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Doc Bug #80032 Can't use valid callback as default value for callable parameters
Submitted: 2020-08-28 19:16 UTC Modified: 2020-10-11 04:22 UTC
From: antonfedonyuk at gmail dot com Assigned: cmb (profile)
Status: No Feedback Package: *General Issues
PHP Version: 7.4.9 OS: Any
Private report: No CVE-ID: None
View Developer Edit
 [2020-08-28 19:16 UTC] antonfedonyuk at gmail dot com 
Description:
------------
Can't use valid callback(string or array) as default value of callable parameters. It's generate fatal error: Default value for parameters with callable type can only be NULL. The guide doesn't contain any notes on this issue.

Test script:
---------------
<?php
function test(callable $callback = 'strtoupper')
{
   return $callback();
}
?>

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 [2020-08-28 21:01 UTC] requinix@php.net
-Status: Open +Status: Verified -Type: Bug +Type: Documentation Problem -Package: Compile Failure +Package: *General Issues
 [2020-09-30 12:19 UTC] cmb@php.net
-Status: Verified +Status: Feedback -Assigned To: +Assigned To: cmb
 [2020-09-30 12:19 UTC] cmb@php.net 
The manual states[1]:

| A function may define C++-style default values for scalar
| arguments as follows:

Since callables are not scalar, is there anything to add?

[1] <https://www.php.net/manual/en/functions.arguments.php#functions.arguments.default>
 [2020-09-30 15:37 UTC] antonfedonyuk at gmail dot com
-Status: Feedback +Status: Assigned
 [2020-09-30 15:37 UTC] antonfedonyuk at gmail dot com 
cmb@php.net iterable not scalar too
 [2020-09-30 15:47 UTC] cmb@php.net
-Status: Assigned +Status: Feedback
 [2020-09-30 15:47 UTC] cmb@php.net 
> iterable not scalar too

Well, the documentation mentions after the scalar examples:

| PHP also allows the use of arrays and the special type NULL as
| default values, […]
 [2020-10-11 04:22 UTC] php-bugs at lists dot php dot net 
No feedback was provided. The bug is being suspended because
we assume that you are no longer experiencing the problem.
If this is not the case and you are able to provide the
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change the status of the bug back to "Re-Opened". Thank you.
 
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