Here a delegate from class C seems to be implicitely converted to a delegate of the module.

import std.stdio;
alias void delegate( int , inout int) GETTER;
class C{
  int i=3;
  GETTER getter(){
    return delegate void(int i, inout int o){ o= 2*this.i;};
  }
 }
void main(){
  auto c= new C;
  int i=0;
  c.getter()(0,i);
  writefln( i); //works: outputs 6
  GETTER q= c.getter(); // implicit conversion?
  q(0, i);
  writefln( i); //random result
}

-manfred

Manfred Nowak wrote:
> Here a delegate from class C seems to be implicitely converted to a delegate of the module.
> 
> import std.stdio;
> alias void delegate( int , inout int) GETTER;
> class C{
>   int i=3;
>   GETTER getter(){
>     return delegate void(int i, inout int o){ o= 2*this.i;};
>   }
>  }
> void main(){
>   auto c= new C;
>   int i=0;
>   c.getter()(0,i);
>   writefln( i); //works: outputs 6
>   GETTER q= c.getter(); // implicit conversion?
>   q(0, i);
>   writefln( i); //random result
> }

First off, on my machine (DMD/Linux):
---
urxae@urxae:~/tmp$ dmd -run test.d
269043800
125854208
---

The delegate isn't one 'of' the class. It's 'of' the C.getter() stack frame, which means it's invalid after the getter() function returned. *Never*[1] return a delegate literal from a function. Unpredictable results will follow.

And what exactly do you mean by "a delegate of the module"? AFAIK there is no such thing.


[1]: Well, at least not until Walter implements full closures that capture local variables.

Frits van Bommel wrote
> it's invalid after the getter() function returned.

> And what exactly do you mean by "a delegate of the module"? AFAIK there is no such thing.

Thank you, you are right with both remarks. I was simply unable to detect my own fault.

-manfred