That error appears at least from PHP 7.
Anyway, keep in mind what the PHP Manual says about the method
PHP 5 introduces a concept of destructor similar to others
object-oriented languages, such as C ++. The destructive method
will be called as soon as there are no other references to an object
determined , or in any other circumstance of completion.
We can say that the destructive method is not stupid, he knows that when invoked is to destroy that object , so the use of
$this is redundant. In PHP 7 they realized this and decided to launch this error message when
unset($this) is invoked, because it really does not make sense to do so.
On the other hand, about destroying an object with
unset the Manual says the following :
It is not possible to remove
$this within a target object method
of PHP 5.
So how do I destroy an object?
In some cases, in PHP the object is destroyed when the script ends (there is no reference to the object). This is the case, for example, with the objects that connect to the database in PDO.
If you want to destroy the object explicitly, due to what is mentioned above, from PHP 5 the object will be destroyed as it happens in the other object-oriented languages: assigning
null to the object.
/*... uso del objeto*/
That's it, PHP takes care of the rest.
But what if the class does not have a destructive method written by me? Absolutely nothing happens ... this method is part of the so-called magic methods . Moreover, it is better that you do not try to write the destructive method. This post recommends never calling the destructive method explicitly ... the effect may be totally the opposite of what was expected.