1 files changed, 24 insertions, 0 deletions
diff --git a/Library/Homebrew/extend/set.rb b/Library/Homebrew/extend/set.rb
new file mode 100644
index 000000000..b45b85de9
--- /dev/null
+++ b/Library/Homebrew/extend/set.rb
@@ -0,0 +1,24 @@
+require 'set'
+
+class ComparableSet < Set
+  def add new
+    # smileys only
+    return super new unless new.respond_to? :>
+
+    objs = find_all { |o| o.class == new.class }
+    objs.each do |o|
+      return self if o > new
+      delete o
+    end
+    super new
+  end
+
+  alias_method :<<, :add
+
+  # Set#merge bypasses enumerating the set's contents,
+  # so the subclassed #add would never be called
+  def merge enum
+    enum.is_a?(Enumerable) or raise ArgumentError, "value must be enumerable"
+    enum.each { |o| add(o) }
+  end
+end