Variable-length args by reference

Hi,

2012/4/18 Stefan Neufeind neufeind@php.net:

Hi,

the topic of variable argument-lists for functions in connection with
getting the parameters by reference came up. This is currently not
possible with func_get_args(), though a "hack" with debug_backtrace() is
possible.

[...]

I don't know what you would like to do, but

function calc(&$args = NULL) {
var_dump(count($args)); // num of args
$args[1] *= 2;
}
calc(array(1,2,3,4));

would work.

Hi,

well yes, but that's not a variable number of parameters then :-)

As Johannes pointed out the problem is that PHP needs to know before
calling the function that it needs to work with references. Calling
calc($a, $b) (with no call-time pass-by-referefence of course)
I've tried the following things out:

function calc(&$dummy0 = NULL, &$dummy1 = NULL)
{
$d = &debug_backtrace();
$args = $d[0]['args'];

    foreach($args as &$a)
    {
            $a *= 2;
    }

}

=> Can have up to two "variable" parameters (since they have a default
of NULL). The workaround for allowing "more" variable would be to add
more dummies then sigh but would work.

What does not work:

function calc(&$dummy0 = NULL, &$dummy1 = NULL)
{
$args = func_get_args();

    foreach($args as &$a)
    {
            $a *= 2;
    }

}

since func_get_args() returns copies one way or the other.

Would it maybe be a good idea for func_get_args() to return an array
with references (as debug_backtrace() does) in case the parameters were
references when the function was called?

Kind regards,
Stefan