From: Mauricio Fernandez <mfp@...>
Date: 2006-07-21T06:38:08+09:00
Subject: Re: Problem when 'loading' a file containing a class derived from a struct

On Fri, Jul 21, 2006 at 06:27:29AM +0900, Chris Roos wrote:
> I actually spotted this in a rails app but traced it back to ruby.  Is
> this a real problem/bug or am I missing something obvious?
> 
> $ cat > person.rb
> class Person < Struct.new(:forename, :surname)
> end
> $ irb
> irb> load 'person.rb'
> => true
> irb> load 'person.rb'
> TypeError: superclass mismatch for class Person
>        from ./person.rb:1
>        from (irb):2
>
> This behaviour has been experienced with both ruby 1.8.2 and 1.8.4.

Each time Struct.new(*args) is evaluated, it creates a new class:

Struct.new(:a,:b)                    # => #<Class:0xa7dd12f4>
Struct.new(:a,:b)                    # => #<Class:0xa7dd10c4>
Struct.new(:foo) == Struct.new(:foo) # => false
class X < Struct.new(:a); end
class Y < Struct.new(:a); end
X.superclass == Y.superclass         # => false


-- 
Mauricio Fernandez  -   http://eigenclass.org   -  singular Ruby