如何在Python中使用类（类在我的代码中不起作用）

Question

I made a code then decided to split it up into a GUI class and a logic class but now that I have done that the code does not function after I made the two classes, it works without the classes but I am trying to make it work with classes. if someone could fix this problem I will be so grateful. Any help will be kindly appreciated thank you.

from tkinter import *
import tkinter as tk
from tkinter import ttk

class GUI:
    notebook = ttk.Notebook(root)
    frame1 = ttk.Frame(notebook)
    notebook.add(frame1, text='Length')
    frame2 = ttk.Frame(notebook)
    notebook.add(frame2, text='Weight')
    frame3 = ttk.Frame(notebook)
    notebook.add(frame3, text='Temperature')
    notebook.pack(expand=1, fill="both")
    #======================================================================
    entry = Entry(frame1)
    entry.grid(row=0, column=0)

    label = Label(frame1, relief='groove', width=20, text='')
    label.grid(row=0, column=3)

    options1 = ['mm', 'cm', 'm', 'km', 'Inches', 'Feet', 'Yards', 'Miles']

    var1 = tk.StringVar(frame1)
    var1.set(options1[0])

    dropdown1 = tk.OptionMenu(frame1, var1, options1[0], options1[1], options1[2], options1[3], options1[4], options1[5], options1[6], options1[7])
    dropdown1.grid(row=1, column=0)

    var2 = tk.StringVar(frame1)
    var2.set(options1[0])

    dropdown2 = tk.OptionMenu(frame1, var2, options1[0], options1[1], options1[2], options1[3], options1[4], options1[5], options1[6], options1[7])
    dropdown2.grid(row=1, column=3)

    equal_button = Button(frame1, text='=', command=Length_Error) 
    equal_button.grid(row=1, column=5)
    #======================================================================
    weight_entry = Entry(frame2)
    weight_entry.grid(row=0, column=0)

    weight_label = Label(frame2, relief='groove', width=20, text='')
    weight_label.grid(row=0, column=3)

    options2 = ['Grams', 'Kilograms', 'Ounces', 'Pounds', 'Tonnes']

    weight_var1 = tk.StringVar(frame2)
    weight_var1.set(options2[0])

    dropdown1 = tk.OptionMenu(frame2, weight_var1, options2[0], options2[1], options2[2], options2[3], options2[4])
    dropdown1.grid(row=1, column=0)

    weight_var2 = tk.StringVar(frame1)
    weight_var2.set(options2[0])

    dropdown2 = tk.OptionMenu(frame2, weight_var2, options2[0], options2[1], options2[2], options2[3], options2[4])
    dropdown2.grid(row=1, column=3)

    weight_equal_button = Button(frame2, text='=', command=Weight_Error) 
    weight_equal_button.grid(row=1, column=5)
    #======================================================================
    temp_entry = Entry(frame3)
    temp_entry.grid(row=0, column=0)

    temp_label = Label(frame3, relief='groove', width=20, text='')
    temp_label.grid(row=0, column=3)

    options3 = ['Celsius', 'Fahrenheit', 'Kelvin']

    temp_var1 = tk.StringVar(frame3)
    temp_var1.set(options3[0])

    temp_dropdown1 = tk.OptionMenu(frame3, temp_var1, options3[0], options3[1], options3[2])
    temp_dropdown1.grid(row=1, column=0)

    temp_var2 = tk.StringVar(frame3)
    temp_var2.set(options3[0])

    temp_dropdown2 = tk.OptionMenu(frame3, temp_var2, options3[0], options3[1], options3[2])
    temp_dropdown2.grid(row=1, column=3)

    temp_equal_button = Button(frame3, text='=', command=Temperature_Error) 
    temp_equal_button.grid(row=1, column=5)
    #======================================================================

