From: Simon Strandgaard <neoneye@...>
Date: 2004-04-13T07:19:13+09:00
Subject: Re: proposal - zip to do padding

On Tue, 13 Apr 2004 07:47:38 +0900, Mark Hubbart wrote:
> On Apr 12, 2004, at 5:29 AM, Simon Strandgaard wrote:
>> My proposal is about changing the current behavier of 1.9,
>> so that it does padding, rather than placing all the
>> supplied arguments to the first element only.
>>
>> The current behavier
>> irb(main):001:0> (4..6).zip('a')
>> => [[4, "a"], [5, nil], [6, nil]]
>> irb(main):002:0> (4..6).zip('a', 'b')
>> => [[4, "a", "b"], [5, nil, nil], [6, nil, nil]]
>> irb(main):003:0>
>>
>> Proposed behavier
>> irb(main):001:0> (4..6).zip('a')
>> => [[4, "a"], [5, "a"], [6, "a"]]
>> irb(main):002:0> (4..6).zip('a', 'b')
>> => [[4, "a", "b"], [5, "a", "b"], [6, "a", "b"]]
>> irb(main):003:0>
> 
> As pointed out by someone else, how should we determine when to pad 
> with an object, and when to zip? Only zip if the object implements 
> #to_ary? or #each? or, perhaps, #next?

Bommer, in the above example I have passed Strings to zip, which
includes Enumerable. I thought about using Enumerable to destinguish
between padding elements and normal elements.

However Fixnum doesn't include Enumerable, so the example would be:
irb(main):001:0> (4..6).zip(666)
=> [[4, 666], [5, 666], [6, 666]]
irb(main):002:0> (4..6).zip(:a, :b)
=> [[4, :a, :b], [5, :a, :b], [6, :a, :b]]
irb(main):003:0>


It seems as if the current #zip uses Enumerable. Thats why I thought
to continue using Enumerable.. Any ideas to distinguish by other
means? 


> 
> Perhaps if you would post some code it would clear this up, so that it 
> would be obvious what the behavior would be.

I have posted an example in the other thread  
http://ruby-talk.org/97006
However it doesn't distinguish by if Enumerable is included,
nor uses continuations.

Maybe I will clean up the example by means of 'enumerator' ?

 
> Note that I'm not against it; I just want to know how it would work. If 
> you can get it to work intuitively, then I would be all for it. :)
> 

Great with mental support. Its hard to defend proposals.
Its good to hear people open to new ideas.

;-)

--
Simon Strandgaard