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Several points to note when defining command space in PHP
- 墨辰丷Original
- 2018-05-31 09:55:441242browse
This article mainly introduces several points to pay attention to when defining command space in PHP. Interested friends can refer to it. I hope it will be helpful to everyone.
1. Declaring the command space must be the first statement of the program script. In addition, all non-PHP code, including whitespace, cannot appear before the namespace declaration.
The following is an example of an error:
<html> <?php namespace MyProject; // 致命错误 - 命名空间必须是程序脚本的第一条语句 ?>
This is also wrong
<?php
// Lots
// of
// interesting
// comments and white space
namespace Foo;
class Bar {
}
?>
2. PHP keywords cannot be used.
The following is an error example:
<?php namespace Project/Classes/Function; // Causes parse errors namespace Project/Abstract/Factory; // Causes parse errors ?>
3. Constant definition in the namespace .
The following MESSAGE is in the global namespace:
<?php namespace test; define('MESSAGE', 'Hello world!'); ?>
Define 2 constants in the test namespace:
<?php namespace test; define('test\HELLO', 'Hello world!'); define(__NAMESPACE__ . '\GOODBYE', 'Goodbye cruel world!'); ?>
The above is the entire content of this article, I hope it will be helpful to everyone's study.
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