Re: How can I put the current value of a variable into a delegate?
On Monday, 6 May 2024 at 16:41:38 UTC, Steven Schveighoffer wrote: This is a very old issue: https://issues.dlang.org/show_bug.cgi?id=2043 since "moved" to https://issues.dlang.org/show_bug.cgi?id=23136 I would love to see a solution, but the workaround at least exists! -Steve Interestingly enough C# used to have the same behaviour but MS decided to go for a breaking change in C# 5; now it behaves as most people expect. Since it's an unsolved problem to keep links working for 10+ years I gave up looking for something official about the subject. Here's an SO question about it though: https://stackoverflow.com/questions/14184515/action-delegate-uses-the-last-values-of-variables-declared-outside-foreach-loop
Re: how can I load html files and not .dt or diet files in vibe.d
On Thursday, 1 February 2024 at 03:20:31 UTC, dunkelheit wrote: this is my code, I'm a begginer on vibe, and I want to use html and not diet files Take a look at the static file example, I think that's close to what you're looking for. https://github.com/vibe-d/vibe.d/blob/master/examples/http_static_server/source/app.d
Re: Error: none of the overloads of template `once.main.each!((l)
On Wednesday, 4 October 2023 at 08:11:12 UTC, Joel wrote:
What am I missing?
Splitter returns a forward range so you can't slice the result.
You can use take() and drop() instead. Also, converting a string
range to int[] doesn't seem to work, but I don't know if it
should. Here is a version that works:
```D
import std;
void main() {
struct DateRem {
Date date;
string rem;
string toString() const => text(date.toSimpleString, " ",
rem);
}
DateRem[] daterem;
data
.splitter('\n')
.filter!(l => l.length && l[0].isDigit)
.each!((l) {
auto parts=l
.splitter
.take(3)
.map!(to!int)
.array;
if (parts.length==3) {
daterem~=DateRem(Date(parts[2],parts[1],parts[0]),
l.splitter.drop(3).join(" "));
}
});
daterem.each!writeln;
}
auto data="04 10 2023 17:28, not much
30 9 2023 21:08, very little";
```
Re: Inheritance and arrays
On Monday, 3 July 2023 at 09:50:20 UTC, Arafel wrote:
Is this a conscious design decision (if so, why?), or just a
leak of some implementation detail, but that could eventually
be made to work?
Besides the pointer adjustment problem mentioned by
FeepingCreature, it's an unsound conversion even with just class
inheritance. Consider:
```
class A {}
class B : A {}
class C : A {}
void main()
{
auto bArr = [new B()];
A[] aArr = bArr; // If this was allowed..
aArr[0] = new C(); // This would be a problem, because bArray
would now contain a C.
}
```
Re: Union with bits ?
On Wednesday, 14 June 2023 at 00:59:30 UTC, Paul wrote:
I would like to have labeled bits in a union with a ubyte.
Something like this:
```d
struct MyStruct {
union {
ubyte status;
bit A, B, C…etc
}
}
```
Is something like this possible?
Thanks
You can do something like this if you don't mind compiling with
-preview=bitfields:
```d
union {
ubyte status;
struct {
bool A : 1, B : 1, C : 1, D : 1;
}
}
```
Re: iota where step is a function
On Wednesday, 24 May 2023 at 16:39:36 UTC, Ben Jones wrote: Is there a range like iota in phobos where step is a function? I want to specify begin/end and have the "step" be next = fun(prev). Should be easy to write, but don't want to reinvent the wheel. I think you’re looking for either recurrence() or sequence(), also defined in std.range.
Re: How to workaround assignment not allowed in a condition?
On Wednesday, 12 October 2022 at 02:15:55 UTC, Steven Schveighoffer wrote: Am I missing something? Perhaps I am, but why not turn it into a numeric comparison, like: ``` while((i = 5) == 0) ```
Re: Way to pass params to a function passed to a fiber?
On Monday, 3 October 2022 at 08:10:43 UTC, Bienlein wrote:
My question is whether someone has an idea for a better
solution.
You can pass a lambda to the fiber constructor. For example:
```
void fiberFunc(int i)
{
writeln(i);
}
void main()
{
auto fiber = new Fiber(() => fiberFunc(5));
fiber.call();
}
```
Re: How Stop Worker Thread if Owner Thread is Finished?
On Tuesday, 27 October 2020 at 11:36:42 UTC, Marcone wrote: I want to use isDaemon to automatic stop worker thread if ownner thread is finished Terminating threads without properly unwinding the stack is generally a very bad idea. Most importantly the destructors of stucts on the stack won't run which can cause problems like locks not being released. This isn't specific to D either. For example Raymond Chen writes about the TerminateThread function in Windows here: https://devblogs.microsoft.com/oldnewthing/20150814-00/?p=91811 You should signal the thread somehow that it's time to stop working
Re: How is this an "Access Violation"
On Tuesday, 27 October 2020 at 02:05:37 UTC, Ruby The Roobster
wrote:
void construct(string type,atom base,atom bonded)
{
base = new
atom(base.name.idup,base.mass,base.electro_negativity,base.valence_electrons,base.electrons,base.protons,base.neutrons,base.pos);
(...)
assert(this.base.valence >= 1 &&
this.bonded.valence >=1 && this.base.electro_negativity >= 0 &&
this.bonded.electro_negativity >= 0,"For a single bond, both
atoms need to have at least one free electron and have to have
electro negativity.");
Going by the assert this is a member function of a class or
struct with base and bonded members. I think you meant to assign
the newly created atoms to those fields instead of overwriting
your arguments.
Re: [windows] Can't delete a closed file?
On Thursday, 9 May 2019 at 12:33:37 UTC, Cym13 wrote: On Thursday, 9 May 2019 at 11:31:20 UTC, Cym13 wrote: ... To dismiss any doubt about AV or other processes coming into play I took the binary and ran it with wine on linux with the exact same end result. For reference my windows system is a 64b windows 10. You could try to use the find handle function in Process Explorer to figure out what process has the file open: https://docs.microsoft.com/en-us/sysinternals/downloads/process-explorer
Re: Memory reference that does not stop garbage collection.
On Friday, 8 February 2019 at 15:42:13 UTC, Jonathan Levi wrote: I should be able to use `core.memory.GC.removeRange` right? That would leave dangling references in the array. You may be interested in this, but I have not used it myself: https://repo.or.cz/w/iv.d.git/blob/HEAD:/weakref.d
Re: cas and interfaces
On Tuesday, 25 December 2018 at 22:07:07 UTC, Johannes Loher
wrote:
Thanks a lot for the info, that clarifies things a bit. But it
still leaves the question, why it works correctly when
inheriting from an abstract class instead of implementing an
interface... Any idea about why that?
Unlike interfaces, base class references don't need adjustment.
You can see this in action by printing addresses:
https://run.dlang.io/is/m6icVr
import std.stdio;
interface I {}
class Base : I {}
class Derived : Base { }
void main()
{
auto derived = new Derived;
Base base = derived;
I i = derived;
writeln(cast(void*)derived);
writeln(cast(void*)base);
writeln(cast(void*)i);
}
7FC1F96EE000
7FC1F96EE000
7FC1F96EE010
Re: How does calling function pointers work?
On Monday, 12 November 2018 at 16:29:24 UTC, helxi wrote:
On Monday, 12 November 2018 at 16:25:13 UTC, Rene Zwanenburg
wrote:
Idk where you got that syntax from, but there's no syntactic
difference between calling normal functions and function
pointers:
import std.stdio;
import std.concurrency;
import core.thread;
void worker(int firstNumber) {
foreach (i; 0 .. 4) {
Thread.sleep(500.msecs);
writeln(firstNumber + i);
}
}
void main() {
foreach (i; 1 .. 3) {
spawn(, i * 10);
}
}
Looks like worker needs an int and spawn(, i * 10) seems
to feed it's second arg to worker(?)
