Section 1 - Object-oriented programming - Classes and Objects in PHP5 [1]

Section 1 - Object-oriented programming - Classes and Objects in PHP5 [1]_PHP Tutorial

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Release： 2016-07-13 17:20:41

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Section 1 - Object-oriented programming

Object-oriented programming is designed to provide solutions for large-scale software projects, especially projects involving multiple people. When the source code grows to 10,000 lines Even more often, every change can lead to undesirable side effects. This happens when modules form secret alliances, like in Europe before World War I.

//haohappy Note: It means that the correlation between modules is too high and the interdependence is too strong. Changing one module will cause other modules to also be changed accordingly.

Imagine if there is A module that handles logins allows a credit card processing module to share its database connection. Of course, the intention is good, saving the expense of another database connection. However, sometimes, the login processing module changes the name of one of the variables, so It may have severed the agreement between the two, causing errors in the processing of the credit card module, which in turn led to errors in the module that processes invoices. Soon, all irrelevant modules in the system may have errors.

Therefore, I think Somewhat dramatically, most programmers are grateful for coupling and encapsulation. Coupling is a measure of the dependence between two modules. The less coupling the better. We want to be able to take a module out of an existing project and put it in Used in another new project.

We also hope to make large-scale changes within a certain module without worrying about the impact on other modules. The principle of encapsulation can provide this solution. Modules are treated as relatively independent , and data communication between modules occurs through interfaces. Modules do not peek into each other's variable names, they send requests politely through functions.

Encapsulation is something you can use in any programming language A principle. In PHP and many procedural languages, it is tempting to be lazy. There is nothing stopping you from building a hypothetical WEB through modules. Object-oriented programming is a way for programmers to not violate the principle of encapsulation. Methods.

In object-oriented programming, modules are organized into objects. These objects have methods and properties. From an abstract point of view, a method is an action performed by an object. Properties are characteristics of objects. From a programming perspective, methods are functions and properties are variables. In an ideal object-oriented system, each part is an object. The system is formed by objects and methods between objects.

A class defines the properties of an object. If you were baking a set of cookie objects, the class would be the cookie machine. The properties and methods of the class are the members that are called. People Can be expressed by saying data members or method members.

Each language provides different ways to access objects. PHP borrows concepts from C++ and provides a data type to be used in an identifier Contains functions and variables below. When PHP was originally designed, and even when PHP3 was developed, PHP was not intended to provide the ability to develop large projects with more than 100,000 lines of code. With the development of PHP and Zend Engine, it has become possible to develop large projects, but no matter how big your project is, writing your scripts in classes will allow code reuse. This is a good idea, especially if you are willing to share your code with others.

The idea of objects is one of the most exciting concepts in computer science. It's hard to master it at first, but I can guarantee that once you do, thinking with its mind will feel very natural.