From: Gavin Sinclair <gsinclair@...>
Date: 2004-12-03T14:37:22+09:00
Subject: Re: nested defs, what if...

On Friday, December 3, 2004, 4:18:38 PM, nobu wrote:

> Hi,

> At Fri, 3 Dec 2004 14:00:44 +0900,
> Gavin Sinclair wrote in [ruby-talk:122305]:
>> >   class A
>> >     def a(y)
>> >       def b(x)
>> >         x + y    # `y' in a or `undefined local variable'?
>> >       end
>> >       10.times{ |i| print b(i) }
>> >     end
>> >   end
>> 
>> Is there any difference between an "inner method" (with 'y' in a) and
>> a lambda?

> Actually, no.  Just a syntax sugar, and it would be implemented
> using a lambda.  And another question; should b be visible from
> other methods called from a?

I don't think so.  I can't imagine a use case, and the _appearance_ of
the code is that b() is private to a().

>> I've happily used lambdas to define private functionality before, but
>> I'm concerned about efficiency:
>> 
>>   class A
>>     def a(y)
>>       b = lambda { |x| x + y }
>>       10.times { |i| print b(i) }
>>     end
>>   end
>> 
>> Does the lambda attached to b get regenerated with each call to a?

> I guess so.

So an inner method, which _looks_ static, would actually be
inefficiently regenerated each time?  (You said the inner method would
be syntax sugar for a lambda.)

Gavin