That's right. spawn() is a function in the standard library that
takes a function pointer, and all the arguments to pass to that
function. It's a bit unusual in that regard: normally when using
function pointers the arguments are provided by the code that
receives the function pointer. Internally, spawn will call the
function pointer just like I did in my example, but on another
thread.
Here's an example where a function pointer is passed around with
the arguments provided by the callee:
https://run.dlang.io/is/ArCN5t
Re: How does calling function pointers work?
On Monday, 12 November 2018 at 16:08:28 UTC, helxi wrote: As far as I understand, calling a function pointer with an argument in D looks like: call(, argTofn0, argTofn1, argTofn3); Idk where you got that syntax from, but there's no syntactic difference between calling normal functions and function pointers: https://run.dlang.io/is/I6u0rg
Re: Test if variable has void value
On Wednesday, 22 August 2018 at 13:50:07 UTC, Andrey wrote:
Hello,
How to test if variable has void value?
string text = void;
if(text == void)
{
writeln("Is void");
}
Tried this:
if(is(text == void))
but doesn't work.
You can't. When using a void initializer the actual value is
garbage until initialized properly, and that garbage can look
like anything including a valid instance.
So if the flow of your program can't guarantee that the value has
been initialized at a certain point, you'll have to track it
yourself some way. Nullable may be of help:
https://dlang.org/phobos/std_typecons.html#Nullable
Re: Coreect way to create delegate for struct method.
On Tuesday, 21 August 2018 at 21:29:38 UTC, Andrey wrote: Hello, This is a code: (...) test.handler = That's an internal pointer, and internal pointers are not allowed in structs precisely because of the issues you're running into: the pointer will be invalid after a move. You may be able to get it kind of working, but I'd recommend looking for another solution to your problem. This is one of those things that will come back to bite you later.
Memory corruption with COM object
I've been staring at this problem the past few hours without making any progress. But I feel like I'm overlooking something obvious.. Using Adam's comhelpers, I've made a JSON plugin for LogParser. However after running for a bit it'll crash with signs of memory corruption. My guess was the GC was collecting things still in use, and disabling the GC does indeed 'fix' the problem. Looking through comhelpers, the code doesn't add a GC root for a created object before handing it off to the C side. I've added root adding and removing, expecting that to fix the problem. However it didn't help. The DLL uses the helper functions like dll_process_attach in DllMain, so druntime is initialized. What would be a good way to figure out why the GC decides to collect objects I'm still holding on to?
Re: Configuring DerelictGL3
On Wednesday, 6 June 2018 at 23:26:23 UTC, Entity325 wrote: I can't imagine things like "glEnable/DisableClientState" are deprecated. They are. All the missing symbols are indeed deprecated. attempting to load the deprecated functions according to the documentation page did a whole lot of nothing Could you post the exact code you used? I'm not using the old functions, but that should work.
Re: Aggressive conditional inlining with ldc only, not dmd
On Sunday, 25 March 2018 at 22:09:43 UTC, Nordlöw wrote: eventhough I compile with -release -inline -nobounds flags. Just to make sure: are you passing -O as well?
Re: How to make AA key a pointer
On Monday, 19 February 2018 at 14:57:47 UTC, Clinton wrote: On Monday, 19 February 2018 at 14:55:01 UTC, Clinton wrote: Hi all, I need advice from better developers on this concern. I'm using an AA to reference another array for quicker access: [...] Sorry, on second look my explanation isn't very clear. I want to know if: bool[string] myAA; myAA[contact.id] = true; // Does this copy contact.id or is this a pointer to contact.id? It's a pointer. In D, string is an alias to immutable(char)[] (Slice of immutable characters). A slice is a combination of pointer and length.
Re: Debugging on Windows
On Thursday, 8 February 2018 at 21:09:33 UTC, JN wrote: Hi, is there any way to debug binaries on Windows? I'd at least like to know which line of code made it crash. If it's D code, I get a call trace usually, but if it's a call to a C library, I get a crash and that's it. I am using VSCode and I'd prefer to debug in it if possible, but using other IDEs is a possibility for me if that will help. You can debug D programs from VS Code using the C++ plugin: https://marketplace.visualstudio.com/items?itemName=ms-vscode.cpptools It requires some configuring, but from what I remember it was all very straightforward.
Re: SegFault with HibernateD
On Friday, 12 January 2018 at 07:33:37 UTC, Mike Parker wrote: On Friday, 12 January 2018 at 05:24:52 UTC, Venkat wrote: I get a SegFault with the main method below which uses HibernateD . The second main method which uses ddbc just works fine. What is wrong with the first main method ? I have attached the error at the bottom although I don't think it says much. This is the error. object.Exception@source/dub/generators/build.d(530): Program It says enough to know that the exception is being thrown from dub and not your program. You program is never executed because dub throws the exception before it gets that far. You should report this at the dub repository: https://github.com/dlang/dub/issues It looks to me like the program is being run through dub, and dub is just reporting the program's exit code. Hard to guess what the issue is, I'd attach a debugger to see where it crashes.
Re: High-resolution thread sleep
On Friday, 15 December 2017 at 01:49:56 UTC, Steven Schveighoffer wrote: So... you plan on rendering more than 1000 frames per second? I think in any case, even if the API allows it, you are probably not getting much better resolution on your non-windows systems. Have you tried it anyway and see how it works? I think it might actually work just fine. -Steve The higher precision would be needed b/c updating and rendering takes time, so the sleep time would be timePerFrame - timeSpendOnRendering. Problem is you'll need vsync anyway to avoid tearing. Applications that use their own timing to limit the framerate without using vsync are easy to recognise: they have a tear slowly moving around on the screen. It's visually even more annoying than regular tearing.
Re: High-resolution thread sleep
On Thursday, 14 December 2017 at 23:45:18 UTC, Ivan Trombley
wrote:
Something along the lines of this:
while (render)
{
immutable auto startTime = MonoTime.currTime;
// Render the frame...
immutable auto remain = m_frameDuration - (startTime -
MonoTime.currTime);
if (remain > Duration.zero)
Thread.sleep(remain);
}
In that case, the best thing you can do is use vsync as the
waiting mechanism ;)
Re: High-resolution thread sleep
On Thursday, 14 December 2017 at 21:11:34 UTC, Ivan Trombley wrote: I need to be able to put a thread to sleep for some amount of time. I was looking at using Thread.sleep but it appears that on Windows, it's limited to millisecond resolution. Is there a way to do this in a cross-platform way that is higher resolution? Sleeping for very short periods is usually a bad idea for various reasons. What do you need it for? If you really need this, go for a loop with a high resolution timer.
Re: Email validation
On Tuesday, 28 November 2017 at 18:47:06 UTC, Vino wrote: Hi All, You can do this easily using the std.net.isemail module: https://dlang.org/phobos/std_net_isemail.html
Re: opAssign for most struct assignment calls not executed
On Thursday, 23 November 2017 at 15:26:03 UTC, Timoses wrote:
A aaa = a;
That's initialization, not assignment, which is subtly different.
It will call the postblit on aaa instead of opAssign. A postblit
can be defined this way:
this(this)
{
}
There is no way to access the original a from the postblit. All
fields have already been copied, you can use it to duplicate
reference types, increment reference counts, and other things
like that.
Re: DateTime trying to do it at compile time.
On Thursday, 26 October 2017 at 17:55:05 UTC, Mr. Jonse wrote:
when calling Clock.currTime() in a this() in a class. I have no
idea why it is trying to do it at compile time and failing. I
thought if ctfe couldn't compile it would do it at run time
anyways? Seems like a bug.
I suspect you're trying to instantiate your class in a static
context, which causes it to be constructed at compile time. For
example:
class A
{
this() {
// Do sth. with datetime
}
}
class B
{
// This will construct A at compile time. This also
// means a single A instance is shared between all
// B instances. This is different from most langs!
A a = new A;
}
// This will also construct at compile time.
A moduleScopedA = new A;
The solution is to new A in your class or module constructor.
