Attempt

Attempt is a simple, fluent class for attempting to run code multiple times whilst handling exceptions. It attempts to mimic PHPs built-in try/catch syntax where possible but sprinkles in some additional magic on top.

Installation

Attempt has been added to packagist and can be installed via composer:

composer require slashequip/attempt

Getting an instance

Depending on your preference you can grab an Attempt instance in a couple of ways:

use SlashEquip\Attempt\Attempt;

$attempt = new Attempt();

$attempt = Attempt::make();

Building your Attempt

Once you have your instance you can begin to build your Attempt.

Try

This is the only required method, the try method accepts a callable argument, the code that you want to run.

$attempt
    ->try(function () {
        // My code that may or may not work.
    })
    ->thenReturn();

Then Return

You may have noticed in the example above the method thenReturn, this method is what tells the Attempt to run. It will also return the value you return from the callable you pass to the try method.

There is also a then method, this too accepts a callable which is executed and passed the value returned by your try callable.

If it's your kind of jam, an attempt is also invokable which means at any point you can invoke the Attempt and it will run.

// $valueOne will be true
$valueOne = $attempt
    ->try(function () {
        return true;
    })
    ->thenReturn();

// $valueTwo will be false
$valueTwo = $attempt
    ->try(function () {
        return true;
    })
    ->then(function ($result) {
        return !$result;
    });

// $valueThree will be true
$valueThree = $attempt
    ->try(function () {
        return true;
    })();

Times

You can set the amount of times the Attempt should be made whilst an exception is being encountered see catch.

$valueOne = $attempt
    ->try(function () {
        throw new RuntimeException();
    })
    ->times(5)
    ->thenReturn();
// The above code would be run 5 times before throwing the RuntimeException

Catch

The catch method allows you to define exceptions you are expecting to encounter during the attempts, when exceptions have been passed to the catch method the Attempt will throw any other types of exceptions it comes across early rather than performing all attempts.

The catch method can be called multiple times to add multiple expected exceptions.

If you do not provide any expected exception via the catch method then the Attempt will ignore all exceptions until all attempts have been made.

$attempt
    ->try(function () {
        throw new UnexpectedException;
    })
    ->catch(TheExceptionWeAreExpecting::class)
    ->catch(AnotherExceptionWeAreExpecting::class)
    ->thenReturn();

// In this example; only one attempt would be made and a UnexpectedException would be thrown

The catch method also allows you to define a callback that will be called when the specified exception is eventually thrown. This can be useful for error logging or you could also return a default value if your code is to continue.

$attempt
    ->try(function () {
        throw new AnExpectedException;
    })
    ->catch(AnExpectedException::class, function (AnExpectedException $e) {
        error_log($e->getMessage());
        return new NullBlogPost();
    })
    ->thenReturn();

No Throw

Attempt can be configured to never throw exceptions, there are situations when you want to execute some code but still continue with the rest of your logic. For these situations you can use noThrow.

$attempt
    ->try(function () {
        throw new RuntimeException();
    })
    ->noThrow()
    ->thenReturn();
// The above exception would not bubble up and instead, simply, be swallowed.

Finally

The finally method allows you to run a callback at the end of the attempt no matter the result, whether the attempt was successful or an exception was thrown the finally callback will always be run.

$attempt
    ->try(function () {
        throw new UnexpectedException;
    })
    ->finally(function () {
        // run some clean up.
    })
    ->thenReturn();

// In this example; the finally callback would be run before the UnexpectedException is thrown

Wait Between

The waitBetween method takes an integer indicating the desired number of milliseconds to wait between attempts. The pause happens before the code runs but does not delay the starting of the Attempt.

$attempt
    ->try(function () use ($data) {
        throw new UnexpectedException;
    })
    ->times(3)
    ->waitBetween(250)
    ->thenReturn();

// In this example, there would be a pause of 250 milliseconds between each attempt.

Example use case

use SlashEquip\Attempt\Attempt;
use GuzzleHttp\Exception\ClientException;

$blogPost = Attempt::make()
    ->try(function () use ($data) {
        return UnstableBlogApiServiceUsingGuzzle::post([
           'data' => $data,
        ]);
    })
    ->times(3)
    ->waitBetween(250)
    ->catch(ClientException::class, function (ClientException $e) {
        error_log("Unstable blog api service is causing issues again.")
        return new BlogPost::nullableObject();
    })
    ->then(function ($apiResponse) {
        return BlogPost::fromApiResponse($apiResponse);
    });