Feature Proposal: The new OO foswiki needs new OO plugins.

Tags/macros

Named callbacks.

    my $cbData = { app => $this, };
    weaken( $cbData->{app} );
    foreach my $cbName ( keys %{ $this->callbacks } ) {
        $this->registerCallback( $cbName, $this->callbacks->{$cbName},
            $cbData );
    }

    $this->callback( 'handleRequestException', { exception => $e, } );

    my $obj = shift;
    my %args = @_;

    my $app = $args{data}{app};
    my $exception = $args{params}{exception};

Method redefinition.

package Foswiki::CoreModule;

use Moo;
with 'Foswiki::NewPlugins::Pluggable';

...

pluggable redefinable => sub {
    # Here is something we do by default.
};

package Foswiki::NewPlugin::SomePlugin;

use Moo;
extends qw(Foswiki::NewPlugin);

...

prefix_method 'Foswiki::CoreModule::redefinable' => sub {
    my $this = shift; # Plugin object.
    my $coreObject = shift; # A instance of Foswiki::CoreModule
    my %params = @_;

    my @args = @{ $params{args} };
    
    # Here we do something.

    if ($thisIsFinal) {
        Foswiki::Exception::Flow::Last->throw(
            text => "The reason why the remaing plugins must not have their chance to run",
            rc => $returnValue,
        );
    }

    if ($weWantToOverrideTheOriginalMethod) {
        Foswiki::Exception::Flow::NoOrig->throw(
            rc => $returnValue,
        );
    }

    # This is what's gonna be passed over to the original method if it gets called.
    $params{args} = \@modifiedArgs;
};

• redefinition of arguments passed over to the remaining plugins and the original method by redefining key args of the parameters hash
• avoiding the original method from being called by setting raising Foswiki::Exception::Flow::NoOrig and setting it's rc parameter to the desired return value. Note this would let run the all the remaining plugins.
• stop the execution flow by rasing Foswiki::Exception::Flow::Last. It is similar to the previous case except that the remaining plugins won't get their chance to run.
• restart the flow with Foswiki::Exception::Flow::Restart. Any changes to the parameters hash are preserved. This would cause the whole execution chain to rerun in a different state.
• skip all remaining plugins by raising Foswiki::Exception::Flow::Skip and pass the control to the original method.

Class redefinition

package Foswiki::NewPlugin::Mighty;

use Moo;
extends qw(Foswiki::NewPlugin);

replace_class 'Foswiki::Meta' => 'Foswiki::NewPlugin::Mighty::Meta';

package Foswiki::NewPlugin::Mighty::Meta;

use Moo;
# Note that there is no extends keyword.

1;

    my $topicObject = $app->create('Foswiki::Meta', web => $web, topic => $topic);

Foswiki::Meta <- Foswiki::NewPlugin::Mighty <- Foswiki::NewPlugin::AllMighty

Foswiki::Meta <- Foswiki::NewPlugin::Mighty::Meta
Foswiki::Meta <- Foswiki::NewPlugin::AllMighty::Meta

Action registering

actionHandler jsonrpc => sub {};

actionHandler jsonrpc => \&jsonActionHandler;

Examples

Impact

Implementation

Discussion

    default => sub {
        my $storeClass = $Foswiki::cfg{Store}{Implementation}
          || 'Foswiki::Store::PlainFile';
        ASSERT( $storeClass, "Foswiki::store base class is not defined" )
          if DEBUG;
        return $_[0]->create($storeClass);
    },

    default => sub { $_[0]->create('Foswiki::Store'); },

%MACRO{...}%
...
%ENDMACRO%

    $this->registerTAGHandler(
        name => 'MACRO',
        isBlock => 1,
        closingMacro => 'ENDMACRO',
        rawParamStr => 1,
        handler => sub { ... },
    );

• Promises are about asynchronous programming. Most of Foswiki internals are straightforward processing – more of a conveyor than McDonald's counter.
• They're bound to event loops. I see no event loop in Foswiki. More than that, Foswiki app is a callback on HTTP server event loop.

• Registering custom tags.
• Callbacks – similar to current plugin handlers but more flexible.

macro 'CUSTOMACRO' => sub {
    my $this = shift;

    ...; # handle the macro
};

callback 'Foswiki::App::postConfig' => sub {
    my $this = shift;
    my %params = @_;

    ...;
};

class_override 'Foswiki::Logger' => 'Foswiki::Contrib::MyPlugin::Logger';
class_inherit 'Foswiki::Config' => 'Foswiki::Contrib::MyPlugin::Config';