Singleton Pattern with struct

[ParticlePeter]

On Thursday, 24 January 2013 at 17:35:58 UTC, Ali Çehreli wrote:
> On 01/24/2013 09:26 AM, ParticlePeter wrote:
>
> > Thanks, I re-read the purpose of ref type function() in the D
> > programming language, and the sole purpose is that such a
> function call
> > can be directly a parameter to another function expecting a
> ref ?
>
> As Maxim Fomin noted, I didn't word it correctly: The caller 
> does get a reference to the returned object.
>
> So, the sole purpose is not to pass a variable to a ref-taking 
> function.
>
> > As:
> >
> > ref int foo() { return some class member ; }
> > void bar( ref int data ) { do something with data ; }
> >
> > This means, it is never ever possible to initialize any
> variable with a
> > reference some class/struct member data ? Unless I return the
> address of
> > the member data ?
>
> Not true. There are no local ref variables nor ref member 
> variables in D. All you need to do is to use pointers instead:
>
> ref int foo()
> {
>     return *new int;
> }
>
> struct S
> {
>     int i;
>     int * j;
>
>     this(int i)
>     {
>         this.i = i;
>         this.j = &foo();  // member pointer
>     }
> }
>
> void main()
> {
>     int* i = &foo();  // local pointer
> }
>
> No, the pointer syntax is not the cleanest. :)
>
> Ali

This is what I meant :-) I can't return a reference ( with 
reference I don't mean reference type, but semantically a 
reference ) to a class member, but I can return the address of 
this member, which, to my understanding is an implicit pointer.

struct Foo  {
	int val = 3 ;
	auto getValPtr()  {  return & val ;  }
}

Foo foo ;
writeln( foo.val ) ; // = 3
auto valPtr = foo.getValPtr() ;
* valPtr  = 7 ;
writeln( foo.val ) ; // = 7