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March 28, 2011
std.conv.to can't convert to bool?
import std.stdio;
import std.conv : to;

void main()
{
   uint state = 1;
   writeln( to!bool(state) );
}

D:\DMD\dmd2\windows\bin\..\..\src\phobos\std\conv.d(99): Error: template std.conv.toImpl(T,S) if (!implicitlyConverts!(S,T) && isSomeString!(T) && isInputRange!(Unqual!(S)) && isSomeChar!(ElementType!(S))) does not match any function template declaration
D:\DMD\dmd2\windows\bin\..\..\src\phobos\std\conv.d(99): Error: template std.conv.toImpl(T,S) if (!implicitlyConverts!(S,T) && isSomeString!(T) && isInputRange!(Unqual!(S)) && isSomeChar!(ElementType!(S))) cannot deduce template function from argument types !(bool)(uint)
D:\DMD\dmd2\windows\bin\..\..\src\phobos\std\conv.d(99): Error: template instance errors instantiating template
boolConv.d(9): Error: template instance std.conv.to!(bool).to!(uint) error instantiating

What's the big problem with converting an int/uint to bool? I'm using a cast for now.
March 28, 2011
Re: std.conv.to can't convert to bool?
Wow not a minute later and I get bitten by my own solution. A C
function returned 1 for a supported feature, and -1 otherwise. And of
course -1 got converted to true, so then I had a bug in my code.

Damn silly C functions which return -1 when they should return 0.

Or damn me for not RTFM'ing.
March 28, 2011
Re: std.conv.to can't convert to bool?
Andrej Mitrovic Wrote:

> Wow not a minute later and I get bitten by my own solution. A C
> function returned 1 for a supported feature, and -1 otherwise. And of
> course -1 got converted to true, so then I had a bug in my code.
> 
> Damn silly C functions which return -1 when they should return 0.
> 
> Or damn me for not RTFM'ing.

Yeah, so the reason it doesn't do that conversion is because it will bite you.

Actually D already uses non-zero as true. Why do you need to cast it?
March 28, 2011
Re: std.conv.to can't convert to bool?
It can't implicitly convert an int to a bool. The C function returns an int.
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