Kevin Wolf <kw...@redhat.com> writes:
> Am 22.09.2022 um 14:42 hat Markus Armbruster geschrieben:
[...]
>> If you have callers that need to distinguish between not found, found
>> but bad, found and good, then return three distinct values.
>>
>> I proposed to return -1 for found but bad (error), 0 for not found (no
>> error), and 1 for loaded (no error).
>
> My intuition with this one was that "not found" is still an error case,
> but it's an error case that we need to distinguish from other error
> cases.
>
> Is this one of the rare use cases for error classes?
If I remember correctly, "not found" is not actually an error for most
callers. If we make it one, these callers have to error_free(). Minor
annoyance, especially when you have to add an else just for that.
Even if we decide to make it an error, I would not create an error class
for it. I like
rc = module_load_one(..., errp);
if (rc == -ENOENT) {
error_free(*errp);
} else if (rc < 0) {
return;
}
better than
Error *err = NULL;
module_load_one(..., &err);
if (err && err->class == ERROR_CLASS_NOT_FOUND) {
error_free(err);
} else if (err) {
error_propagate(errp, err);
return;
}
I respect your intuition. Would it still say "error case" when the
function is called module_load_if_exists()?
Hmm, another thought... a need to distinguish error cases can be a
symptom of trying to do too much in one function. We could split this
into "look up module" and "actually load it".
