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This article mainly introduces the example analysis of polymorphism in PHP object-oriented, which is very detailed and has certain reference value. Friends who are interested must read it!

What is polymorphism?

Polymorphism is the third feature of object-oriented language after database abstraction and inheritance. Polymorphism is a variety of forms, with the ability to express a variety of forms. In an object-oriented representation, it is handled differently depending on the type of object. Polymorphism allows each object to respond to a common message in a way that suits it. Polymorphism enhances the flexibility and reusability of the software.

For example, we create a doing () method that prints the class if it is a student and prints to go to work if it is a company employee.

Common practice

Use if to judge

/ * *

* PHP polymorphism

, /

/ / define student classes

Class student {

Public function cla () {

Echo "the student worker is in class!"

}

}

/ / define the employee class

Class office {

Public function Wor () {

Echo "staff are at work!"

}

}

/ / method of judging object type

Function doing ($obj) {

If ($obj instanceof student) {

$obj- > cla ()

} elseif ($obj instanceof office) {

$obj- > wor ()

} else {

Echo "there is no such object!"

}

}

Doing (new student ()); / / students are in class

Doing (new office ()); / / staff are at work

The output of the above results:

The students are in class.

The staff is at work.

The drawback of this common approach is that if there are many objects, then if..else.. Very long, inflexible.

Polymorphic practice

Define a public abstract method that all subclasses inherit.

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* PHP polymorphism

, /

/ / define a public class

Class pub {

Protected function working () {

Echo "this method needs to be overloaded in subclasses!"

}

}

/ / define the student class and inherit the public class pub

Class student extends pub {

Public function working () {

Echo "the student worker is in class!"

}

}

/ / define the employee class, which inherits the public class pub

Class office extends pub {

Public function working () {

Echo "staff are at work!"

}

}

/ / method of judging object type

Function doing ($obj) {

If ($obj instanceof pub) {

$obj- > working ()

} else {

Echo "there is no such object!"

}

}

Doing (new student ()); / / students are in class

Doing (new office ()); / / staff are at work

This is the characteristic of polymorphism, flexible reuse.

Other practices

From the point of view of the implementation of polymorphism, it is nothing more than standardizing a method that each class should overload the parent class, so as to achieve a unified effect. It is also possible for us to add a unified method when defining classes. Therefore, the above example can also be implemented as follows:

The copy code is as follows:

/ * *

* PHP polymorphism

* Qiongtai blog

, /

/ / define student classes

Class student {

/ / define a unified method pub

Public function pub () {

Echo "the student worker is in class!"

}

}

/ / define the employee class

Class office {

/ / define a unified method pub

Public function pub () {

Echo "staff are at work!"

}

}

/ / method of judging object type

Function doing ($obj) {

If ($obj) {

/ / call the unified method of the class

$obj- > pub ()

} else {

Echo 'does not have this object'

}

}

Doing (new student ()); / / students are in class

Doing (new office ()); / / staff are at work

Of course, the above examples do not show that polymorphism can be solved in this way. After all, polymorphism can effectively achieve flexible reuse in complex programming.

Polymorphism can also be understood as a way of programming, and the ultimate goal of programming is nothing more than flexibility, polymorphism, reuse and efficiency.

This is all the content of the article "sample Analysis of Polymorphism in PHP object-oriented". Thank you for reading! Hope to share the content to help you, more related knowledge, welcome to follow the industry information channel!

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