Re: weird exception on windows
On Friday, 15 December 2017 at 21:56:48 UTC, Steven Schveighoffer wrote: On 12/15/17 10:08 AM, Kagamin wrote: Maybe this https://issues.dlang.org/show_bug.cgi?id=18084 Thanks for looking into this. I created a PR to fix. Szabo, can you please try with this patch and see if it fixes your issue? https://github.com/dlang/phobos/pull/5932 -Steve I created the original issue in Szabo's post. I applied your fix, but nothing changed—the test program still crashes with the same exception :/ What gives?
Re: Treating a slice as an InputRange
Thanks for the insights everyone, it really helped!
I actually discovered that it wasn't working because one of the
parsing functions used `std.range.take` and, since I was giving
it a slice, `take` decided to save the fwdrange instead of
mutating it. I realised the `take` call was 100% useless, so I
removed it and it works perfectly now, and refactored to be more
idiomatic :)
On Wednesday, 15 November 2017 at 21:02:35 UTC, Jonathan M Davis
wrote:
If you specifically want a function to accept a range and
mutate it without returning it, then it should take its
argument by ref. Having it take auto ref is actually quite odd,
since that means that the behavior can depend on whether an
lvalue or rvalue is passed in.
I was under the impression that templated parameters needed `auto
ref` to work as `ref` properly. Good to know that's not true.
On Wednesday, 15 November 2017 at 21:11:16 UTC, Steven
Schveighoffer wrote:
I'd model your functions after the std.conv.parse functions:
https://dlang.org/phobos/std_conv.html#parse
This always takes the range by reference, and takes the type to
parse via a template parameter (more idiomatic D to have
parse!int than parseInt).
Yes, that is much more idiomatic than what I was going for. I've
been writing some Java, so I guess it got to my head :)
On Wednesday, 15 November 2017 at 21:14:04 UTC, Ali Çehreli wrote:
That should work:
import std.range;
T read(T, Range)(auto ref Range range) if (isInputRange!Range) {
range.popFront();
return 42;
}
unittest {
ubyte[] slice = [ 1, 2 ];
read!int(slice);
assert(slice == [2]);
}
void main() {
}
That is exactly what I was looking for, thanks!
Treating a slice as an InputRange
Hello, I'm writing a small parser for a specific binary format. The format is parsed by way of a sequence of functions, each deserializing a small portion of the format into a D type such as int, double, string, etc., operating on a single InputRange. The problem is, if I pass a slice to each of these functions, the slice doesn't get mutated by the popFront function used in the functions, so something like this: ubyte[] slice; ... int a = readInt(slice); double b = readDouble(slice); Ends up failing, because readInt properly reads an int, but the slice is not mutated "outside" of itself, which means readDouble will not read from where readInt stopped, and instead read from the start of the slice, and failing because there is an int encoded there and not a double. Both functions' signatures are like this: T readXXX(Range)(auto ref Range range) if (isInputRange!Range) So my question is, is there a way to treat a slice strictly as an InputRange, so that it is mutated no matter what? Or is there another way to do what I'm trying to do? I've worked around it using a "wrapper" InputRange struct, but I feel like there must be another way. Thanks!
Re: Undefined symbol for, apparently, valid code?
On Thursday, 6 July 2017 at 16:16:17 UTC, H. S. Teoh wrote: Which version of the compiler are you using? I just tested on the latest dmd git HEAD, and it (correctly) tells me that it's illegal to override a non-virtual function. I'm surprised you got your code to compile at all. `dmd --version` outputs: --- DMD32 D Compiler v2.074.1 Copyright (c) 1999-2017 by Digital Mars written by Walter Bright --- I downloaded it 3 days ago, for Windows. It's not git HEAD, but it's the one available for download in the homepage. Thankfully, it seems fixed for the next version then?
Re: Undefined symbol for, apparently, valid code?
On Thursday, 6 July 2017 at 06:48:57 UTC, rikki cattermole wrote: Templates+classes = require function body. Why? Templated methods are not virtual, they are final and cannot be inherited (so its a little strange that the override is valid). Ah well. I would've expected a compiler error, not an obscure linker error, but as Arafel said: Finally, have also in mind that if the function had been declared abstract (as it arguably should), a compile-time error would have been generated [2]. Maybe it was an error on my part for not declaring the function as abstract? My view was that the abstract attribute on a class marks all its members as virtual unless they have a body, which is how it works in, say, Java. Still, kinda odd that the linker is the one to call me out, and not the compiler. Pretty unexpected.
Undefined symbol for, apparently, valid code?
Hello. I am trying to compile this:
---
module asd.asd;
abstract class Asd
{
void opCall(Args...)(Args args);
}
@system unittest
{
class Foo : Asd
{
override void opCall(Args...)(Args args)
{
/* nothing */
}
}
Asd a = new Foo();
a(1, 2, 3);
}
---
This file is under source/asd/asd.d and I'm compiling with `dmd
-unittest -main -ofasd.exe source\asd\asd.d -m32 -g` under
Windows x64. For some reason, after the successful compilation
step, the linker then complains:
---
OPTLINK (R) for Win32 Release 8.00.17
Copyright (C) Digital Mars 1989-2013 All rights reserved.
http://www.digitalmars.com/ctg/optlink.html
asd.obj(asd)
Error 42: Symbol Undefined
_D3asd3asd3Asd17__T6opCallTiTiTiZ6opCallMFiiiZv
Error: linker exited with status 1
---
Am I doing something wrong, or is this a linker bug?
Thanks!
Re: Interfacing with C - calling member function of D struct from C?
On Sunday, 25 June 2017 at 02:09:53 UTC, Adam D. Ruppe wrote:
On Sunday, 25 June 2017 at 02:05:35 UTC, unleashy wrote:
How would I call `addToBar` from C code?
You don't. Instead write it like:
struct Foo
{
int bar;
}
extern(C) void addToBar(Foo* foo, int what) {
foo.bar += what;
}
Then define it in C the same way and you call it the normal way
from C.
But from D, you can UFCS call it:
Foo* foo = new Foo();
foo.addToBar(5); // cool
though I'd prolly just call it from D the same way you do from
C too.
Thank you, this is what I suspected :)
Interfacing with C - calling member function of D struct from C?
Hello! If I have a D struct like:
struct Foo
{
int bar;
void addToBar(int what) {
bar += what;
}
}
How would I call `addToBar` from C code? Would I need to put the
`addToBar` function outside of the struct and mark it as `extern
(C)` and in normal D code take advantage of UFCS or is there some
magic C incantation?
I've scoured the forums and other places for anything about this
but couldn't find any information whatsoever... so yeah. (or my
Google-fu is terrible)
Thanks!
