lib/bio/db/pdb/chain.rb in bio-1.4.2 vs lib/bio/db/pdb/chain.rb in bio-1.4.3

@@ -4,19 +4,18 @@
 # Copyright:: Copyright (C) 2004, 2006
 #             Alex Gutteridge <[e-mail]>
 #             Naohisa Goto <[e-mail]>
 # License::   The Ruby License
 # 
-# $Id: chain.rb,v 1.10 2008/04/01 10:36:44 ngoto Exp $
 #
 # = Bio::PDB::Chain
 # 
 # Please refer Bio::PDB::Chain.
 #
 
-require 'bio/db/pdb'
-
 module Bio
+
+  require 'bio/db/pdb' unless const_defined?(:PDB)
 
   class PDB
 
     # Bio::PDB::Chain is a class to store a chain.
     #