From: Ezra Zygmuntowicz <ezmobius@...>
Date: 2006-10-19T10:12:16+09:00
Subject: Re: whats this lambda code doing?


On Oct 18, 2006, at 6:02 PM, 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
>


	It looks like it would only call the last lambda but it does call  
all of them. Here is a simplification of whats happening.

irb(main):065:0>  def scoper(klasses=[:foo, :bar, :baz], &block)
irb(main):066:1>    klasses.inject(block) do |blk, klass|
irb(main):067:2*      lambda { puts klass; blk.call}
irb(main):068:2>    end.call
irb(main):069:1>  end
=> nil
irb(main):070:0* scoper { puts '&block called' }
baz
bar
foo
&block called
=> nil
irb(main):071:0>



-- Ezra Zygmuntowicz 
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