From: Sander Land <sander.land@...>
Date: 2006-08-07T04:08:30+09:00
Subject: Re: Singleton methods with method_missing

On 8/6/06, Pat Maddox <devlists-ruby-talk@devlists.com> wrote:
> I don't have any practical use for this, but I was experimenting a bit.
> I just want to create singleton methods on objects of this class.
> There's more to come, but this is the part I'm stuck at :)
>
> This code doesn't actually work, but I think it's close (I hope?)
>
> When I do this I get "NameError: undefined local variable or method `m'
> for #<Class:#<OneShot:0x32cf74>>" so I think it means that m just isn't
> in scope for the singleton class.  How can I define the singleton
> method?  Is there any way to use binding here?

It is close :)
class<<self .... end is not a closure (only blocks are), so m is not
defined there. A solution is to use blocks for everything, using *eval
functions.

class OneShot
 def method_missing(m,*a)
   puts "method #{m} missing!"
   (class<<self;self;end).class_eval {
     define_method(m) { puts m.to_s }
   }
   send(m)
 end
end

a = OneShot.new
a.foo
a.foo
b = OneShot.new
b.foo
b.foo

output:
method foo missing!
foo
foo
method foo missing!
foo
foo

Which is what you want, right?