class logic:
    #======================================================================
    def Length_Error(*args):
        try:
            v = float(entry.get())       
        except ValueError:
            label['text']=('Enter Valid Input')
        else:
            Length_converter()
    #======================================================================
    def Weight_Error(*args):
        try:
            v = float(weight_entry.get())
        except ValueError:
            weight_label['text']=('Enter Valid Input')
        else:
            Weight_converter()
    #======================================================================
    def Temperature_Error(*args):
        try:
            v = float(temp_entry.get())
        except ValueError:
            temp_label['text']=('Enter Valid Input')
        else:
            Temperature_converter()
    #======================================================================
    def Length_converter(*args):
        v = float(entry.get())
        metre_dict = dict(mm= 0.001, cm= 0.01, m= 1, km= 1000, Inches= 0.0254, Feet= 0.3048, Yards= 0.9144, Miles= 1609.344)
        M = v * metre_dict[var1.get()]
        k = M / metre_dict[var2.get()]
        label['text']=k
    #======================================================================
    def Weight_converter(*args):
        v = float(weight_entry.get())
        weight_dict = dict(Grams= 1, Kilograms= 1000, Ounces= 28.34952313, Pounds= 453.59237, Tonnes= 1000000)
        M = v * weight_dict[weight_var1.get()]
        k = M / weight_dict[weight_var2.get()]
        weight_label['text']=k
    #======================================================================
    def Temperature_converter(*args):
        temp_dict = dict(Fahrenheit=(1/1.8, -32/1.8), Celsius=(1, 0), Kelvin=(1, -273.15))
        x, y= temp_dict[temp_var1.get()]
        cels = float(temp_entry.get()) * x + y
        x, y = temp_dict[temp_var2.get()]
        answer = (cels - y) / x
        temp_label['text']=answer

        root.mainloop

Answer 1

If you create class for logic then it should get arguments and return result and not use widgets. Button should run function which get values from widgets and use them with Logic, and latere get result and put to widget.

This class Logic doesn't have to remeber values so I think method can be static.

In class we put code rateher in methods and we use self. to have access to the same variables in different methods in class

#### from tkinter import *  <-- not preferred

import tkinter as tk
from tkinter import ttk

class GUI:

    def __init__(self):  # <-- init class

        root = tk.Tk()  # <-- main window

        notebook = ttk.Notebook(root)
        frame1 = ttk.Frame(notebook)

        notebook.add(frame1, text='Length')
        frame2 = ttk.Frame(notebook)

        notebook.add(frame2, text='Weight')
        frame3 = ttk.Frame(notebook)

        notebook.add(frame3, text='Temperature')
        notebook.pack(expand=1, fill="both")

        #======================================================================

        self.entry = tk.Entry(frame1)  # <-- self. / tk.
        self.entry.grid(row=0, column=0)  # <-- self.

        self.label = tk.Label(frame1, relief='groove', width=20, text='')  # <-- self. / tk.
        self.label.grid(row=0, column=3)  # <-- self.

        options1 = ['mm', 'cm', 'm', 'km', 'Inches', 'Feet', 'Yards', 'Miles']

        self.var1 = tk.StringVar(frame1)  # <-- self.
        self.var1.set(options1[0])  # <-- self.

        dropdown1 = tk.OptionMenu(frame1, self.var1, *options1)  # <-- self. / *options1
        dropdown1.grid(row=1, column=0)

        self.var2 = tk.StringVar(frame1)  # <-- self.
        self.var2.set(options1[0])  # <-- self.

        dropdown2 = tk.OptionMenu(frame1, self.var2, *options1)  # <-- self. / *options1
        dropdown2.grid(row=1, column=3)

        equal_button = tk.Button(frame1, text='=', command=self.convert_length)   # <-- tk. / function in GUI
        equal_button.grid(row=1, column=5)

        #======================================================================

        self.weight_entry = tk.Entry(frame2)  # <-- self. / tk.
        self.weight_entry.grid(row=0, column=0)  # <-- self.

        self.weight_label = tk.Label(frame2, relief='groove', width=20, text='')  # <-- self. / tk.
        self.weight_label.grid(row=0, column=3)  # <-- self.

        options2 = ['Grams', 'Kilograms', 'Ounces', 'Pounds', 'Tonnes']

        self.weight_var1 = tk.StringVar(frame2)  # <-- self.
        self.weight_var1.set(options2[0])  # <-- self.

        dropdown1 = tk.OptionMenu(frame2, self.weight_var1, *options2)  # <-- self. / *options2
        dropdown1.grid(row=1, column=0)

        self.weight_var2 = tk.StringVar(frame1)  # <-- self.
        self.weight_var2.set(options2[0])  # <-- self.

