Re: [Vala] Fwd: Re: GenericArray problem

[Andy Lees <andrewl oz gmail com>]

Thanks for the very detailed response, Evan.  I have filed a bug
accordingly.

In the meantime a simple [Compact] vala implementation of the generic array
functionality I need appears to take fewer cpu cycles than GenericArray
(when optimised) when tested with a few operation patterns, so it's not a
stopper issue for me, and the derivation works fine in that case.

On Sun, Oct 18, 2015 at 5:25 AM, Evan Nemerson <evan coeus-group com> wrote:

> On Sun, 2015-10-18 at 00:13 +1100, Andy Lees wrote:
> > I wonder if anyone has suggestions as to why GenericArray should
> > demonstrate this behaviour?
>
> The types in GLib aren't designed for inheritance.  Due to restrictions
> in the C API it can never be fully functional, so it is generally
> better to use composition.
>
> That said, this specific case *could* work with a bit of work in the
> compiler.  Support for inheriting from a compact class which uses
> simple generics in the constructor (a fairly uncommon thing to do) is,
> apparently, a bit buggy.  Specifically, the generic free function isn't
> passed.  It would be great if you filed a bug about this.
>
> > Also I note that the doco for GenericArray indicates that it takes a
> > defaulted initial size parameter, but it appears that it just ain't
> > so -
> > giving an initial size causes a compilation error on too many args.
>
> If you take a look at the VAPI, you'll notice it looks like this:
>
>     #if GLIB_2_30
>     [CCode (cname = "g_ptr_array_new_full", simple_generics = true)]
>     public GenericArray (uint reserved_size = 0);
>     #else
>     [CCode (cname = "g_ptr_array_new_with_free_func", simple_generics =
>     true)]
>     public GenericArray ();
>     #endif
>
> The version with the reserved_size argument is only available if you
> target a version of glib >= 2.30, which makes sense given that
> g_ptr_array_new_full was only added in glib 2.30.
>
> Pass --target-glib=2.30 (or greater) to valac and the extra argument
> will work.
>
> I believe valadoc.org produces documentation which assumes you are
> targeting the current stable version of glib.  Unfortunately it's not
> really possible to produce output which contains both versions without
> substantial changes to the parser in libvala, so a choice had to be
> made.  Targeting the current stable version seemed like the best
> approach.
>
>
> > On Sat, Oct 17, 2015 at 11:58 PM, Daniel Espinosa <esodan gmail com>
> > wrote:
> >
> > > ---------- Mensaje reenviado ----------
> > > De: "Daniel Espinosa" <esodan gmail com>
> > > Fecha: oct. 17, 2015 7:58 AM
> > > Asunto: Re: [Vala] GenericArray problem
> > > Para: "Andy Lees" <andrewl oz gmail com>
> > > Cc:
> > >
> > > In LibreSCL (www.librescl.org) I just declare an empty class
> > > derived from
> > > a
> > > generic one, this makes to call
> > >
> > > var a = new Intclass ();
> > >
> > > Just works.
> > >
> > > If you want a binding friendly class definition you should define
> > > your own
> > > get/set methods returning the actual value type not a generic, as
> > > in:
> > >
> > >
> > > https://github.com/powerwaremediacore/librescl/blob/master/librescl
> > > /tDA.vala
> > >
> > > I plan to add iterator methods to collections, this will allow
> > > bindings to
> > > use them on loops. Because we relay on Gee, its iterators are
> > > generic
> > > making hard/impossible to use on GObject Introspection bindings.
> > > El oct. 16, 2015 6:22 PM, "Andy Lees" <andrewl oz gmail com>
> > > escribió:
> > >
> > > > Hi,
> > > >
> > > > If I declare a derived class of GenericArray, like so:
> > > >
> > > > public class IntArray : GenericArray<int> {
> > > >   public IntArray() {
> > > >   }
> > > > }
> > > >
> > > > I get a gcc error, like so:
> > > > /tmp/a.vala.AH856X.c: In function ‘int_array_new’:
> > > > /tmp/a.vala.AH856X.c:66:2: error: too few arguments to function
> > > > ‘g_ptr_array_new_with_free_func’
> > > >   self = (IntArray*) g_ptr_array_new_with_free_func ();
> > > >
> > > > whereas with Array (for example) it just works.
> > > >
> > > > Is there something I'm doing wrong, or is this a bug?
> > > >
> > > > Using Vala 0.30.0
> > > >
> > > > Regards,
> > > >
> > > > Andrew Lees
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