peter-b/geda-gaf — comment on commit 0c64a4bf43c653931e2b0f13b982c02c75b5dc10
File:  line 0
By istankovic:

I'd suggest that every public function accepting a GError ** have this,
or something like this, at the beginning:

``g_return_val_if_fail(err == NULL || *err == NULL, something);``

This makes sure that the caller either invokes the function with error return location
set to NULL (which means he ignores errors) or that he properly initializes the location
with NULL. Of course, one does not need to do this in functions that just pass the
error location to glib functions that do have these checks.