From: "Iñaki Baz Castillo" <ibc@...>
Date: 2011-05-02T06:02:40+09:00
Subject: Re: Is it usual/valid to extend custom classes under Errno module?

2011/5/1 Christopher Dicely <cmdicely@gmail.com>:
> If you are writing an asynchronous, non-blocking DNS library on top of
> EventMachine, and returning results the same way you get them back
> (via callbacks), then, yeah, raising an exception is just going to
> cause all kinds of problems.

Yes, non-blocking paradigm breaks all the rules (joking) :)


> You could probably return (not raise) an exception (have a separate
> Exception class for each broad type of errors, and populated it with
> the appropriate details; this seems to be approximately what your
> Errno based approach would do -- Errno, after all, is a descendant of
> Exception) in your error callbacks.
>
> OTOH, if you aren't going to be providing any additional information
> other than the general type of error, either a symbol or an opaque
> constant defined in your library works just as well.

Thanks. The C library on top of my Ruby library (udns) returns 3-4
kinds of error, and being DNS they are self-descriptive (no more info
is required). Basically "domain not found", "resource record not
found", "malformed response", "timeout", so for now I'm done with 4
Symbols. But yes, perhaps I will change and return an instance of a
custom error class (in fact the same instance always, the one
generated within the Ruby C extension, as no more info is required in
the error).

Thanks a lot.

-- 
Iñaki Baz Castillo
<ibc@aliax.net>