From: Matthew Smillie <M.B.Smillie@...>
Date: 2006-08-10T01:39:00+09:00
Subject: Re: Code structure and using "require"

On Aug 9, 2006, at 17:26, Jean Nibee wrote:

> Hi
>
> I'm coming from a java world and I'm trying to understand the  
> structure
> of a Ruby project and how 'require's are resolved.
>
> In java we have this nice package routine where we put our .java files
> into a directory hierarchy that is nice and neat.
>
> Can I do the same in Ruby (I assume yes) but if I do how are  
> "requires"
> resolved when needed and what happend if I move code around the
> hierarchy; are the resolve paths relative or abosolute based on some
> 'root' directory I"m unaware of.
>
> (Currently to learn and test all my .rb files are in one directory...
> it's getting messy)

It's actually something like Java's classpath.  There are several  
default locations to search, and paths can be relative to any of them  
- Ruby will pick the first one it finds.

You can set the paths to be searched in the environment variable  
RUBYLIB, or access/modify it within Ruby using the built-in variable $:

A concrete example:

irb(main):001:0> $:
=> ["/Users/matt/PhD/scripts", "/usr/local/lib/ruby/site_ruby/1.8", "/ 
usr/local/lib/ruby/site_ruby/1.8/powerpc-darwin8.4.0", "/usr/local/ 
lib/ruby/site_ruby", "/usr/local/lib/ruby/1.8", "/usr/local/lib/ruby/ 
1.8/powerpc-darwin8.4.0", "."]

So require 'foo' will use the first 'foo.rb' it comes across in any  
of these directories.

You can, in a similar way to Java package names, specify  
subdirectories as well.  'require 'foo/bar' will look for a 'foo'  
subdirectory containing 'bar.rb'

matthew smillie.