From: Logan Capaldo <logancapaldo@...>
Date: 2006-08-01T13:21:01+09:00
Subject: Re: I thought this was the one that worked?


On Aug 1, 2006, at 12:06 AM, Chad Perrin wrote:

> On Tue, Aug 01, 2006 at 12:47:50PM +0900, Logan Capaldo wrote:
>> On Jul 31, 2006, at 11:26 PM, Chad Perrin wrote:
>>
>>>  Closure
>>>      A "closure" is an expression (typically a function) that can
>>> have
>>>      free variables together with an environment that binds those
>>>      variables (that "closes" the expression).
>>>
>>
>> In ruby this environment always exists for a block regardless of the
>> presence of free variables, since the declaration of the variables
>> that are free in the block can be added after (in time) the creation
>> of the closure.
>
> I think that depends on what you mean by "creation of the closure" in
> this case.  Are you talking about the code used to create it, or the
> assignment of the return value of the closure's enclosing scope to a
> variable?
>

I'm talking about what happens inside the ruby interpreter when it  
sees that code. As far as ruby is concerned, it doesn't know how to  
make a block that isn't a "closure". The same code path gets followed  
whether ruby sees

def foo
  a = 1
  lambda { ... a ... }
end

or

def foo
   lambda { ... }
end

All the "closure bookkeeping" is done whenever you create a block. No  
extra bookkeeping is done whether or not you take advantage of the  
fact that you have a "closure".



> -- 
> CCD CopyWrite Chad Perrin [ http://ccd.apotheon.org ]
> "A script is what you give the actors.  A program
> is what you give the audience." - Larry Wall
>