[Issue 9365] Allow partially specified template aliases

[d-bugmail at puremagic.com]

https://d.puremagic.com/issues/show_bug.cgi?id=9365



--- Comment #7 from Peter Alexander <peter.alexander.au at gmail.com> 2013-11-10 13:58:24 PST ---
(In reply to comment #6)
> In reply to comment #4)
> > (In reply to comment #3)
> > > Something like
> > > 
> > > alias A(T) = B!(x, T);
> > > 
> > > Is more likely and more flexible.
> > 
> > See my use case, with your suggestions, this wouldn't work:
> > 
> > alias equalRoR = equal!equal;
> > 
> > An alternative suggestion, is to change how function templates are expanded.
> > Currently we have:
> > 
> > void foo(A, B)(A a, B b)
> > 
> > expanding to
> > 
> > template foo(A, B)
> > {
> >     void foo(A a, B b);
> > }
> > 
> > If instead, it expanded to:
> > 
> > template foo(A)
> > {
> >     template foo(B)
> >     {
> >         void foo(A a, B b);
> >     }
> > }
> > 
> > Then foo!int becomes a valid, alias-able symbol, which would solve the problem
> > as well.
> 
> I think this would also come with its own problems:
> 
> For example, how would you tell apart full/partial, eg:
> 
> void foo(U)();
> void foo(U, V)();
> 
> alias F = foo!int; //which one is this?

This is no different than:

alias F = foo;

It matches the template, not the instantiation. See my rewrite suggestion.

> There's also some problems with constraints. It's difficult to do what you
> suggest if there is a constraint that depends on both A/B. At best, you can
> validate when the last parameter is specified.

It's the same as aliasing a template -- you validate only when it is used.

-- 
Configure issuemail: https://d.puremagic.com/issues/userprefs.cgi?tab=email
------- You are receiving this mail because: -------