The representation of the destructor method in the inheritance in PHP construction method, PHP construction _php Tutorial

The representation of the destructor method in the inheritance in the PHP construction method, PHP constructs

This article for you to share the PHP construction method of the analysis method in the inheritance of the performance, for your reference, the specific content as follows

When a constructor method is not defined in a subclass, the constructor method of the parent class is automatically called. Therefore, when you instantiate a subclass, you do so in the form of the parent class's construction method.

Modified to:

When a subclass defines its own constructor method, the constructor of the parent class is not automatically called, but it can be called manually: Parent::__construct ();

But usually, in subclasses, many times, in a constructor method, you should (need) call the constructor of the parent class to save code and increase readability:

The destructor method of the parent class is automatically called when no destructor is defined in the subclass. When a subclass defines its own destructor method, the destructor of the parent class is not automatically called, but it can be called manually: Parent::__destruct (). overriding override

Rewriting, or overwrite, is to redefine the property or method inherited from the parent class--that is, from the new write.

Note: The subclass overrides the parent class method, although it is possible to call the parent class with the same name method to do some work, but it is not necessary. It is also possible that the result of the method performed by the parent class is not suitable for subclasses, at which time the subclass is completely self-written.

Basic requirements for rewriting:

Access control permissions: Subordinate access control permissions should not be lower than the superior access control rights: Superior: Public subordinate: Only public Superior: Protected subordinate: Protected, public Superior: private subordinate: Private Protected public--The actual situation is meaningless. Private can not be covered, but completely as a brand-new.

The Parameter form of the method: should be consistent with the parent class.

Overriding problem with private properties and private methods: private properties and methods cannot be overridden, but subclasses can define properties or methods that are private to the parent class with the same name. Just as a new property or method of its own. However, the parameters of the method must be identical. The overriding problem with the constructor method: The constructor method can be overridden not just like other common methods, but more lenient than the normal method: the arguments can be inconsistent when overridden.

Final class:

Usually, a class, without special statements, "others" can be arbitrarily used and "extended"-inheritance.

But:

If a class does not want to extend it, it can be declared as a "final class."

Form:

Final class class name {.... Class definition .... }

Final method

Typically, a method, if not specifically declared, can be overridden by a subordinate class.

But:

If a method does not want to be overridden by a subordinate class, it can be a "final method" of its life.

Form:

Final function Method name () {.... Method definition .... }

The above is the whole content of this article, I hope that everyone's study has helped.

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