195 lines
9.7 KiB
Markdown
195 lines
9.7 KiB
Markdown
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# PHP Enum implementation inspired from SplEnum
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[![GitHub Actions][GA Image]][GA Link]
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[](https://packagist.org/packages/myclabs/php-enum)
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[](https://packagist.org/packages/myclabs/php-enum)
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[![Psalm Shepherd][Shepherd Image]][Shepherd Link]
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Maintenance for this project is [supported via Tidelift](https://tidelift.com/subscription/pkg/packagist-myclabs-php-enum?utm_source=packagist-myclabs-php-enum&utm_medium=referral&utm_campaign=readme).
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## Why?
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First, and mainly, `SplEnum` is not integrated to PHP, you have to install the extension separately.
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Using an enum instead of class constants provides the following advantages:
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- You can use an enum as a parameter type: `function setAction(Action $action) {`
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- You can use an enum as a return type: `function getAction() : Action {`
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- You can enrich the enum with methods (e.g. `format`, `parse`, …)
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- You can extend the enum to add new values (make your enum `final` to prevent it)
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- You can get a list of all the possible values (see below)
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This Enum class is not intended to replace class constants, but only to be used when it makes sense.
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## Installation
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```
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composer require myclabs/php-enum
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```
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## Declaration
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```php
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use MyCLabs\Enum\Enum;
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/**
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* Action enum
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*/
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final class Action extends Enum
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{
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private const VIEW = 'view';
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private const EDIT = 'edit';
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}
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```
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## Usage
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```php
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$action = Action::VIEW();
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// or with a dynamic key:
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$action = Action::$key();
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// or with a dynamic value:
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$action = Action::from($value);
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// or
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$action = new Action($value);
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```
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As you can see, static methods are automatically implemented to provide quick access to an enum value.
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One advantage over using class constants is to be able to use an enum as a parameter type:
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```php
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function setAction(Action $action) {
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// ...
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}
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```
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## Documentation
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- `__construct()` The constructor checks that the value exist in the enum
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- `__toString()` You can `echo $myValue`, it will display the enum value (value of the constant)
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- `getValue()` Returns the current value of the enum
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- `getKey()` Returns the key of the current value on Enum
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- `equals()` Tests whether enum instances are equal (returns `true` if enum values are equal, `false` otherwise)
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Static methods:
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- `from()` Creates an Enum instance, checking that the value exist in the enum
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- `toArray()` method Returns all possible values as an array (constant name in key, constant value in value)
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- `keys()` Returns the names (keys) of all constants in the Enum class
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- `values()` Returns instances of the Enum class of all Enum constants (constant name in key, Enum instance in value)
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- `isValid()` Check if tested value is valid on enum set
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- `isValidKey()` Check if tested key is valid on enum set
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- `assertValidValue()` Assert the value is valid on enum set, throwing exception otherwise
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- `search()` Return key for searched value
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### Static methods
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```php
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final class Action extends Enum
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{
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private const VIEW = 'view';
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private const EDIT = 'edit';
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}
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// Static method:
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$action = Action::VIEW();
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$action = Action::EDIT();
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```
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Static method helpers are implemented using [`__callStatic()`](http://www.php.net/manual/en/language.oop5.overloading.php#object.callstatic).
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If you care about IDE autocompletion, you can either implement the static methods yourself:
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```php
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final class Action extends Enum
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{
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private const VIEW = 'view';
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/**
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* @return Action
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*/
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public static function VIEW() {
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return new Action(self::VIEW);
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}
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}
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```
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or you can use phpdoc (this is supported in PhpStorm for example):
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```php
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/**
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* @method static Action VIEW()
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* @method static Action EDIT()
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*/
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final class Action extends Enum
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{
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private const VIEW = 'view';
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private const EDIT = 'edit';
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}
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```
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## Native enums and migration
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Native enum arrived to PHP in version 8.1: https://www.php.net/enumerations
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If your project is running PHP 8.1+ or your library has it as a minimum requirement you should use it instead of this library.
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When migrating from `myclabs/php-enum`, the effort should be small if the usage was in the recommended way:
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- private constants
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- final classes
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- no method overridden
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Changes for migration:
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- Class definition should be changed from
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```php
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/**
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* @method static Action VIEW()
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* @method static Action EDIT()
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*/
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final class Action extends Enum
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{
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private const VIEW = 'view';
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private const EDIT = 'edit';
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}
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```
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to
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```php
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enum Action: string
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{
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case VIEW = 'view';
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case EDIT = 'edit';
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}
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```
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All places where the class was used as a type will continue to work.
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Usages and the change needed:
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| Operation | myclabs/php-enum | native enum |
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|----------------------------------------------------------------|----------------------------------------------------------------------------|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
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| Obtain an instance will change from | `$enumCase = Action::VIEW()` | `$enumCase = Action::VIEW` |
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| Create an enum from a backed value | `$enumCase = new Action('view')` | `$enumCase = Action::from('view')` |
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| Get the backed value of the enum instance | `$enumCase->getValue()` | `$enumCase->value` |
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| Compare two enum instances | `$enumCase1 == $enumCase2` <br/> or <br/> `$enumCase1->equals($enumCase2)` | `$enumCase1 === $enumCase2` |
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| Get the key/name of the enum instance | `$enumCase->getKey()` | `$enumCase->name` |
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| Get a list of all the possible instances of the enum | `Action::values()` | `Action::cases()` |
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| Get a map of possible instances of the enum mapped by name | `Action::values()` | `array_combine(array_map(fn($case) => $case->name, Action::cases()), Action::cases())` <br/> or <br/> `(new ReflectionEnum(Action::class))->getConstants()` |
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| Get a list of all possible names of the enum | `Action::keys()` | `array_map(fn($case) => $case->name, Action::cases())` |
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| Get a list of all possible backed values of the enum | `Action::toArray()` | `array_map(fn($case) => $case->value, Action::cases())` |
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| Get a map of possible backed values of the enum mapped by name | `Action::toArray()` | `array_combine(array_map(fn($case) => $case->name, Action::cases()), array_map(fn($case) => $case->value, Action::cases()))` <br/> or <br/> `array_map(fn($case) => $case->value, (new ReflectionEnum(Action::class))->getConstants()))` |
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## Related projects
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- [PHP 8.1+ native enum](https://www.php.net/enumerations)
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- [Doctrine enum mapping](https://github.com/acelaya/doctrine-enum-type)
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- [Symfony ParamConverter integration](https://github.com/Ex3v/MyCLabsEnumParamConverter)
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- [PHPStan integration](https://github.com/timeweb/phpstan-enum)
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[GA Image]: https://github.com/myclabs/php-enum/workflows/CI/badge.svg
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[GA Link]: https://github.com/myclabs/php-enum/actions?query=workflow%3A%22CI%22+branch%3Amaster
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[Shepherd Image]: https://shepherd.dev/github/myclabs/php-enum/coverage.svg
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[Shepherd Link]: https://shepherd.dev/github/myclabs/php-enum
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