From: Robert Klemme <shortcutter@...>
Date: 2009-02-13T17:33:33+09:00
Subject: Re: performance tips

2008/4/10 Joel VanderWerf <vjoel@path.berkeley.edu>:
> Vince Forgetta wrote:
>>
>> Hi all,
>>
>> I've been using ruby for about 2 years, but only recently got around
>> trying
>> and learning it well.
>>
>> Is there some central repository I can get performance tips/discussions
>> such
>> as the one posted here:
>>
>> http://blade.nagaokaut.ac.jp/cgi-bin/scat.rb/ruby/ruby-talk/158212
>
> Instead of:
>
> lines = File.readlines('sometextfile').each {|l| l.chomp!}
>
> do this:
>
> lines = File.open "test" do |f|
>  f.map {|line| line.chomp}
> end
>
> That saves you from having the large string returned by #readlines.

???  I could have understood if you argued that your solution avoids
traversing lines twice but this statement is plain wrong:
File.readlines never returned a single String.

http://www.ruby-doc.org/core/classes/IO.html#M002269

> Sorry, no idea if these tips are collected somewhere. The rubygarden wiki
> used to have them, IIRC, but it got killed by spam.

Many performance considerations can be found here.  Searching for
"Benchmark" should get you pretty far. :-)

Apart from that IMHO there are two major rules of performance which
can help eliminate many performance issues:

1. Do not do unnecessary work.

2. Carefully choose object life cycles.

Kind regards

robert

-- 
remember.guy do |as, often| as.you_can - without end