Question

我只编写了3个月的编程，因此即使与我的具体问题相关，我也会对任何有关改进代码的建议表示赞赏。

这是一个带有tkinter的简单小项目。输入您的名字和姓氏的两个字段然后您点击交换按钮，它将交换您在名称字段中放置的内容。问题是我不想使用全局变量而我似乎无法弄清楚我知道它可能很简单，我确实花时间试图解决它。如果您对代码有任何改进，请告诉我。

from tkinter import *

### I dont Want Globals but cant figure out another method for doing this
### Hope some one can help me with this part

evar = ""
evar1 = ""


def mainWindow():
    root = Tk()
    root.title("Swap Names")
    root.geometry("400x150+100+250")

    return root

def createVar():
        global evar
        global evar1

        evar = StringVar()
        evar1 = StringVar()

def firstNameFrame(root):
    frame1 = Frame(root)
    frame1.pack(side=TOP, padx=2, pady=2)

    label = Label(frame1, text="First Name:")
    label.pack(side=LEFT, padx=2, pady=2)

    entry = Entry(frame1, textvariable = evar)
    entry.pack(side=LEFT, pady = 2)

def lastNameFrame(root):

    frame2 = Frame(root)
    frame2.pack(side=TOP, padx=2, pady=2)

    label = Label(frame2, text="Last Name:")
    label.pack(side=LEFT, padx=1, pady=1)

    entry = Entry(frame2, textvariable = evar1)
    entry.pack(side=LEFT, pady = 5)

def swapFrame(root):
    frame3 = Frame(root)
    frame3.pack(side=TOP, padx=10, pady = 10)

    swapButton = Button(frame3, text="Swap",command = swap)
    swapButton.pack(side=LEFT, padx =5, pady=5)

### I would like to some how use swap with out using a global 
def swap():
    b=evar.get()
    evar.set(evar1.get())
    evar1.set(b)



def main():
    root = mainWindow()
    createVar()
    firstNameFrame(root)
    lastNameFrame(root)
    swapFrame(root)
    root.mainloop()


main()

Answer 1

其中一个解决方案可以包装所有与初始化相关的代码，并在一个单独的类中使用Tk，因此我们将使用类实例变量而不是全局变量：

from tkinter import *


class Gui(object):
    def __init__(self):
        self.root = Gui._init_main_window()
        self.first_name_var = StringVar()
        self.last_name_var = StringVar()

        self._init_first_name_frame()
        self._init_last_name_frame()
        self._init_swap_frame()

    @staticmethod
    def _init_main_window():
        root = Tk()
        root.title("Swap Names")
        root.geometry("400x150+100+250")

        return root

    def _init_first_name_frame(self):
        frame1 = Frame(self.root)
        frame1.pack(side=TOP, padx=2, pady=2)

        label = Label(frame1, text="First Name:")
        label.pack(side=LEFT, padx=2, pady=2)

        entry = Entry(frame1, textvariable=self.first_name_var)
        entry.pack(side=LEFT, pady=2)

    def _init_last_name_frame(self):
        frame2 = Frame(self.root)
        frame2.pack(side=TOP, padx=2, pady=2)

        label = Label(frame2, text="Last Name:")
        label.pack(side=LEFT, padx=1, pady=1)

        entry = Entry(frame2, textvariable=self.last_name_var)
        entry.pack(side=LEFT, pady=5)

    def _init_swap_frame(self):
        frame3 = Frame(self.root)
        frame3.pack(side=TOP, padx=10, pady=10)

        swap_button = Button(frame3, text="Swap", command=self._swap)
        swap_button.pack(side=LEFT, padx=5, pady=5)

    def _swap(self):
        tmp = self.first_name_var.get()
        self.first_name_var.set(self.last_name_var.get())
        self.last_name_var.set(tmp)

    def mainloop(self):
        return self.root.mainloop()


def main():
    gui = Gui()
    gui.mainloop()


if __name__ == '__main__':
    main()

~~对上述代码的一个小注释：向变量或方法添加前缀__允许您使用the name mangling.~~ <在类外部通过名称直接隐藏对它们的访问/ p>

UPD：根据@Coal comment，将双下划线前缀更改为单下划线，因为不需要使用名称修改。

Answer 2

假设当您说您不想使用global时，您还意味着不想要使用self：

from tkinter import Tk, Button, Entry

def swap(fn, ln):

    # Get the contents of the two fields.
    first = fn.get()
    last = ln.get()

    # Clear the contents of both fields.
    first_name.delete(0, 'end')
    last_name.delete(0, 'end')

    # Set each field to the previous content of the other field.
    first_name.insert(0, last)
    last_name.insert(0, first)


root = Tk()

first_name = Entry(root)
last_name = Entry(root)

first_name.insert(0, "Enter first name")
last_name.insert(0, "Enter last name")

first_name.pack()
last_name.pack()

swap_button = Button(root, text="SWAP", command=lambda:swap(first_name, last_name))
swap_button.pack()



root.mainloop()

Python3.6：尝试避免使用tkinter

2 个答案: