函数内的`static`关键字? [英] `static` keyword inside function?

问题描述

我在查看 Drupal 7 的源代码，发现了一些我以前从未见过的东西.我在php手册中做了一些初步查找，但没有解释这些示例.

I was looking at the source for Drupal 7, and I found some things I hadn't seen before. I did some initial looking in the php manual, but it didn't explain these examples.

关键字static对函数内的变量有什么作用?

What does the keyword static do to a variable inside a function?

function module_load_all($bootstrap = FALSE) {
    static $has_run = FALSE

推荐答案

它使函数在多次调用之间记住给定变量的值(在您的示例中为$has_run).

It makes the function remember the value of the given variable ($has_run in your example) between multiple calls.

您可以将其用于不同的目的，例如:

You could use this for different purposes, for example:

function doStuff() {
  static $cache = null;

  if ($cache === null) {
     $cache = '%heavy database stuff or something%';
  }

  // code using $cache
}

在这个例子中，if 只会被执行一次.即使多次调用 doStuff 也会发生.

In this example, the if would only be executed once. Even if multiple calls to doStuff would occur.

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