Construct a ReflectionProperty object

# ReflectionProperty::__construct

(PHP 5, PHP 7, PHP 8)

ReflectionProperty::__construct — Construct a ReflectionProperty object

### 说明

public function ReflectionProperty::__construct(object|string `$class`, string `$property`)

### 参数

`class`

  Either a string containing the name of the class to reflect, or an object.

`property`

  The name of the property being reflected.

### 错误／异常

Trying to get or set private or protected class property's values will result in an exception being thrown.

### 示例

示例 #1 ReflectionProperty::__construct() example

    <?php

    class Str
    {
        public $length  = 5;
    }

    // Create an instance of the ReflectionProperty class
    $prop = new ReflectionProperty('Str', 'length');

    // Print out basic information
    printf(
        "===> The%s%s%s%s property '%s' (which was %s)\n" .
        "     having the modifiers %s\n",
            $prop->isPublic() ? ' public' : '',
            $prop->isPrivate() ? ' private' : '',
            $prop->isProtected() ? ' protected' : '',
            $prop->isStatic() ? ' static' : '',
            $prop->getName(),
            $prop->isDefault() ? 'declared at compile-time' : 'created at run-time',
            var_export(Reflection::getModifierNames($prop->getModifiers()), true)
    );

    // Create an instance of Str
    $obj= new Str();

    // Get current value
    printf("---> Value is: ");
    var_dump($prop->getValue($obj));

    // Change value
    $prop->setValue($obj, 10);
    printf("---> Setting value to 10, new value is: ");
    var_dump($prop->getValue($obj));

    // Dump object
    var_dump($obj);

    ?>

以上示例的输出类似于：

    ===> The public property 'length' (which was declared at compile-time)
         having the modifiers array (
      0 => 'public',
    )
    ---> Value is: int(5)
    ---> Setting value to 10, new value is: int(10)
    object(Str)#2 (1) {
      ["length"]=>
      int(10)
    }

示例 #2 Getting value from private and protected properties using ReflectionProperty class

    <?php

    class Foo
    {
        public $x = 1;
        protected $y = 2;
        private $z = 3;
    }

    $obj = new Foo;

    $prop = new ReflectionProperty('Foo', 'y');
    $prop->setAccessible(true);
    var_dump($prop->getValue($obj)); // int(2)

    $prop = new ReflectionProperty('Foo', 'z');
    $prop->setAccessible(true);
    var_dump($prop->getValue($obj)); // int(2)

    ?>

以上示例的输出类似于：

    int(2)
    int(3)

### 参见

- ReflectionProperty::getName() - Gets property name
- Constructors

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