Singleton Pattern with struct
ParticlePeter
ParticlePeter at gmx.de
Thu Jan 24 10:14:35 PST 2013
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
More information about the Digitalmars-d-learn
mailing list