Question

I have two variables:

$a = 'some_class';
$b = 'some_method';

What I want to do is something like this (the method is static):

$a::$b;

Is it possible? I’ve tried the reflection class, but I can’t call static methods…

Answer 1

How to invoke the static method, 3 options

You have a few options:

Code

<?PHP

    class test {
        static function doThis($arg) {
            echo '<br>hello world '.$arg;
        }
    }

    $class='test';
    $method='doThis';
    $arg='stack';

    //just call
    $class::$method($arg);

    //with function
    call_user_func(array($class, $method), $arg);

    //ugly but possible
    $command=$class.'::'.$method.'("'.$arg.'");';
    eval($command);

Output

    hello world stack
    hello world stack
    hello world stack

What happens when you call it with those options

Code with a backtrace so you can see what happens under the hood in PHP:

Code

<?PHP

class test {
    static function doThis($arg) {
        echo 'hello world with argument: '.$arg.PHP_EOL;
        print_R(debug_backtrace());
    }
}

function runTest() {

    $class='test';
    $method='doThis';
    $arg='stack';



    //just call
    $class::$method($arg);

    //with function
    call_user_func(array($class, $method), $arg);

    //ugly but possible
    $command=$class.'::'.$method.'("'.$arg.'");';
    eval($command);

}

echo '<pre>';
runTest();

Output

$class::$method($arg);

hello world with argument: stack
Array
(
    [0] => Array
        (
            [file] => folder/test.php
            [line] => 19
            [function] => doThis
            [class] => test
            [type] => ::
            [args] => Array
                (
                    [0] => stack
                )

        )

    [1] => Array
        (
            [file] => folder/test.php
            [line] => 31
            [function] => runTest
            [args] => Array
                (
                )

        )

)

call_user_func(array($class, $method), $arg);

hello world with argument: stack
Array
(
    [0] => Array
        (
            [function] => doThis
            [class] => test
            [type] => ::
            [args] => Array
                (
                    [0] => stack
                )

        )

    [1] => Array
        (
            [file] => folder/test.php
            [line] => 22
            [function] => call_user_func
            [args] => Array
                (
                    [0] => Array
                        (
                            [0] => test
                            [1] => doThis
                        )

                    [1] => stack
                )

        )

    [2] => Array
        (
            [file] => folder/test.php
            [line] => 31
            [function] => runTest
            [args] => Array
                (
                )

        )

)

eval($command);

hello world with argument: stack
Array
(
    [0] => Array
        (
            [file] => folder/test.php(26) : eval()d code
            [line] => 1
            [function] => doThis
            [class] => test
            [type] => ::
            [args] => Array
                (
                    [0] => stack
                )

        )

    [1] => Array
        (
            [file] => folder/test.php
            [line] => 26
            [function] => eval
        )

    [2] => Array
        (
            [file] => folder/test.php
            [line] => 31
            [function] => runTest
            [args] => Array
                (
                )

        )

)

As you can see first way has no step in between which is being registered, it directly makes the call while the other 2 options act by themselves as a function and make the call from themselves.

In practice not a lot of difference but it might make sense when optimizing such a process.