optional typed variadic arguments

Question

PHP has variadic argument unpacking since version 5.6.

function doSomething(User ...$users) {
     return count($users);
}
$userOrNoUserList = [$user1, null, $user2];
doSomething(...$userOrNoUserList); // wanted: 3

This throws the following error:

Catchable fatal error: Argument 2 passed to doSomething() must be an instance of user, null given

But I want to preserve the list structure inside doSomething(); I do not want to filter null values before invocation. Is it possible to allow null values too?

Did you try it? _Catchable fatal error: Argument 2 passed to doSomething() must be an instance of user, null given_ — AbraCadaver, Jan 22 '18 at 20:37
@AbraCadaver yeah this is the problem I wonder if it is possible to define the function such that it does not raise an error — Nicolas Heimann, Jan 22 '18 at 20:38
You should not pass null values in the first place. This sounds more like a design flaw. — Mike Doe, Feb 20 '18 at 10:49
can you explain why it is a design flaw to pass a list of optional values? — Nicolas Heimann, Mar 29 '18 at 09:15

score 5 · Accepted Answer · edited Jan 22 '18 at 21:13

5

You have to define a Nullable Type using the ? character before the type User (available in PHP 7.1.0):

function doSomething(?User ...$users) {
     return count($users);
}

Then you could call:

$userOrNoUserList = [$user1, null, $user3];
doSomething(...$userOrNoUserList); // 3

edited Jan 22 '18 at 21:13

AbraCadaver

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answered Jan 22 '18 at 20:39

3

PHP >= 7.1.0 only. – AbraCadaver Jan 22 '18 at 20:42
exactly what I was looking for, even though I hoped it is already available in PHP5.6, thank you! – Nicolas Heimann Jan 22 '18 at 20:43
1

Can you add a link to the manual for this please, I couldn't find one. – AbraCadaver Jan 22 '18 at 20:56
see also [What is a Nullable Type?](https://stackoverflow.com/a/48450841/9193372) – Syscall Dec 28 '22 at 17:34

optional typed variadic arguments

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