Re: Challenge: Make a data type for holding one of 8 directions allowing increment and overflow
On Tuesday, 12 March 2024 at 05:38:03 UTC, Liam McGillivray wrote:
I am in need of a data type for holding direction information;
one of 8 directions on a single axis. They are named in terms
of compass directions. If D had a 4-bit datatype, I would just
use this and do `+=2` whenever I want to change the datatype,
but it doesn't.
Perhaps this would be a good programming challenge for someone
more experienced than me. Make a data type (probably a struct)
for holding one of 8 directional values using 3 bits. It should
accept the use of increment operators to change the angle.
Ideally (but optionally), it should work as an enum of the same
name; "Direction".
Here's a unittest that it should ideally pass:
D actually supports both 3 and 4 bit integers. People will likely
warn you of minor portability risks... but if you target a
limited amount of platforms and prefer concise readable code,
then it's a text book example for bitfields. The risk can easily
be mitigated by having an unittest to catch the error directly(if
you try to port to some exotic platform).
dmd -preview=bitfields
(Some lines stolen from Rikki)
```d
struct Direction
{
private uint value : 3;
alias this = value;
enum Direction N = Direction(0);
enum Direction NE = Direction(1);
enum Direction E = Direction(2);
enum Direction SE = Direction(3);
enum Direction S = Direction(4);
enum Direction SW = Direction(5);
enum Direction W = Direction(6);
enum Direction NW = Direction(7);
}
```
Re: gdc or ldc for faster programs?
On Tuesday, 25 January 2022 at 20:04:04 UTC, Adam D Ruppe wrote: On Tuesday, 25 January 2022 at 19:52:17 UTC, Ali Çehreli wrote: ldc: ~0.95 seconds gdc: ~0.79 seconds dmd: ~1.77 seconds Maybe you can try --ffast-math on ldc.
Re: Trying to reduce memory usage
On Saturday, 13 February 2021 at 04:19:17 UTC, Ali Çehreli wrote:
On 2/11/21 6:22 PM, H. S. Teoh wrote:
>bool[size_t] hashes;
I would start with an even simpler solution until it's proven
that there still is a memory issue:
import std.stdio;
void main() {
bool[string] lines;
foreach (line; stdin.byLine) {
if (line !in lines) {
stdout.writeln(line);
lines[line.idup] = true;
}
// else this line already seen before; just skip it
}
}
(Grr... Thanks for the tab characters! :p)
Ali
Try this Boost Licensed tool.
https://github.com/eBay/tsv-utils/tree/master/tsv-uniq
Re: Is garbage detection a thing?
On Sunday, 29 November 2020 at 16:35:26 UTC, Mark wrote: Maybe I should just install Linux. But ... the drivers... My Thinkpad just doesn't like any Linux. I run out of ideas. In the first place all I wanted to do is make some music. Kind regards You could try a linux image in VirtualBox or VMware, to more easily evaluate if linux + ASAN matches your expectations or if it's another dead-end. Regards, Daniel
Re: Is garbage detection a thing?
On Sunday, 29 November 2020 at 16:05:04 UTC, Mark wrote: Thanks a lot for reading, and sorry for a lot of text that is off-topic and is not related to D. Sounds like what you want is ASAN? You can use it with plain C or D(LDC). https://clang.llvm.org/docs/AddressSanitizer.html
Re: Run code before dub dependency's `shared static this()`
On Sunday, 5 May 2019 at 08:24:29 UTC, Vladimirs Nordholm wrote:
Hello.
I have dub dependency which has a `shared static this()`.
In my project, can I run code code before the dependency's
`shared static this()`?
This might work:
pragma(crt_constructor)
extern(C)
void early_init()
{
}
Re: bug in doc?
On Thursday, 14 March 2019 at 14:47:18 UTC, Adam D. Ruppe wrote: On Thursday, 14 March 2019 at 14:22:52 UTC, spir wrote: https://dlang.org/spec/hash-map.html#static_initialization: Well, bug in implementation. That is *supposed* to work, but the compiler never implemented it. The docs really should point out this fact explicitly, though. Especially since it's hard to workaround inside function scope.
