Re: 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?