Re: How to modify process environment variables
On Tuesday, 17 October 2017 at 05:57:50 UTC, Ky-Anh Huynh wrote: On Tuesday, 17 October 2017 at 04:56:23 UTC, ketmar wrote: you can use libc's `putenv()` in D too, it is ok. just import `core.sys.posix.stdlib`, it is there. D is not antagonistic to C, and doesn't try to replace the whole libc with it's own libraries. so if you see something that libc has and you'd like to use -- just do it! ;-) I see :) I have always tried to avoid C if possible :D As an alternative, a search on code.dlang.org turned up this lib: http://code.dlang.org/packages/dotenv
Re: Making a repo of downloaded dub package
On Tuesday, 5 September 2017 at 06:23:26 UTC, Dukc wrote: On Monday, 4 September 2017 at 20:31:35 UTC, Igor wrote: Search for word "local" here: https://code.dlang.org/docs/commandline. Maybe some of those can help you. If not you could make a pull request for dub that would support such a thing :) That will make a Dub package out of a Git package, but I'm trying to do it vice-versa (And so that it is able to use the same histoy as the repository). I think it will require Git commands, but what commands exactly? I was unable to figure that out myself. When you go to the package's page on code.dlang, look for the github repository link in the top right corner. You can fork from there.
Re: Remove all blank lines from a file
On Thursday, 31 August 2017 at 14:44:07 UTC, vino wrote:
Hi All,
Can some provide me a example of how to remove all blank
lines from a file.
From,
Vino.B
This one doesn't read the entire file into memory:
import std.stdio;
import std.array;
import std.algorithm;
import std.uni;
void main(string[] args)
{
auto inputFile = File(args[1]);
auto outputFile = File(args[2], "wb");
inputFile
.byLine
.filter!(line => !line.all!isWhite)
.copy(outputFile.lockingTextWriter);
}
But if you want to replace the input file, you'd have to write to
a temp file, remove the original, then move the temp file.
Re: Getting enum from value
On Saturday, 5 August 2017 at 15:33:57 UTC, Matthew Remmel wrote:
Any ideas?
You can use to! in std.conv:
import std.stdio;
import std.conv;
enum Foo
{
A = "A",
B = "B"
}
void main()
{
writeln("A".to!Foo);
}
Re: Function with static array as parameter
On Wednesday, 12 July 2017 at 12:57:19 UTC, Rene Zwanenburg wrote:
On Wednesday, 12 July 2017 at 12:20:11 UTC, Miguel L wrote:
What is the best way in D to create a function that receives a
static array of any length?
Templatize the array length:
void foo(size_t length)(int[length] arr)
{
}
That being said, this may lead to template bloat and excessive
copying. What are you trying to do? Is there a reason you can't
use a slice?
Re: Function with static array as parameter
On Wednesday, 12 July 2017 at 12:20:11 UTC, Miguel L wrote:
What is the best way in D to create a function that receives a
static array of any length?
Templatize the array length:
void foo(size_t length)(int[length] arr)
{
}
Re: D and memory mapped devices
On Wednesday, 14 June 2017 at 08:10:57 UTC, Russel Winder wrote: but the bitfields mixin template appears to do more than add all the bit twiddling functions to emulate the bitfields. This would appear a priori to not allow for actual memory mapped devices using it, or am I missing something? I've casted void buffers to structs containing bitfields to read pre-existing binary files, and that worked just fine. I don't see why it would be different for memory mapped devices. What do yo mean by 'do more'?
Re: purity question
On Tuesday, 30 May 2017 at 11:34:52 UTC, ketmar wrote: If malloc were marked as pure, wouldn't that mean it must return the same pointer every time you call it with the same size? of course. but D "pure" is not what other world knows as "pure". we love to mess with words. Well, there's the ability to modify non-const reference parameters from a pure function, but that's not applicable to malloc. Are there any other special rules?
Re: purity question
On Monday, 29 May 2017 at 01:36:24 UTC, Jonathan M Davis wrote: A simple example: anything that has a malloc/free pair. Yeah, if you do it right, you should be fine, but you have to do it right, and it's very easy to miss some detail that makes it wrong to insist to the compiler that what you're doing is pure. If malloc were marked as pure, wouldn't that mean it must return the same pointer every time you call it with the same size?
Re: Why map return [] ?
On Friday, 14 April 2017 at 15:49:00 UTC, Suliman wrote: I found problem! ResultRange should be converted to array before it can be `map`ed That shouldn't be necessary. Can you post your complete code?
Re: Can't build simple project. Very strange errors
On Friday, 14 April 2017 at 15:42:33 UTC, Suliman wrote: On Friday, 14 April 2017 at 15:40:18 UTC, Rene Zwanenburg wrote: On Friday, 14 April 2017 at 15:31:21 UTC, Suliman wrote: On Friday, 14 April 2017 at 15:22:49 UTC, Rene Zwanenburg wrote: On Friday, 14 April 2017 at 09:49:09 UTC, Suliman wrote: on: dub build --compiler=ldc2 link OPTLINK (R) for Win32 Release 8.00.17 Optlink isn't able to link object files produced by ldc. Could you try an x64_86 build? You'll need the Microsoft linker. I do not have VS on my PC :( You don't need VS, the Windows SDK should be fine too. It's a free download :) How to check if it's installed and how to use linker from it? If it's installed you can find it in the programs and features list as 'Windows Software Development Kit for Windows X'. The DMD installer will look for it during installation, so reinstalling DMD after installing the SDK should work. I'm not sure how LDC does it, but last time I installed LDC it also just worked.
Re: Can't build simple project. Very strange errors
On Friday, 14 April 2017 at 15:31:21 UTC, Suliman wrote: On Friday, 14 April 2017 at 15:22:49 UTC, Rene Zwanenburg wrote: On Friday, 14 April 2017 at 09:49:09 UTC, Suliman wrote: on: dub build --compiler=ldc2 link OPTLINK (R) for Win32 Release 8.00.17 Optlink isn't able to link object files produced by ldc. Could you try an x64_86 build? You'll need the Microsoft linker. I do not have VS on my PC :( You don't need VS, the Windows SDK should be fine too. It's a free download :)
Re: Can't build simple project. Very strange errors
On Friday, 14 April 2017 at 09:49:09 UTC, Suliman wrote: on: dub build --compiler=ldc2 link OPTLINK (R) for Win32 Release 8.00.17 Optlink isn't able to link object files produced by ldc. Could you try an x64_86 build? You'll need the Microsoft linker.
Re: DUB mismatch between project structure and dub.json contents
On Monday, 10 April 2017 at 12:56:49 UTC, Nordlöw wrote: src/knet/traversal.d(20,8): Error: module factixs from file src/knet/factixs.d must be imported with 'import factixs;' What am I doing wrong? My first guess would be that the module declaration in that file is incorrect. Are you sure it's set to knet.factixs? The module declaration needs to be present or it will be put in the root package.
Re: delegate with optional parameters
On Monday, 3 April 2017 at 05:00:15 UTC, Inquie wrote: Yes, but they are really not any different. They only look different. A field can be a function just like a method because they look exactly the same except on is in a vtable and the other is in the fields memory. But both point functions. It should be possible to create a wrapper struct around your 'overloads' with an opDispatch which selects the right delegate.
Re: Why is [0] @safer than array.ptr?
On Tuesday, 24 January 2017 at 11:38:16 UTC, Jonathan M Davis
wrote:
Likely because it does bounds checking, so you at least know
that it's not null. But I don't see why that would really
improve much considering that the odds are that you're really
going to be accessing far more than just the first element with
the pointer. It seems _slightly_ better from a safety
perspective but only slightly. So, I don't know what the point
is in suggesting it as an alternative.
- Jonathan M Davis
Pointer arithmetic is forbidden in @safe code so that's not a
problem. The reason this was introduced was indeed bounds
checking. For example:
@safe:
int parse(ref char[] input)
{
// Pop all numeric characters from the front of the input slice
and convert to int
}
void main()
{
auto input = "123".dup;
parse(input);
// Since all numeric chars have been popped, input is now
effectively input[$ .. $].
