为什么导入并不总是导入嵌套包? [英] Why does an import not always import nested packages?
问题描述
为什么第一个代码不起作用而第二个代码起作用?
第一个代码:
导入硒驱动程序 = selenium.webdriver.Firefox()
<块引用>
AttributeError: 'module' 对象没有属性 'webdriver'
第二个代码:
from selenium import webdriver驱动程序 = webdriver.Firefox()
嵌套包不会自动加载;直到您导入 selenium.webdriver
才能将其作为属性使用.仅导入 selenium
是不够的.
这样做:
import selenium.webdriver驱动程序 = selenium.webdriver.Firefox()
有时包本身会在 __init__.py
包初始化器中导入一个嵌套包;os
导入 os.path
,因此即使您只导入 os
,os.path
也立即可用.>
Why the first code doesn't work while the second does?
First code:
import selenium
driver = selenium.webdriver.Firefox()
AttributeError: 'module' object has no attribute 'webdriver'
Second code:
from selenium import webdriver
driver = webdriver.Firefox()
Nested packages are not automatically loaded; not until you import selenium.webdriver
is it available as an attribute. Importing just selenium
is not enough.
Do this:
import selenium.webdriver
driver = selenium.webdriver.Firefox()
Sometimes the package itself will import a nested package in the __init__.py
package initializer; os
imports os.path
, so os.path
is immediately available even if you import just os
.
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