如何在嵌套调用中使用默认参数值？

Question

I have this situation: function a (a class method, but it's not important, here...) invokes function b .
Function a has one parameter (say, $p2 ), with a default value.
Function b has one parameter (say, $q2 ), with a default value, too.

If function a is called without the parameter $p2 , function b should be called without the parameter $q2 , too, to force it using it's default value.
If function a is called with the parameter $p2 , function b should be called with the parameter $q2 .

To clearify with an example:

function a($p1, $p2 = "default value one") {
  if ($p2 === "default value") {
    b($p1);
  } else {
    b($p1, $p2);
  }
}

function b(q1, q2 = "default value two") {
  ...
}

Of course it's possible to use a test, as in the example above, but it looks me a really ugly solution... The question is:

Is there a better (faster, cleaner, smarter) code to implement this use case?

Answer 1

I think something like this should be what you're looking for:

Just get all function arguments with func_get_args() , then simply call your next function with call_user_func_array() .

function a($p1, $p2 = "default value") {
    call_user_func_array("b", func_get_args());
}

Answer 2

Function a default parameter must have same value as function b default parameter:

function a($p1, $p2 = null) {
    b($p1, $p2);
}

function b($p1, $p2 = null) {
    var_dump($p1, $p2);
}

So calling a with both parameters will pass these parameters to function b , while calling function a with only first parameter set will call b with passed first from user and second parameter as default value:

a(2, 5); // --> (int)2 (int)5

a(2); // --> (int)2 NULL

---

[UPDATE]

If functions can have different default values, than you need to detect default value:

function a($p1, $p2 = null) {
    $p2 = !is_null($p2) ? $p2 : 'defaultB';

    b($p1, $p2); // For string use `stricmp($p2, 'defaultA') !== 0`
}

function b($p1, $p2 = 'defaultB');