3 files changed, 41 insertions, 0 deletions
diff --git a/lib/puppet/interface/action.rb b/lib/puppet/interface/action.rb
index fe77a9658..fc1121eb6 100644
--- a/lib/puppet/interface/action.rb
+++ b/lib/puppet/interface/action.rb
@@ -199,6 +199,7 @@ def #{@name}(#{decl.join(", ")})
   options = args.last
 
   action = get_action(#{name.inspect})
+  action.add_default_args(args)
   action.validate_args(args)
   __invoke_decorations(:before, action, args, options)
   rval = self.__send__(#{internal_name.inspect}, *args)
@@ -252,6 +253,14 @@ WRAPPER
     option
   end
 
+  def add_default_args(args)
+    options.map {|x| get_option(x) }.each do |option|
+      if option.has_default? and not option.aliases.any? {|x| args.last.has_key? x}
+        args.last[option.name] = option.default
+      end
+    end
+  end
+
   def validate_args(args)
     # Check for multiple aliases for the same option...
     args.last.keys.each do |name|
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)
diff --git a/lib/puppet/interface/option_builder.rb b/lib/puppet/interface/option_builder.rb
index 5676ec977..c87adc2c0 100644
--- a/lib/puppet/interface/option_builder.rb
+++ b/lib/puppet/interface/option_builder.rb
@@ -51,4 +51,17 @@ class Puppet::Interface::OptionBuilder
   def required(value = true)
     @option.required = value
   end
+
+  def default_to(&block)
+    block or raise ArgumentError, "#{@option} default_to requires a block"
+    if @option.has_default?
+      raise ArgumentError, "#{@option} already has a default value"
+    end
+    # Ruby 1.8 treats a block without arguments as accepting any number; 1.9
+    # gets this right, so we work around it for now... --daniel 2011-07-20
+    unless block.arity == 0 or (RUBY_VERSION =~ /^1\.8/ and block.arity == -1)
+      raise ArgumentError, "#{@option} default_to block should not take any arguments"
+    end
+    @option.default = block
+  end
 end