Mixins, alias parameters, and alias template instantiations

[Reiner Pope]

I find it rather frustrating that D seems like it should be able to do 
what I want, but somehow it can't.

One common form of boilerplate code that mixins seem like a good 
candidate for is properties -- especially getters. So, I tried to write 
mixins that made this less work (like Ruby's attr_reader). Basically, I 
was hoping that we could mix in and rename a function, but the renaming 
bit doesn't seem to work. Here's what I tried:

template getter(alias val)
{
         typeof(val) getter() { return val; }
}

class Foo
{
         int a;
         mixin getter!(a) bar;
         alias getter!(a) foo; // Fails with error message 1 below.

         unittest
         {
             Foo f = new Foo();
             writefln(f.getter()); // This works, but it isn't what I want
             writefln(f.foo()); // I want the property to appear like this
             writefln(f.bar()); // Or this, but this gives errors 2 and 3.
             // And of course, f.foo() doesn't exist since it couldn't 
be alias'ed in.
         }
}

Error messages:
1. template instance cannot use local 'a' as template parameter
2. undefined identifier (f dotexp mixin getter!(a);
).opCall
3. function expected before (), not (f dotexp mixin getter!(a);
).opCall of type void

I can understand why the alias instantiation fails, and I understand 
that the following would achieve what I want:

mixin getter!(a) _g;
alias _g.getter bar;

but that then means two lines of code, and namespace pollution, for what 
should really be a trivial task.

What I would like is, just like for normal templates, a single item 
would be an Implicit Template Property, and could thus be renamed. This 
would just be a special syntactical shorthand for single elements, such 
as the case I described here.

I hope you like it.

Cheers,

Reiner