1 files changed, 19 insertions, 0 deletions
diff --git a/lib/puppet/interface/option.rb b/lib/puppet/interface/option.rb
index 3cd930acf..01f6f2307 100644
--- a/lib/puppet/interface/option.rb
+++ b/lib/puppet/interface/option.rb
@@ -6,6 +6,7 @@ class Puppet::Interface::Option
   def initialize(parent, *declaration, &block)
     @parent   = parent
     @optparse = []
+    @default  = nil
 
     # Collect and sort the arguments in the declaration.
     dups = {}
@@ -81,8 +82,26 @@ class Puppet::Interface::Option
     !!@required
   end
 
+  def has_default?
+    !!@default
+  end
+
+  def default=(proc)
+    required and raise ArgumentError, "#{self} can't be optional and have a default value"
+    proc.is_a? Proc or raise ArgumentError, "default value for #{self} is a #{proc.class.name.inspect}, not a proc"
+    @default = proc
+  end
+
+  def default
+    @default and @default.call
+  end
+
   attr_reader   :parent, :name, :aliases, :optparse
   attr_accessor :required
+  def required=(value)
+    has_default? and raise ArgumentError, "#{self} can't be optional and have a default value"
+    @required = value
+  end
 
   attr_accessor :before_action
   def before_action=(proc)