Template Declarations - Why not Template definitions?

[anonymous via Digitalmars-d-learn]

On Tuesday, 30 June 2015 at 21:06:58 UTC, WhatMeWorry wrote:
> All the stuff I've read about templates always refers to them 
> as template declarations.
>
> So with the following code segment:
>
> template codeBlockTemplate(T, U)
> {
>     T a = 7;
>     U b = 'z';
> }
>
> codeBlockTemplate!(int, char);  // error here
>
> Microsof's Visual Studio IDE tells me <identifier> expected, ; 
> found
>
> But aren't templates instantiated at compile time? If so, isn't 
> memory allocated at compile time, so in theory couldn't 
> templates support code definitions?

I'm having trouble understanding the question/problem, but maybe 
you're looking for `mixin`:

mixin codeBlockTemplate!(int, char);

>
>
> Bonus question: Isn't a Zero-parameter template declaration 
> pretty much worthless?

Pretty much, yeah. A function with an empty body is pretty much 
worthless, too. I see no point in adding extra logic to forbid 
them, though. They don't do any harm and there are probably cases 
when it'd be annoying were they forbidden.