        dropdown2 = tk.OptionMenu(frame2, self.weight_var2, *options2)  # <-- self. / *options2
        dropdown2.grid(row=1, column=3)

        weight_equal_button = tk.Button(frame2, text='=', command=self.convert_weight)  # <-- tk. / function in GUI
        weight_equal_button.grid(row=1, column=5)

        #======================================================================

        self.temp_entry = tk.Entry(frame3)  # <-- self. / tk.
        self.temp_entry.grid(row=0, column=0)  # <-- self.

        self.temp_label = tk.Label(frame3, relief='groove', width=20, text='')  # <-- self. / tk.
        self.temp_label.grid(row=0, column=3)  # <-- self.

        options3 = ['Celsius', 'Fahrenheit', 'Kelvin']

        self.temp_var1 = tk.StringVar(frame3)  # <-- self.
        self.temp_var1.set(options3[0])  # <-- self.

        temp_dropdown1 = tk.OptionMenu(frame3, self.temp_var1, *options3)  # <-- self. / *options3
        temp_dropdown1.grid(row=1, column=0)

        self.temp_var2 = tk.StringVar(frame3)  # <-- self.
        self.temp_var2.set(options3[0])  # <-- self.

        temp_dropdown2 = tk.OptionMenu(frame3, self.temp_var2, *options3)  # <-- self. / *options3
        temp_dropdown2.grid(row=1, column=3)

        temp_equal_button = tk.Button(frame3, text='=', command=self.convert_temp)   # <-- tk. / function in GUI
        temp_equal_button.grid(row=1, column=5)

        #======================================================================

        root.mainloop()  # <--- () , it starts window

    # <-- functions assigned to buttons

    def convert_length(self):
        var1 = self.var1.get()
        var2 = self.var2.get()

        try:
            value = float(self.entry.get())       
        except ValueError:
            self.label['text'] = 'Enter Valid Input'
            return

        try:
            self.label['text'] = Converter.convert_length(value, var1, var2)
        except Exception as ex:
            self.label['text'] = 'Exception: {}'.format(ex)

    def convert_weight(self):
        var1 = self.weight_var1.get()
        var2 = self.weight_var2.get()

        try:
            value = float(self.weight_entry.get())       
        except ValueError:
            self.weight_label['text'] = 'Enter Valid Input'
            return

        try:
            self.weight_label['text'] = Converter.convert_weight(value, var1, var2)
        except Exception as ex:
            self.weight_label['text'] = 'Exception: {}'.format(ex)

    def convert_temp(self):
        var1 = self.temp_var1.get()
        var2 = self.temp_var2.get()

        try:
            value = float(self.temp_entry.get())       
        except ValueError:
            self.temp_label['text'] = 'Enter Valid Input'
            return

        try:
            self.temp_label['text'] = Converter.convert_temperature(value, var1, var2)
        except Exception as ex:
            self.temp_label['text'] = 'Exception: {}'.format(ex)


class Converter: # <-- UpperCaseName

    @staticmethod
    def convert_length(v, var1, var2):  # <-- lower_case_name / arguments

        metre_dict = dict(mm= 0.001, cm= 0.01, m= 1, km= 1000, Inches= 0.0254, Feet= 0.3048, Yards= 0.9144, Miles= 1609.344)

        M = v * metre_dict[var1]
        k = M / metre_dict[var2]

        return k

    #======================================================================

    @staticmethod
    def convert_weight(v, var1, var2):  # <-- lower_case_name / arguments

        weight_dict = dict(Grams= 1, Kilograms= 1000, Ounces= 28.34952313, Pounds= 453.59237, Tonnes= 1000000)

        M = v * weight_dict[var1]
        k = M / weight_dict[var2]

        return k

    #======================================================================

    @staticmethod
    def convert_temperature(v, var1, var2):  # <-- lower_case_name / arguments

        temp_dict = dict(Fahrenheit=(1/1.8, -32/1.8), Celsius=(1, 0), Kelvin=(1, -273.15))

        x, y= temp_dict[var1]
        cels = v * x + y
        x, y = temp_dict[var2]

        return (cels - y) / x

# --- main ----

if __name__ == '__main__':
    GUI()