// This means input.ptr is pointing past the end of the array.
writeln(input.ptr); // Out of bounds access
}
Re: Strange Bug
On Friday, 20 January 2017 at 08:19:57 UTC, Chris M. wrote: I have no idea if this is an issue with D, or OpenSSL, or if I'm just doing something completely wrong. I'm writing a program that will either encrypt or decrypt a string using AES in ECB mode (for a school assignment) and it's giving me a very strange bug. [...] auto encOut = new ubyte[inputStr.length]; // Encrypt and convert to base64 AES_set_encrypt_key(aesKey.ptr, aesKey.sizeof * 8, ); AES_ecb_encrypt(inputStr.ptr, encOut.ptr, , AES_ENCRYPT); Here's the problem. I tried running this without the if-else statements (i.e. encrypting and decrypting all in one run of the program, code below). If I leave in the base64 encoding and decoding, and use decB64 as the input to decrypt, it still doesn't work. However, if I decrypt with encOut directly, or assign encOut to decB64, it somehow works. My guess: The encrypted output will be a bit longer than your input. You're not getting an out of bounds exception during encryption since OpenSSL only has the pointer to write to, not a buffer length it can check. The memory behind your buffer is apparently committed, and will be written to by OpenSSL. This is why using the same buffer to decrypt works: it continues to read after the end of the buffer. (In case it's not clear, writing and reading past the end of the buffer is really bad) I expect OpenSSL to have a helper function to calculate the required buffer size for a given input length. Use that to allocate the buffer.
Re: Phobos: Determining number of hours or minutes or seconds till now
On Friday, 20 January 2017 at 03:48:14 UTC, rikki cattermole wrote: As per the documentation this is wrong for anything beyond a few weeks. Although I have no idea if that's the case implementation wise. I think the documentation is talking about the units used, not length of the duration. The reason Duration makes this distinction is because months and everything larger have a variable length. I'm not sure though.
Re: Phobos: Determining number of hours or minutes or seconds till now
On Thursday, 19 January 2017 at 14:04:36 UTC, aberba wrote: Using the standard library, how do a get number of hours or seconds or minutes or days or months or years till current time from a past timestamp (like "2 mins ago")? Not with manual calculations but from Phobos functions. You can get a duration by subtracting two timestamps. For example: auto delta = (Clock.currTime - timeStamp).total!"seconds";
Re: Thread will get garbage collected?
On Tuesday, 17 January 2017 at 08:58:33 UTC, Arun Chandrasekaran wrote: Interesting. Why doesn't the thread get GC'd in this case even without any reference still active? There will be a reference to it in druntime itself: http://dlang.org/phobos/core_thread.html#.Thread.getThis
Re: Changing template parameters
On Monday, 16 January 2017 at 15:56:16 UTC, Jack Stouffer wrote:
Same way you use any template parameters,
auto i = uniform!("(]")(0, 1000);
Also, if the template parameter consists of a single token you
can omit the parens:
auto i = uniform!"(]"(0, 1000);
Re: Alias variable from another class
On Tuesday, 13 December 2016 at 19:13:24 UTC, Begah wrote: Any ideas? Closest you can get is wrapping it in a property. If you need to do this often you may be able to generate them, check the recent "Getters/Setters generator" thread in Announce for some inspiration.
Re: Updated D then undefined symbols in vibed
On Thursday, 24 November 2016 at 16:17:19 UTC, Jot wrote: Any more ideas? Obviously something isn't getting linked in in the VS project. This is definitely a stale object file problem. From that error message it appears to use the .dub directory to store object files of your dependencies. Try nuking it, then run dub to recreate it.
Re: Updated D then undefined symbols in vibed
On Thursday, 24 November 2016 at 09:52:32 UTC, Jot wrote: Seems like someone decided to screw up a lot of people by removing a lot of stuff ;/ I guess I should learn my lesson about assuming a "stable" dmd release won't completely kill my project. There are still some old object files or libs hanging around. MSBuild doesn't know you've updated DMD and reuses them. Dub shouldn't have this problem. If you've generated the solution from a dub file, try a rebuild with Dub first. I suspect MSbuild will work after that.
Re: Why don't Function Lambdas Cast to Delegate?
On Monday, 21 November 2016 at 16:24:38 UTC, Q. Schroll wrote: Why don't lambdas cast to a delegate if they are of type R function(Args)? I don't see any reason to that; a lambda should be a delegate type by default, and a function only as a special guarantee/optimization. It just makes them cumbersome to use with toDelegate. Probably there is a good reason why R function(Args) does not implicitly cast to R delegate(Args); I can imagine something internally (memory layout etc.) causes that. I'd just like to know. A delegate has the hidden context pointer as parameter in addition to the 'visible' parameters. That causes functions and delegates with the same declared params to look different on the ABI level.
Re: [vibe.d] showing images
On Wednesday, 26 October 2016 at 12:42:09 UTC, Nicholas Wilson
wrote:
doctype html
html
body
-foreach(s; images)
// it doesn't seem to like #{s} or !{s}
img(src=s)
--
shared static this()
{
auto router = new URLRouter;
router.registerWebInterface(new CamController);
auto settings = new HTTPServerSettings;
settings.port = 8081;
settings.bindAddresses = ["::1", "127.0.0.1"];
listenHTTP(settings, router);
}
class Controller
{
void index(HTTPServerRequest req, HTTPServerResponse res)
{
auto images =
dirEntries("public/images",SpanMode.breadth)
.map!(f=> f.name).array;
writeln(images); // ["public/images/testprog.jpg"]
res.render!("index.dt",images);
}
}
What am I missing? I just get a 404 for the image.
You need to make the images accessible over HTTP. Note the use of
staticFileServer in the following example:
http://vibed.org/docs#http-routing
Re: File.write write extra CR character if a string has CRLF on windows
On Thursday, 6 October 2016 at 15:00:00 UTC, Pham wrote:
string s is multi-lines (CRLF as line break)
The write function will write extra CR character for each CRLF
pair -> why (bug?)
import std.file;
import std.stdio;
string s = ...;
auto fHandle = File("f:\\text.txt", "w"); // open for writing
fHandle.write(s);
fHandle.close();
Take a look at this thread:
http://forum.dlang.org/post/ehdnboaufaadgiaah...@forum.dlang.org
Re: Member not accessible in delegate body
On Friday, 23 September 2016 at 07:54:15 UTC, John C wrote:
How is it possible that "onTextChanged" isn't accessible but
the private method "changeSize" *is*?
Smells like an oversight. I guess the compiler doesn't see the
delegate as a member of a Control subclass, so it can't access
protected members. Private works because private in D means
module private.
Please file an issue. As a workaround you can try to take the
address of the method in the closure (untested):
void delegate() foo()
{
auto func =
return () => func(); // I think this will work
}
Re: Vibe.d compilation error: backend/cgelem.c 5018 dmd failed with exit code 1.
On Friday, 23 September 2016 at 08:39:44 UTC, llaine wrote: Okay I tried yesterday, after 4hours of process, I never went through the end of minification. At the beginning I enter YES should I enter NO instead? Hmm that's strange. I don't get any yes or no questions. What is the exact message you get? I've been looking into using dustmite with dub a bit, and running dub dustmite "../DustmiteResult" --compiler-regex=".*backend/cgelem\.c 501.*" --build=release in your project directory should just work..
Re: Vibe.d compilation error: backend/cgelem.c 5018 dmd failed with exit code 1.
On Wednesday, 21 September 2016 at 20:22:42 UTC, llaine wrote: The project is pretty big, DustMite would handle this? Yes, but it may take some time. For large projects, running it on a server is advisable. 3K LOC should be doable on a desktop machine. Dub has built-in support for running Dustmite. I'm not very familiar with it, but it looks like you'll want to use 'dub dustmite' with the --compiler-regex switch with a regex matching the ICE assert message.
