From: James Edward Gray II <james@...>
Date: 2007-01-19T05:54:32+09:00
Subject: Re: auto assign arguments?

On Jan 18, 2007, at 2:13 PM, David Chelimsky wrote:

> I see where to put bugs and patches, but this is a feature request. Is
> this the right place to submit these?
>
> In any case, here's a feature request:
>
> I find that I do a lot of this:
>
> def initialize(thing, other)
>  @thing = thing
>  @other = other
> end
>
> One thing I'd love to see in a future version of ruby is this;
>
> def initialize(@thing, @other)
> end
>
> ... and have that automagically initialize @thing and @other with the
> submitted values.

Some thinking-out-loud:

#!/usr/bin/env ruby -w

class Module
   def constructor(*attrs)
     define_method(:initialize) do |*passed|
       raise ArgumentError, "Wrong number of arguments" \
         unless attrs.size == passed.size

       attrs.each_with_index do |att, i|
         instance_variable_set("@#{att}", passed[i])
       end

       after_initialize if respond_to? :after_initialize
     end
   end
end

class ABC
   constructor :a, :b, :c

   def after_initialize
     p instance_variables.map { |var| [var, instance_variable_get 
(var)] }.sort
   end
end

ABC.new(1, :two, "three")
ABC.new(*%w[testing my code])
# >> [["@a", 1], ["@b", :two], ["@c", "three"]]
# >> [["@a", "testing"], ["@b", "my"], ["@c", "code"]]

__END__

James Edward Gray II