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digitalmars.D.bugs - classinfo issue

reply "Ben Hinkle" <bhinkle mathworks.com> writes:
The documentation for stack allocation of classes has the line
 Foo f = new(std.c.stdlib.alloca(Foo.classinfo.init.length)) Foo;
which works fine. The problem is when I try to Foo.classinfo in another
class. For example

class clsB {
  new(uint sz, void* p){ return p; }
  int x,y;
}
struct StorageFor(T:Object) {
  ubyte[T.classinfo.init.length] data;
}
class clsA {
  StorageFor!(clsB) storageForB;
  clsB b;
  this() {
    b = new(&storageForB) clsB;
  }
}
int main() {
  clsA a = new clsA;
  return 0;
}

it errors during the "semantic" phase that clsB doesn't has a property
'classinfo' (even if I remove the template). My guess is that the
classinfo's are valid only during a later semantic phase. It would be nice
to be able to use classinfo's for placing storage in other classes as well
as on the stack.

-Ben
Oct 19 2004
parent Vathix <vathix dprogramming.com> writes:
On Tue, 19 Oct 2004 12:10:49 -0400, Ben Hinkle <bhinkle mathworks.com>  
wrote:

 class clsB {
   new(uint sz, void* p){ return p; }
   int x,y;
 }
 struct StorageFor(T:Object) {
   ubyte[T.classinfo.init.length] data;
 }
 class clsA {
   StorageFor!(clsB) storageForB;
   clsB b;
   this() {
     b = new(&storageForB) clsB;
   }
 }
 int main() {
   clsA a = new clsA;
   return 0;
 }

Cool idea. (cast(TypeInfoClass)typeid(T)).info.init.length works, but it's not a constant.
Oct 19 2004