<?php

class Foo
{
    private $value;
    
    public function __construct($value)
    {
        $this->value = $value;
    }
}

$foo = new Foo('string');

// Instead of bind to closure you can use call in php 7
$closure = function() {
    return md5($this->value);
};

var_dump($closure->call($foo));


string(32) "b45cffe084dd3d20d928bee85e7b0f21"

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PHP 7.3, Zend 3.0, Symfony 4.3, Laravel 5.8, PHPUnit 8.0, Doctrine 2.10