::parent Operator¶
PHP provides the X::class operator to access a class’s fully qualified name. To get the parent’s class, one must use the get_parent_class() native function. Wouldn’t it be cool to have the same operator?
To build that operator, we’ll use a special trait t: it defines a constant, build with parent::class. This operator is the contrary to what we need, but it is the only situation where we use it. Note that parent is a valid constant, or method, name.
Note also that recent PHP versions do not accept a direct call to a trait, so it is not possible to call t::parent, which has no parent.
The ::parent will be case sensitive. The case insensitive versions of this operator is left as an exercise for the reader.
From there, any class that needs to use the ::parent needs to use t;. It is possible to use that trait in any class, but avoid calling the ::parent operator on classes that have no parents.
The trick here is that z::parent actually calls the trait class, which, in turns, uses the parent relative class. Even parent::parent works, as the first one is the keyword, and the second one is the constant.
Make sure that each class use t, as any unconfigured class will defer execution to its own parent, and return… a wrong value.
After ::parent, the ::grandparent operator, based on the same strategy was tempting, and … tried! Sadly, const grandparent = self::parent::parent; yields a (expression)::class cannot be used in constant expressions, even when not used.
See Also¶
::parent operator [Try me]