From: Shadowfirebird <shadowfirebird@...>
Date: 2008-07-23T18:48:13+09:00
Subject: circular 'require'

Hi,

I'm new to ruby and I'm really enjoying it.   However, there is one thing...

I gather from this list and my poor efforts that ruby does not like
files that 'require' each other circularly.  I can find nothing in the
documentation about this, though; in fact, the description of require
seems to actually rule it out.   Can anyone explain what is going on
here?

(This happens in 1.8 and 1.9 and JRuby 1.0.  So it's definitely me,
not Ruby, that has the problem.)


To flesh things out a little:

'require' is supposed to load files, unless they have been already
loaded.  It stores an array of loaded files in $" for this purpose.

Okay, suppose we have two programs in two different files:

# test1.rb
require "test2.rb"
class One
  def self.testone(); Two.whoistwo; end
  def self.whoisone();  puts "class one"; end
end

# test2.rb
require "test1.rb"
class Two
  def self.testtwo(); One.whoisone; end
  def self.whoistwo(); puts "class two"; end
end

>ruby -w test1.rb
./test1.rb:4: unititialized constant Two (NameError)

Why does this happen?  I would have thought that test1 would load
test2; then test2 would go to load test1 but find it already loaded.
Apparently what happens is that test2 doesn't get loaded at all.

OTOH if I replace the 'require' with a homebrew, like this:

# test1.rb
$" << "test1.rb"
load("test2.rb") if !$".include?("test2.rb")
...

...then everything works fine, which seems to imply that 'replace'
isn't behaving as described in the slightest.

Anyone that can provide a description of what replace actually does
while staying high-level enough for my head not to spin, will earn my
undying gratitude.

Ta,
Shadowfirebird.

-- 
Me, I imagine places that I have never seen / The colored lights in
fountains, blue and green / And I imagine places that I will never go
/ Behind these clouds that hang here dark and low
But it's there when I'm holding you / There when I'm sleeping too /
There when there's nothing left of me / Hanging out behind the
burned-out factories / Out of reach but leading me / Into the
beautiful sea