From: Eric Hodel <drbrain@...7.net>
Date: 2005-03-31T04:37:42+09:00
Subject: Re: Syntax sugar idea for loops

On 30 Mar 2005, at 11:23, Berger, Daniel wrote:

>> From: pmak@aaanime.net [mailto:pmak@aaanime.net]
>>
>> Consider the following Ruby code:
>>
>>     every_other = true
>>     people.each do |person|
>>         every_other = !every_other
>>         row_class = every_other ? 'row1' : 'row2'
>>         puts "<tr class=#{row_class}><td>#{person.name}</td>
>> <td>#{person.email}</td></tr>"
>>     end
>>
>> Consider these two lines of the code, though:
>>
>>     every_other = true
>>         every_other = !every_other
>>
>> These lines could be replaced by syntax sugar. Traction has
>> the following "Special Loop Tags":
>>
>>     <loop.first>: true if this is the first iteration of the loop
>>     <loop.inner> true if this is not the first or last
>> iteration of the loop
>>     <loop.odd> true if this is an odd iteration
>>     <loop.last>: true if this is the last iteration of the loop
>
> I think Enumerable#each_with_index largely eliminates the need for such
> syntactic sugar.  Consider:
>
> people.each_with_index do |person, i|
>    puts "First person: #{person}" if i == 0
>    row_class = i%2 == 0 ? "row1" : "row2"
>    puts "<tr class=#{row_class}><td>#{person.name}</td>
>    puts "Last person: #{person}" if i == people.length - 1
> end
>
> I suppose you could extend Fixnum within a loop to include extra 
> methods
> so that you could do something like this:

people.each_with_index do |person, i|
    puts "First person: #{person} if person == people.first
    row_class = i.even? ? "row1" : "row2"
    puts "Last person: #{person} if person == people.last
end

How about that?

-- 
Eric Hodel - drbrain@segment7.net - http://segment7.net
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