Re: Copy a struct and its context
On Sunday, 11 September 2016 at 05:44:13 UTC, Yuxuan Shui wrote: I recently noticed nested struct capture its context by reference (which, BTW, is not mentioned at all here: https://dlang.org/spec/struct.html#nested). And bliting a struct obviously doesn't do a deep copy of its context. So my question is, is there a way to deep copy the context of a struct? I've tried a few things, but I don't think you can. The root issue is that the context pointer is void*, so you can't do meaningful reflection on it.
Re: Storing a reference
On Thursday, 1 September 2016 at 20:38:13 UTC, Yuxuan Shui wrote:
I think my approach is probably better, because I believe
(correct me if I'm wrong): 1) it will never refer to a null
object.
That's true, but you can ensure the same thing for the wrapper:
struct Ref()
{
@disable this();
this(T* value)
{
assert(value !is null);
this.value = value;
}
// rest same as before
}
2) after DIP1000 is implemented we will be able to make sure
there will be no dangling reference.
I'm not very familiar with the details of DIP1000, so I can't
comment on that.
Re: Storing a reference
On Thursday, 1 September 2016 at 19:37:25 UTC, Yuxuan Shui wrote:
I just figured out how to store a reference:
@safe:
auto x(ref int a) {
struct A {
ref int xa() { return a; }
}
return A();
}
void main() {
import std.stdio;
int b = 10;
auto a = x(b);
a.xa = 20;
writeln(b); //Prints 20
}
I have no idea if this is a right thing to do. Can someone tell
me if this is idiomatic D, and whether there're any catches to
this method or not?
Thanks.
This will allocate a closure. A struct definition inside a
function has a hidden context / closure pointer, unless it's a
static struct.
There is nothing like a ref variable in D. If you want to refer
to something someplace else, use a pointer. You can create a
pointer wrapper which acts like a reference (untested):
auto toRef(ref T value)
{
return Ref!T();
}
struct Ref(T)
{
private T* value;
@property ref T _value() { return *value; }
alias _value this;
}
Note that D's pointer syntax is a bit friendlier than C++'s: the
dot operator works fine on pointers. A good reason to use the Ref
wrapper is to forward arithmetic operations to the wrapped value.
Re: Checking all elements are unique.
On Wednesday, 31 August 2016 at 08:38:11 UTC, Andrea Fontana wrote: Something like this: https://dpaste.dzfl.pl/9fa55b2a7927 ? Andrea Or use findAdjacent: auto idsAreUnique = ids.array.sort.findAdjacent.empty; http://dlang.org/phobos/std_algorithm_searching.html#.findAdjacent
Re: DerelictGL3.reload with specified path question.
On Wednesday, 17 August 2016 at 22:59:31 UTC, WhatMeWorry wrote: I want to store all my shared/dynamic libraries within a special directory relative to where the application directory is. All of the derelictXX.loads(path) compiles except DerelictGL3.reload(lib); which doesn't seem to be implemented. Don't ever ship OpenGL.dll with your application: it's provided by the graphics driver. The only exception to this rule that I can think of is if you want to use a software implementation for some reason.
Re: randomIO, std.file, core.stdc.stdio
On Wednesday, 27 July 2016 at 02:20:57 UTC, Charles Hixson wrote: O, dear. It was sounding like such an excellent approach until this last paragraph, but growing the file is going to be one of the common operations. (Certainly at first.) (...) So I'm probably better off sticking to using a seek based i/o system. Not necessarily. The usual approach is to over-allocate your file so you don't need to grow it that often. This is the exact same strategy used by D's dynamic arrays and grow-able array-backed lists in other languages - the difference between list length and capacity. There is no built-in support for this in std.mmfile afaik. But it's not hard to do yourself.
Re: Dynamic arrays, emplace and GC
On Tuesday, 5 July 2016 at 13:48:46 UTC, Claude wrote: Ah ok. I tried using void[size] static array and it seems to work without having to use GC.addRange(). Correct. void[] means the type of the data is unknown, so the GC has to assume it can contain pointers. This also means that _everything_ in any void buffer has to be treated as a potential pointer. In other words, if you allocate a void buffer and fill it with ints, and one of those ints happens to have a value equal to the address of a GC-allocated object, the GC will assume the int is a pointer to that object and not free it.
Re: Initializing static array with contents of (static and dynamic) arrays
On Tuesday, 5 July 2016 at 12:34:20 UTC, Johannes Loher wrote: I tried this, but it does not work correctly with slices. The length of a slice is a runtime value, which is why it can't be used to set static array size. What were you trying to achieve? Avoid copying the input arrays, or accepting any slice? In case of the first, you can put ref in front of the Args: auto combineArrays(Args...)(ref Args args) The second case will be a bit harder to solve nicely..
Re: Initializing static array with contents of (static and dynamic) arrays
On Monday, 4 July 2016 at 19:22:52 UTC, Johannes Loher wrote: This looks really nice, but I have several occurences of this, with different arrays (and lengths), so i would need to create several of those structs. But it looks really clean :) You can use a template to remove the boilerplate. Here's a quick example: https://dpaste.dzfl.pl/43b379992648
Re: Commit size and Page fault's very large for simple program
On Monday, 4 July 2016 at 11:42:40 UTC, Rene Zwanenburg wrote: ... I forgot to mention: If you're on Windows compilation defaults to 32 bit, false pointers can be a problem with D's current GC in 32 bit applications. This isn't an issue for the sample application though, since you're not putting random numbers in the allocated arrays. 64 bit doesn't suffer from this. There's also a GSoC project underway, aimed at improving the GC. I'm not sure what the exact goals are, but IIRC work on making the GC precise is being done, which would eliminate the false pointer issue.
Re: Commit size and Page fault's very large for simple program
On Monday, 4 July 2016 at 01:57:19 UTC, Hiemlick Hiemlicker wrote:
version(Windows)
void main()
{
import std.random;
while(getchar() != EOF)
{
auto x = new int[std.random.uniform(100, 1000)];
writeln("");
bThread.Now();
}
}
more or less, ends up with a huge amount of page faults and a
several hundred MB commit size(hold enter down a bit). I'm
trying to understand this. Is that normal behavior for normal
programs(haven't tried it with a similar C++ example though).
The PF's are most likely due to default initialization, so you
may not see those in a C++ equivalent (or, actually, the exact
equivalent would be to initialize the array as well, in that case
you'd get PF's too). If you've determined default initialization
is causing performance problems in a hot piece of code, D
provides facilities to disable it.
I realize the GC has to do some work and all that but the
program only has a working set of a few MB yet a commit of 10
times that.
Is commit size essentially "touched" memory but really doesn't
mean much to overall free ram?(can other programs use it at
some point)?
Strictly speaking there's no relation between commit size and
RAM, from your application's POV there's only the virtual address
space. Committed memory can be paged to disk if the OS determines
your application isn't actively using certain pages.
We know the program is not using more than 10MB
It's an array of ints, so you'll have to multiply that by four ;)
of extra memory(since x is local)... so I'd only expect the
footprint to be a max of around 15-20MB. not 150MB+(depends on
how fast and long you hit enter).
Keeping memory usage to an absolute minimum would mean the GC has
to do a collection on every allocation. As a very coarse rule of
thumb, expect a GC heap (not just the D GC) to be about 1.5 to 2
times as large as strictly necessary. This is to reduce the
amount of collections. Since your example is doing nothing but
hammering the GC I'm not surprised the heap is a bit larger than
that.
Re: Range non-emptyness assertions and opIndex
On Friday, 1 July 2016 at 10:35:04 UTC, Nordlöw wrote:
I think this is a important issue since asserts are not
optimized away in release mode and D is very much about
performance.
