From: Ken Bloom <kbloom@...>
Date: 2006-10-19T10:15:06+09:00
Subject: Re: whats this lambda code doing?

On Thu, 19 Oct 2006 10:02:11 +0900, David Vallner wrote:

> Ezra Zygmuntowicz wrote:
>>    klasses.inject(block) do |blk, klass|
>>      lambda { klass.with_scope(scope_hash, &blk) }
>>    end.call
>> 
>> That outer block that ends on end returns the lambda made inside of that
>> block. So end.call ends up being  lambda { klass.with_scope(scope_hash,
>> &blk) }.call
>> 
> 
> Hmm. Unless I'm very mistaken, it would also only call the lambda for
> the last object in klasses, generating several garbage (and relatively
> expensive) lambdas. Boggle. Am I missing something?
> 
> David Vallner

This some wierd kind of lambda chaining. You're confusing "block" with
"blk", so you're thinking that each version of this code is using the
original block, but this is not so. Each lambda is chained to call the
previous lambda. I haven't got a clue what with_scope does, but this would
all be a lot easier to understand if it was possible to eliminate the
lambda, and deal with each class separately.

-- 
Ken Bloom. PhD candidate. Linguistic Cognition Laboratory.
Department of Computer Science. Illinois Institute of Technology.
http://www.iit.edu/~kbloom1/
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