From: dblack@...
Date: 2003-08-07T01:30:38+09:00
Subject: Re: adding methods to an existing class

Hi --


On Thu, 7 Aug 2003, Volkmann, Mark wrote:

> I'm fumbling over syntax trying to figure out how I could write a method
> that adds a method to a given class.  I'd call it like this.
>
> addTestMethod(Foo)
>
> where Foo is a class.
>
> addTestMethod would add a fixed "test" method to the class passed to it.
>
> An example would be greatly appreciated!

  def add_test_method(klass)
    klass.class_eval {
      define_method(:some_test) { puts "testing!" }
    }
  # or: klass.class_eval "def some_test; puts \"testing!\"; end"
  # or (1.8.0 only):
  #     klass.class_eval { def some_test; puts "testing!"; end }
  end

  class A
  end

  a = A.new
  add_test_method(A)
  a.some_test      # =>  testing!

(I've chosen "some_test" so as not to interfere with Kernel#test.)


David

-- 
David Alan Black
home: dblack@superlink.net
work: blackdav@shu.edu
Web:  http://pirate.shu.edu/~blackdav