Pass by reference, with a variable numbers of parameters in PHP?

Question

I have a function that takes a variable number of parameters, and I have to pass them by reference to another function.

Such as

function my_function($arg0, $arg1, $arg2, ...)
{
    my_other_function(&$arg0, &$arg1, &$arg2, ...); 
}

So that when I pass things by reference to my_function, my_other_function also gets them by reference.

Is there a way to do this?

Yeah, the problem is that if I just use it as is, the passed-by-reference values will get passed by copy to the other function. — elite5472
– elite5472, Commented Jul 21, 2012 at 21:10

johannes · Accepted Answer · 2012-07-21 21:20:36Z

3

I wonder why you need this. In general references are bad in PHP.

If you really want to do this the only proper way (ignoring call-time pass-by-ref hacks, which won't work with PHP 5.4 anymore anyways) is to use an array wrapping the parameters:

function myfunc(array $data) {
    $data[0] += 42;
    /* ... */
}

$var = 0;
myfunc(array(&$var /*, ... */));
echo $var; // prints 42

For passing to the other function you can then use call_user_func_array()

edited Jul 21, 2012 at 21:20

answered Jul 21, 2012 at 21:13

johannes

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2 Comments

elite5472 Over a year ago

Great, this worked for me. As for why I'm using it, this is for some meta-programming features in my framework.

johannes Over a year ago

Still references seem to e the wrong solution. Maybe wrap stuff that has to be changed in objects? (Remember objects are passed by handle - which mostly feels like passing them by ref)

Community · Accepted Answer · 2017-05-23 12:13:17Z

1

Technically you are not doing this:

function my_function($arg0, $arg1, $arg2, ...)
{
    my_other_function(&$arg0, &$arg1, &$arg2, ...); 
}

but this:

function my_function(&$arg0, &$arg1, &$arg2, ...)
{
    my_other_function($arg0, $arg1, $arg2, ...); 
}

However as @johannes already wrote, there is no good support for variable number of arguments that are references in PHP (and who could know better). func_get_args^Docs for example does not work with references.

Instead make use of the suggestion to pass all references via an array parameter. That works.

function my_function(array $args)
{
    my_other_function($args); 
}

edited May 23, 2017 at 12:13

CommunityBot

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answered Jul 21, 2012 at 21:30

hakre

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