[PHP] How to unset object's inherited properties ?

Question

I have an Object

    (
        [id] => 1
        [parent_id] => 0
        [result:Database:private] => 
        [db:Database:private] => mysqli Object
            (
                [affected_rows] => 0
                ...
            )

    )

Obviously, the Object has inherited the 'db' and 'result' properties of the parent Database class.

unset($object->result) nor unset($object->result:Database) nor unset($object->result:Database:private) work.

How could I unset those properties when they are no longer needed (i.e. when the object properties are about to be output)?

Is it a generally a good idea to have a database object as an inherited property of other classes (extend one Database class with all other classes that use database connections)?

Answer 1

Try $object->result = null

Is it a generally a good idea to have a database object as an inherited property of other classes (extend one Database class with all other classes that use database connections)?

No. It is best that your class have one responsibility. Keep your database connections in a class or set of classes whose responsibility is to read and write data from the database. Your other domain objects should handle their own responsibilities without being crowded by SQL and database code - even if it is inherited.

You may also want to read up on the concept of "favor composition over inheritance."

Answer 2

If you are using unset() only in one object you are not unsetting the object, because it exists in the memory somewhere and what you have in your object is just a reference. The same reference is used by all you other objects holding this DB object. The only thing you can do is to set this reference to equal NULL, but you are not freeing any memory since the DB is still there used by other objects.

Generally I would not worry about unsetting the DB object as you will not get any performance boost. PHP will automatically garbage collect its objects when the execution ends.

Yes, it is a good idea to have one static DB object or inherit it in your classes that are using the database.