From: "David A. Black" <dblack@...>
Date: 2008-08-27T00:13:08+09:00
Subject: Re: Passing a block with define_method

Hi --

On Wed, 27 Aug 2008, James Coglan wrote:

>> module_eval a string.
>
>
>
> I'm actually wrapping existing methods so I need to use define_method to
> retain access to the old method. Here's my (broken) code so far:
>
> module Continuations
>  def accepts_continuation(*args)
>    args.each do |method_name|
>      func = instance_method(method_name)
>      define_method(method_name) do |*params, &block|
>        value = func.bind(self).call(*params)
>      end
>    end
>  end
> end

In Ruby 1.9 you can do this:

>> func = ->(*a,&block) { block.call if block; puts a }
=> #<Proc:0x388bdc@(irb):1 (lambda)>
>> C = Class.new { define_method(:hi, &func) }
=> C
>> C.new.hi(10) { puts "In block" }
In block
10

The ->(){} thing lets you create a lambda with method-argument
semantics.


David

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