<?php

class Foo
{
    private $value;
    
    public function __construct($value)
    {
        $this->value = (string) $value;
    }
    
    /**
     * @param Closure $closure 
     * @return string the hash value
     */
    public function getHash(Closure $closure)
    {
        $closure = $closure->bindTo($this, self::CLASS);
        return $closure();
    }
    
    /**
     * @param Closure $closure
     * @return string the hash value
     */
    public function getHash2(Closure $closure)
    {
        return $closure($this->value);
    }
}

$foo = new Foo('string');

// you need to know the inside of class
$c1 = function() {
    return md5($this->value);
};
$c2 = function() {
    return sha1($this->value);
};

echo 'bindTo solution' . PHP_EOL;
echo $foo->getHash($c1) . PHP_EOL;
echo $foo->getHash($c2) . PHP_EOL . PHP_EOL;


// You need to know that your function
// gets a string
$c1 = function($value) {
    return md5($value);
};
$c2 = function($value) {
    return sha1($value);
};

echo 'injection of value solution' . PHP_EOL;
echo $foo->getHash2($c1) . PHP_EOL;
echo $foo->getHash2($c2);

bindTo solution
b45cffe084dd3d20d928bee85e7b0f21
ecb252044b5ea0f679ee78ec1a12904739e2904d

injection of value solution
b45cffe084dd3d20d928bee85e7b0f21
ecb252044b5ea0f679ee78ec1a12904739e2904d

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