php
is_callable() does actually work for constructors in context
https://www.php.net/manual/en/function.is-callable.php says
is_callable()reports constructors as not being callable.
This is not true. At least not when called from a context where the constructor is callable, e.g. a child class constructor.
<?php
class ParentWithConstructor
{
public function __construct()
{
?>
ParentWithConstructor::__construct() was called<br/>
<?php
}
}
class ParentWithoutConstructor
{
}
class ChildOfParentWithConstructor extends ParentWithConstructor
{
public function __construct()
{
$isCallable = \is_callable([parent::class, '__construct']);
?>
<?=static::class?>::__construct() was called<br/>
$isCallable = <?=$isCallable?><br />
<?php
if ($isCallable) {
parent::__construct();
}
}
}
class ChildOfParentWithoutConstructor extends ParentWithoutConstructor
{
public function __construct()
{
$isCallable = \is_callable([parent::class, '__construct']);
?>
<?=static::class?>::__construct() was called<br/>
$isCallable = <?=$isCallable?><br />
<?php
if ($isCallable) {
parent::__construct();
}
}
}
?>
<p>
<?php
new ChildOfParentWithConstructor();
?>
</p>
<p>
<?php
new ChildOfParentWithoutConstructor();
?>
</p>
<p>
PHP version <?=PHP_VERSION?>
</p>
The output was
ChildOfParentWithConstructor::__construct() was called $isCallable = 1 ParentWithConstructor::__construct() was called
ChildOfParentWithoutConstructor::__construct() was called $isCallable =
PHP version 7.3.11
This needs to be clarified, rather than having a blanket statement saying it does not work, when in fact it does in the right situations.
Actually, the usefulness of that example is doubtful, especially since that as of PHP 8.0.0 that is to be expected (calling non-static functions statically is no longer supported). And of course, a constructor is callable when checked on an object of the respective type, and also in the cases you've mentioned (https://3v4l.org/rCodI).
