An idea to improve eponymous templates

[Steven Schveighoffer]

On Thu, 12 Apr 2012 14:04:44 -0400, Timon Gehr <timon.gehr at gmx.ch> wrote:

> The general idea is useful, but there are issues.
>
> 'this' is the wrong keyword for the job. A class or struct instance is  
> very different from a template instance and the proposed usage would  
> clash with existing and useful ones. (assuming that it would work for  
> symbol lookups in addition to declarations)
> 'template' or maybe 'scope' would be superior choices.

I think static is underused keyword, maybe it should have a dual meaning  
here.

In all seriousness, I'm not sure template is right either.  Scope sounds  
like a very bad choice to me.

Are there any eponymous examples where the name of the template is the  
first token?  If so that would clash with declaring a new template.

I would find this weird:

template X(T)
{
    alias T template;
    template t {
       ...
    }
}

It looks like you are using template as an alias to T, but the second  
'template' inside is using it for creating a new template.

Also, consider this:

template X(T)
{
    class template {
       static typeof(this) create() { return new typeof(this);}
    }
}

I don't think you could realistically use any keyword instead of  
typeof(this), I really think the best solution is what we have, or use a  
new keyword.

Another option is to do something like:

@eponymous template X(T) // changed from Y(T)
{
    class Y { } // oops forgot to change this to X!
}

Error: template X did not declare eponymous symbol

At least changes would be loud errors.

-Steve