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从闭包中访问私有变量

closures scope php

12

Kendall Hopkins · 技术社区 · 16 年前

我试图从闭包中引用对象的私有变量。下面的代码似乎可以工作,但它会抱怨 Fatal error: Cannot access self:: when no class scope is active in test.php on line 12 和 Fatal error: Using $this when not in object context in test.php on line 20 .

class MyClass
{

    static private $_var1;
    private $_var2;

    static function setVar1( $value )
    {
        $closure = function () use ( $value ) {
            self::$_var1 = $value;
        };
        $closure();
    }

    function setVar2( $value )
    {
        $closure = function () use ( $value ) {
            $this->_var2 = $value;
        };
        $closure();
    }

}

MyClass::setVar1( "hello" ); //doesn't work

$myclass = new MyClass;
$myclass->setVar2( "hello" ); //doesn't work

3 回复 | 直到 13 年前

1

14

Community Mohan Dere 9 年前

按注释编辑, 这个答案原本是为 第5.3页 this answer

这是不可能的。特别是,闭包没有关联的作用域,因此它们不能访问私有和受保护的成员。

但是,您可以使用引用:

<?php
class MyClass
{

    static private $_var1;
    private $_var2;

    static function setVar1( $value )
    {
        $field =& self::$_var1;
        $closure = function () use ( $value,  &$field ) {
            $field = $value;
        };
        $closure();
    }

    function setVar2( $value )
    {
        $field =& $this->_var2;
        $closure = function () use ( $value, &$field ) {
            $field = $value;
        };
        $closure();
    }

}

MyClass::setVar1( "hello" );

$myclass = new MyClass;
$myclass->setVar2( "hello" );

2

4

Ari Asulin 13 年前

这可以从PHP5.4.0开始

class test {
    function testMe() {
        $test = new test;
        $func = function() use ($test) {
            $test->findMe();        // Can see protected method
            $test::findMeStatically();  // Can see static protected method
        };
        $func();
        return $func;
    }

    protected function findMe() {
        echo " [find Me] \n";
    }

    protected static function findMeStatically() {
        echo " [find Me Statically] \n";
    }
}

$test = new test;
$func = $test->testMe();
$func();        // Can call from another context as long as 
            // the closure was created in the proper context.

3

2

DMI 16 年前

闭包没有 $this 或 self --它们不会以那种方式与物体相连。这意味着您必须通过 use

$_var1 =& self::$_var1;
$closure = function() use ($value, &$_var1) {
  $_var1 = $value;
};

$_var2 =& $this->_var2;
$closure = function() use ($value, &$_var2) {
  $_var2 = $value;
};

我还没有测试上面的代码,但我相信它是正确的。