README

Command dispatcher/invoker library supporting:

pre- and post-command handlers
undoable commands
chainable commands
command queueing
command history

Dispatcher classes:

Dispatcher (basic dispatcher)
QueueDispatcher
ChainDispatcher

Motivation

Basic idea behind command dispatcher library is to abstract program logic into separate classes, with logic expressed by class names derived from domain language.

Benefits include:

Proper use of domain language describes what the code should do, so it communicates it's intent better for all interested parties
Common supporting tasks like logging for each command can be easily added and abstracted away into command classes, so that they do not clutter the main program code
Easy unit testing of command logic

Usage

Basic dispatcher

class SomeCommand extends AbstractCommand implements CommandInterface
{
    public function __construct($param1, $param2)
    {
        // add dependencies, construct command "environment"
    }

    public function execute()
    {
        // command logic added here
    }
}

$dispatcher = new Dispatcher();
$dispatcher->handle(
    SomeCommand::create(array($param1, $param2))
);

Dispatch and log same command twice with different contructor parameter:

class SomeCommand extends AbstractCommand implements CommandInterface
{
    public function __construct($parameter)
    {
        // ...
    }

    public function execute()
    {
        //...
    }
    
    public function log($logger)
    {
        // use logger
    }
}

$dispatcher = new Dispatcher();
$dispatcher->addPostCommandHandler(function($command) use ($logger) {
    $command->log($logger);
});
$dispatcher->handleCommands(array(
    SomeCommand::create(array($oneValue)),
    SomeCommand::create(array($anotherValue)),
));

See basic dispatcher example.

Chain dispatcher

With Chain dispatcher, each command takes previous command's output as execute() -method's input:

class FirstCommand extends AbstractCommand implements ChainableCommandInterface
{
    public function execute(array $input)
    {
        //...
    }
}

class SecondCommand extends AbstractCommand implements ChainableCommandInterface
{
    public function execute(array $input)
    {
        //...
    }
}

$dispatcher = new ChainDispatcher();

$firstCommandInput = 'wow';
// $firstCommandInput is FirstCommand's input, $output is SecondCommand's return value
$output = $dispatcher->handleCommands(array(
    FirstCommand::create(),
    SecondCommand::create()
), $firstCommandInput);

See chain dispatcher example.

Installation

To add command-dispatcher library to Composer, see packagist for version information: https://packagist.org/packages/stiggg/command-dispatcher

Requirements

PHP >=5.3
Composer

Licence

MIT

Version history

Versioning supports semver: http://semver.org/

See version history

stiggg / command-dispatcher

Maintainers

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