This package provides a standard for tracking states of applications in PHP. The package aims to create a multi-use standard.

This package contains interfaces and a simple implementations for tracking states.

composer require php-unified/state

This interface is an indication that an optional StateInterface interface can be supplied. The class that would implement this interface is one that keeps track of value for a state (optionally).

This interface provides a standard for implementing state tracking into applications. The following functions are expected to be implemented.

For this interface, an implementation is provided. See: PhpUnified\State\State.

The object has 2 setters and 2 getters. These methods are:

• setValue and getValue for setting and getting the value of the object.
• setIdentifier and getIdentifier for setting and getting the identifier of the object.

The output of the method __toString should convert a state to a human readable string. The result of this method with a single state could look like:

version: 1.0.0

Where version is the set identifier and 1.0.0 the set version.

For a state with multiple sub-states, output could look like:

packages:
    name: php-unified/state
    version: 1.0.0

Every line is a new state, with their respective identifier: value pairs.

The method for exporting states to an array is exportState. The output of the method could look like:

$output = [
    'packages' => '',
    'states' => [
        'name' => 'php-unified/state',
        'version' => '1.0.0'
    ]
]

To add a state to a state, the method addState is expected to be implemented. These states should be iterated over in both of the exporting states implementations.

Please see CHANGELOG for more information on what has changed recently.

Please see CONTRIBUTING and CODE_OF_CONDUCT for details.

By taking the approach of using nested states, the application can actively update their values. This would result a single repository of states, which can be used in logging. And thus creating more insight for debugging purposes.

For example, the application could monitor the last action from a database connection like so:

use PhpUnified\State\State;
use Application\Database\Connection;
use Application\Logger\Logger;

$systemState = new State();
$systemState->setIdentifier('system-state');

$databaseTransactionState = new State();
$databaseTransactionState->setIdentifier('last-db-transaction-state');

$systemState->addState($databaseTransactionState);

$logger = new Logger();
$connection = new Connection($databaseTransactionState);
try {
    $connection->doQuery();
} catch (Throwable $e) {
    $logger->log('warning', $e->getMessage());
    $logger->info($systemState->__toString());
}

Then the (fictional) Connection class could look like:

namespace Application\Database;

use PhpUnified\State\Common\StateInterface;

class Connection
{
    /**
     * State tracker
     *
     * @var StateInterface
     */
    private $state;

    /**
     * Constructor
     *
     * @param StateInterface $state
     */
    public function __construct(StateInterface $state)
    {
        $this->state = $state;
    }

    /**
     * Fictional doQuery function
     *
     * @return void
     */
    public function doQuery(): void
    {
        $state->setValue('Starting database connection');
        $connection = connectToDatabase();

        $state->setValue('Starting transaction');
        $connection->startTransaction();

        $state->setValue('Executing transaction');
        if($connection->doTransaction()) {
            $state->setValue(
                sprintf(
                    'Transaction with id %d transaction success',
                    $connection->getLastTransactionId()
                )
            );
            return true;
        }

        $state->setValue('Rolling back transaction');
        $connection->rollBackTransaction();
        $state->setValue('Rollback executed');
    }
}

If any of the above function calls in the doQuery function would result in an exception being thrown, the latest state can still be logged.

Copyright (c) 2019 GrizzIT

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