Re: [Vala] Vala : Suggestion for improvement : String Class wrapper for strings in Vala : Addendum

[Abderrahim Kitouni <a kitouni gmail com>]

Hello,

على 21 يون, 2011 م 07:18, كتب Serge Hulne:
> Apparently
>
>    string a = "hello";
>    string * b = a;
>
> and :
>
>     string a = "hello";
>     unowned string  b = a;
>
> appear to be translated by Vala into the exact same C code.
>
> Are these two ways to declare the same thing or is this just a bug which
> happens to work perchance ?

Not exactly the same thing, but the difference is relatively subtle: 
unowned means that the variable doesn't "own" the reference, that is, it 
doesn't need to be freed when the variable goes out of scope; a pointer, 
however, means that vala doesn't do the memory management at all, it's 
the *programmer's* responsibility to free the reference (or not) before 
the variable goes out of scope (using the delete statement).

For example, with
        unowned string b = a.dup ();
the compiler will report an error, while with
        string* b = a.dup ();
it won't, and you need to explicitly
        delete b;
after you're done with it.

Generally, if you're optimizing your program to reduce copying, it's 
better to use an unowned reference rather than a pointer.

HTH,
Abderrahim