Send method as parameter to other class constructor and execute it - php

Question

I have two class A and B
I want to 'send' a method from A to B via B constructor and then execute it in B. I've been trying to work with anonymous functions just like this :
class A
{
public function __construct()
{
// Send testMethod() to B with an anonymous function
new B(function (string $test) {
$this->testMethod($test);
});
}
protected function testMethod(string $test) {
echo ($test);
}
}
class B
{
protected $testFct;
public function __construct($fctToExecute)
{
// Asign anonymous function to $testFct to be executed in all object
$this->testFct= function (string $test) {
$fctToExecute($test);
};
}
// Want to be able now to call this $testFct function in a method like :
protected function methodWhereICallTestfct() {
$this->testFct("I'm dumb!"); // It has to echo "I'm dumb!"
}
}
But when I try to set it up I get always an error like :
Uncaught Error: Call to undefined method testFct()
Do you have any idea what the problem is? I would like to specify that my php version is PHP 7.1.3.
EDIT :
Here is it possible to see a more similare code as mine which return the error

Answer 1

You have got 2 mistakes in your code.
First mistake is that you ignore the parameter $fctToExecute in B::__construct(). If you would like to save the passed closure into a property of object B then you do not need another closure.
public function __construct(closure $fctToExecute) {
// Asign anonymous function to $testFct to be executed in all object
$this->testFct = $fctToExecute;
}
The second problem is that when you are trying to execute the closure you are actually trying to execute a function called testFct. You should use parentheses to declare precedence of operations.
$this->testFct("I'm dumb!"); // This looks for a function called testFct
($this->testFct)("I'm dumb!"); // This will execute the closure stored in the property called $testFct
The parentheses make a lot of difference here.