CommandBus Builder

[ghost]

What do you think about adding a simple builder?

For example:

<?php

use League\Tactician\CommandBus;
use League\Tactician\Handler\CommandHandlerMiddleware;
use League\Tactician\Handler\CommandNameExtractor\ClassNameExtractor;
use League\Tactician\Handler\CommandNameExtractor\CommandNameExtractor;
use League\Tactician\Handler\Locator\HandlerLocator;
use League\Tactician\Handler\MethodNameInflector\HandleInflector;
use League\Tactician\Handler\MethodNameInflector\MethodNameInflector;
use League\Tactician\Middleware;

class Builder
{
    private $middlewares = [];
    private $handlerLocator;
    private $commandNameExtractor;
    private $inflector;

    public function __construct(
        HandlerLocator $handlerLocator,
        CommandNameExtractor $commandNameExtractor = null,
        MethodNameInflector $inflector = null
    ) {
        $this->handlerLocator = $handlerLocator;
        $this->commandNameExtractor = $commandNameExtractor ?: new ClassNameExtractor();
        $this->inflector = $inflector ?: new HandleInflector();
    }

    public function attachMiddleware(Middleware $middleware, $priority = null)
    {
        if ($priority !== null) {
            $this->middlewares[$priority] = $middleware;
        } else {
            $this->middlewares[] = $middleware;
        }
    }

    public function build()
    {
        ksort($this->middlewares);
        $this->middlewares[] = new CommandHandlerMiddleware(
            $this->commandNameExtractor,
            $this->handlerLocator,
            $this->inflector
        );

        return new CommandBus($this->middlewares);
    }
}

And then, we can configure CommandBus using a configuration file, for example:

<?php

$builder = new Builder(new ContainerBasedLocator($container));
$middlewares = require './middlewares.php';
foreach ($middlewares as $middleware) {
    if (is_array($middleware)) {
        if (sizeof($middleware) != 2) {
            throw new \LogicException('Invalid middleware definition.');
        }
        list($middleware, $priority) = $middleware;
    } else {
        $priority = null;
    }
    $builder->attachMiddleware($container->get($middleware), $priority);
}
$bus = $builder->build();

<?php

// middlewares.php

return [
    [LockingMiddleware::class, -255],
    [LoggingMiddleware::class, 255],
    [TransactionMiddleware::class, 0],
];

[rosstuck]

Hi @Kilte,

First off, sorry for the delay answering you, I was busy most of the weekend. My apologies! :sweat:

I like the general idea though I'm not sure how common the usecase is for it. If we were to include something similar in core, perhaps it could be a refactored version of the Quickstart setup object? Would that be interesting to you?

I would probably want to remove the priority numbers though, since I've tried to avoid these and discourage them whenever I can. The order of middleware is very important to how the app runs so I want folks to make explicit decisions on that whenever possible.

[ghost]

Hi @rosstuck.

Yes, QuickStart is similar and can be replaced by Builder.

About priorities, maybe you're right. In my case they are necessary, since the bus is configured from multiple places. I can implement priorities manually, it does not matter.

Finally, we can replace QuickStart by simple builder (without middleware priorities). In my opinion this will be more useful.

[sagikazarmark]

Hey @Kilte @rosstuck

I am thinking about exactly this for the last few days. I like the idea, I have a few use cases. Actually this might be a big help in DI.

:+1: :100:

[rosstuck]

If you two are both on board for this, perhaps it'd be good to layout some rough API notes and square this off, then we can merge it to core. :)

[ghost]

@rosstuck, @sagikazarmark, I've created a pull request. Waiting for suggestions =).