From: Eric Christopherson <echristopherson@...>
Date: 2012-12-05T09:57:25+09:00
Subject: Re: Weird rescue

On Tue, Dec 4, 2012 at 5:01 PM, Eric Christopherson
<echristopherson@gmail.com> wrote:
> On Tue, Dec 4, 2012 at 12:13 PM, Kai König <kai@kairichardkoenig.de> wrote:
>> Can somebody tell why this happens ?
>>
>>
>> x = StandardError.new(:hello)
>> y = StandardError.new(:hello)
>> puts x == y # => true
>> puts x === y # => true
>>
>> begin
>>   raise x
>> rescue x
>>   puts "ok" # gets printed
>> end
>>
>> begin
>>   raise x
>> rescue y
>>   puts "ok" # doesn't get printed
>> end
>>
>
> That is strange. According to the Pickaxe[1] (the online one at least;
> I don't have my 1.9 copy handy) the exception matching is supposed to
> be done with kind_of?; and the source code[2] seems to bear that out.
> Clearly StandardError.new(:hello).kind_of?(StandardError.new(:hello))
> is not true; it raises a TypeError because the argument isn't a class
> or module.
>
> [1] http://www.ruby-doc.org/docs/ProgrammingRuby/html/tut_exceptions.html
> [2] http://rxr.whitequark.org/mri/source/eval.c#714
>

OK, so apparently this has been answered on StackOverflow:
http://stackoverflow.com/questions/13709100/what-is-wrong-with-this-rescue-example