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Resolver

The Resolver is a contract to be implemented by concrete resolvers providing the ability to resolve the CommandHandler class and their dependencies. Initially, one ArrayResolver will exist which takes an array of Commands and their CommandHandlers with an additional array of instantiated (or instantiatable) CommandHandler dependencies. In the future, other concrete resolvers may exist to allow for dependency injection using a framework's container so that it can also resolve interface bindings.

Dev Tasks:

• Checkout a new feature branch named GH-3 (same as the issue key).
• Break down the issue into units of work.
  • The resolver (it) can retrieve and instantiate a command handler for a given command.
  • It throws an exception if the handler class does not exist.
  • It throws an exception of the handler is not an instance of Handler.
  • It can inject the initialised command handler's dependencies.
  • It throws an exception if the handler's dependency cannot be injected.
• Configure PhpUnit, including testing namespace and an extensible TestCase.
• Configure the directory settings in PhpStorm
• Work on the units and commit successful refactored changes.
• Add any required usage documentation if applicable. #GH-5
• Review and deploy to "origin"
• Pull request and merge to "upstream".

Prepare contribution notes and update the Readme file accordingly.

Initials Setup Tasks:

• Create new milestone and assign this issue to it.
• Create issue labels for future categorisation.
• Install and launch VM on local workstation.
• Fork the repository.
• Setup Git locally for origin and upstream.
• Setup protected branches on GitHub.
• Checkout new issue branch.
• Setup up IDE.
• Type initial Readme.
• Initialise a Composer project.
• Add initial dependencies to composer.json.
• Setup package on Packagist with automated updates.
• Document install and contribution notes in Readme. Contribution notes moved to #GH-2
• Merge code and deploy to Packagist.
• Review and close issue.

The Command Bus:

Given an instance of a CommandHandlerResolver, it should be able to dispatch the command to the Handler.

Like so:

// An array of commands with handlers.
$commandsWithHandlers = [
    Domain\Command\DoSometing::class =>
        Domain\Hanlder\DoSomething::class,

    Domain\Command\DoSomethingElse::class =>
        Domain\Handler\DoSomethingElse::class,
];


$commandBus = new \SwellPhp\Admiral\CommandBus(
    new \SwellPhp\Admiral\ArrayResolver($commandsWithHandlers)
);

// Instantiates the command.
$command = new \Domain\Command\DoSometing(
    'some',
    'parameters'
);

// Dispath a command and it will be handled in the backgound.
$commandBus->dispatch($command)