Singleton Pattern with struct

[Ali Çehreli]

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