From: Jan Svitok <jan.svitok@...>
Date: 2006-08-30T23:02:01+09:00
Subject: Re: Why must LoadError be explicitly caught from require()

On 8/30/06, Ben Harper <rogojin@gmail.com> wrote:
> Why do I explicitly have to catch LoadError as thrown by 'require'?
>
> The following code demonstrates my problem:
> ------------------------------------------
> begin
>  require 'not_existent'
> rescue
>  print 'I am never reached'
> #rescue LoadError
> # print "But uncommenting these lines allows me to handle it"
> end
> ------------------------------------------
>
> I am running 1.8.4 on Windows.

Because empty 'rescue' clause is the same as 'rescue StandardError',
and LoadError is not its subclass. See [1] for the hierarchy (or it's
in PickAxe as well).

This is documented in rdoc [2]; but don't worry, I overlooked it as well ;-)

[1] http://www.zenspider.com/Languages/Ruby/QuickRef.html#34
[2] http://ruby-doc.org/docs/ProgrammingRuby/html/tut_exceptions.html#S2:
...If you write a rescue clause with no parameter list, the parameter
defaults to StandardError.