From: Christian Neukirchen <chneukirchen@...>
Date: 2007-01-24T05:00:03+09:00
Subject: Re: Minor Change Proposal for Classes 'Object' and 'Method'

"Phrogz" <gavin@refinery.com> writes:

> gwtmp01@mac.com wrote:
>> On Jan 22, 2007, at 1:55 PM, Christian Neukirchen wrote:
>> > While we are at it, can we please have UnboundMethod#to_proc?
>> > It would greatly help to implement callbacks from class methods.
>>
>> This doesn't make sense.  Without an object bound to the method
>> 'self' will be undefined and so it is nonsensical to try to execute
>> the associated code.
>
> Only if the method relies on the 'self'. For example:
>
>   class Foo
>     def self.square( x )
>       x*x
>     end
>   end
>
> could be reasonably translated to a lambda of:
>
>   square = lambda{ |x| x*x }
>
> (I personally don't have a use case, but its certainly possible in some
> scenarios.)

Let me try to remember it... I actually grepped the logs:

Dec 08 14:14:05 <chris2>        i want to use ordinary ruby modules as a mean to extend a lambda based object system

Anyway, the case was I had a callback that was a module method, and I
wanted an easy way to turn it into a proc.

irb(main):001:0> module M; def foo; "foo!"; end; end
=> nil
irb(main):002:0> M.instance_method(:foo)
=> #<UnboundMethod: M#foo>

I imagine this to be useful for building DSLs, bundling callbacks etc,
too?  At least, allow binding unbound methods to nil without
raising... that would make the not-existing self explicit, too:

irb(main):004:0> M.instance_method(:foo).bind(nil)
TypeError: bind argument must be an instance of M

-- 
Christian Neukirchen  <chneukirchen@gmail.com>  http://chneukirchen.org