Add custom "finish" method for options

4 files changed, 36 insertions, 2 deletions

diff --git a/lib/slop/option.rb b/lib/slop/option.rb
index a624110..9c11080 100644
--- a/lib/slop/option.rb
+++ b/lib/slop/option.rb
@@ -1,6 +1,7 @@
 module Slop
   class Option
     attr_reader :flags, :desc, :config, :count
+    attr_writer :value
 
     def initialize(flags, desc, **config)
       @flags  = flags
@@ -24,11 +25,17 @@ module Slop
       @value = call(value)
     end
 
-    def call(value)
+    def call(_value)
       raise NotImplementedError,
         "you must override the `call' method for option #{self.class}"
     end
 
+    # By default this method does nothing. It's called when all options
+    # have been parsed and allows you to mutate the `@value` attribute
+    # according to other options.
+    def finish(_result)
+    end
+
     def value
       @value || config[:default]
     end
diff --git a/lib/slop/parser.rb b/lib/slop/parser.rb
index 0ef4931..ef31ee1 100644
--- a/lib/slop/parser.rb
+++ b/lib/slop/parser.rb
@@ -30,7 +30,9 @@ module Slop
         end
       end
 
-      Result.new(self)
+      Result.new(self).tap do |result|
+        used_options.each { |o| o.finish(result) }
+      end
     end
 
     def unused_options
diff --git a/lib/slop/result.rb b/lib/slop/result.rb
index 5dd5213..0d0a3ab 100644
--- a/lib/slop/result.rb
+++ b/lib/slop/result.rb
@@ -27,6 +27,14 @@ module Slop
       end
     end
 
+    def used_options
+      parser.used_options
+    end
+
+    def unused_options
+      parser.unused_options
+    end
+
     # Returns a hash with option key => value.
     def to_hash
       Hash[options.map { |o| [o.key, o.value] }]
diff --git a/test/result_test.rb b/test/result_test.rb
index 68fd83f..cfa66d2 100644
--- a/test/result_test.rb
+++ b/test/result_test.rb
@@ -1,5 +1,15 @@
 require 'test_helper'
 
+module Slop
+  class ReverseEverythingOption < BoolOption
+    def finish(result)
+      result.used_options.grep(Slop::StringOption).each do |opt|
+        opt.value = opt.value.reverse
+      end
+    end
+  end
+end
+
 describe Slop::Result do
   before do
     @options = Slop::Options.new
@@ -22,6 +32,13 @@ describe Slop::Result do
     assert_equal "bar", @result[:foo]
   end
 
+  it "handles custom finishing" do
+    @options.string "--foo"
+    @options.reverse_everything "-r"
+    @result.parser.reset.parse %w(-r --name lee --foo bar)
+    assert_equal %w(eel rab), @result.to_hash.values_at(:name, :foo)
+  end
+
   describe "#[]" do
     it "returns an options value" do
       assert_equal "lee", @result["name"]