如何从外部Python文件调用另一个文件中的嵌套内部函数？

嵌套函数some_function的作用域仅限于外部函数one_function内部，模块的全局命名空间里不存在这个函数，所以直接通过from ... import some_function的方式肯定找不到它。

方法1：将嵌套函数移到模块级别 #

直接把some_function从one_function内部提取到模块顶层，这样就能正常导入使用。如果需要用到原内部的threshold，可以把它改成模块级变量：

修改stats_file.py：

# 模块级变量，原内部的threshold移到这里
threshold = 1

# 直接定义在模块级别
def some_function(variable_1, variable_2, variable_3):
    outcome_text = ""
    # 注意：原代码中的x、y、ratio需要替换为实际从参数或其他地方获取的变量，否则会报错
    if x > y > threshold:
        if ratio <= 0.69 * threshold:
            outcome_text = "text 1"
        elif ratio <= 0.70 * threshold:
            outcome_text = "text 2"
        elif ratio >= 0.80 * threshold:
            outcome_text = "text 3"
        elif ratio >= 0.90 * threshold:
            outcome_text = "text 4"
        else:
            outcome_text = "text 5"
    else:
        outcome_text = "text 6"
    return outcome_text

def one_function():
    def get_outcome_text(variable_1, variable_2, variable_3):
        outcome_text = some_function(variable_1, variable_2, variable_3)
        return outcome_text

    outcome_text = get_outcome_text(variable_1, variable_2, variable_3)
    print(outcome_text)

之后shared_data.py和loop_file.py就可以正常导入：
shared_data.py：

from stats_file import some_function

loop_file.py：

from shared_data import some_function

方法2：让外部函数返回嵌套函数 #

如果不想改动原有嵌套结构，可以修改one_function，让它执行后返回some_function，这样导入外部函数后调用就能拿到嵌套函数：

修改stats_file.py：

def one_function():
    threshold = 1
    def some_function(variable_1, variable_2, variable_3):
        outcome_text = ""
        if x > y > threshold:
            if ratio <= 0.69 * threshold:
                outcome_text = "text 1"
            elif ratio <= 0.70 * threshold:
                outcome_text = "text 2"
            elif ratio >= 0.80 * threshold:
                outcome_text = "text 3"
            elif ratio >= 0.90 * threshold:
                outcome_text = "text 4"
            else:
                outcome_text = "text 5"
        else:
            outcome_text = "text 6"
        return outcome_text

    def get_outcome_text(variable_1, variable_2, variable_3):
        outcome_text = some_function(variable_1, variable_2, variable_3)
        return outcome_text

    outcome_text = get_outcome_text(variable_1, variable_2, variable_3)
    print(outcome_text)
    # 返回嵌套函数
    return some_function

shared_data.py中转处理：

from stats_file import one_function
# 调用one_function获取嵌套函数
some_function = one_function()

loop_file.py直接导入使用：

from shared_data import some_function

方法3：给外部函数绑定嵌套函数作为属性 #

在one_function内部，把some_function绑定为外部函数的属性，这样导入外部函数后可以通过属性访问：

修改stats_file.py：

def one_function():
    threshold = 1
    def some_function(variable_1, variable_2, variable_3):
        outcome_text = ""
        if x > y > threshold:
            if ratio <= 0.69 * threshold:
                outcome_text = "text 1"
            elif ratio <= 0.70 * threshold:
                outcome_text = "text 2"
            elif ratio >= 0.80 * threshold:
                outcome_text = "text 3"
            elif ratio >= 0.90 * threshold:
                outcome_text = "text 4"
            else:
                outcome_text = "text 5"
        else:
            outcome_text = "text 6"
        return outcome_text

    # 将嵌套函数绑定为外部函数的属性
    one_function.some_function = some_function

    def get_outcome_text(variable_1, variable_2, variable_3):
        outcome_text = some_function(variable_1, variable_2, variable_3)
        return outcome_text

    outcome_text = get_outcome_text(variable_1, variable_2, variable_3)
    print(outcome_text)

shared_data.py中转处理：

from stats_file import one_function
# 必须先调用一次one_function，属性才会被绑定
one_function()
# 访问外部函数的属性获取嵌套函数
some_function = one_function.some_function

loop_file.py直接导入使用即可。

内容的提问来源于stack exchange，提问作者Newbie