mixin identifiers concept

[Ola Fosheim Grøstad]

On Monday, 31 January 2022 at 20:45:53 UTC, Paul Backus wrote:
> Using `std.format` for this incurs a substantial compile-time 
> performance penalty--dozens of templates must be instantiated, 
> memory must be allocated for CTFE, the format string must be 
> validated, etc. If the mixin is inside a template which is 
> itself instantiated many times, this overhead can really add up.

String mixins should be discouraged, not encouraged. Adding more 
band aids or special cases is not the right approach.

If compile time string processing is the root issue then one 
shouldn't solve that by changing the semantics of mixin(). That 
performance issue can be fixed by introducing classic string 
interpolation.