Adds Module#< and Module#<=

mrbgems/mruby-class-ext/mrblib/module.rb

+class Module
+
+  ##
+  # call-seq:
+  #   mod < other   ->  true, false, or nil
+  #
+  # Returns true if <i>mod</i> is a subclass of <i>other</i>. Returns
+  # <code>nil</code> if there's no relationship between the two.
+  # (Think of the relationship in terms of the class definition:
+  # "class A < B" implies "A < B".)
+  #
+  def <(other)
+    raise TypeError, 'compared with non class/module' unless other.is_a?(Module)
+    if self.equal?(other)
+      false
+    else
+      self <= other
+    end
+  end
+
+  ##
+  # call-seq:
+  #   mod <= other   ->  true, false, or nil
+  #
+  # Returns true if <i>mod</i> is a subclass of <i>other</i> or
+  # is the same as <i>other</i>. Returns
+  # <code>nil</code> if there's no relationship between the two.
+  # (Think of the relationship in terms of the class definition:
+  # "class A < B" implies "A < B".)
+  def <=(other)
+    raise TypeError, 'compared with non class/module' unless other.is_a?(Module)
+    if self.ancestors.include?(other)
+      return true
+    elsif other.ancestors.include?(self)
+      return false
+    end
+  end
+
+end

mrbgems/mruby-class-ext/test/module.rb

+assert 'Module#<' do
+  a = Class.new
+  b = Class.new(a)
+  c = Class.new(a)
+  d = Module.new
+  e = Class.new { include d }
+  f = Module.new { include d }
+
+  # compare class to class
+  assert_true b < a
+  assert_false b < b
+  assert_false a < b
+  assert_nil c < b
+
+  # compare class to module
+  assert_true e < d
+  assert_false d < e
+  assert_nil a < d
+
+  # compare module to module
+  assert_true f < d
+  assert_false f < f
+  assert_false d < f
+
+  assert_raise(TypeError) { a < Object.new }
+end
+
+assert 'Module#<=' do
+  a = Class.new
+  b = Class.new(a)
+  c = Class.new(a)
+  d = Module.new
+  e = Class.new { include d }
+  f = Module.new { include d }
+
+  # compare class to class
+  assert_true b <= a
+  assert_true b <= b
+  assert_false a <= b
+  assert_nil c <= b
+
+  # compare class to module
+  assert_true e <= d
+  assert_false d <= e
+  assert_nil a <= d
+
+  # compare module to module
+  assert_true f <= d
+  assert_true f <= f
+  assert_false d <= f
+
+  assert_raise(TypeError) { a <= Object.new }
+end
+
 assert 'Module#name' do
   module Outer
     class Inner; end