Optional parameters aren't truly optional

Question

I would like to have real optional parameters in PHP. I realize that I can do something like this:

function my_function($req_var, $opt_var1 = 90, $opt_var2 = "lala") {
    die("WEEEEEEEE!");
}

However, if I want to only specify the value of $opt_var2, I still must specify a value for $opt_var1.

Here's an example.

my_function("lala", 90, "omg");

In other words, I have to explicitly write 90 as $opt_var1 even though it's only $opt_var2 that I want to change.

Is it possible to do something like this?

my_function("lala", default, "omg");

That would be so helpful.

Define your **optional** parameters after your **required** parameters — George, May 15 '13 at 08:43
That's not the solution. Notice that I have 2 optional parameters, and I only wish to change the last one. — Mathias Lykkegaard Lorenzen, May 15 '13 at 08:44
You may use an array of parameters. It's a workaround, though. — Voitcus, May 15 '13 at 08:44
Definitely check out this answer http://stackoverflow.com/questions/680368/emulating-named-function-parameters-in-php-good-or-bad-idea it emulates the `Python` kwargs behaviour. — Morgan Wilde, May 15 '13 at 08:46

score 6 · Answer 1 · answered May 15 '13 at 08:45

6

function my_function($req_var, $opt_var1 = NULL, $opt_var2 = NULL) {
    if ($opt_var1 === NULL) {
        $opt_var1 = 90;
    }
    if ($opt_var2 === NULL) {
        $opt_var2 = "lala"
    }
}
my_function("lala", NULL, "omg");

answered May 15 '13 at 08:45

Your Common Sense

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And what if `NULL` might also be a valid value that I wish to be able to parse into the function? – Mathias Lykkegaard Lorenzen May 17 '13 at 18:00

score 3 · Accepted Answer · answered May 15 '13 at 08:47

There is a way with array parameters:

function my_func(array $params = array()){
    $arg1 = isset($params['one']) ? $params['one'] : 'default';
    $arg2 = isset($params['two']) ? $params['two'] : 'default';
    $arg3 = isset($params['three']) ? $params['three'] : 'default';

    // ...
}

score 2 · Answer 3 · answered May 15 '13 at 08:55

2

You can use a parameter that is an associative array and extract it:

function func($options= array()) {
    $option1= "default value";
    ..
    extract($options);
    ..
}

answered May 15 '13 at 08:55

Adder

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Optional parameters aren't truly optional

3 Answers3