Pass a function by reference in PHP

Question

Is it possible to pass functions by reference?

Something like this:

function call($func){
    $func();
}

function test(){
    echo \"hello world!\";         


        

Answer 1

function func1(){
    echo 'echo1 ';
    return 'return1';
}

function func2($func){
    echo 'echo2 ' . $func();
}

func2('func1');

Result:

echo1 echo2 return1