问题描述
所以...我正在修改一些基本的python/tkinter程序，并将正在阅读的书中python 2.x的代码翻译为3.x，以确保我理解所有内容.我还尝试用名为"proper"的导入而不是通配符导入来编写代码，即from tkinter import *，但效果不佳...
So... I'm tinkering with some basic python/tkinter programs, and translating the code from python 2.x in the book I'm reading, to 3.x to make sure I understand everything. I was also attempting to write the code with 'proper' named imports instead of wild card import i.e. from tkinter import * but its not working out so well...
此刻我感到困惑的是:原始代码对tkinter进行了通配符导入，并且似乎可以不使用诸如sticky=W之类的参数变量引号来逃避"名为import的导入，我必须在'W'周围使用引号，否则会出现错误Unresolved reference 'W'.
What has me baffled at the moment is this: the original code does a wildcard import of tkinter, and seems to be able to 'get away with' not using quotes around parameter variables like sticky=W, while if I do a named import I have to use quotes around the 'W' or I get an error Unresolved reference 'W'.
示例代码(通配符导入):
Example code (wildcard import):
from tkinter import *
root = Tk()
Label(root, text="Username").grid(row=0, sticky=W)
Label(root, text="Password").grid(row=1, sticky=W)
Entry(root).grid(row=0, column=1, sticky=E)
Entry(root).grid(row=1, column=1, sticky=E)
Button(root, text="Login").grid(row=2, column=1, sticky=E)
root.mainloop()
命名导入:
import tkinter as tk
root = tk.Tk()
tk.Label(root, text="Username").grid(row=0, sticky='W')
tk.Label(root, text="Password").grid(row=1, sticky='W')
tk.Entry(root).grid(row=0, column=1, sticky='E')
tk.Entry(root).grid(row=1, column=1, sticky='E')
tk.Button(root, text="Login").grid(row=2, column=1, sticky='E')
root.mainloop()
两者都能工作，但是python为什么一次只能识别一种方式，而另一次却不能呢?
Both work, but why does python recognize it one way one time, and not the other?
推荐答案
from tkinter import *
从tkinter模块加载所有内容，并将其放入全局名称空间中.
Loads everything from tkinter module, and puts it in the global namespace.
import tkinter as tk
从tkinter模块的加载所有内容，并将它们全部放在tk命名空间中.所以Label现在是tk.Label，而W是tk.W
Loads everything from tkinter module, and put it all in the tk namespace. So Label is now tk.Label, and W is tk.W
您的第三个选项是:
from tkinter import Label, Entry, Button, W, E, Tk
等等.同样，当您只需要一两个时，效果会更好.不利于您的情况.只是为了完整起见.
Etc. Again, better when you just need one or two. Not good for your situation. Just included for completeness.
tkinter.W = 'w'
tkinter.E = 'e'
tkinter.S = 's'
tkinter.N = 'n'
它们只是常量.您可以传递字符串 value ，它也可以正常工作.
They're just constants. You could pass the string value and it would work just as well.
这篇关于为什么命名/通配符导入会/如何影响参数?的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持！