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digitalmars.D - mixin extension (question)

reply Andrew Edwards <ridimz_at yahoo.dot.com> writes:
Is it possible, or would it even be feasible, to extend mixins such that 
  the scope of a given mixin terminates upon encountering another mixin?

For example:

template someMixin(){ int x; }
template someOtherMixin(){ int y; }

class someClass {

   mixin someMixin;

   void foo() {
     int x; // error: x already defined
     x = 10;
     mixin someOtherMixin; // end of someMixin (within foo())
     y = 10;
     int xy = x * y; // error: x not defined
   }
   mixin someOtherMixin;
   writef(x * y); // outputs 100
}

I can see that there's already allot of problems with this idea. Maybe 
it would be better if we could explicitly terminate the lifespan of a 
particular mixin?

   mixin someMixin;
   x = 10;
   remove someMixin;
   writef(x); // error; x not defined

Any thoughts?

Andrew
Jul 23 2004
parent Sha Chancellor <schancel pacific.net> writes:
In article <cdsco0$ig$1 digitaldaemon.com>, Andrew Edwards says...
Is it possible, or would it even be feasible, to extend mixins such that 
  the scope of a given mixin terminates upon encountering another mixin?

For example:

template someMixin(){ int x; }
template someOtherMixin(){ int y; }

class someClass {

   mixin someMixin;

   void foo() {
     int x; // error: x already defined
     x = 10;
     mixin someOtherMixin; // end of someMixin (within foo())
     y = 10;
     int xy = x * y; // error: x not defined
   }
   mixin someOtherMixin;
   writef(x * y); // outputs 100
}

I can see that there's already allot of problems with this idea. Maybe 
it would be better if we could explicitly terminate the lifespan of a 
particular mixin?

   mixin someMixin;
   x = 10;
   remove someMixin;
   writef(x); // error; x not defined

Any thoughts?

Andrew

How is this good or usefull? Or how is it different from doing: void foo() { { mixin someMixin; } { mixin someOtherMixin; } } What are you trying to accomplish?
Jul 23 2004