Re: Follow-on question about delegates

[BCS]

Hello Jerry,

OK, having thought a bit more about delegates, I now have another
question.
The ABI shows a delegate as consisting of a context ptr and a function
ptr.  The context ptr can be a class reference, ptr to struct, ptr to
closure or ptr to stack frame.

If you're passing one of these delegates into another function, how
does the receiving function figure out what kind of context it's
looking at?  Each of these things will look different in memory.
Also, structs at least don't have a header that can be used to
disambiguate the situation.

Thanks,
Jerry

ok here is a brain twister: the context can be anything, it's just a size_t 
full of bits.

**** THE FOLLOWING IS NOT RECOMMENDED *****

http://codepad.org/8nnoIKNQ

import std.stdio;
struct S
{
   int go()
   {
       U u;
       u.s = this;
       return u.a + u.b;
   }
}

union U
{
   S* s;
   struct {  short a; short b; }
}

void main()
{
    U u;
    u.a= 54;
    u.b = 42;

    int delegate() dg = &u.s.go;


    writef("%s\n", dg()); 
}