python - tkinter:将多个按钮 lambda 映射到一个标签？

Question

描述:我希望能够单击一个按钮并将其值发送到标签小部件(lab_1)，我知道要执行一个按钮，您必须使用command=lambda: lab_1.configure(text=0) 但是，当我使用 for 循环创建所有按钮时，您将如何将值打印到标签嵌入列表。截至目前，所有按钮都有名为 key_press 的变量。

简化的问题:

• 如何将所有值写入我的标签 (lab_1)？

• 如何使用 for 循环，以便每次单击该按钮时都会向 Label 显示其值？

<小时/>

import tkinter as tk

root = tk.Tk()
# Change the original tkinter icon
root.iconbitmap('C:\\Users\\bmxfi\Downloads\images.ico')
# Set the title of the window
root.title('Calculator')
# Change the geometry of the window
root.geometry('300x450+750+150')
# Setting Minimum and Maximum window width and height
root.minsize(width=300, height=450)
root.maxsize(width=300, height=450)
# Create Rows and Columns to display widgets
root.rowconfigure(0, weight=100)
root.rowconfigure(1, weight=100)
root.rowconfigure(2, weight=100)
# Columns start here:
root.columnconfigure(0, weight=100)
root.columnconfigure(1, weight=100)
root.columnconfigure(2, weight=100)
# Configuring the Main window named: root
root.configure(bg='#353535')
# Creating the main label that will display the calculated results
lab_1 = tk.Label(root, width=40)
lab_1.grid(row=0, column=1, columnspan=1, sticky='we')
lab_1.configure(bg='#545454', font=('Computer Modern', 25, 'bold'),
                fg='White', justify='right')
# Main Calculator Layout
# List Box for a calculator layout
box_1 = tk.Listbox(root)
box_1.grid(row=1, column=1, rowspan=2)
box_1.configure(bg='#353535', relief='flat')
# Button Layout
calculator_layout = [[(7, 1), (8, 1), (9, 1), ('(', 1), (')', 1)],
                     [(4, 1), (5, 1), (6, 1), ('×', 1), ('÷', 1)],
                     [(1, 1), (2, 1), (3, 1), ('+', 1), ('-', 1)],
                     [(0, 1), ('±', 1), ('.', 1), ('-', 1), ('=', 1)]]

# Iterating through my list to get a set of buttons
row = 0
for i in calculator_layout:
    col = 0
    for a in i:
        key_press = tk.Button(box_1, text=a[0])
        key_press.grid(row=row, column=col, ipadx=10, ipady=8, sticky='we')
        key_press.configure(background='#545454', fg='white',
                            font=('Computer Modern', 10),
                            activebackground='red', state='normal')
        col += a[1]
    row += 1

root.mainloop()

Answer 1

您可以通过为每个 Button 的 lambda 提供一个具有默认值的参数来实现此目的。不需要任何额外的 for 循环以这种方式执行此操作(它是在创建 Buttons 的循环中完成的)。

如何做到这一点在下面带有 # CHANGED 注释的地方显示。每个定义的 lambda 函数中的其余代码均重新配置名为 lab_1 的 Label 的 text 选项通过调用其 configure() 方法并向其传递 text 选项的当前内容，并附加关联的 Button 符号。

...

# Iterating through my list to get a set of buttons
row = 0
for i in calculator_layout:
    col = 0
    for a in i:
        key_press = tk.Button(box_1, text=a[0])
        key_press.grid(row=row, column=col, ipadx=10, ipady=8, sticky='we')
        key_press.configure(background='#545454', fg='white',
                            font=('Computer Modern', 10),
                            activebackground='red', state='normal',
                            # CHANGED.
                            command=lambda sym=str(a[0]):
                                lab_1.configure(text=lab_1.cget('text')+sym))
        col += a[1]
    row += 1

root.mainloop()