From: Gavin Kistner <gavin@...>
Date: 2005-02-10T23:57:22+09:00
Subject: Re: Class of the Instance [was Re: Building a Better Functor]

On Feb 10, 2005, at 7:47 AM, Gavin Kistner wrote:
> Or (what I'm really looking for) perhaps it might be nice to have a 
> define_method method that worked directly for instances. Hrm, but what 
> would the syntax be? Perhaps that's not such a good idea.

Well, no, maybe it would be nice. Something like:

class Object
	def add_method( name, &block )
		case self
			when Class
				self.class_eval{
					define_method( name, &block )
				}
			else
				class<<self; self; end.class_eval{
					define_method( name, &block )
				}
		end
	end
end

class Foo
	def whee; puts "#{self} says 'whee'"; end
end

Foo.add_method( 'yow' ){ puts "#{self} says 'yow!'" }

f1 = Foo.new
f2 = Foo.new

f1.whee
#=> #<Foo:0x1cbdec> says 'whee'

f1.yow
#=> #<Foo:0x1cbdec> says 'yow!'

f2.add_method( 'booya!' ){ puts "#{self} says 'booya!'" }
f2.booya!
#=> #<Foo:0x1cbdc4> says 'booya!'

f1.booya!
#=> tmp.rb:33: undefined method `booya!' for #<Foo:0x1cbdec> 
(NoMethodError)


I'm certainly adding that to my personal library, but it seems like it 
would be a nice (useful, good, less-hacks-needed) built-in.


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