead of =. Usually the compiler protects me from mistakes like that: ``` int[4] a; a == a; ``` Error: a == a has no effect However, because I was using slices it didn't: ``` int[4] a; a[] == a[]; ``` No errors Does slicing have an effect I'm not aware of, or is this a bug? It calls druntime( https://d.godbolt.org/z/3gS3-E ), so technically it does have an effect, even if that effect is completely unused and therefore optimized away. Whether this should be considered an effect or not is up to you
