Detailed introduction to overloading and rewriting in PHP object-oriented

This article mainly introduces overloading and rewriting in PHP object-oriented objects. It has a very good reference value. Let’s take a look at it with the editor.

Overriding is a manifestation of polymorphism between parent classes and subclasses. Overloading is polymorphism in a class. An expression of sex. Overloaded method can change the type of return value. In other words, the return value types of overloads can be the same or different.

Overloading

a. Method overloading is a means for a class to process different types of data in a unified way. Multiple functions with the same name exist at the same time, with different number/type of parameters. Overloading is a manifestation of polymorphism in a class.

b. Java method overloading means that you can create multiple methods in a class. They have the same name but different parameters and different definitions. When calling methods, you decide which method to use based on the number and type of parameters passed to them. This is polymorphism.

c. When overloading, the method names should be the same, but the parameter types and numbers are different, and the return value types can be the same or different. The return type cannot be used as a criterion for distinguishing overloaded functions.

2. Overriding

a. Polymorphism between the parent class and the subclass, redefining the functions of the parent class. If a method defined in a subclass has the same name and parameters as its parent class, we say the method is overriding. In Java, subclasses can inherit methods from their parent class without rewriting the same methods. But sometimes the subclass does not want to inherit the methods of the parent class unchanged, but wants to make certain modifications, which requires method rewriting. Method overriding is also called method overwriting.

b. If a method in the subclass has the same method name, return type, and parameter list as a method in the parent class, the new method will overwrite the original method. **If you need the original method in the parent class, you can use the super keyword, which refers to the parent class of the current class**.

c. The access modification rights of subclass functions cannot be less than those of the parent class;

If the name, return type, parameter type and number of the parent class member method are exactly the same, only its internal The code is different. In Java, this rewriting method is called member method refactoring

The subclass can re-adjust the permissions in the parent class method (from stingy to generous), extend or re-adjust the permissions of the parent class Functions, etc., thus often making the sub-category green to be in blue, but better than blue. During the development process, program developers should make good use of these features of subclasses. But from another perspective, it is also necessary to impose certain restrictions on the permissions of subclasses. When necessary, permissions should be controlled on certain methods in the parent class to prevent them from being abused by subclasses.

The above is a detailed introduction to overloading and rewriting in PHP objects. For more related content, please pay attention to the PHP Chinese website (www.php.cn)!