Asserts are removed in release mode, enforce isn't. Here's an
example:
=
void main(string[] args)
{
assert(args.length >= 1);
}
=
dmd testfile.d
This calls the assert function as expected:
=
_Dmain:
: 55 pushrbp
0001: 48 8B EC mov rbp,rsp
0004: 48 83 39 01cmp qword ptr
[rcx],1
0008: 73 0E jae
0018
000A: B9 03 00 00 00 mov ecx,3
000F: 48 83 EC 20sub rsp,20h
0013: E8 00 00 00 00 call
_D5test28__assertFiZv
0018: 31 C0 xor eax,eax
001A: 5D pop rbp
001B: C3 ret
=
Now compiling in release mode:
dmd -release testfile.d
No assert in sight:
=
_Dmain:
: 55 pushrbp
0001: 48 8B EC mov rbp,rsp
0004: 31 C0 xor eax,eax
0006: 5D pop rbp
0007: C3 ret
=
Re: How to use a char[] buffer in D
On Thursday, 23 June 2016 at 05:59:10 UTC, Andrew Chapman wrote:
Perfect, thank you! :-) Works like a charm.
On Wednesday, 22 June 2016 at 22:41:24 UTC, H. S. Teoh wrote:
On Wed, Jun 22, 2016 at 09:57:04PM +, Andrew Chapman via
Digitalmars-d-learn wrote:
Maybe try:
if (buffer[] in myHash) { ... }
? Does that make a difference?
T
If the keys are fixed-length, you may want to consider using
immutable(char[4]) as key. That way there is no GC allocation for
the strings at all, the only allocations are done by the AA.
Re: Templated class defaults and inheritence
On Saturday, 18 June 2016 at 17:48:47 UTC, Joerg Joergonson wrote:
class foo(T) if (is(T : subfoo)) X;
FYI this can also be done in the template parameter list:
class foo(T : subfoo){}
Re: Out of order execution
On Thursday, 16 June 2016 at 01:57:19 UTC, Joerg Joergonson wrote: Is there an efficient lazy way to make this happen? No, I don't see how that would work. Suppose I can't run the loop twice for performance reasons(there is other stuff in it) and I don't want to store the state and call info then sort them out afterwards. Storing the state is your best bet. Based on your recent post about OpenGL I assume this is for the same project? If so, you can reuse the storage buffer between frames. Generally speaking it's the allocations that are slow, copying some state to a buffer shouldn't be expensive. Use separate buffers for the Do1 and Do2 calls so you don't have to sort.
Re: GTKD - Application crashes - or not? [Coedit]
On Wednesday, 15 June 2016 at 10:31:18 UTC, TheDGuy wrote: Thanks a lot for your answer, getcwd() returns the path where coedit is located on my harddrive: C:\Program Files (x86)\Coedit_32\coedit.2update6.win32 How can i change that? I'm not familiar with Coedit, but the run options seem to contain a field for setting it: https://github.com/BBasile/Coedit/wiki#run-options You may be able to use the symbolic strings there: https://github.com/BBasile/Coedit/wiki#symbolic-strings
Re: GTKD - Application crashes - or not? [Coedit]
On Wednesday, 15 June 2016 at 09:48:19 UTC, TheDGuy wrote: But if i execute the app my hand (in the windows command window or my double click) it works as expected (so no error)? Why is that? My first guess would be that Coedit does not use the directory where the executable is located as working directory. You can check what getcwd returns: https://dlang.org/phobos/std_file.html#.getcwd
Re: What's up with GDC?
On Monday, 13 June 2016 at 20:21:28 UTC, Joerg Joergonson wrote: Are you running some other program that might be sending a lot of broadcast messages? Not that I know of. I haven't tried running it outside VS though so it might be doing something weird. I'll investigate further when I get a chance and get further down the road. It's often useful to attach a sampling profiler when the process is eating CPU. It should tell you what's going on at a glance. I believe VS has a sampling profiler built in, but it most likely won't demangle D symbols, so the function names will be a bit hard to read.
Re: Range and poolTask
On Monday, 6 June 2016 at 10:26:11 UTC, moechofe wrote: The functions passed to map or amap take the type of the element of the range as argument, but not a range itself. Right. I don't think I understand what the semantics of your example would be though.. Could you elaborate a bit?
Re: Range and poolTask
On Monday, 6 June 2016 at 09:32:30 UTC, moechofe wrote:
I wonder if it is possible to write something like this:
---
// taskPool.distribute -- take a range and distribute entries
to different threads.
dirEntries().distribute(function(R1,R2)(R1 from,R2 to){
from
.filter!xxx
.map!yyy
.tee!zzz(to);
})
.each!www;
---
This would be great.
This might be useful:
http://dlang.org/phobos/std_parallelism.html#.TaskPool
Or, more specifically,
http://dlang.org/phobos/std_parallelism.html#.TaskPool.amap
http://dlang.org/phobos/std_parallelism.html#.TaskPool.map
Re: Creating a "fixed-range int" with opDispatch and/or alias this?
On Wednesday, 1 June 2016 at 19:59:51 UTC, Mark Isaacson wrote: FWIW, the fixed range int part of this question is just an example, I'm mostly just interested in whether this idea is possible without a lot of bloat/duplication. I suspect not.. Here's how std.typecons.Proxy is doing it: https://github.com/dlang/phobos/blob/master/std/typecons.d#L5109
Re: Using referenceCounters
On Wednesday, 1 June 2016 at 18:14:33 UTC, Begah wrote:
I started using reference counters for my assets in my
application :
- Images
- Models
-
For my resource manager I started out with something similar to
what you're describing, but I eventually changed the design which
turned out to be an immense improvement so I'll just describe
that ^^
- Differentiate between the type implementing a resource, and
handles to a resource.
- Split up the resource manager, which stores the 'real' resource
for a given handle, and the cache where you look up resources by
name.
A stripped down version of the resource manager looks something
like this:
template ResourceManager(ResourceType)
{
struct HandleImpl
{
~this()
{
// Destroy the resource, make sure you mark the
corresponding slot in the array as free
}
size_t slot;
}
alias Handle = RefCounted!HandleImpl;
private ResourceType[] resources;
// When creating a resource add it to the manager and pass
around the opaque handle instead.
Handle add(ResourceType resource)
{
// Find an empty slot in the resources array, put the
resource there, and return a handle pointing to that slot.
}
// This should be used sparingly. Most code shouldn't care
about resource implementation. The parts that do can get at it
via this function, but shouldn't hold on to the reference longer
than necessary.
ResourceType getActualResource(Handle handle) { ... }
// This allows you to hot-swap resources while keeping the
resource implementation logically const. Hot-swapping is
extremely valuable, I've always found myself wanting to support
it sooner or later. I've tried to do it in different ways, but it
always ended up in a mess. Using handles on the other hand turned
out to be clean and easy.
void update(Handle handle, ResourceType newResource) { ... }
}
Note that it doesn't allow you to search for resource by name or
anything, this is just a simple mapping between handles and the
resource implementation. It doesn't store instances of the
RefCounted handles itself, so there are no issues with resources
not being cleaned up.
Now when you have this in place you can build a caching mechanism
on top of it:
template ResourceCache(ResourceType, alias loadByName)
{
alias Manager = ResourceManager!ResourceType;
Manager.Handle[string] cache;
Manager.Handle get(string name)
{
// Check if the resource is already in the cache, if not load
it using the loadByName function and store it.
}
void purge()
{
// the keys property allocates a new array with the AA keys,
which is important since we're modifying the AA.
foreach(key; cache.keys)
{
// This is the part you were actually interested in. It's
important to take a pointer to the handle here, and not reference
it directly. I had some issues with that in the past, I'm not
sure if that's still the case.
auto ptr = key in cache;
if(ptr.refCountedStore.refCount == 1) // If this is the
last reference
{
destroy(*ptr); // I'm not sure if this is still
necessary, there was some issue with AAs in the past. It may be
fixed today. Destroying the handle doesn't hurt either way so I
left it in.
cache.remove(key);
}
}
}
}
So cached resources don't get cleaned automatically if you don't
call purge, but that's usually the right thing to do anyways. For
example when you're changing scenes (I assume this is for some
kind of game?) you can simply destroy the current scene, load
another, then purge the cache, without having to reload resources
used by both scene 1 and 2.
