If I have a function like this:
function abc($a,$b,$c = 'foo',$d = 'bar') { ... }
And I want $c to assume it's default value, but need to set $d, how would I go about making that call in PHP?
views:
116answers:
4
+7
A:
PHP can't do this, unfortunately. You could work around this by checking for null. For example:
function abc($a, $b, $c = 'foo', $d = 'bar') {
if ($c === null)
$c = 'foo';
// Do something...
}
Then you'd call the function like this:
abc('a', 'b', null, 'd');
No, it's not exactly pretty, but it does the job. If you're feeling really adventurous, you could pass in an associative array instead of the last two arguments, but I think that's way more work than you want it to be.
musicfreak
2009-07-12 01:51:01
+1 Nice work around. I'd probably leave out the $='foo' part in the signature since the null check handles the default now.
Michael Haren
2009-07-12 01:56:50
True, but what if you want to omit both `$c` and `$d`? It would now throw an error because the function has 3 required arguments.
musicfreak
2009-07-12 02:04:22
The problem is that my functions have 5+ vars. This is for a system for possible future people who aren't PHP savvy to manipulate the code by setting specific variables.
Shadow
2009-07-12 02:10:06
Like I said, there's no other way to do this. You could, like I mentioned, pass an associative array into the function and just set any unset values to their defaults. But otherwise, you're out of luck; sorry.
musicfreak
2009-07-12 02:21:58
+2
A:
Associative arrays aren't so bad here, especially when the argument list starts getting bigger:
function abc($args = array()) {
$defaults = array('c' => 'foo', 'd' => 'bar');
$args = array_merge($defaults, $args);
}
If you wanted to explicitly make some of them required, you could put them in front:
function abc($a, $b, $args = array()) {
}
It's up to you, I've seen big projects use both approaches (forcing passing null and this) and I honestly sort of prefer this one. If you are familiar with Javascript a lot of scripts take use of this behavior when you pass options to them, so it's not completely foreign.
Paolo Bergantino
2009-07-12 04:07:22