On Thursday, 24 January 2013 at 17:00:44 UTC, Ali Çehreli wrote:
On 01/24/2013 08:52 AM, ParticlePeter wrote:
> This method here ( my first approach ) does return a
reference to an
> object on the heap, right ?
Yes, but the caller does not get a reference.
> static ref Singleton instance() {
> if ( s is null )
> s = new Singleton( 0 ) ;
> return * s ;
> }
>
> so when I use it with:
> auto another_s = Singleton.instance ;
>
> Why is the s inside the struct and another_s not identical ?
> Afaik that is the purpose of the ref keyword ?
When you print the type of another_s you will see that it is
not a ref, because unlike C++, D does not have local ref
variables; it has pointers for that purpose.
import std.stdio;
ref int foo()
{
return *new int;
}
void main()
{
auto i = foo();
writeln(typeid(i));
}
Prints 'int', not 'ref int'. So, i is a copy of the dynamically
created int.
Ali
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:
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 ?
