Eliminating code duplication for static/nonstatic functions

[Benjamin Thaut]

Am 19.09.2013 19:10, schrieb Andrei Alexandrescu:
> Consider a struct that may or may not have state depending on a type
> parameter:
>
> struct S(T)
> {
>    enum hasState = FieldTypeTuple!T.length || isNested!T;
>    static if (hasState)
>      T _theT;
>    else
>      alias _theT = T;
>    ...
> }
>
> This is really nice because I don't bloat S unnecessarily and I get to
> use _theT.method() uniformly whether or not it's the type itself or the
> data member.
>
> The duplication problem appears when S itself must define a method that
> should be static or nonstatic depending on the existence of state.
> Consider:
>
> struct S(T)
> {
>    ... continued from above ...
>    if (hasState)
>      int method() { return 1 + _theT.method(); }
>    else
>      static int method() { return 1 + _theT.method(); }
> }
>
> In the general case the body of S!T.method() may be of course larger,
> which makes for a nasty duplication - essentially all but the "static"
> keyword must be duplicated.
>
> Any ideas for a clean solution? I can't get much further than string
> mixins, which wouldn't be clean :o).
>
>
> Thanks,
>
> Andrei

Can't we make the compiler deduce the static attribute? If a template 
method or a method of a template struct / class does not access any of 
its members it becomes static automatically?