Re: Benchmarking sigmoid function between C and D
On Saturday, 7 April 2018 at 18:53:57 UTC, Arun Chandrasekaran wrote: What am I doing wrong here that makes the D equivalent 2.5 times slower than it's C equivalent? Compilers used: LDC2: LDC - the LLVM D compiler (1.8.0) GCC: gcc (Ubuntu 5.4.0-6ubuntu1~16.04.9) 5.4.0 20160609 11:36:39 ~/code/c/test2$ ldc2 sigmoid.d -O5 && ./sigmoid When benchmarking against C you need to add more switches to ldc2, like: -release -boundscheck=off
Re: Looking for an equivalent to C++ std::getline in D
On Monday, 8 May 2017 at 10:51:52 UTC, Ola Fosheim Grøstad wrote: On Sunday, 7 May 2017 at 20:50:10 UTC, Patrick Schluter wrote: If you look on TIOBE [1] newest stats, D does not look so bad after all. It's ranked 23 with a 1.38% share. The so Tiobe is a "hoax". Stack overflow counts for alternative languages: "swift": 146,374 "scala": 65,594 "go": 22,212 "rust": 6,596 "d": 2,211 "nim": 167 Stack-Overflow usage is clearly not representative of language usage. 1) Our forum is flourishing, why would any D developer use SO? 2) The number of questions is directly proportional with the difficulty of the language.(D is quite easy to learn, especially compared to rust).
Re: Mixin template confusion / compiler error.
On Thursday, 19 January 2017 at 08:41:53 UTC, Chris Katko wrote: Thank you! So: 1 - Is there any way TO get the output 64,64? Would this work for you? import std.meta; alias sizer1D = AliasSeq!(64); alias sizer2D = AliasSeq!(64,64); array_t!sizer2D caseX; array2_t!sizer1D caseY;
Re: Using Dub
On Sunday, 15 January 2017 at 13:23:25 UTC, Russel Winder wrote: Is there any way of setting dub to default to ldc2 rather than dmd as the compiler of use? (I do not want to have to put --compiler ldc2 on every dub command.) I have never used dub, but I know it's now also bundled with ldc2. I would assume that if your PATH to ldc2 comes before that of dmd, it would find the ldc2 bundled version of dub and it would do the smart thing(if not, that's a bug).
Re: BetterC classes
On Friday, 16 December 2016 at 15:17:15 UTC, Ilya Yaroshenko wrote: Hi Is it possible to use classes, which do not have monitor and other DRuntime stuff? Object can be allocated/deallocated using allocators, but they are very complex for betterC mode (monitor, mutex, object.d dependency). Can we have something more primitive? Ilya extern(c++) class Works pretty good in my experience, at least it gets rid of the monitor, yay!
struct to json/yaml/xml/whatever codegen
Is anyone aware of a tool which does something akin to the
following:
Given a C-like definition, automatically generate pure C code
with no dependencies.
Input c-struct:
struct Person
{
int id;
char* name;
}
Output minimal c-code:
void dumpPerson(Person* p)
{
printf("%d%s", p->id,
p->name);
}
It's easy to write in D... just want to avoid reinventing the
wheel.
Re: Is there a way to make a class variable visible but constant to outsiders, but changeable (mutable) to the class itself?
On Saturday, 21 May 2016 at 17:32:47 UTC, dan wrote:
Is it possible to have a class which has a variable which can
be seen from the outside, but which can only be modified from
the inside?
Something like:
class C {
int my_var = 3; // semi_const??
void do_something() { my_var = 4; }
}
Yes, I prefer this idiom:
class C
{
union
{
private int var_rw;
public const(int) var_ro;
}
}
Re: Is this template constraint a bug?