Another upside is that this doesn't require every resource to be
named / backed by file. Resources can be dynamically generated at
runtime without special casing anywhere.
Re: Base64 of String without casting
On Wednesday, 1 June 2016 at 09:31:51 UTC, tcak wrote:
I understand that Base64 uses Ranges, and since String is seen
and used as unicode by Ranges (please tell me if I am wrong).
I am guessing, for this reason, auto btoa =
std.base64.Base64.encode("Blah"); doesn't work. You need to be
casting the string to ubyte[] to make it work which doesn't
look and feel nice at all.
Can/shall we add another alias into the module for encode
method, so it accepts a string, and casts it to ubyte[] by
itself?
This should do the trick:
https://dlang.org/phobos/std_string.html#.representation
Re: Preferred method of creating objects, structs, and arrays with deterministic memory management
I was wondering: what's the preferred method for deterministic
memory management?
You may be interested in RefCounted. It only works for structs,
not classes, but it's still useful.
- Classes/Structs have constructors and destructors. I am
unconfident with my knowledge as to how this works with malloc
and free.
malloc() and free() operate on a lower level, they only care
about raw memory. When you malloc() some space, you can construct
an object there using emplace(), and it can be destructed by
using detroy().
- Many features and types use the GC such as exceptions, the
new keyword, and all arrays except statics.
It's important to differentiate static arrays, and slices with
static storage. For example:
class C
{
static int[] someSlice; // This is a slice with static storage.
The memory it is referring to may be GC allocated, but it doesn't
have to (this is true for all slices btw).
int[4] someStaticArray; // This is a static array, i.e. an
array with a fixed length. In D static arrays are value types, so
it's allocated in its enclosing scope and copied when you pass it
around.
}
- std.container.array can be used for deterministic arrays,
but has the issue of dangling pointers. There is probably a
good solution to this, but I don't know it.
I don't know of any dangling pointer issues with Array. It's
possible to create cycles resulting in a leak, but that's only
likely to happen if you heavily rely on refcounting everything.
- There seems to be no way to completely turn off the GC. That
is, never have the runtime allocate the memory used by the GC.
Like Rikki said, if you really want to the GC can be replaced
with an asserting stub. This isn't as hard as it sounds, just add
something like the file he linked to to your project. Since all
declarations are extern(C) there is no name mangling, and the
linker will prefer your own definitions over the ones in
druntime. I don't recommend you do this though unless you really
know what you're doing.
This are the pieces I've gathered, but I don't really know
what's true or how to use this knowledge. Some ideas I've
gleaned may also be outdated. Does anyone know the "correct"
way one would go about a non-GC program, and if a program can
be ran without ever instantiating a GC? Has there been any
progress on reducing the std library's usage of the GC?
You can annotate your functions as @nogc. The compiler will
disallow any potential GC use, including calling other functions
that are not @nogc.
P0nce is doing real time audio stuff, iirc he's using a thread
with a @nogc entry point for the strictly real-time parts, and
regular GC-using code in another thread for everything else.
Re: Benchmark Dlang vs Node vs Ruby
On Friday, 27 May 2016 at 15:18:38 UTC, llaine wrote: - And how can I minimize allocations? My previous post still allocates though, through that call to array at the end. I'm not sure how to completely remove all allocations (I'm not that familiar with vibe.d), but I strongly suspect it's possible. Someone else may know how. That said, it's a an optimization which should not be necessary in the general case. Only if you're doing something where there's tight maximum latency requirements (or when doing benchmarks ^^)
Re: Benchmark Dlang vs Node vs Ruby
On Friday, 27 May 2016 at 15:04:31 UTC, llaine wrote:
My level of D is really slow, so can you help me to improve
this? :)
Here's an alternative getCompanies. Untested so it may contain
some mistakes.
Company[] getCompanies() {
auto conn = client.lockConnection();
immutable result = conn.execStatement("SELECT id, name from
companies LIMIT 1", ValueFormat.TEXT);
delete conn;
import std.algorithm : map;
import std.array : array;
return result
.rangify
.map!(row => Company(row["id"].as!PGtext,
row["name"].as!PGtext))
.array;
}
Re: Benchmark Dlang vs Node vs Ruby
On Friday, 27 May 2016 at 13:45:23 UTC, llaine wrote: Hi guys, In my journey of learning about D I tried to benchmark D with Vibe.d vs node with express and Ruby with Sinatra. And the results are pretty surprising. I have to admit that I though D was more faster than that. How is this even possible ? I am doing something wrong ? Here are the numbers with the project : https://github.com/llaine/benchmarks/blob/master/README.md Could this line be the problem? https://github.com/llaine/benchmarks/blob/master/vibed/source/app.d#L30 You keep appending the db result to a class member, so the response size grows with every call. Additionally minimizing allocations should give a nice speed boost.
Re: Introspect alias name of an aliased type
On Monday, 23 May 2016 at 10:45:49 UTC, ParticlePeter wrote: Is there a way to get the alias uint32_t instead ? Nope. For the compiler uint32_t and uint are the same thing, this is by design. Typedef can be used to create a separate type with the same semantics as the type it's based upon: https://dlang.org/phobos/std_typecons.html#.Typedef
Re: How to share an appender!string?
On Thursday, 19 May 2016 at 10:58:42 UTC, Rene Zwanenburg wrote:
Calling task() only creates a Task, you also have to start it
somehow. The documentation contains an example:
https://dlang.org/phobos/std_parallelism.html#.task
I should add that a single shared array will cause contention if
the number of calls to addLine is large compared to the amount of
work done.
If performance is a problem, another way is to use a thread local
array and merge the arrays to a single global one on thread
termination. Something like this:
// thread local. Can be appended to without locking
string[] lines;
__gshared Mutex mutex;
shared static this()
{
mutex = new Mutex();
}
__gshared string allLines;
static ~this()
{
synchronized(mutex)
{
allLines ~= lines;
}
}
This will not preserve order of course, and you'll have to make
sure all your worker threads are terminated before using
allLines. Both can be fixed if required but will make the code
more complicated.
The upside is that this will avoid contention on the mutex.
You'll still have to be careful with the GC though, just about
every GC operation takes a global lock so it doesn't play nice
with high perf multi-threaded code.
Re: How to share an appender!string?
On Thursday, 19 May 2016 at 10:41:14 UTC, Thorsten Sommer wrote: On Thursday, 19 May 2016 at 10:13:21 UTC, rikki cattermole wrote: At this point I'd recommend you to just ignore Appender. Write your own. Dear rikki, Thanks for the proposal :) Here is the new attempt #4 as simple test case: https://dpaste.dzfl.pl/f6a9663320e5 It compiles & runs, but the array of strings gets not shared across threads :( I am sure that I missed something about the shared() concept... Hmm... Best regards, Thorsten Calling task() only creates a Task, you also have to start it somehow. The documentation contains an example: https://dlang.org/phobos/std_parallelism.html#.task
Re: Does DUB create .dll files?
On Tuesday, 17 May 2016 at 05:30:33 UTC, WhatMeWorry wrote: Am I supposed to get ALURE32.DLL from somewhere outside of DUB, or did I miss a step or command when I built derelict-alure-master? thanks. You'll need to get the dll somewhere else and set up DUB to copy it to your output directory. The derelict packages don't include prebuilt binaries for the libraries they're binding to. Here's how dlangui does it for example: https://github.com/buggins/dlangui/blob/master/dub.json#L60
Re: DMD flag -gs and -gx
On Friday, 13 May 2016 at 10:19:04 UTC, Nordlöw wrote: -gsalways emit stack frame IIRC, not emitting a stack frame is an optimization which confuses debuggers. So I think this can be used to make optimized builds a bit easier to debug. -gxadd stack stomp code After a function returns the stack normally still contains the local variables of that function, but they can be overwritten at any time (which is why it's unsafe to escape references to stack variables from a function). Using this switch will cause the compiler to overwrite the stack with bogus values before returning, which will help with early detection of bugs like the above. It can also be useful in security contexts where a function operates on sensitive data.
