From: Jeffrey Schwab <jeff@...>
Date: 2006-03-02T01:23:37+09:00
Subject: Re: Formatting to "Thousands"

Logan Capaldo wrote:
> 
> On Feb 28, 2006, at 11:59 AM, James Edward Gray II wrote:
> 
>> On Feb 28, 2006, at 10:53 AM, Jeffrey Schwab wrote:
>>
>>> James Edward Gray II wrote:
>>>
>>>> def commify( number )
>>>>   number.to_s.reverse.gsub!(/(\d\d\d)(?=\d)(?!\d*\.)/,  '\1,').reverse
>>>> end
>>>
>>>
>>> That's nice, except that gsub! returns nil if no substitutions are  
>>> performed, e.g. if the number has fewer than 4 digits.  This can  
>>> result in an exception like:
>>>
>>>   main.rb:3:in `commify':
>>>     undefined method `reverse' for nil:NilClass(NoMethodError)
>>>
>>> Of course, you could just break the chain across multiple lines:
>>>
>>>   def commify(number)
>>>     s = number.to_s
>>>     s.reverse!
>>>     s.gsub!(/(\d\d\d)(?=\d)(?!\d*\.)/, '\1,')
>>>     s.reverse!
>>>   end
>>
>>
>> Good catch.  I originally had it in multiple lines and I forgot to  
>> remove the ! when I shortened it for this post.
>>
>> Thanks.
>>
>> James Edward Gray II
>>
>>
> 
> I don't know why but using regexps to do this kind of scares me.  Maybe 
> its cause I don't have as much regexp fu but it just seems like
> ruby
> ruby
> perl
> ruby
> ruby
> 
> Not that I have anything against perl or regexps, but that particular  
> regexp seems to scream "I'm doing this with a regexp not because it's  
> easier but because it's faster and shorter." Not that that's wrong.  Hmm 
> I seem to be trying really hard not to offend anyone :-p. I guess  a 
> rule of thumb for me is more than 1 lookahead assertion and my eyes  
> glaze over ;)

Try the Friedl book.  It will open your eyes. :)