template specialization for arrays

[Jonathan M Davis]

On Saturday, October 29, 2011 16:44:16 J Arrizza wrote:
> On Sat, Oct 29, 2011 at 4:14 PM, Andrei Alexandrescu <
> 
> SeeWebsiteForEmail at erdani.org> wrote:
> > What's wrong with isStaticArray? Also, OP may want to look at
> > isNarrowString.
> > 
> > 
> > Andrei
> 
> Tried isStaticArray:
> 
> void abc(T:U[], U) (T parm1)
>   if (isDynamicArray!T)
>   {
>   writeln("dynamic array : ", parm1);
>   }
> void abc(T:U[], U) (T parm1)
>   if (isStaticArray!T)
>   {
>   writeln("static array : ", parm1);
>   }
> 
> 
> It didn't match. The output was:
> 
> simpleparm: 1
> dynamic array : str
> dynamic array : [1, 2]
> simpleparm: [3, 4]
> 
> 
> isNarrowString isn't in the traits online doc. Looked it up in std/traits.d
> and I tried it:
> 
> void abc(T) (T parm1)
>   if (isNarrowString!T)
>   {
>   writeln("string : ", parm1);
>   }
> void abc(T:U[], U) (T parm1)
>   if (isDynamicArray!T)
>   {
>   writeln("dynamic array : ", parm1);
>   }
> 
> 
> and get compiler ambiguity for abc("str") between the two templates above.

Of course you do. A narrow string is a dynamic array, so it matches both. You 
need to change the second constraint to if(isDynamicArray!T && 
!isNarrowString!T), then narrow strings won't match both.

- Jonathan M Davis