How to rescue all exceptions under a certain namespace?

Question

Is there a way to rescue all exceptions under a certain namespace?

For example, I want to rescue all of the Errno::* exceptions (Errno::ECONNRESET, Errno::ETIMEDOUT). I can go ahead and list them all out on my exception line, but I was wondering if I can do something like.

begin   # my code rescue Errno   # handle exception end 

The above idea doesn't seem to work, thus is there something similar that can work?

Answer 1

All the Errno exceptions subclass SystemCallError:

Module Errno is created dynamically to map these operating system errors to Ruby classes, with each error number generating its own subclass of SystemCallError. As the subclass is created in module Errno, its name will start Errno::.

So you could trap SystemCallError and then do a simple name check:

rescue SystemCallError => e   raise e if(e.class.name.start_with?('Errno::'))   # do your thing... end 

Answer 2

Here is another interesting alternative. Can be adapted to what you want.

Pasting most interesting part:

def match_message(regexp)   lambda{ |error| regexp === error.message } end  begin   raise StandardError, "Error message about a socket." rescue match_message(/socket/) => error   puts "Error #{error} matches /socket/; ignored." end 

See the original site for ruby 1.8.7 solution.

It turns out lambda not accepted my more recent ruby versions. It seems the option is to use what worked in 1.8.7 but that's IM slower (to create a new class in all comparisons. So I don't recommend using it and have not even tried it:

def exceptions_matching(&block)   Class.new do     def self.===(other)       @block.call(other)     end   end.tap do |c|     c.instance_variable_set(:@block, block)   end end  begin   raise "FOOBAR: We're all doomed!" rescue exceptions_matching { |e| e.message =~ /^FOOBAR/ }   puts "rescued!" end 

If somebody knows when ruby removed lambda support in rescue please comment.