php类和扩展类

Question

I like to ask a question related to php classes! Let's assume I have a clients' table, a streets table and another table called towns. In OOPs I must assume that I have a clients class, a streets class and also a towns class. So every class is related to another one like the following:

Client: clientId, clientFirstname1, clientLastname1, clientAddress, clientStreetCode, clientTownCode, clientPostCode.....

Streets: streetCode, streetName, townCode

Towns: townCode, townName

What I would like to ask is, if I am creating a client record shall I extend one class to another or shall I leave them NOT EXTENDED, and then include them in php as single classes?

Answer 1

Extending in OOP isn an is-a relation. In terms of the three classes Client, City, Street, none of them is-a instance of any other of them.

Instead you should just use references. A Client has a Street and a Street has a City.

class Client {
    /**
     * @var Street
     */
    protected $street;

    // ....
}

class Street {
    /**
     * @var City
     */
    protected $city;

    // ...
}

class City {
    // ...
}

Maybe you should also think about introducing a new class Address, which contains an reference to a City and a Street, instead of an Street with an reference to an City