How do I get a list of files that have been `required` in Ruby?

Question

This is purely an experiment, but I\'m wondering if it\'s possible to get a list of the require\'d gems at runtime via some kind of metaprogramming. For example

Answer 1

Here's a way to get all the calls to require. Create this file: show_requires.rb

alias :orig_require :require
def require s
  print "Requires #{s}\n" if orig_require(s)
end

Then start your app with

ruby -r show_requires.rb myapp.rb

This produces something like:

C:\code\test>ruby -r show_requires.rb test.rb
Requires stringio
Requires yaml/error
Requires syck
Requires yaml/ypath
Requires yaml/basenode
Requires yaml/syck
Requires yaml/tag
Requires yaml/stream
Requires yaml/constants
Requires date/format
Requires date
Requires yaml/rubytypes
Requires yaml/types
Requires yaml
Requires etc
Requires dl
Requires rbreadline
Requires readline

If you want only the top-level requires, add a global to track the nesting level:

$_rq_lvl = 0
alias :orig_require :require
def require s
  $_rq_lvl+=1
  print "Requires #{s}\n" if orig_require(s) and $_rq_lvl == 1
  $_rq_lvl -=1
end

Then you get:

C:\code\test>ruby -r require_test.rb test.rb
Requires yaml
Requires readline