template specialization question

[Ellery Newcomer]

On 02/01/2010 07:29 PM, Ali Çehreli wrote:
> daoryn wrote:
>  > According to http://digitalmars.com/d/2.0/template.html it is
> possible to specify template specialization so that DMD prefers them
> when instanciating templates, however the following code:
>  >
>  >
>  > ---------------------------------
>  > import std.stdio;
>  >
>  > void print(T)(T thing)
>  > {
>  > writeln("Calling print(T)");
>  > writeln(T.stringof);
>  > }
>  >
>  > void print(T:T[])(T[] things)
>
> Regardless of the intent of the document, which may very well be
> outdated or wrong at this time; the specialization above is confusing.
>

It is.

> If (T:T[]) is supposed to mean "array type", then the function parameter
> 'T[] things' above would mean "array of array". i.e. If T is T[], then
> the parameter is T[][]...

I wondered that too.

I think what happens is the type is matched to T[], and not T, and then 
it figures out from there what T should be, so that T[] in the function 
parameter is the same as the type passed in.

>
> For that reason this is more logical to me, and I would expect it to be
> sufficient to express the specialization:
>
> void print(T:T[])(T things)
>
> But it still selects the general definition above...
>
> I don't know... :)
>
> Ali