From: "Ara.T.Howard" <Ara.T.Howard@...>
Date: 2005-09-10T00:39:17+09:00
Subject: Re: 'which' command for Ruby (like csh which?)

On Fri, 9 Sep 2005, Dan Bikle wrote:

> Hi,
>
> suppose I have,
>
> require "redgreenblue"
> in
> runme.rb
>
> Is there a way I can tell which
> redgreenblue.rb file will get pulled in to runme.rb
> at run time?
>
> Most UNIX shells have a 'which' builtin command which
> offers similar behavior.
>
> If I type
> which runme
> the builtin which command will tell which runme file
> the shell would run should I choose to run it.
>
> Thanks.
>
> -Dan

no.  but not hard to write:

     jib:~ > cat a.rb
     require 'rbconfig'
     require 'pathname'

     def which_lib lib, opts = {}
       lib         = Pathname::new lib
       search_path = opts['search_path'] || opts[:search_path] || $LOAD_PATH

       dl_ext = "." << Config::CONFIG["DLEXT"]
       rb_ext = "." << "rb"
       pat    = %r/#{ Regexp::escape dl_ext }$ | #{ Regexp::escape rb_ext }$/x

       glob_for = lambda do |stem|
         glob = "%s{,%s,%s}" % [stem, dl_ext, rb_ext]
         Dir[glob].each do |path|
           throw 'which', path if pat.match(path) and test(?r, path)
         end
       end

       File::expand_path(
         catch('which') do
           if lib.absolute?
             glob_for[ lib ]
           else
             search_path.each{|dir| glob_for[ File::join(dir, lib) ]}
           end
           return nil
         end
       )
     end

     p which_lib('session')
     p which_lib('pty.so')
     p which_lib(File::expand_path(__FILE__))
     p which_lib('fubar')


     jib:~ > ruby a.rb
     "/dmsp/reference/ruby-1.8.1/lib/ruby/site_ruby/session.rb"
     "/dmsp/reference/ruby-1.8.1/lib/ruby/1.8/i686-linux/pty.so"
     "/home/ahoward/a.rb"
     nil


should work on windows - but untested.

cheers.

-a
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