Section 2 - Object Model of PHP5_PHP Tutorial-PHP Tutorial-php.cn

Section 2 - Object Model of PHP5_PHP Tutorial

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Release： 2016-07-21 16:00:55

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| = Notes from the Chapter Classes and Objects
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Section 2--PHP5 object model

PHP5 has a single A heavy-inherited, restricted-access, overloadable object model. "Inheritance," discussed in detail later in this chapter, involves parent-child relationships between classes. In addition, PHP supports restricted access to properties and methods. You can Declare members as private and do not allow external classes to access them. Finally, PHP allows a subclass to overload members from its parent class.

//haohappy Note: There is no private in PHP4, only public.private for more information There are benefits to implementing encapsulation well.

PHP5's object model treats objects as different from any other data type and is passed by reference. PHP does not require you to explicitly pass and return objects by reference. The handle-based object model will be explained in detail at the end of this chapter. It is the most important new feature in PHP5.

With a more direct object model, the handle-based system has additional advantages: improved efficiency, It takes up less memory and has greater flexibility.

In previous versions of PHP, scripts copied objects by default. Now PHP5 only moves the handle, which takes less time. The improvement in script execution efficiency is Because unnecessary copying is avoided, while the object system brings complexity, it also brings benefits in execution efficiency. At the same time, reducing copying means that less memory is occupied, and more memory can be left for other operations. This also improves efficiency.

//haohappy Note: Based on handles, it means that two objects can point to the same memory, which not only reduces copy actions but also reduces memory usage.

Zand Engine 2 has greater flexibility. A happy development is to allow destruction - executing a class method before the object is destroyed. This is also good for utilizing memory, letting PHP clearly know when there is no object left. Reference, allocate the free memory to other uses.