From: Mark Hubbart <discord@...>
Date: 2004-04-13T06:47:38+09:00
Subject: Re: proposal - zip to do padding


On Apr 12, 2004, at 5:29 AM, Simon Strandgaard wrote:

> I also use 1.9.. but gets different result.
> What date does your 'ruby -v' tell?
>
> server> ruby -v
> ruby 1.9.0 (2004-04-06) [i386-freebsd5.1]
> server> irb
> irb(main):001:0> (4..6).zip(nil)
> => [[4, nil], [5, nil], [6, nil]]
> irb(main):002:0>

okay, I guess that particular release (2004-02-21) of 1.9 was flawed :) 
I got the latest snapshot and the error went away. #to_a was not 
implemented for nil in that release. However, now (4..6).zip(1) doesn't 
work, since Fixnum#to_a is not implemented. hmmm...

I remember a warning on 1.8, I believe, hat stated that Object#to_a was 
being deprecated, and may be removed in future versions. Perhaps this 
is the result?


>> Maybe are missing the point of what zip does... when you call #zip, it
>> ensures the object you pass to it is an array; then it zips it. I'm
>> guessing #zip calls to_a on it...
>>
>
> What you described is the behavier of Ruby-1.8.1.
>
> I should have mentioned that I am using 1.9
> server> ruby -v
> ruby 1.9.0 (2004-04-06) [i386-freebsd5.1]
> server>
>
>
>> But I may be misunderstanding your proposal... Isn't what you are
>> proposing something like this?
>>
>> irb(main):003:0> (4..6).map{|i|[i,'a']}
>> => [[4, "a"], [5, "a"], [6, "a"]]
>>
>> (as was suggested by daz elsewhere in the thread)
>
> No, thats the subject of another thread..
> that is not what my proposal is about.
>
>
> 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?

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

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. :)

--Mark