From: dblack@...
Date: 2006-10-04T09:00:35+09:00
Subject: Re: Special variable within iterators to hold results?

Hi --

On Wed, 4 Oct 2006, Timothy Goddard wrote:
>
> Wes Gamble wrote:
>> I have this:
>>
>> FILTER_COLUMNS = Array.new
>> DISPLAYABLE_COLUMNS.each do |field_array|
>>   FILTER_COLUMNS << [ field_array[1], field_array[0] ]
>> end
>>
>> Is there any way to write this so that it could look something like:
>>
>> FILTER_COLUMNS = DISPLAYABLE_COLUMNS.each do |field_array|
>>   ??? << [ field_array[1], field_array[0] ]
>> end
>>
>> so that I don't have to bother initializing FILTER_COLUMNS - is there
>> some special variable that holds the intermediate result of the iterator
>> body?
>>
>> Or perhaps an appropriate call to collect?
>>
> Firstly, you shouldn't capitalize your variables like that. Ruby will
> treat any variable with a capital first letter as a constant - it will
> behave differently.
>
> A better implementation would be:
>
> filter_columns = displayable_columns.map {|field_array|
> [field_array[1], field_array[0]]
>
> or
>
> filter_columns = displayable_columns.map {|field_array|
> field_array[0,2].reverse]

You could also do:

   filter_columns = displayable_columns.map {|field_array|
     field_array.values_at(1,0) }


David

-- 
                   David A. Black | dblack@wobblini.net
Author of "Ruby for Rails"   [1] | Ruby/Rails training & consultancy [3]
DABlog (DAB's Weblog)        [2] | Co-director, Ruby Central, Inc.   [4]
[1] http://www.manning.com/black | [3] http://www.rubypowerandlight.com
[2] http://dablog.rubypal.com    | [4] http://www.rubycentral.org