如何将闭包绑定到 PHP 中的静态类变量？答案

【问题标题】：How do I bind a closure to a static class variable in PHP?如何将闭包绑定到 PHP 中的静态类变量？
【发布时间】：2020-03-10 15:14:14
【问题描述】：

<?php

class A
{
    public $closure;

    public static function myFunc($input): string
    {
        $output = $input . ' is Number';
        return $output;
    }

    public static function closure(): Closure
    {
        return function ($input) {
            return self::myFunc($input);
        };
    }

    public static function run()
    {
        $closure = self::closure();
        echo $closure(1); // 1 is Number

        self::$closure = $closure;
        echo self::$closure(2); // Fatal error
    }
}

A::run();

我想将self::closure() 绑定到self::$closure，并在内部使用它，但它在某处消失了。如何在 PHP 中将闭包绑定到静态类变量？

【问题讨论】：

标签： php static closures bind

【解决方案1】：

将您的属性更改为静态static $closure;
将您的可调用对象括在括号中(self::$closure)(2);

http://sandbox.onlinephpfunctions.com/code/d41490759cac39b8459e396b3acf99bf22c65a68

<?php

class A
{
    static $closure;

    public static function myFunc($input): string
    {
        $output = $input . ' is Number';
        return $output;
    }

    public static function closure(): Closure
    {
        return function ($input) {
            return self::myFunc($input);
        };
    }

    public static function run()
    {
        $closure = self::closure();
        echo $closure(1); // 1 is Number

        self::$closure = $closure;

        // Wrap your callable in brackets
        echo (self::$closure)(2); 
    }
}

A::run();

【讨论】：

【解决方案2】：

有2个问题：

缺少static：

public static $closure;

缺少括号：

echo (self::$closure)(2);

<?php

class A
{
    public static $closure;

    public static function myFunc($input): string
    {
        $output = $input . ' is Number';
        return $output;
    }

    public static function closure(): Closure
    {
        return function ($input) {
            return self::myFunc($input);
        };
    }

    public static function run()
    {
        $closure = self::closure();
        echo $closure(1); // 1 is Number

        self::$closure = $closure;
        echo (self::$closure)(2); // 2 is Number
    }
}

A::run();

【讨论】：