Re: Accepting function or delegate as function argument
On Wednesday, 4 May 2016 at 14:54:39 UTC, chmike wrote: Two constructors, one accepting a function and the other one accepting a delegate would do the job for the API. Is there a simple method to convert a function pointer into a delegate pointer that is also efficient ? http://dlang.org/phobos/std_functional.html#.toDelegate You can also make your constructor a template, constrain it on isCallable if you wish, and then use toDelegate. If the argument is already a delegate toDelegate will avoid doing extra work.
Static introspection in a class hierarchy
I'm in the process of making my code compile with DMD 2.071.
There's a construction I've been using which now results in a
deprecation message, and I'm not sure how to properly fix it.
It's a bit like design by introspection within a class hierarchy.
For example:
abstract class Base
{
private void initialize(){}
}
class Derived : Base
{
private void initialize(){}
}
Then an external function walks the inheritance chain of a
statically known derived type and call the init functions.
Something like this:
void callInitialize(T)(T instance)
{
static if(BaseClassesTuple!T.length > 1)
{
callInitialize!(BaseClassesTuple!T[0])(instance);
}
static if(only(__traits(derivedMembers,
T)).canFind("initialize"))
{
auto initializePtr = &__traits(getMember, instance,
"initialize")
initializePtr();
}
}
That __traits(getMember, ... trick was used to access private
initialize() functions but now results in a deprecation warning:
Deprecation: Derived.initialize is not visible from module
moduleWhereCallInitializeIsDefined
Declaring both initialize functions as public final doesn't work
at all:
Error: function Derived.initialize cannot override final function
Base.initialize
I thought shadowing like this was allowed? Apparently not..
Anyway, what would be the right way to do something like this? I
don't want to use virtual functions; the need to call
Base.initialize() in Derived.initialize is leaking implementation
details and error prone, and I can't afford the overhead.
(Initialize is a bad example regarding overhead, but I use the
same mechanism to register callbacks if present. Using static
introspection makes the difference between thousands of static
calls that do actual work and millions of useless virtual calls,
every second)
Re: Linker error for d.o: relocation R_X86_64_32 against `__dmd_personality_v0'
On Thursday, 21 April 2016 at 16:29:14 UTC, rcorre wrote:
- What happens when you compile a binary without phobos and
druntime, and with a custom entry point? I've never done that
myself and don't remember how to do that off the top of my
head, but the info should be somewhere on dlang.org.
I'll look into it.
Declaring a C-like main and the -defaultlib switch do the trick:
cmain.d
extern(C) void main() nothrow {}
---
dmd cmain.d -defaultlib=""
If even that fails to link I honestly wouldn't know where to look
next..
Re: Linker error for d.o: relocation R_X86_64_32 against `__dmd_personality_v0'
On Thursday, 21 April 2016 at 11:54:27 UTC, rcorre wrote: Thanks for the tip. Here's the linking code it shows: cc d.o -o d -m64 -L/usr/lib -L/usr/lib32 -Xlinker --export-dynamic -Xlinker -Bstatic -lphobos2 -Xlinker -Bdynamic -lpthread -lm -lrt -ldl /usr/bin/ld: d.o: relocation R_X86_64_32 against `__dmd_personality_v0' can not be used when making a shared object; recompile with -fPIC I tried `cc d.o -o d -m64 -fPIC and still get the error. Right, the -fPIC should be used while compiling the source code, but that's a gcc option. I think DMD is supposed to always generates position independent code. Here are a few things you can try to narrow the problem down. I'm not too familiar with this stuff though, so I'm just shooting in the dark here and not all of it may make sense ^^ - What happens when you mark main() as nothrow? That personality symbol has to do with exception handling. - Is it possible the linker is picking up 32 bit libraries? That -L/usr/lib32 switch is a bit suspicious. - What happens when you compile for 32 bit? - What happens when you compile a binary without phobos and druntime, and with a custom entry point? I've never done that myself and don't remember how to do that off the top of my head, but the info should be somewhere on dlang.org. - What happens when you compile some D code as a static lib, and link it with a main written in C? Oh, and I take it you've already tried to simply reinstall DMD? If you uninstall DMD, look if there are still sc.ini's and libphobos.a's floating around.
Re: Linker error for d.o: relocation R_X86_64_32 against `__dmd_personality_v0'
On Thursday, 21 April 2016 at 01:20:27 UTC, rcorre wrote: s/compile/link I _can_ compile a D library, but as soon as I try to link anything compiled with DMD it falls over. What is dmd's verbose output? (add -v switch) Some of the things it outputs are the location of the config file it uses, you can inspect that file to see if it has been borked somehow. Near the bottom you can find the used link command, that could also reveal the problem.
Re: Shallow copy object when type is know
On Wednesday, 20 April 2016 at 19:58:15 UTC, Tofu Ninja wrote:
To implement a copy/paste/duplicate functionality in a game
editor. I have an entity-component system, to duplicate an
entity, all it's components need to be duplicated. I have many
many components, I don't want to rely on manually writing copy
methods for each, it is too error prone. There are only a very
few that need special copies, almost all can get by with a
simple shallow copy. I would like a generic way to do that
shallow copy.
How are you handling loading and saving of your components? Can't
you use the same mechanism, without going through the storage
format?
Anyway, to answer your question, perhaps something like this:
(untested, it probably needs some minor modifications to compile)
T shallowCopy(T)(T source)
{
assert(source.classinfo == T.typeinfo);
auto rv = new T;
shallowCopy(source, rv);
return rv;
}
void shallowCopy(T)(T source, T target)
{
foreach(i; 0 .. T.tupleof.length)
{
target.tupleof[i] = source.tupleof[i];
}
import std.traits : BaseClassesTuple;
alias baseClasses = BaseClassesTuple!T;
static if(baseClasses.length > 0)
{
shallowCopy!(baseClasses[0])(source, target);
}
}
How does D not have shallow copy? Seems like a very basic
functionality...
Generally speaking copying class instances is a very bad idea.
That's one of the things structs are for.
Re: @nogc inconsistent for array comparison depending on mutability of elements
On Friday, 8 April 2016 at 09:56:41 UTC, Nick Treleaven wrote: If the comparison with b shouldn't be allowed, I suggest we add opEquals to std.range.only. This removes a need to import std.algorithm.equal and reduces bracket nesting: assert(b == only(1, 2)); equal[1] can compare ranges of different types. It's a bit less clear than the original code though. b.equal(only(1, 2)); [1] http://dlang.org/phobos/std_algorithm_comparison.html#.equal
Re: Issue with 2.071: Regression or valid error?
On Friday, 8 April 2016 at 08:26:11 UTC, Daniel Kozak wrote:
On Friday, 8 April 2016 at 06:08:38 UTC, 9il wrote:
On Thursday, 7 April 2016 at 15:55:16 UTC, Steven
Schveighoffer wrote:
Wow, totally agree with you. Compiler shouldn't make you jump
through this hoop:
void foo(Cat cat)
{
Animal a = cat;
a.create();
}
Please file a bug report, not sure why this happened.
-Steve
Why this is a bug? private methods are not virtual, are they?
--Ilya
No they are not virtual, so this is not a bug.
I disagree, virtuality has nothing to do with this. After all,
moving Cat to the same module as Animal, or making create()
public final will make the code compile.
Private symbols can (only) be accessed from the module where they
are defined, so anything in the animal module should be able to
call create() on a Cat just fine.
Re: VibeCustomMain not working
On Thursday, 7 April 2016 at 13:40:17 UTC, Rene Zwanenburg wrote: That's possible of course, but I'd expect something so fundamental breaking to be noticed sooner. Just to make sure, could you run dub with --force to rule out that it's picking up some stale object files from somewhere? And if that doesn't work, post the output of dub --force --verbose and we should be able to figure out where it goes wrong.
