On 06/04/2024 07:24, Saki Takamachi wrote:
Take a look at the methods shown below: ``` protected static function resultPropertyRules(string $propertyName, mixed $value1, mixed $value2): mixed {} ```This method determines which operand value to use in the result after calculation for a property that the user has defined by extending the class.
While this is an intriguing idea, it only solves a narrow set of use cases. For instance:
- The class might want different behaviour for different operations; e.g. Money(42, 'USD') + Money(42, 'USD') should give Money(84, 'USD'); but Money(42, 'USD') * Money(42, 'USD') should be an error.
- Properties might need to interact with each other; e.g. Distance(2, 'metres') + Distance(2, 'feet') could result in Distance(2.6096, 'metres'); but if you calculate one property at a time, you'll end up with Distance(4, 'metres'), which is clearly wrong.
The fundamental problem is that it ignores the OOP concept of encapsulation: how an object stores its internal state should not define its behaviour. Instead, the object should be able to directly define behaviour for the operations it supports.
Regards, -- Rowan Tommins [IMSoP]