On Thursday, 12 May 2016 at 15:33:24 UTC, Eric wrote:
is(T : A!T) tells if T can automatically be converted to A!T.
The
last line below is doing just that, yet the template constraint
does not work.
class A(T) if (is(T : A!T))
{
}
Yes, it's a bug. Please file an issue.
Meanwhile try this workaround:
class A(T)
{
static assert(is(T : A!T), "...");
}
Re: mixed-in ctor not on par with explicit one?
On Wednesday, 13 January 2016 at 12:39:36 UTC, Jacob Carlborg
wrote:
On 2016-01-13 10:48, Shriramana Sharma wrote:
This is not what alias <> this is supposed to do, right?
No.
So how am I supposed to get the mixed in ctors work?
Looks like a limitation in the language.
This works:
mixin template myCtors()
{
this(int i) {}
this(char c) {}
}
struct Test
{
this(string s) {}
mixin myCtors mixed;
alias __ctor = mixed.__ctor;
}
void main()
{
auto a = Test("hello");
auto b = Test(1);
auto c = Test('c');
}
Re: Capturing __FILE__ and __LINE in a variadic templated function
On Monday, 2 November 2015 at 09:54:50 UTC, John Colvin wrote: Why can't I make Args a sequence of aliases? Works for me on multiple compilers. To be precise, this worked: Except it prints Arg instead of x, try: debug write(Args[i].stringof, " is ", Arg);
Re: Capturing __FILE__ and __LINE in a variadic templated function
On Monday, 2 November 2015 at 11:36:27 UTC, Nordlöw wrote: I want it to print the name of Arg in the closing as x is 11 See my previous comment: Arg -> Args[i].stringof
Re: friends with phobos, workaround?
On Thursday, 10 September 2015 at 13:19:08 UTC, Adam D. Ruppe wrote: On Thursday, 10 September 2015 at 08:22:29 UTC, Daniel N wrote: this(string caller = __MODULE__)(int val) if(caller == "std.conv") // Use scoped!Awesome That's disgustingly genius. I'm a bit jealous I didn't think of it myself! One slight problem though: you couldn't call super() from a derived class, since the constructor wouldn't even exist due to the constraint. super(): Hmm, yes that's a slight nuisance but manageable. Thanks, coming from you that means a lot. :) Hmm, maybe I'll wait a week or two before I share my next trick to give you ample time to think of it also, meanwhile I'll just scribble it down in the margin of my copy of "D Cookbook". ;) ... just hope I didn't jinx myself now ...
Re: Huge output size for simple programs
On Friday, 11 September 2015 at 11:15:33 UTC, NX wrote: I compile a simple hello world program in C and the results: hello_world.o -> 1.5 KB hello_world (linux executable) -> 8.5 KB If you care about binary sizes, use ldc2: ldc 225544 bytes (stripped + writeln) ldc 175736 bytes (stripped + puts) with tricks you can get lower, but that's out of the box...
Re: friends with phobos, workaround?
On Thursday, 10 September 2015 at 08:22:29 UTC, Daniel N wrote:
import std.typecons;
class Awesome1
{
private:
int val;
this(string caller = __MODULE__)(int val) if(caller ==
"std.conv") // Use scoped!Awesome
{
this.val = val;
}
}
class Awesome2
{
private:
int val;
this(string caller = __MODULE__)(int val)
{
static assert(caller == "std.conv", "Use
scoped!Awesome(...)!");
this.val = val;
}
}
void main()
{
static assert(__traits(compiles, scoped!Awesome1(1)));
static assert(__traits(compiles, scoped!Awesome2(1)));
static assert(!__traits(compiles, new Awesome1(1)));
static assert(!__traits(compiles, new Awesome2(1)));
}
PS 'private:' should of course be 'public:' when using this idiom.
Re: friends with phobos, workaround?
On Wednesday, 9 September 2015 at 23:44:14 UTC, Idan Arye wrote:
How about using a mixin
template(http://dlang.org/template-mixin.html)?
