Re: [gnome-db] GdaDataModel is hard to implement on Vala

[Vivien Malerba <vmalerba gmail com>]

On 22 December 2011 23:21, Daniel Espinosa <esodan gmail com> wrote:

Find attached a patch (ready to commit) to implement missing invokers
on GdaDataModel. This allows vala extensions to implement GdaDataModel
with no problems.

2011/12/22 Daniel Espinosa <esodan gmail com>:

> I'm implementing GdaDataModel interface in an Gee Collection object
> called GdaData.DataModelIterable, but I can't implement the following
> virtual functions:
>
>                [NoWrapper]
>                public abstract bool i_get_notify ();
>                [NoWrapper]
>                public abstract bool i_iter_at_row (Gda.DataModelIter iter, int row);
>                [NoWrapper]
>                public abstract bool i_iter_next (Gda.DataModelIter iter);
>                [NoWrapper]
>                public abstract bool i_iter_prev (Gda.DataModelIter iter);
>                [NoWrapper]
>                public abstract bool i_iter_set_value (Gda.DataModelIter iter, int
> col, GLib.Value value) throws GLib.Error;
>                [NoWrapper]
>                public abstract void i_set_notify (bool do_notify_changes);
>
> These functions are declared *abstract* because they must be
> implemented and with the annotation [NoWrapper] because they don't
> have any function in the public header to call like the for example
> get_n_rows ();
>
>                [CCode (vfunc_name = "i_get_n_rows")]
>                public abstract int get_n_rows ();
>
> In the last function implementors must declare a get_n_rows ().
>
> In the case of the above functions they have the following problems:
>
> * i_iter_at_row, i_iter_next, i_iter_prev are functions that are
> implemented on a separated object GdaDataModelIter, then how to deal
> with that in C? Is this correct or can be modified in future version?
>
>
>  * i_set_notify and  i_get_notify they have a function that wrap it
> but they are "incompatible" because require different number of
> arguments and return type: freeze() and thaw (), initially I've
> declared them in GIR  as the one to call for the virtual functions but
> fails when Vala try to use them. Now they are declared as above with
> no invoker and with [NoWrapper] in Vala bindings.
>
> To fix all this problems is possible to add the following functions to
> the GdaDataModel just to have an invoker as a function to call and
> make easy to Vala (and maybe other languages) to implement
> GdaDataModel interface:
>
> gda_data_model_get_notify (GdaDataModel*)
> gda_data_model_set_notify (GdaDataModel*, gboolean)
> gda_data_model_iter_at_row (GdaDataModel*, GdaDataModelIter*, int)
> gda_data_model_iter_next (GdaDataModel*, GdaDataModelIter*)
> gda_data_model_iter_prev (GdaDataModel*, GdaDataModelIter*)
>
> Please tell me if this is correct in order to implement them and
> continue on Vala extensions.
>
> --
> Trabajar, la mejor arma para tu superación
> "de grano en grano, se hace la arena" (R) (en trámite, pero para los
> cuates: LIBRE
 

The patch does not apply to the current git master branch, but I think you can apply it yourself; please also add the "Since: 5.2.0" in each new function's comment.

Thanks,

Vivien