Is there any way to save pointer to class method, and call it later?

I know about ptr, and funcptr properties of delegates. I tried to change ptr and or funcptr manually after delegate was obtained. It worked in some situations. I don't know if it is a correct use of delegate:

import std.writeln;

class Foo
{
   string name;
   this(string e)
   {
       name = e;
   }
   void Print()
   {
       writeln("Print on ", name);
   }
   void Print2()
   {
       writeln("Print2 on ", name);
   }

}

auto foo = new Foo("foo");
auto dg = &foo.Print;
auto foo2 = new Foo("foo2");

dg();                        // Print on foo
dg.ptr = foo2;
dg();                        // Print on foo2
dg.funcptr = &Foo.Print2;
dg();                        // Print2 on foo2

The problem i see is that in funcptr there is real entry point for method used, not the index in virtual table, so the polymorphism can't work with that.

As I have written - i don't know whether it is correct use for delegate. Possibly the ptr, funcptr should be both const (Then is it possible to call method on object like in C++ ->* or .*?)
If not, then maybe delegates should work a little different.

wrzosk Wrote:

> The problem i see is that in funcptr there is real entry point for method used, not the index in virtual table, so the polymorphism can't work with that.
> 
> As I have written - i don't know whether it is correct use for delegate.
> Possibly the ptr, funcptr should be both const (Then is it possible to
> call method on object like in C++ ->* or .*?)
> If not, then maybe delegates should work a little different.

You would want something like:

dg();                        // Print on foo
dg = &foo2.Print;
dg();                        // Print on foo2
dg = &foo2.Print2;
dg();                        // Print2 on foo2

On 23.11.2010 01:22, Jesse Phillips wrote:
> wrzosk Wrote:
>
>> The problem i see is that in funcptr there is real entry point for
>> method used, not the index in virtual table, so the polymorphism can't
>> work with that.
>>
>> As I have written - i don't know whether it is correct use for delegate.
>> Possibly the ptr, funcptr should be both const (Then is it possible to
>> call method on object like in C++ ->* or .*?)
>> If not, then maybe delegates should work a little different.
>
> You would want something like:
>
> dg();                        // Print on foo
> dg =&foo2.Print;
> dg();                        // Print on foo2
> dg =&foo2.Print2;
> dg();                        // Print2 on foo2
>
That's obvious to me how to use is. But what is the purpose of read write ptr and funcptr ?