• Traveler Hauptman (32/32) Sep 20 2005 I like the way my code looks written in D but I need to keep my C safety...

Traveler Hauptman <th barrett.com> writes:

I like the way my code looks written in D but I need to keep my C safety net.
So 
it is important for me to be able to use *all* my code written in D.

I have only very basic literacy in C++. So I have some questions that might be 
obvious to someone from a C++/OOP background.

What is the point of object.vtbl[]? It's per type info so you know everything 
about member functions at compile time and function names appear to show up in 
the object file mangled in a way that makes sense for virtual functions. Is 
there something dynamic happening to vtbl[]? I can imagine use in getting a 
pointer to an unknown object and then searching it's vtbl[] for a destructor... 
but there doesn't seem to be enough info available to do that.

Will the present behavior of extern(C) on classes be part of the specification
of D?

extern(C){
   class Foo{
     int func1();
     int func1(int i);
   }
}

Right now this appears to put Dmangled function names with C calling
conventions 
with a pointer to the object to operate on as the first parameter.

To work with my object from C:
extern int _D6FooMod3Foo5func1UZk(void*);
extern int _D6FooMod3Foo5func1UkZk(void*,int);
{
   void* foo;
   int i;

   foo = get_allocated_object_pointer();
   i = _D6FooMod3Foo5func1UZk(foo);
}

With a few #defines to clean up the mangled function names I have a sane 
interface into D objects. Can I depend on this behavior?


Thanks,

Traveler Hauptman