Dynamically creating class methods

I want to create a class method which allows us to create further class
methods, so something like:

class Test
  class << self
    def create_method(name, proc)
        self.class.send(:define_method, name, proc)
    end
  end
end

proc = lambda {puts 'Hello world'}
Test.create_method(:foo, proc)
Test.foo #want this
Integer.foo #don't want this

The problem with the above is that create_method adds foo to all
classes. self.send on its own doesn't seem to do what I want - it adds
foo as instance method instead.

The method will eventually be placed in an module to be mixed in when
desired, although I don't think that matters here.

Ideas?

···

--
Posted via http://www.ruby-forum.com/.

Hi --

I want to create a class method which allows us to create further class
methods, so something like:

class Test
class << self
   def create_method(name, proc)
       self.class.send(:define_method, name, proc)
   end
end
end

proc = lambda {puts 'Hello world'}
Test.create_method(:foo, proc)
Test.foo #want this
Integer.foo #don't want this

The problem with the above is that create_method adds foo to all
classes. self.send on its own doesn't seem to do what I want - it adds
foo as instance method instead.

There are three candidates for the class to which you might send the
:define_method message:

   1. Test
   2. Class
   3. the singleton class of Test

#3 is the one you want. The code you've written sends the message to
Class, and the self.send that you've tried sends it to Test.

Try this:

class Test
   def self.create_method(name, proc)
     s_class = class << self; self; end
     s_class.send(:define_method, name, proc)
   end
end

There are other ways (including using class_eval), but that's the
general idea.

David

···

On Wed, 1 Jul 2009, Shak Shak wrote:

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