Re: clarification: GErrors and GQuarks

[David NeÄas <yeti physics muni cz>]

On Thu, May 10, 2012 at 04:45:09PM -0800, Christopher Howard wrote:
> Quick glib question here: I've been getting into glib's error reporting
> system and trying to integrate it into some code. (My code is using
> glib, but not GTK+ itself.) Overall it seems rather straightforward, but
> there was one point I was hoping for clarification on:
>
> In the g_set_error() parameters, the "domain" parameter is a GQuark.
> Does this mean that I am supposed to use something like
> "g_quark_from_string (MODULE_ERROR_DOMAIN_NAME)" for that parameter each
> time I call g_set_error?
>
> That would make sense, from what I've read in the GQuark part of the
> API. But I'm a little confused because the example given in the API for
> g_set_error() usage does not do this. (In the example, they just pass in
> some mysterious constant of unexplained origin.)

The mysterious constants follow the common usage pattern.  For Bar in
package Foo, header:

#define FOO_BAR_ERROR foo_bar_error_quark()

GQuark foo_bar_error_quark(void) G_GNUC_CONST;

typedef enum {
    FOO_BAR_ERROR_BAD_WHATEVER...
} FooBarError;

and code:

GQuark
foo_bar_error_quark(void)
{
    return g_quark_from_static_string("foo-bar-error-quark");
}

You then do

    g_set_error(error, FOO_BAR_ERROR, FOO_BAR_ERROR_BAD_WHATEVER, ...);

Yeti