PHP: 注解语法

注解语法

注解语法由几个关键组件组成。属性声明以 #[ 开始，以 ] 结束。内部可以列出一个或多个注解，注解之间用逗号分隔。注解名称如使用命名空间基础中所述，可以是未限定、限定或完全限定的。注解的参数是可选的，并用圆括号 () 括起来。参数只能是字面值或常量表达式，同时支持位置参数和命名参数语法。

注解名称及其参数会解析为类，并在通过反射 API 请求注解实例时，将参数传递给其构造方法。因此，建议为每个注解都引入对应的类。

示例 #1 注解语法

<?php
// a.php
namespace MyExample;

use Attribute;

#[Attribute]
class MyAttribute
{
    const VALUE = 'value';

    private $value;

    public function __construct($value = null)
    {
        $this->value = $value;
    }
}

// b.php

namespace Another;

use MyExample\MyAttribute;

#[MyAttribute]
#[\MyExample\MyAttribute]
#[MyAttribute(1234)]
#[MyAttribute(value: 1234)]
#[MyAttribute(MyAttribute::VALUE)]
#[MyAttribute(array("key" => "value"))]
#[MyAttribute(100 + 200)]
class Thing
{
}

#[MyAttribute(1234), MyAttribute(5678)]
class AnotherThing
{
}

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down

yarns dot purport0n at icloud dot com ¶

1 year ago

It wasn't obvious to me for a while but you can subclass attributes

https://3v4l.org/TrMTe

<?php

#[Attribute(Attribute::TARGET_PROPERTY)]
class PropertyAttributes
 {
    public function __construct(
        public readonly ?string $name = null,
        public readonly ?string $label = null,
    ) {}
 }

#[Attribute(Attribute::TARGET_PROPERTY)]
class IntegerPropertyAttributes extends PropertyAttributes
 {
    public function __construct(
        ?string $name = null,
        ?string $label = null,
        public readonly ?int $default = null,
        public readonly ?int $min = null,
        public readonly ?int $max = null,
        public readonly ?int $step = null,
    ) {
        parent::__construct($name, $label);
    }
 }

#[Attribute(Attribute::TARGET_PROPERTY)]
class FloatPropertyAttributes extends PropertyAttributes
 {
    public function __construct(
        ?string $name = null,
        ?string $label = null,
        public readonly ?float $default = null,
        public readonly ?float $min = null,
        public readonly ?float $max = null,
    ) {
        parent::__construct($name, $label);
    }
 }

class MyClass
 {
     #[IntegerPropertyAttributes('prop', 'property: ', 5, 0, 10, 1)]
     public int $prop;
 }

$refl = new ReflectionProperty('MyClass', 'prop');
$attributes = $refl->getAttributes();

    foreach ($attributes as $attribute) {
       var_dump($attribute->getName());
       var_dump($attribute->getArguments());
       var_dump($attribute->newInstance());
    }
?>

down

yarns_purport0n at icloud dot com ¶

1 hour ago

Attribute Subclassing https://3v4l.org/8jqK3#vnull

<?php /** @author ciid */

#[Attribute(Attribute::TARGET_PROPERTY)]
class PropertyAttributes {
    public function __construct(
        public readonly ?string $name = null,
        public readonly ?string $label = null,
    ) {}
 }

#[Attribute(Attribute::TARGET_PROPERTY)]
class IntegerPropertyAttributes extends PropertyAttributes {
    public function __construct(
        ?string $name = null,
        ?string $label = null,
        public readonly ?int $default = null,
        public readonly ?int $min = null,
        public readonly ?int $max = null,
        public readonly ?int $step = null,
    ) { parent::__construct($name, $label); }
 }

#[Attribute(Attribute::TARGET_PROPERTY)]
class FloatPropertyAttributes extends PropertyAttributes {
    public function __construct(
        ?string $name = null,
        ?string $label = null,
        public readonly ?float $default = null,
        public readonly ?float $min = null,
        public readonly ?float $max = null,
    ) { parent::__construct($name, $label); }
 }

// model class with properties to edit in UI
class MyClass {
     #[IntegerPropertyAttributes('prop','property: ',5,0,10,1)]
     public int $prop;
     #[FloatPropertyAttributes('float','double: ',5.5,0.0,9.9)]
     public float $double;
 }

// index.php implementation
$props = [['MyClass', 'prop'], ['MyClass', 'double']];

foreach ($props as $prop) {        // class, property
    $refl = new ReflectionProperty($prop[0], $prop[1]);
    $reflAttrs = $refl->getAttributes();
    foreach ($reflAttrs as $attr)
        echo buildHtmlFormControl($attr->newInstance());
  }
/** TL:DR: */
function buildHtmlFormControl(PropertyAttributes $args): string {
    $html = [];
    $html[] = "<label>{$args->label} <input name=\"{$args->name}\" value=\"{$args->default}\"";
    switch ($args::class) {
        case 'IntegerPropertyAttributes':
            $html[] = " type=\"number\" min=\"{$args->min}\" max=\"{$args->max}\" step=\"{$args->step}\""; break;
        case 'FloatPropertyAttributes':
            $html[] = " type=\"number\" min=\"{$args->min}\" max=\"{$args->max}\""; break;
     }
    $html[] = "></label>\n";
    return implode('', $html);
 }
?>