PHP 全局或 $GLOBALS

Question

当我想使用在函数外部声明的变量时，是否有最佳实践/建议:

1. 全局 $myVar
2. $GLOBALS['myVar']

谢谢。

Answer 1

嗯，你应该只在有限的情况下使用全局变量，但要回答你的问题:

1. global 可能稍微快一些(它很少会产生影响)。
2. $GLOBALS(不是 $GLOBAL)更具可读性，因为每次看到它，您就知道您正在访问/更改全局变量。这对于避免讨厌的错误至关重要。
3. 在函数内部，如果你想取消设置一个全局变量，你必须使用unset($GLOBALS['varname'])，而不是global $varname;取消设置($变量名)；。

关于第 1 点和第 2 点，我会 quote萨拉戈蒙在这里:

What does that mean for your use of the $GLOBALS array? That's right, the global keyword is technically faster. Now, I want to be really clear about one thing here. The minor speed affordance given by using your globals as localized [compiled variables] needs to be seriously weighed against the maintainability of looking at your code in five years and knowing that $foo came from the global scope. something_using($GLOBALS['foo']); will ALWAYS be clearer to you down the line than global $foo; /* buncha code */ something_using($foo); Don't be penny-wise and pound foolish..