在Python中导入函数

Question

如何导入使用当前文件中定义的变量的函数？

卖弄.朋友

from functions import a

x = 1

print(a())

functions.朋友

def a():
    return x

错误信息

Traceback (most recent call last):
  File "c:\Users\Test\.vscode\extensions\ms-python.python-2019.4.11987\pythonFiles\ptvsd_launcher.py", line 43, in <module>
    main(ptvsdArgs)
  File "c:\Users\Test\.vscode\extensions\ms-python.python-2019.4.11987\pythonFiles\lib\python\ptvsd\__main__.py", line 410, in main
    run()
  File "c:\Users\Test\.vscode\extensions\ms-python.python-2019.4.11987\pythonFiles\lib\python\ptvsd\__main__.py", line 291, in run_file
    runpy.run_path(target, run_name='__main__')
  File "C:\Users\Test\AppData\Local\Programs\Python\Python37\lib\runpy.py", line 263, in run_path
    pkg_name=pkg_name, script_name=fname)
  File "C:\Users\Test\AppData\Local\Programs\Python\Python37\lib\runpy.py", line 96, in _run_module_code
    mod_name, mod_spec, pkg_name, script_name)
  File "C:\Users\Test\AppData\Local\Programs\Python\Python37\lib\runpy.py", line 85, in _run_code
    exec(code, run_globals)
  File "c:\Users\Test\Google Drive\Dev\Test\main.py", line 5, in <module>
    print(a())
  File "c:\Users\Test\Google Drive\Dev\Test\functions.py", line 2, in a
    return x
NameError: name 'x' is not defined

Answer 1

正如另一个答案所指出的那样，由于Python范围变量的原因，这将不起作用。

因此，我建议您将所有这些变量移动到单独的文件中，例如， constants.py：

main.py

from functions import a

print(a())

constants.py

X = 1

functions.py

from constants import X

def a():
    return X

然后，运行import main打印1。

Answer 2

没有进程范围的全局变量，只有模块级全局变量。 a使用functions.x，而不是x在任何全球范围内调用它。

import functions
from functions import a, b, c

functions.x = 1
functions.y = 2
functions.z = 3

print(a())
print(b())
print(c())

因为Python是词法范围的，所以每个函数都会引用它所定义的全局范围。名称查找使用该范围来解析自由变量。