From: Brian Candler <b.candler@...>
Date: 2011-01-07T00:48:24+09:00
Subject: Re: Class Initialization?

Kedar Mhaswade wrote in post #972556:
> It was not clear if the "class body" will be executed at most once.
> That's now clear.

And indeed, the execution of the code is what defines the class. The 
class and methods are defined *at runtime*.

Foo.bar rescue nil     # uninitialized constant Foo
class Foo
  def self.bar
    puts "hello!"
  end
end
Foo.bar                # this works

Amongst other things, this means you can conditionally define classes 
and methods.

However the code will be executed multiple times if you force it to be - 
for example using 'load' instead of 'require'. This can also happen if 
you require the same file using variations of the name, e.g.

require 'foo'
require './foo'
require '/path/to/foo'

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