Re: [Vala] Vala : Suggestion for improvement : String Class wrapper for strings in Vala : Erratum (2)

[Serge Hulne <serge hulne gmail com>]

I stand corrected !

Thank you Abderrahim for this detailed explanation.

Serge.



On Tue, Jun 21, 2011 at 8:56 PM, Abderrahim Kitouni <a kitouni gmail com>wrote:

> 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