implement --version

lib/App/Cmd.pm

@@ -128,19 +128,25 @@ Valid arguments are:
 
   no_help_plugin     - if true, the help plugin is not added
 
+  no_version_plugin  - if true, the version plugin is not added
+
   plugin_search_path - The path to search for commands in. Defaults to
                        results of plugin_search_path method
 
-If C<no_commands_plugin> is not given, App::Cmd::Command::commands will be
+If C<no_commands_plugin> is not given, L<App::Cmd::Command::commands> will be
 required, and it will be registered to handle all of its command names not
 handled by other plugins.
 
-If C<no_help_plugin> is not given, App::Cmd::Command::help will be required,
+If C<no_help_plugin> is not given, L<App::Cmd::Command::help> will be required,
 and it will be registered to handle all of its command names not handled by
 other plugins. B<Note:> "help" is the default command, so if you do not load
 the default help plugin, you should provide your own or override the
 C<default_command> method.
 
+If C<no_version_plugin> is not given, L<App::Cmd::Command::version> will be
+required to show the application's version with command C<--version>. The
+version command is not included in the command list.
+
 =cut
 
 sub new {
@@ -197,7 +203,7 @@ sub _command {
     }
   }
 
-  $self->_load_default_plugin($_, $arg, \%plugin) for qw(commands help);
+  $self->_load_default_plugin($_, $arg, \%plugin) for qw(commands help version);
 
   if ($self->allow_any_unambiguous_abbrev) {
     # add abbreviations to list of authorized commands

lib/App/Cmd/Command/commands.pm

@@ -34,6 +34,7 @@ sub execute {
   print { $target } "Available commands:\n\n";
 
   my @primary_commands =
+    grep { $_ ne '--version' }
     map { ($_->command_names)[0] }
     $self->app->command_plugins;
 

lib/App/Cmd/Command/version.pm

@@ -0,0 +1,27 @@
+use strict;
+use warnings;
+
+package App::Cmd::Command::version;
+use App::Cmd::Command;
+BEGIN { our @ISA = 'App::Cmd::Command'; }
+
+# ABSTRACT: display an app's version
+
+=head1 DESCRIPTION
+
+This plugin implements the C<--version> command. On execution it shows the
+program name, it's base class with version number, and the full program name.
+
+=cut
+
+sub command_names { qw/--version/ }
+
+sub execute {
+  my ($self, $opts, $args) = @_;
+
+  printf "%s (%s) version %s (%s)\n",
+    $self->app->arg0, ref($self->app),
+    $self->app->VERSION, $self->app->full_arg0;
+}
+
+1;

t/abbrev.t

@@ -13,6 +13,7 @@ use Test::MyCmdAbbrev;
 my $app = Test::MyCmdAbbrev->new( {
     no_commands_plugin => 1,
     no_help_plugin     => 1,
+    no_version_plugin  => 1,
 } );
 
 is_deeply(

t/basic.t

@@ -3,7 +3,7 @@
 use strict;
 use warnings;
 
-use Test::More tests => 13;
+use Test::More tests => 15;
 use App::Cmd::Tester;
 
 use lib 't/lib';
@@ -16,7 +16,7 @@ isa_ok($app, 'Test::MyCmd');
 
 is_deeply(
   [ sort $app->command_names ],
-  [ sort qw(help --help -h -? commands exit frob frobulate hello justusage stock) ],
+  [ sort qw(help --help -h --version -? commands exit frob frobulate hello justusage stock) ],
   "got correct list of registered command names",
 );
 
@@ -25,6 +25,7 @@ is_deeply(
   [ qw(
     App::Cmd::Command::commands
     App::Cmd::Command::help
+    App::Cmd::Command::version
     Test::MyCmd::Command::exit
     Test::MyCmd::Command::frobulate
     Test::MyCmd::Command::hello
@@ -65,11 +66,16 @@ is_deeply(
   like($@, qr/mandatory method/, "un-subclassed &run leads to death");
 }
 
-my $return = test_app('Test::MyCmd', [ qw(commands) ]);
+my $return = test_app('Test::MyCmd', [ qw(--version) ]);
+my $version_expect = "basic.t (Test::MyCmd) version 0.123 (t/basic.t)\n";
+is($return->stdout, $version_expect, "version plugin enabled");
+
+$return = test_app('Test::MyCmd', [ qw(commands) ]);
 
 for my $name (qw(commands frobulate hello justusage stock)) {
   like($return->stdout, qr/^\s+\Q$name\E/sm, "$name plugin in listing");
 }
+unlike($return->stdout, qr/--version/, "version plugin not in listing");
 
 {
   my $return = test_app('Test::MyCmd', [ qw(exit 1) ]);

t/callback.t

@@ -17,7 +17,7 @@ my $app = $CLASS->new;
 
 is_deeply(
   [ sort $app->command_names ],
-  [ sort qw(help --help -h -? commands lol) ],
+  [ sort qw(help --help -h --version -? commands lol) ],
   "got correct list of registered command names",
 );
 

t/lib/Test/MyCmd.pm

@@ -5,4 +5,6 @@ use warnings;
 
 use base qw(App::Cmd);
 
+our $VERSION = '0.123';
+
 1;

t/setup-inner.t

@@ -16,7 +16,7 @@ my $app = $CLASS->new;
 
 is_deeply(
   [ sort $app->command_names ],
-  [ sort qw(help --help -h -? commands poot) ],
+  [ sort qw(help --help -h --version -? commands poot) ],
   "got correct list of registered command names",
 );
 
@@ -25,6 +25,7 @@ is_deeply(
   [ qw(
     App::Cmd::Command::commands
     App::Cmd::Command::help
+    App::Cmd::Command::version
     Test::WSOF::Command::poot
   ) ],
   "got correct list of registered command plugins",

t/setup-nocmd.t

@@ -25,7 +25,7 @@ my $app = $CLASS->new;
 
 is_deeply(
   [ sort $app->command_names ],
-  [ sort qw(help --help -h -? commands blort) ],
+  [ sort qw(help --help -h --version -? commands blort) ],
   "got correct list of registered command names",
 );
 
@@ -34,6 +34,7 @@ is_deeply(
   [ qw(
     App::Cmd::Command::commands
     App::Cmd::Command::help
+    App::Cmd::Command::version
     Test::WSNCC::Command::blort
   ) ],
   "got correct list of registered command plugins",

t/setup.t

@@ -16,7 +16,7 @@ my $app = $CLASS->new;
 
 is_deeply(
   [ sort $app->command_names ],
-  [ sort qw(help --help -h -? commands alfie bertie) ],
+  [ sort qw(help --help -h --version -? commands alfie bertie) ],
   "got correct list of registered command names",
 );
 
@@ -25,6 +25,7 @@ is_deeply(
   [ qw(
     App::Cmd::Command::commands
     App::Cmd::Command::help
+    App::Cmd::Command::version
     Test::WithSetup::Command::alfie
     Test::WithSetup::Command::bertie
   ) ],