PHP5.4のClosure::bindToを使ってJavaScriptのクロージャ的なものを作った。

context.php

<?php

function context(Closure $function)
{
    Context::create($function)->run();
}

class Context
{
    private static $_chain = [];

    public static function create(Closure $function)
    {
        $context = new self($function);
        array_push(static::$_chain, $context);

        return $context;
    }

    public static function get($index)
    {
        return isset(self::$_chain[$index]) ? self::$_chain[$index] : false;
    }

    public static function search(self $context)
    {
        return array_search($context, self::$_chain, true);
    }

    private $_values;
    private $_function;

    private function __construct(Closure $function)
    {
        $this->_values = [];
        $this->_function = $function->bindTo($this);
    }

    public function run()
    {
        $function = $this->_function;
        $function();
    }

    private function _parent()
    {
        $index = self::search($this);

        if ($index) {
            return self::get($index - 1);
        }

        return false;
    }

    public function __set($name, $value)
    {
        $this->_values[$name] = $value;
    }
    
    public function __get($name)
    {
        if (isset($this->_values[$name])) {
            return $this->_values[$name];
        }

        if ( ! ($parent = $this->_parent())) {
            return null;
        }

        return $parent->__get($name);
    }
}

example.php

<?php
require 'context.php';

context(function () {

    $this->hoge = "outer hoge";
    $this->fuga = "outer fuga";

    context(function () {

        $this->fuga = "inner fuga";

        echo $this->hoge, "\n"; // display "outer hoge"
        echo $this->fuga, "\n"; // display "inner fuga". overwrite by inner $this->fuga
    });

});