Thanks, it's a good solution. My only reservation is I would
prefer to find a way to directly invoke a symbol in std.* as
otherwise different frameworks might invent their own
conventions(well they might do that anyway). After a nights
sleep, I actually found such a solution!
This opens the door to a new class of meta-programming;
introspect the caller! :)
import std.typecons;
class Awesome1
{
private:
int val;
this(string caller = __MODULE__)(int val) if(caller ==
"std.conv") // Use scoped!Awesome
{
this.val = val;
}
}
class Awesome2
{
private:
int val;
this(string caller = __MODULE__)(int val)
{
static assert(caller == "std.conv", "Use
scoped!Awesome(...)!");
this.val = val;
}
}
void main()
{
static assert(__traits(compiles, scoped!Awesome1(1)));
static assert(__traits(compiles, scoped!Awesome2(1)));
static assert(!__traits(compiles, new Awesome1(1)));
static assert(!__traits(compiles, new Awesome2(1)));
}
friends with phobos, workaround?
For the record, I think D made the right decision... omitting
friends.
However there's one case in particular which I find useful,
anyone see a good workaround for this?
#include
class Friendly
{
private:
int val;
Friendly(int&& val) : val(val) {}
friend std::unique_ptr
std::make_unique(int&& val);
};
int main()
{
auto yay = std::make_unique(1);
auto nay = new Friendly(1);
}
Re: Array initialization with Struct templates
On Monday, 31 August 2015 at 05:38:54 UTC, Jonathan M Davis wrote:
So, you're going to need to pass it a Chameleon!(float,
purpose.POSITIONAL) and a Chameleon!(float, purpose.COLOR_ONLY
color), not 6 doubles - either that, or you're going to need to
declare a constructor for VertexData which takes 6 doubles or
floats and converts them to what's require to assign to its
member variables.
- Jonathan M Davis
Or turn Chameleon into a mixin template.
enum Purpose { POSITIONAL, COLOR_ONLY, COLOR_AND_ALPHA,
GENERIC_TRIPLE, GENERIC_QUAD }
Purpose purpose;
mixin template Chameleon(T, Purpose p) // mixin template
{
static if (p == Purpose.POSITIONAL) { // <-- NOT is
expression
T x, y, z;
} else static if (p == Purpose.COLOR_ONLY) {
T r, g, b;
} else static if (p == Purpose.COLOR_AND_ALPHA) {
T r, g, b, a;
} else static if (p == Purpose.GENERIC_TRIPLE) {
T a, b, c;
} else static if (p == Purpose.GENERIC_QUAD) {
T a, b, c, d;
}
};
struct VertexData
{
mixin Chameleon!(float, purpose.POSITIONAL) position;
mixin Chameleon!(float, purpose.COLOR_ONLY) color;
}
alias Vert = VertexData;
VertexData[] vertices =
[
Vert(1.0f, 1.0f, 1.0f, 0.0, 0.0, 0.0),
];
void main()
{}
Re: [Rosettacode] sum of powers conjecture
On Sunday, 26 July 2015 at 18:40:59 UTC, bearophile wrote: I've translated the C++ entry to D as third D entry, but it's not a good translation, I've just converted iterators to pointers instead of using ranges (the resulting speed is acceptable). You're welcome to improve it: http://rosettacode.org/wiki/Euler%27s_sum_of_powers_conjecture#Third_version Bye, bearophile Bear, welcome back! You and all your inspirational ideas have been missed! Good to see you.
Re: Mixin template functions are ignored in struct
On Tuesday, 14 October 2014 at 20:58:19 UTC, tcak wrote:
I have written a struct and a mixin template, and that mixin
template is mixed into that struct as follows.
Use a normal mixin + token strings(q{}).
enum TestCommonMethods = q{
public bool apply( int d, int e ){
return false;
}
};
public struct Test{
mixin(TestCommonMethods);
public bool apply(char c){
return true;
}
}
void main(){
Test t;
t.apply( 5, 3 );
}
