From: Zev Blut <rubyzbibd@...>
Date: 2005-02-18T20:24:28+09:00
Subject: Require  when Executed file is required by another file.

Hello,

My colleagues and I just encountered an interesting gotcha with
"require".

Put the following in a file called "req1.rb"

-------------- [req1.rb]
#!/usr/local/bin/ruby1.8 -w

puts "$0 #{$0}"
base = $0.split("/")
PATH = base[0...(base.size - 1)].join("/")

def jump
   require "req2"
end

puts "Fun"

if __FILE__ == $0
   puts "Require 1"
   jump
end
---------- [req1.rb]

And then put the following in another file called "req2.rb"

---------- [req2.rb]
require "#{PATH}/req1"

puts "Require 2"
---------- [req2.rb]

Now run req1.rb from the full path.

Here is an example of my output:
========
$ /home/zev/projects/rubyplay/recurse_require/req1.rb
$0 /home/zev/projects/rubyplay/recurse_require/req1.rb
Fun
Require 1
$0 /home/zev/projects/rubyplay/recurse_require/req1.rb
/home/zev/projects/rubyplay/recurse_require/req1.rb:5: warning:
already initialized constant PATH

/home/zev/projects/rubyplay/recurse_require/req1.rb:7: warning: method
redefined; discarding old jump

Fun
Require 1
Require 2
=========

Notice that the __FILE__ == $0 gets called twice!
Also the fact that PATH and jump get redefined too...

Is there a way to easily stop this?

Thanks,
Zev