From f1c874c3725f159f1b00295bf825b2a270cf57bc Mon Sep 17 00:00:00 2001
From: Moritz Bunkus <moritz@bunkus.org>
Date: Thu, 30 Dec 2010 16:32:18 +0100
Subject: [PATCH] =?utf8?q?Ein=20System=20von=20Hooks,=20die=20vor=20oder?=
 =?utf8?q?=20nach=20Actions=20ausgef=C3=BChrt=20werden=20k=C3=B6nnen?=
MIME-Version: 1.0
Content-Type: text/plain; charset=utf8
Content-Transfer-Encoding: 8bit

---
 SL/Controller/Base.pm | 116 +++++++++++++++++++++++++++++++++++++++---
 1 file changed, 109 insertions(+), 7 deletions(-)

diff --git a/SL/Controller/Base.pm b/SL/Controller/Base.pm
index 0c8147015..8e7e721dd 100644
--- a/SL/Controller/Base.pm
+++ b/SL/Controller/Base.pm
@@ -77,18 +77,66 @@ sub render {
   return $output;
 }
 
+#
+# Before/after run hooks
+#
+
+sub run_before {
+  _add_hook('before', @_);
+}
+
+sub run_after {
+  _add_hook('after', @_);
+}
+
+my %hooks;
+
+sub _add_hook {
+  my ($when, $class, $sub, %params) = @_;
+
+  foreach my $key (qw(only except)) {
+    $params{$key} = { map { ( $_ => 1 ) } @{ $params{$key} } } if $params{$key};
+  }
+
+  my $idx = "${when}/${class}";
+  $hooks{$idx} ||= [ ];
+  push @{ $hooks{$idx} }, { %params, code => $sub };
+}
+
+sub _run_hooks {
+  my ($self, $when, $action) = @_;
+
+  my $idx = "${when}/" . ref($self);
+
+  foreach my $hook (@{ $hooks{$idx} || [] }) {
+    next if ($hook->{only  } && !$hook->{only  }->{$action})
+         || ($hook->{except} &&  $hook->{except}->{$action});
+
+    if (ref($hook->{code}) eq 'CODE') {
+      $hook->{code}->($self);
+    } else {
+      my $sub = $hook->{code};
+      $self->$sub;
+    }
+  }
+}
+
 #
 # private functions -- for use in Base only
 #
 
 sub _run_action {
   my $self   = shift;
-  my $action = "action_" . shift;
+  my $action = shift;
+  my $sub    = "action_${action}";
+
+  return $self->_dispatch(@_) if $action eq 'dispatch';
 
-  return $self->_dispatch(@_) if $action eq 'action_dispatch';
+  $::form->error("Invalid action '${action}' for controller " . ref($self)) if !$self->can($sub);
 
-  $::form->error("Invalid action ${action} for controller " . ref($self)) if !$self->can($action);
-  $self->$action(@_);
+  $self->_run_hooks('before', $action);
+  $self->$sub(@_);
+  $self->_run_hooks('after', $action);
 }
 
 sub _controller_name {
@@ -99,10 +147,13 @@ sub _dispatch {
   my $self    = shift;
 
   no strict 'refs';
-  my @actions = grep { m/^action_/ } keys %{ ref($self) . "::" };
-  my $action  = first { $::form->{$_} } @actions;
+  my @actions = map { s/^action_//; $_ } grep { m/^action_/ } keys %{ ref($self) . "::" };
+  my $action  = first { $::form->{"action_${_}"} } @actions;
+  my $sub     = "action_${action}";
 
-  $self->$action(@_);
+  $self->_run_hooks('before', $action);
+  $self->$sub(@_);
+  $self->_run_hooks('after', $action);
 }
 
 sub _template_obj {
@@ -201,6 +252,24 @@ Usage from a template usually looks like this:
 
 The dispatching is handled by the function L</_dispatch>.
 
+=head2 HOOKS
+
+Hooks are functions that are called before or after the controller's
+action is called. The controller package defines the hooks, and those
+hooks themselves are run as instance methods.
+
+Hooks are run in the order they're added.
+
+The return value of the hooks is discarded.
+
+Hooks can be defined to run for all actions, for only specific actions
+or for all actions except a list of actions. Each entry is the action
+name, not the sub's name. Therefore in order to run a hook before one
+of the subs C<action_edit> or C<action_save> is called the following
+code can be used:
+
+  __PACKAGE__->run_before('things_to_do_before_edit_and_save', only => [ 'edit', 'save' ]);
+
 =head1 FUNCTIONS
 
 =head2 PUBLIC HELPER FUNCTIONS
@@ -298,6 +367,39 @@ Redirects the browser to a new URL by outputting a HTTP redirect
 header. The URL is generated by calling L</url_for> with
 C<%url_params>.
 
+=item C<run_before $sub, %params>
+
+=item C<run_after $sub, %params>
+
+Adds a hook to run before or after certain actions are run for the
+current package. The code to run is C<$sub> which is either the name
+of an instance method or a code reference. If it's the latter then the
+first parameter will be C<$self>.
+
+C<%params> can contain two possible values that restrict the code to
+be run only for certain actions:
+
+=over 2
+
+=item C<< only => \@list >>
+
+Only run the code for actions given in C<@list>. The entries are the
+action names, not the names of the sub (so it's C<list> instead of
+C<action_list>).
+
+=item C<< except => \@list >>
+
+Run the code for all actions but for those given in C<@list>. The
+entries are the action names, not the names of the sub (so it's
+C<list> instead of C<action_list>).
+
+=back
+
+If neither restriction is used then the code will be run for any
+action.
+
+The hook's return values are discarded.
+
 =back
 
 =head2 PRIVATE FUNCTIONS
-- 
2.20.1