class 声明和对象初始化在同一个文件中符合 PSR-1 吗?

Is class declaration and object initialization in the same file PSR-1 compliant?

PSR-1 状态:

Files SHOULD either declare symbols (classes, functions, constants, etc.) or cause side-effects (e.g. generate output, change .ini settings, etc.) but SHOULD NOT do both.

假设我们有以下代码:

// db.php file
class Db{
    // Some code here
}

$DB = new Db();

实例化一个对象算作副作用吗?也就是说,上面的代码符合 PSR-1 规范吗?

根据 PSR-1

"Side effects" include but are not limited to: [...] connecting to external services [...]

更一般地,指定为:

The phrase "side effects" means execution of logic not directly related to declaring classes, functions, constants

所以答案是:它不符合 PSR-1。

您应该将 db.php 文件包含在主逻辑文件中。然后实例化您的数据库对象。