Re: [gnome-db] How do I read a GdaNumeric as a gdouble?

["Daniel Espinosa" <esodan gmail com>]

2006/3/15, Murray Cumming <murrayc murrayc com>:

On Wed, 2006-03-15 at 14:00 -0600, Daniel Espinosa wrote:
>
>
> 2006/3/15, Murray Cumming <murrayc murrayc com>:
>         On Wed, 2006-03-15 at 13:33 +0100, Vivien Malerba wrote:
>         > On 3/15/06, Juan Pablo <jpdborgna yahoo com ar> wrote:
>         > > With v=(GdaValue *)
>         > >
>         gda_data_model_get_value_at(dm,gda_data_model_get_column_position(dm,"stock1a"),0);
>         > > i get a numeric (from database) and i want to use it like
>         this (in the
>         > > ideal world...)
>         > >
>         gtk_spin_button_set_value(GTK_SPIN_BUTTON(lookup_widget(widget,"stock1a")),
>         > > gda_value_get_double(v));
>         > > But it is numeric, so im afraid i have to stringify it and
>         then
>         > > g_strotod it (it works but its ugly).
>         > >
>         > > ¿Is there any direct way to do it?
>         >
>         > For the moment you need to either use a string
>         representation, or
>         > build your own gdouble value from the GdaNumeric structure.
>         >
>         > However, I've added in my local working repository a
>         function to
>         > transform a GdaValue into another one called
>         g_value_transform() which
>         > you'll be able to use instead (but I've not yet committed
>         it).
>
>         Some kind of get_value_numeric_as_double() would be a lot
>         simpler.
>
>         GdaNumeric contains a string representation of the number
>         (presumably as
>         per the C locale, hopefully). At the moment, I need to parse
>         that string
>         representation to a double myself.
>
> Why it is used the GdaNumeric structure?
>
> Is realy necesary?
>
> If we think about that GdaValue is a GValue, you can store a long
> value and get transform, etc.

I don't believe that a long can store a floating point value (with a
decimal point).

You're right, but gdouble yes, then:

Who is using the GdaNumeric to store values?

Why don't store gdouble or gfloat when the providers return a value?

The client just nead to test if is it a double or a float using G_VALUE_TYPE(value) to know the returned type.

When I work in the port of GdaValue to GValue, I'll try to not modify the API for it, and not modify the provider's code; now and view the changes, and if not exist a good reazon to keep the actual API, I can simplify it. For example, I can use GDate enstead GdaDate and allow the client to use the GLib API to manipulate dates; and this apply to all the types like GdaNumeric, GdaTime and GdaMoney.

May elliminate the G_VALUE_TYPE_* #define, and use only the G_VALUE_TYPE, derive some types like GdaMoney form gfloat and others, to allow the client still know if is getting a Money type from the server and manipulate usign the standart locate functions to print or stringify it; of course this changes afact directly to the providers but may, in the future, create a more consistent API to use Values.

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