From: "Mauricio Fernández" <mfp@...>
Date: 2005-09-16T22:52:43+09:00
Subject: Re: bug in require?

On Fri, Sep 16, 2005 at 12:18:33PM +0900, Ara.T.Howard wrote:
>   [ahoward@localhost ~]$ strace ruby -e' 4.times{ require "digest/md5.so" 
                                                                       ===
[...]
>   [ahoward@localhost ~]$ cat a.rb
>   4.times{ require 'digest/md5' }
                               ===
> why the difference?

batsman@tux-chan:/tmp$ strace ruby -e' 4.times{ require "digest/md5.so" }' 2>&1 |grep open|grep md5
open("/home/batsman/usr//lib/ruby/1.8/i686-linux/digest/md5.so", O_RDONLY|O_LARGEFILE) = 3
open("/home/batsman/usr//lib/ruby/1.8/i686-linux/digest/md5.so", O_RDONLY) = 3
batsman@tux-chan:/tmp$ strace ruby -e' 4.times{ require "digest/md5" }' 2>&1 |grep open|grep md5
open("/home/batsman/usr//lib/ruby/1.8/i686-linux/digest/md5.so", O_RDONLY|O_LARGEFILE) = 3
open("/home/batsman/usr//lib/ruby/1.8/i686-linux/digest/md5.so", O_RDONLY|O_LARGEFILE) = 3
open("/home/batsman/usr//lib/ruby/1.8/i686-linux/digest/md5.so", O_RDONLY) = 3
open("/home/batsman/usr//lib/ruby/1.8/i686-linux/digest/md5.so", O_RDONLY|O_LARGEFILE) = 3
open("/home/batsman/usr//lib/ruby/1.8/i686-linux/digest/md5.so", O_RDONLY|O_LARGEFILE) = 3
open("/home/batsman/usr//lib/ruby/1.8/i686-linux/digest/md5.so", O_RDONLY|O_LARGEFILE) = 3

If no extension is given, ruby verifies if any new 'feature' can be loaded:

batsman@tux-chan:/tmp$ strace ruby -rfileutils -e'require "digest/md5"; FileUtils.mkdir("digest"); File.open("digest/md5.rb","w"){|f| f.puts %{puts "==== opened & loaded md5.rb"} }; $:.unshift "."; require "digest/md5" ' 2>&1 |grep open|grep md5
execve("/home/batsman/usr/bin/ruby", ["ruby", "-rfileutils", "-erequire \"digest/md5\"; FileUtils.mkdir(\"digest\"); File.open(\"digest/md5.rb\",\"w\"){|f| f.puts %{puts \"==== opened & loaded md5.rb\"} }; $:.unshift \".\"; require \"digest/md5\" "], [/* 31 vars */]) = 0
open("/home/batsman/usr//lib/ruby/1.8/i686-linux/digest/md5.so", O_RDONLY|O_LARGEFILE) = 3
open("/home/batsman/usr//lib/ruby/1.8/i686-linux/digest/md5.so", O_RDONLY|O_LARGEFILE) = 3
open("/home/batsman/usr//lib/ruby/1.8/i686-linux/digest/md5.so", O_RDONLY) = 3
open("digest/md5.rb", O_WRONLY|O_CREAT|O_TRUNC|O_LARGEFILE, 0666) = 3
write(3, "puts \"==== opened & loaded md5.r"..., 35) = 35
open("./digest/md5.rb", O_RDONLY|O_LARGEFILE) = 3
open("./digest/md5.rb", O_RDONLY|O_LARGEFILE) = 3
open("./digest/md5.rb", O_RDONLY|O_LARGEFILE) = 3
open("./digest/md5.rb", O_RDONLY|O_LARGEFILE) = 3
open("./digest/md5.rb", O_RDONLY|O_LARGEFILE) = 3
read(3, "puts \"==== opened & loaded md5.r"..., 4096) = 35
write(1, "==== opened & loaded md5.rb\n", 28==== opened & loaded md5.rb

-- 
Mauricio Fernandez