From: dblack@...
Date: 2007-06-06T21:27:42+09:00
Subject: Re: efficient regex scanning

Hi --

On Wed, 6 Jun 2007, Robert Klemme wrote:

> On 06.06.2007 13:08, dblack@wobblini.net wrote:
>> Hi --
>> 
>> On Wed, 6 Jun 2007, Trochalakis Christos wrote:
>> 
>>> Hello there,
>>> 
>>> I wan't to extract all the words from a file and so i wrote the
>>> following code:
>>> 
>>> file = ARGV[0]
>>> File.open('output','w') {|f|
>>>        IO.read(file).scan(/\w+/).each{|w| f.print w}
>>> }
>>> 
>>> The problem with this code is that it stores all the words in an array
>>> which is not so good in terms of efficiency.
>>> Is there a better way to do it?
>>> Something like IO.read(file).each_scan { foo }
>> 
>> You could do something like this (untested, and reversing your logic
>> somewhat):
>>
>>   File.open(file).each {|line| f.print(line.scan(/\w+/)) }
>> 
>> (You might want to join them with a space or something so they don't
>> all run together.)
>
> You're not closing the IO.  I know it's not an issue for a small script 
> but...

It's not a complete script; I was only showing one line.  At the very
least it's not going to run unless you assign something to f :-)


David

-- 
Q. What is THE Ruby book for Rails developers?
A. RUBY FOR RAILS by David A. Black (http://www.manning.com/black)
    (See what readers are saying!  http://www.rubypal.com/r4rrevs.pdf)
Q. Where can I get Ruby/Rails on-site training, consulting, coaching?
A. Ruby Power and Light, LLC (http://www.rubypal.com)