From: Robert Klemme <shortcutter@...>
Date: 2007-05-26T17:30:03+09:00
Subject: Re: Introducing the "it" keyword

On 25.05.2007 11:40, Robert Klemme wrote:
> On 25.05.2007 10:21, Greg Fodor wrote:
>>> And don't tell me that this is too much typing for you.
>> Well, it is kinda, but that's not as bad as the fact that
>> 'it' will be un Gc-able till the end of the block unless
>> we do:
>>
>> it = v+1
>> return it if it < 10
>> it = nil
>>
>> It's reminiscent of the all too common ruby memory 'leak':
>> (http://whytheluckystiff.net/articles/theFullyUpturnedBin.html)
>>
>> x = [1, 2, 3]
>> loop do
>>   # add some crap to x and use it
>> end
>>
>> slow_method_that_doesnt_use_x()
>>
>> This problem is even trickier w/ closures grabbing x into their
>> binding too AFAIK. "it" needs to show "it"self to the door
>> when "it"'s no longer wanted. (It's late)
> 
> I see your point.  I do wonder though how relevant this is in practice. 
>  If you write 100+ lines methods then you have other problems than a few 
> objects that are kept around longer than needed.  Even with short 
> methods that exhibit the behavior you described above it is only an 
> issue if the object kept around keeps a lot of memory from being 
> reclaimed (which is not the case for the example above) or if the method 
> is active multiple times.  After all the cost of changing the language 
> should be smaller than the cost incurred by this missing feature.

Btw, here is a solution that does not need new syntax and does not 
exibit memory issues (I think):

irb(main):001:0> def it_test(v)
irb(main):002:1>   (v+1).instance_eval do
irb(main):003:2*     return self if self < 10
irb(main):004:2>   end
irb(main):005:1>   "nothing"
irb(main):006:1> end
=> nil
irb(main):007:0> it_test 0
=> 1
irb(main):008:0> (0..10).map {|i| it_test i}
=> [1, 2, 3, 4, 5, 6, 7, 8, 9, "nothing", "nothing"]

Kind regards

	robert