From: David Alan Black <dblack@...>
Date: 2002-07-12T03:15:41+09:00
Subject: Re: spliter of for...each: looping

Hi --

On Fri, 12 Jul 2002, Tom Sawyer wrote:

> >    arr.collect{|x| "junk#{x}morejunk" }.join(",")
>
> can you put conditionals in that?
>
> q = ''
> arr.each_with_nindex do |x, n|
>   q << 'junk' << x
>   q << 'morejunk' if x == 'more'
>   q << ',' if n != -1
> end

Sure:

  arr.collect {|x| "junk#{x}#{'more' if x=='more'}" }.join ","

That's in the nature of #collect (aka #map): you're basically
translating from your original array to a new array of the same
length, using what happens in the block (one element at a time) as the
translator or transformer.  And "what happens in the block" can
certainly be conditional on the value of the element(s).

By the way, another way to do the all-but-last thing with an array is:

  arr[0..-2].each {|e| <do something> }


David

-- 
David Alan Black
home: dblack@candle.superlink.net
work: blackdav@shu.edu
Web:  http://pirate.shu.edu/~blackdav