PHP equivalent for a python decorator?

Question

I want to be able to wrap a PHP function by another function, but leaving its original name/parameter list intact.

For instance:

function A() {
    print "inside A()\n";
}

function Wrap_A() {
    print "Calling A()\n";
    A();
    print "Finished calling A()\n";
}

// <--- Do some magic here (effectively "A = Wrap_A")

A();

Output:

Calling A()
inside A()
Finished calling A()

Answer 1

Here is my method of mimicking decorators from python in php.

function call_decorator ($decorator, $function, $args, $kwargs) {

    // Call the decorator and pass the function to it
    $decorator($function, $args, $kwargs);
}

function testing ($args, $kwargs) {
    echo PHP_EOL . 'test 1234' . PHP_EOL;
}

function wrap_testing ($func, $args, $kwargs) {

    // Before call on passed function
    echo 'Before testing';

    // Call the passed function
    $func($args, $kwargs);

    // After call on passed function
    echo 'After testing';
}

// Run test
call_decorator('wrap_testing', 'testing');

Output:

Before testing
testing 1234
After testing

With this implementation you can also do something like this with an anonymous function:

// Run new test
call_decorator('wrap_testing', function($args, $kwargs) {
    echo PHP_EOL . 'Hello!' . PHP_EOL;
});

Output:

Before testing
Hello!
After testing

And lastly you can even do something like this, if you are so inclined.

// Run test
call_decorator(function ($func, $args, $kwargs) {
    echo 'Hello ';
    $func($args, $kwargs);
}, function($args, $kwargs) {
    echo 'World!';
});

Output:

Hello World!

With this construction above, you can pass variables to the inner function or wrapper, if need be. Here is that implementation with an anonymous inner function:

$test_val = 'I am accessible!';

call_decorator('wrap_testing', function($args, $kwargs){
    echo $args[0];
}, array($test_val));

It will work exactly the same without an anonymous function:

function test ($args, $kwargs) {
    echo $kwargs['test'];
}

$test_var = 'Hello again!';

call_decorator('wrap_testing', 'test', array(), array('test' => $test_var));

Lastly, if you need to modify the variable inside either the wrapper or the wrappie, you just need to pass the variable by reference.

Without reference:

$test_var = 'testing this';
call_decorator(function($func, $args, $kwargs) {
    $func($args, $kwargs);
}, function($args, $kwargs) {
    $args[0] = 'I changed!';
}, array($test_var));

Output:

testing this

With reference:

$test_var = 'testing this';
call_decorator(function($func, $args, $kwargs) {
    $func($args, $kwargs);
}, function($args, $kwargs) {
    $args[0] = 'I changed!';

// Reference the variable here
}, array(&$test_var));

Output:

I changed!

That is all I have for now, it is a pretty useful in a lot of cases, and you can even wrap them multiple times if you want to.

Answer 2

Apparently runkit might help you.

Also, you can always do this the OO way. Put the original fun in a class, and the decorator into an extended class. Instantiate and go.