如何确定通过`from m import *`导入什么? [英] How to determine what is imported via `from m import *`?

问题描述

我正在对导入语句进行一些修补，我需要确切地知道从m import * 中导入了哪些成员.该文档似乎表明缺少 __ all __ 时，将导入所有不以下划线开头的成员.在所有情况下这都是正确的吗?我知道 inspect.getmembers()， dir()和 m .__ dict __ 的逻辑都略有不同，所以我并不完全确保哪个(如果有)将提供与 import * 相同的列表.

解决方案

让我们看一下 import * 语句中的做什么:

 >>>dis.dis(compile('from m import *'，'< module>'，'single'))1 0 LOAD_CONST 0(0)2 LOAD_CONST 1(('*'，))4 IMPORT_NAME 0(m)6 IMPORT_STAR8 LOAD_CONST 2(无)10 RETURN_VALUE 

此处的关键是它实际上会调用专用的操作码 IMPORT_STAR ，这是特定于将执行此代码的解释器的实现.该运算符最初是在 PEP-0221 中指定的，但是指定的实现详细信息在此特定提交引入的注释中.

在CPython中，可以在 /Python/ceval.c (Python 3.7.2)，然后依次调用 /pypy/interpreter/pyopcode.py ，再次类似于C实现它会调用 解决方案

Let's take a look at what that from m import * statement does:

>>> dis.dis(compile('from m import *', '<module>', 'single'))
  1           0 LOAD_CONST               0 (0)
              2 LOAD_CONST               1 (('*',))
              4 IMPORT_NAME              0 (m)
              6 IMPORT_STAR
              8 LOAD_CONST               2 (None)
             10 RETURN_VALUE

The key here is that it actually invokes a dedicated opcode IMPORT_STAR, and this is implementation specific to the interpreter that will execute this code. This operator was originally specified in PEP-0221 but the implementation details specified is in the comments introduced by this specific commit.

In CPython, this is found in /Python/ceval.c (Python 3.7.2) and it in turns call import_all_from which shows the general logic on what that actually does inside the bytecode interpreter.

In PyPy, this is found in /pypy/interpreter/pyopcode.py, and again much like the C implementation it invokes the import_all_from function defined in RPython, which again has a similar logic but in a more familiar syntax for Python programmers.

In both the CPython and pypy implementation, if __all__ is presented as a list of names inside the imported module, all matching assignments will be added to the current local scope, including those names that are prefixed with an underscore (_). Otherwise, every assignment inside the module that do not start with an underscore will be added to the current local scope.

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