Several methods of importing ThinkPHP

import(' Class library name ', ' Starting path ', ' Class library suffix ')
import('@.Test.Translate');
@, Represents the project root . Suppose the root directory is ：App/
The path to import the class library is ：App/Lib/Test/Translate.class.php
Conclusion ：import('@') Is relative to the project directory Lib In terms of catalogue

Loader::import(' route ', EXTEND_PATH);
// Helper functions
import(' route ', EXTEND_PATH);
EXTEND_PATH  thinkphp The default is a third-party directory extend
import('Think') Is relative to the system directory Lib In terms of catalogue
import('ORG') or import('COM') It is relative to the system extension class library directory （./ThinkPHP/Extend/Library/）
Points can be used in the middle of the path to link such as  a/b   It can be used a.b 

include
Include and run the specified file . The included file is first searched according to the path given by the parameter , If no directory is given （ Only the filename ） When it comes to include_path The specified directory looks for .
If in include_path If the file is not found, then include Finally, we find it in the directory where the script file is called and the current working directory . If the file is not found in the end include 
The structure will issue a warning about this and require Different , The latter will make a fatal error
require The two methods are similar The main difference is that fatal errors are reported
include_once,require_once The only difference is PHP Will check if the file has been included , If so, it will not contain .