From: Robert Klemme <shortcutter@...>
Date: 2009-12-11T00:35:16+09:00
Subject: Re: human-readable listing of array elements

2009/12/10 Aldric Giacomoni <aldric@trevoke.net>:
> Robert Klemme wrote:
>> By using String#<< your code will become more efficient because you do
>> not create new String objects all the time.
> Thanks :)
>>
>> For the fun of it here are two other solutions:
>>
>> irb(main):026:0> def stringify array
>> irb(main):027:1>   lead = array.slice 0...-1
>> irb(main):028:1>   lead.empty? ? array.last.to_s : [lead.join(", "),
>> array.last].join(" and ")
>> irb(main):029:1> end
>>
>> irb(main):039:0> def stringify array
>> irb(main):040:1>   tail = array.slice -2..-1
>> irb(main):041:1>   tail ? (array.slice(0...-2) << tail.join(" and
>> ")).join(", ") : array.first.to_s
>> irb(main):042:1> end
>>
>> Note, I don't claim that this is necessarily more rubyish. :-)
>
> Your solutions *stink* of LISP, but maybe that's only because you're ..
> er.. processing lists.

Oh no.  Pascal is responsible for lispish solutions - I'm not. :-)

> I like your first one - it feels more elegant than mine. The second one
> feels a little too convoluted.

Yep.

> I also find that using 'slice' is too
> wordy, and usually just settle for array[0...-1] or array[-2..-1] -- but
> clearly that's just preference.

I just felt #slice deserved a mention because it is so rarely seen.
Initially I also thought about using #slice! which cannot be done with
#[].  But then you would either modify the argument or have to dup the
Array.

> Thanks for the further examples, I'll
> remember them (and possibly even use them someday!)

You're welcome!  Thanks for the opportunity to play around a bit. :-)

Kind regards

robert

-- 
remember.guy do |as, often| as.you_can - without end
http://blog.rubybestpractices.com/