From: Robert Klemme <bob.news@...>
Date: 2005-09-19T19:46:39+09:00
Subject: Re: Reference to 'this block'

Mauricio Fern�ndez wrote:
> On Mon, Sep 19, 2005 at 06:23:23PM +0900, Brian Candler wrote:
>> I want the object to be self-contained. 'self' doesn't work. Best I
>> can come up with is to try and hide it:
>>
>>   a = __myfoo = lambda { |x| x < 2 ? 1 : x * __myfoo.call(x-1) }
>
> You can use the Y combinator or something as simple as
>
> #  make sure _l is block-local
> a = lambda{ _l = lambda{|x| x < 2 ? 1 : x * _l[x-1]}}[]
> p a[5]
> _l = 1 # doesn't matter
> p a[5]

If you want to be sure use a function:

>> def t() f = lambda {|x| x < 2 ? 1 : x * f[x - 1]} end
=> nil
>> t[10]
=> 3628800

Btw, recursions don't perform well with Ruby so an iterative solution is
usually better.

Kind regards

    robert