OOP in PHP: Class-function from a variable?

Question

Is it possible to call functions from class like this:

$class = new class;
$function_name = \"do_the_thing\";
$req = $class->$function_name();

Answer 1

Yes, it is possible, that is know as variable functions, have a look at this.

Example from PHP's official site:

<?php
class Foo
{
    function Variable()
    {
        $name = 'Bar';
        $this->$name(); // This calls the Bar() method
    }

    function Bar()
    {
        echo "This is Bar";
    }
}

$foo = new Foo();
$funcname = "Variable";
$foo->$funcname();  // This calls $foo->Variable()

?>

In your case, make sure that the function do_the_thing exists. Also note that you are storing the return value of the function:

$req = $class->$function_name();

Try to see what the variable $req contains. For example this should give you info:

print_r($req); // or simple echo as per return value of your function

Note:

Variable functions won't work with language constructs such as echo(), print(), unset(), isset(), empty(), include(), require() and the like. Utilize wrapper functions to make use of any of these constructs as variable functions.

Answer 2

My easiest example is:

$class = new class;
$function_name = "do_the_thing";
$req = $class->${$function_name}();

${$function_name} is the trick

Also works with static methods:

$req = $class::{$function_name}();

Answer 3

You can use ReflectionClass.

Example:

$functionName = 'myMethod';
$myClass = new MyClass();
$reflectionMyMethod = (new ReflectionClass($myClass))->getMethod($functionName);

$relectionMyMethod->invoke($myClass); // same as $myClass->myMethod();

Remember to catch ReflectionException If Method Not Exist.