Unusual template specialisation behavior

[Matthias Walter]

Sergey Gromov Wrote:

> Christopher Wright <dhasenan at gmail.com> wrote:
> > Matthias Walter wrote:
> > > Hello guys,
> > > 
> > > Here's a (minimal) code snippet for my problem:
> > > 
> > > | struct Expression (R, E) { }
> > > | 
> > > | struct ResolveReference (T)
> > > | {
> > > |     alias T reference_type;
> > > | }
> > > | 
> > > | struct ResolveReference (T : Expression !(R, E))
> > 
> > The compiler should have caught this, I think. You have R and E, but 
> > they aren't defined. They default to int (which is why you saw that 
> > behavior), but not being defined, they should be a compile-time error.
> > 
> > The proper way to do this, unfortunately, involves static if rather than 
> > overloading. At least if you want your users to supply a single argument 
> > in all cases.
> 
> struct ResolveReference (T : Expression !(R, E), R, E)
> {
>     alias T* reference_type;
> }
> 
> works just fine:
> 
> void main (char[][] args)
> {
>     printRefType !(uint);
>     printRefType !(int);
>     printRefType !(long);
>     printRefType !(char);
>     printRefType !(float);
> 
>     Stdout (ResolveReference !(uint).reference_type.stringof).newline;
> }
> 
> Expression!(uint,uint)*
> Expression!(int,int)*
> Expression!(long,long)*
> Expression!(char,char)*
> Expression!(float,float)*
> uint
> 
> -- 
> SnakE

Thank you both! I guess, this works, because when passing an Expression !(R, E), the 2nd and 3rd specialisation parameters R and E are deduced and everything works fine, right? Thanks for your help!

best regards
Matthias Walter