Why value of pointer to this is different in global function, member function and constructor?
//---------------------------------------------------------------------------------------------------
module test;
class Foo{
  this(){
    writefln("ctor 0x%08X", cast(dword)&this);
  }

  void func(){
    writefln("func 0x%08X", cast(dword)&this);
  }
}
import std.stdio;

void main(){
    Foo foo = new Foo;
    writefln("main 0x%08X", cast(dword)&foo);
    foo.func();
}
//---------------------------------------------------------------------------------------------------
sample output:
ctor 0x0012FEC8
main 0x0012FEE8
func 0x0012FEB8

On Wed, 21 Oct 2009 16:53:20 -0400, Zarathustra <adam.chrapkowski@gmail.com> wrote:

> Why value of pointer to this is different in global function, member function and constructor?
> //---------------------------------------------------------------------------------------------------
> module test;
> class Foo{
>   this(){
>     writefln("ctor 0x%08X", cast(dword)&this);
>   }
>
>   void func(){
>     writefln("func 0x%08X", cast(dword)&this);
>   }
> }
> import std.stdio;
>
> void main(){
>     Foo foo = new Foo;
>     writefln("main 0x%08X", cast(dword)&foo);
>     foo.func();
> }
> //---------------------------------------------------------------------------------------------------
> sample output:
> ctor 0x0012FEC8
> main 0x0012FEE8
> func 0x0012FEB8

&this is the address of the pointer itself (local function argument on the stack), not what it points to.  you want cast(void *)this.

-Steve

Steven Schveighoffer Wrote:

> On Wed, 21 Oct 2009 16:53:20 -0400, Zarathustra <adam.chrapkowski@gmail.com> wrote:
> 
> > Why value of pointer to this is different in global function, member
> > function and constructor?
> > //---------------------------------------------------------------------------------------------------
> > module test;
> > class Foo{
> >   this(){
> >     writefln("ctor 0x%08X", cast(dword)&this);
> >   }
> >
> >   void func(){
> >     writefln("func 0x%08X", cast(dword)&this);
> >   }
> > }
> > import std.stdio;
> >
> > void main(){
> >     Foo foo = new Foo;
> >     writefln("main 0x%08X", cast(dword)&foo);
> >     foo.func();
> > }
> > //---------------------------------------------------------------------------------------------------
> > sample output:
> > ctor 0x0012FEC8
> > main 0x0012FEE8
> > func 0x0012FEB8
> 
> &this is the address of the pointer itself (local function argument on the stack), not what it points to.  you want cast(void *)this.
> 
> -Steve

Thank's a lot. God blesses C++ for the '->' operator ;)

Hello Zarathustra,

> Thank's a lot. God blesses C++ for the '->' operator ;)

God curse C++ for the '->' operator. 

And I'm not making a Joke, I hate that thing! 

It makes a distinction between value and reference semantics where they don't matter (lookup) and does nothing for the cases (assignment, arg passing) where it does.