Re: GConf - defaults.

[Owen Taylor <otaylor redhat com>]

Dietmar Maurer <dietmar ximian com> writes:

> Hi Havoc,
> 
> I do not suggest to remove the ability to get default values from the
> configuration engine. But what do you do when:
> 
> gconf_client_get_int (c, "user_level", ...)
> 
> fails? Do you exit the program? I suggested to do something useful instead.

Well, the problem with writing:

 GError *error = NULL;
 
 level = gconf_client_get_int (c, "user_level", &error);
 if (error)
   {
     level = DEFAULT_LEVEL;
     g_error_free (error);
   }

is not just the problem with writing this all over the place, but it
is also that these fall back defaults don't get used at all normally,
so they'll rot, and may not work at all. 

The idea proposed to deal with failures of:

 - corrupt (wrong type) keys in the database
 - Backend not being reachable.

Is that we provide a fallback way of getting the real default values -
reading them from the schema file directly. These means that the as
long as the schema file is there, we have something half-way reasonable
to provide. If the schema file isn't there, we have a hosed install,
and exiting is probably the friendliest thing to do.

In GConf, the basic idea is that by using such a fallback default, and
providing appropriate global error handling settings, you can make
writing:

 level = gconf_client_get_int (c, "user_level", NULL);

the _right_ thing to do, not just a lazy thing that people will do
anyways. I'm sure there is a translation of this idea into
bonobo-config terms as well.

Regards,
                                        Owen