Don’t set default options as explicit keys

By setting default values for options explicitly, i.e. using #[]=, it becomes impossible to distinguish beteen explicity-specified options and implicitly-defaulted options. By using Hash#new, it becomes possible to return default values but not have them explicitly set as keys.

See #94.

README.md

@@ -267,6 +267,33 @@ OPTIONS
     -a --animal[=<value>]      add animal (default: giraffe)
 ```
 
+If the option is not given on the command line, the `options` hash will not have key for this option, but will still have a default value:
+
+```ruby
+option :a, :animal, 'add animal', default: 'giraffe', argument: :required
+
+run do |opts, args, cmd|
+  puts "Animal = #{opts[:animal]}"
+  puts "Option given? #{opts.key?(:animal)}"
+end
+```
+
+```sh
+% ./run --animal=donkey
+Animal = donkey
+Option given? true
+
+% ./run --animal=giraffe
+Animal = giraffe
+Option given? true
+
+% ./run
+Animal = giraffe
+Option given? false
+```
+
+This can be useful to distinguish between an explicitly-passed-in value and a default value. In the example above, the `animal` option is set to `giraffe` in the second and third cases, but it is possible to detect whether the value is a default or not.
+
 #### Multivalued options (`multiple:`)
 
 The `:multiple` parameter allows an option to be specified more than once on the command line. When set to `true`, multiple option valus are accepted, and the option values will be stored in an array.

lib/cri/command.rb

@@ -345,7 +345,7 @@ def run_this(opts_and_args, parent_opts = {})
         handle_errors_while { parser.run }
         local_opts  = parser.options
         global_opts = parent_opts.merge(parser.options)
-        add_defaults(global_opts)
+        global_opts = add_defaults(global_opts)
 
         # Handle options
         handle_options(local_opts)
@@ -435,14 +435,21 @@ def handle_errors_while
     end
 
     def add_defaults(options)
-      all_opt_defns.each do |opt_defn|
-        key = (opt_defn.long || opt_defn.short).to_sym
+      all_opt_defns_by_key =
+        all_opt_defns.each_with_object({}) do |opt_defn, hash|
+          key = (opt_defn.long || opt_defn.short).to_sym
+          hash[key] = opt_defn
+        end
 
-        next if opt_defn.default.nil?
-        next if options.key?(key)
+      new_options = Hash.new do |hash, key|
+        hash.fetch(key) { all_opt_defns_by_key[key]&.default }
+      end
 
-        options[key] = opt_defn.default
+      options.each do |key, value|
+        new_options[key] = value
       end
+
+      new_options
     end
   end
 end

test/test_command.rb

@@ -126,7 +126,7 @@ def test_invoke_simple_without_opts_or_args
         simple_cmd.run(%w[])
       end
 
-      assert_equal ['Awesome moo!', '', 'ddd=false,eee=false'], lines(out)
+      assert_equal ['Awesome moo!', '', ''], lines(out)
       assert_equal [], lines(err)
     end
 
@@ -135,7 +135,7 @@ def test_invoke_simple_with_args
         simple_cmd.run(%w[abc xyz])
       end
 
-      assert_equal ['Awesome moo!', 'abc,xyz', 'ddd=false,eee=false'], lines(out)
+      assert_equal ['Awesome moo!', 'abc,xyz', ''], lines(out)
       assert_equal [], lines(err)
     end
 
@@ -144,7 +144,7 @@ def test_invoke_simple_with_opts
         simple_cmd.run(%w[-c -b x])
       end
 
-      assert_equal ['Awesome moo!', '', 'bbb=x,ccc=true,ddd=false,eee=false'], lines(out)
+      assert_equal ['Awesome moo!', '', 'bbb=x,ccc=true'], lines(out)
       assert_equal [], lines(err)
     end
 
@@ -216,7 +216,7 @@ def test_invoke_simple_with_opt_with_block
         simple_cmd.run(%w[-a 123])
       end
 
-      assert_equal ['moo:123', 'Awesome moo!', '', 'aaa=123,ddd=false,eee=false'], lines(out)
+      assert_equal ['moo:123', 'Awesome moo!', '', 'aaa=123'], lines(out)
       assert_equal [], lines(err)
     end
 
@@ -246,7 +246,7 @@ def test_invoke_nested_with_correct_command_name
         nested_cmd.run(%w[sub])
       end
 
-      assert_equal ['Sub-awesome!', '', 'ddd=false,eee=false,ppp=false,qqq=false'], lines(out)
+      assert_equal ['Sub-awesome!', '', ''], lines(out)
       assert_equal [], lines(err)
     end
 
@@ -297,7 +297,7 @@ def test_invoke_nested_with_alias
         nested_cmd.run(%w[sup])
       end
 
-      assert_equal ['Sub-awesome!', '', 'ddd=false,eee=false,ppp=false,qqq=false'], lines(out)
+      assert_equal ['Sub-awesome!', '', ''], lines(out)
       assert_equal [], lines(err)
     end
 
@@ -306,7 +306,7 @@ def test_invoke_nested_with_options_before_command
         nested_cmd.run(%w[-a 666 sub])
       end
 
-      assert_equal ['super:666', 'Sub-awesome!', '', 'aaa=666,ddd=false,eee=false,ppp=false,qqq=false'], lines(out)
+      assert_equal ['super:666', 'Sub-awesome!', '', 'aaa=666'], lines(out)
       assert_equal [], lines(err)
     end
 
@@ -902,14 +902,14 @@ def test_flag_defaults_to_false
         option :f, :force2, 'push with force', argument: :forbidden
 
         run do |opts, _args, _cmd|
-          puts "Force? #{opts[:force2].inspect}!"
+          puts "Force? #{opts[:force2].inspect}! Key present? #{opts.key?(:force2)}!"
         end
       end
 
       out, err = capture_io_while do
         cmd.run(%w[])
       end
-      assert_equal ['Force? false!'], lines(out)
+      assert_equal ['Force? false! Key present? false!'], lines(out)
       assert_equal [], lines(err)
     end
 
@@ -919,14 +919,14 @@ def test_required_option_defaults_to_given_value
         option :a, :animal, 'specify animal', argument: :required, default: 'cow'
 
         run do |opts, _args, _cmd|
-          puts "Animal = #{opts[:animal]}"
+          puts "Animal = #{opts[:animal]}! Key present? #{opts.key?(:animal)}!"
         end
       end
 
       out, err = capture_io_while do
         cmd.run(%w[])
       end
-      assert_equal ['Animal = cow'], lines(out)
+      assert_equal ['Animal = cow! Key present? false!'], lines(out)
       assert_equal [], lines(err)
     end