why should one prefer call_user_func_array over regular calling of function?

Question

function foobar($arg, $arg2) {
    echo __FUNCTION__, \" got $arg and $arg2\\n\";
}
foobar(\'one\',\'two\'); // OUTPUTS : foobar got one and two 

call_user_func_arr         


        

Answer 1

As of php 5.6, to pass an array instead of an argument list to a function simply precede the array with an ellipsis (this is called "argument unpacking").

function foo($var1, $var2, $var3) {
   echo $var1 + $var2 + var3;
}

$array = [1,2,3];

foo(...$array);  // 6
// same as call_user_func_array('foo',$array);

The difference between call_user_func_array() and variable functions as of php 5.6 is that variable functions do not allow you to call a static method:

$params = [1,2,3,4,5];

function test_function() {
  echo implode('+',func_get_args()) .'='. array_sum(func_get_args())."\r\n";
}    

// Normal function as callback
$callback_function = 'test_function';
call_user_func_array($callback_function,$params); // 1+2+3+4+5=15
$callback_function(...$params); // 1+2+3+4+5=15

class TestClass
{
  static function testStaticMethod() {
    echo implode('+',func_get_args()) .'='. array_sum(func_get_args())."\r\n";
  }

  public function testMethod() {
    echo implode('+',func_get_args()) .'='. array_sum(func_get_args())."\r\n";
  }
}

// Class method as callback
$obj = new TestClass;
$callback_function = [$obj,'testMethod'];
call_user_func_array($callback_function,$params); // 1+2+3+4+5=15
$callback_function(...$params); // 1+2+3+4+5=15

// Static method callback
$callback_function = 'TestClass::testStaticMethod';
call_user_func_array($callback_function,$params); // 1+2+3+4+5=15
$callback_function(...$params); // Fatal error: undefined function

Php 7 adds the ability to call static methods via a variable function, so as of php 7 this difference no longer exists. In conclusion, call_user_func_array() gives your code greater compatibility.