From: Gavin Kistner <gavin@...>
Date: 2005-07-13T21:42:13+09:00
Subject: Re: Initialization via a Module

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On Jul 12, 2005, at 10:20 PM, Daniel Brockman wrote:
> Call `super' from `initialize'.

Gleah, of course. My library was fine, my use of it was broken.  
Thanks :)

I did discover this, problem, however:

module Foo
   attr_reader :foo
   def initialize( *args )
     super
     @foo = 'foo'
   end
end

class Bar
   include Foo
   def initialize
     super
     @bar = 'bar'
   end
end

b = Bar.new
p b.foo  #=> "foo"

class Bar2
   include Foo
   def initialize( bar_value )
     super
     @bar = bar_value
   end
end

b2 = Bar2.new( 'bar2' )

/Users/gavinkistner/Desktop/tmp.rb:5:in `initialize': wrong number of  
arguments (1 for 0) (ArgumentError)
     from /Users/gavinkistner/Desktop/tmp.rb:5:in `initialize'
     from /Users/gavinkistner/Desktop/tmp.rb:23:in `initialize'
     from /Users/gavinkistner/Desktop/tmp.rb:28:in `new'
     from /Users/gavinkistner/Desktop/tmp.rb:28


Obviously I can leave the call to #super out of my module, and leave  
it up to the consumer of my module to know that including mine means  
that any inherited class's initialization won't be called, unless the  
user explicitly looks for that ancestor and binds and so on. But that  
seems gross.

Is there a good solution for writing a module's initialize so that it  
can properly pass initialization to the parent class first? Something  
longwinded involving arity checking?


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