>
> class Fixnum
> attr_accessor :note
> end
>
> 13.note = "a baker's dozen"
> 25.note = "5 squared"
>
> notes = [13, 21, 25].collect { |x| x.note } # ["a baker's dozen",
> nil, "5 squared"]
>


It's really cool.
--
Posted via http://www.ruby-forum.com/.

[Note: parts of this message were removed to make it a legal post.]

Welcome to Monkey Patching! This is how ActiveResource gives you things
like:

4.days.ago

"some string".underscore

and the like.

It's one of the many things that makes Ruby code very fun to write.

Jason

On Jan 5, 2008 10:07 AM, Barca Junior <wuzhengchun@gmail.com> wrote:

>
> >
> > class Fixnum
> > attr_accessor :note
> > end
> >
> > 13.note = "a baker's dozen"
> > 25.note = "5 squared"
> >
> > notes = [13, 21, 25].collect { |x| x.note } # ["a baker's dozen",
> > nil, "5 squared"]
> >
>
>
> It's really cool.
> --
> Posted via http://www.ruby-forum.com/.
>
>

On Jan 5, 2008, at 10:15 AM, Jason Roelofs wrote:

> Welcome to Monkey Patching! This is how ActiveResource gives you
> things
> like:
>
> 4.days.ago
>
> "some string".underscore
>
> and the like.
>
> It's one of the many things that makes Ruby code very fun to write

Actually it is a bit different. Monkey patching is just adding
methods to classes. Fixnum and String in your examples.

Instance variables on Fixnums (or Symbols or Nil) is different.
It is a good example of uniformity in Ruby but I'm hard pressed
to think of a nice use case for the feature.

Gary Wright

On Jan 5, 2008 4:32 PM, Gary Wright <gwtmp01@mac.com> wrote:
> Actually it is a bit different. Monkey patching is just adding
> methods to classes. Fixnum and String in your examples.
>
> Instance variables on Fixnums (or Symbols or Nil) is different.
> It is a good example of uniformity in Ruby but I'm hard pressed
> to think of a nice use case for the feature.
>
> Gary Wright
You can use it to cache the result of method calls.

class Fixnum
def factorial
@factorial ||= self * (self-1).factorial
end
end
0.instance_variable_set('@factorial',1)