From: Jarmo Pertman <jarmo.p@...>
Date: 2010-09-23T06:35:32+09:00
Subject: Unexpected behaviour of defined? under 1.8.x

Hello!

I've just landed upon a very interesting landmine by using defined?

Consider the following code:

# a.rb
module A
  autoload :B, "b.rb"
end

defined?(A::B::C)
p A::B
p A::B.new.one
p A::B.new.two


# b.rb
module A
    class B
        puts "loading"
        def one; 1; end

        raise "no-no-no!"

        def two; 2; end
    end
end

So, when running a.rb what would you expect?

I would expect defined? line to raise an RuntimeError, but instead i
will see this:
loading
A::B
1
a.rb:8: undefined method `two' for #<A::B:0x49590c0> (NoMethodError)

This happens with 1.8.6 and 1.8.7, but is working as expected with
1.9.1.

In real life the code was something like this:
return unless defined?(A::B.some_method)

During the autoload, there was a ton of require statements of which
one failed with LoadError, but this didn't get raised to the console
and half of the unit-tests were failing. Yes, you guessed it right - i
did spend some amount of time with the debugger :)

Anyway, i've fixed that line to use respond_to? instead, but it is
still odd behaviour...


Jarmo Pertman
-----
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