Usage of namespace in php

Usage of namespace in php

Now, I feel a little out of date, but I still feel that there are not many people using namespace. It is probably because I am not used to it.

Class organizes functions one by one. namespace can be understood as an orderly organization of classes and functions. I personally think the main advantages of namespace are:

First, better code management

Second, if there are more files, the duplicate names of the class and function can be avoided.

Third, enhanced code readability

1. Define namespace

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Namespace userCenter;   // Php code       Namespace userCenter \ register;   // Php code       Namespace userCenter \ login {   // Php code   }

The namespace cannot be nested or declared multiple times in the same code (only the last one will be recognized ). However, you can define multiple namespace-based codes in the same file. A proper practice is to define a namespace (or the same namespace) for each file ).

2. Call namespace

\ UserCenter \ register; // an absolute call

UserCenter \ login; // relative call

Use userCenter \ register; // Reference Space

Use userCenter \ register as reg; // reference the space and add an alias

3. instance description

Login. class. php

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<? Php       Namespace userCenter;       Function check_username (){   Echo "login OK <br> ";   }       Class login {   Public function save (){   Echo "login had saved <br> ";   }   }   ?>   Regist. class. php       <? Php   Namespace userCenter \ regist   {   Function check_username (){   Echo "regist OK <br> ";   }       Class regist {   Public function save (){   Echo "regist had saved <br> ";   }   }   }       ?>

Test. php

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<? Php       Require "login. class. php ";   Require "regist. class. php ";       Use userCenter \ regist; // use to call a space   Use userCenter \ regist as reg; // as defines the alias       Echo \ userCenter \ check_username (); // call absolutely       $ Login = new \ userCenter \ login ();   Echo $ login-> save ();       Echo regist \ check_username (); // relative call   Echo reg \ check_username (); // alias call       $ Regist = new reg \ regist ();   Echo $ regist-> save ();

It is better to use it than to call it. It is like adding a prefix to class and function. This makes it clearer.