From: Joel VanderWerf <vjoel@...>
Date: 2007-11-01T05:53:20+09:00
Subject: Re: Generation of initialize

Trans wrote:
> 
> On Oct 31, 4:10 pm, arcadiorubiogar...@gmail.com wrote:
>> Hi again,
>>
>> I'm trying to enhance the previous solution (shown again at the end).
>> I'd like to call the initialize method of the superclass from the
>> generated initialize. For the moment it's ok to call it without
>> parameters. Simply placing super inside the method definition doesn't
>> work. Can anyone explain me how to do it. Thanks in advance.
> 
> Why doesn't it work?
> 
>  def initialize_with(*params)
>    define_method(:initialize) do |*args|
>      if args.size != params.size then
>        raise ArgumentError.new("wrong number of arguments"\
>          " (#{args.size} for #{params.size})")
>      end
>      super() if defined?(super)
>      params.zip(args) do |param, arg|
>        instance_variable_set("@#{param}", arg)
>      end
>    end
>    return params
>  end
> 
> The "()" on super clears the auto-passing of parameters.

It seems to work (if this is what you meant):

module HasInitializeWith
  def initialize_with(*params)
    define_method(:initialize) do |*args|
      if args.size != params.size then
        raise ArgumentError.new("wrong number of arguments"\
          " (#{args.size} for #{params.size})")
      end
      super() if defined?(super)
      params.zip(args) do |param, arg|
        instance_variable_set("@#{param}", arg)
      end
    end
    return params
  end
end

class A
   extend HasInitializeWith
   self.initialize_with :foo
end

p A.new(3)  # ==> #<A:0xb7c28cbc @foo=3>

-- 
       vjoel : Joel VanderWerf : path berkeley edu : 510 665 3407