[英]Python - accessing a local variable from another class
I have tried to condense the code down as much as possible to make it clear what I am asking...我试图尽可能地压缩代码以明确我在问什么......
I have a variable called chosen_name
, determined in a class called booking_frame
, that I would like to access in the calendar_frame
class.我有一个名为 selected_name 的变量,在名为
chosen_name
的booking_frame
中确定,我想在calendar_frame
class 中访问它。
Therefore, it would be obvious for calendar_frame
to inherit the attributes of booking_frame
- however, I believe (I'm probably completely wrong lol) that calendar_frame
has to inherit the characteristics of Frame
so that the whole program functions correctly.因此,
calendar_frame
继承booking_frame
的属性是很明显的——但是,我相信(我可能完全错了,lol) calendar_frame
必须继承Frame
的特性,以便整个程序正常运行。
The reason that calendar_frame
is a completely separate class is so that it can appear as a different frame. calendar_frame
是一个完全独立的 class 的原因是它可以显示为不同的框架。
Extremely grateful for any help given:)非常感谢提供的任何帮助:)
# import tkinter modules
from tkinter import *
from tkinter import ttk
import tkinter.font as tkFont
from PIL import ImageTk, Image
from tkcalendar import *
# define self
class tkinterApp(Tk):
def __init__(self,*args, **kwargs):
Tk.__init__(self, *args, **kwargs)
# creating a container
container = Frame(self)
container.pack(side = "top", fill = "both", expand = True)
container.grid_rowconfigure(0, weight = 1)
container.grid_columnconfigure(0, weight = 1)
# initialising frames to an empty array
self.frames = {}
menu_bar = Menu(container)
main_menu = Menu(menu_bar)
menu_bar.add_cascade(label="Main Menu", menu=main_menu)
main_menu.add_command(label="Welcome page", command=lambda: self.show_frame(welcome_frame))
main_menu.add_command(label="Book a vehicle", command=lambda: self.show_frame(booking_frame))
main_menu.add_command(label="Register as new user", command=lambda: self.show_frame(register_frame))
Tk.config(self, menu=menu_bar)
for F in (welcome_frame, booking_frame, register_frame, calendar_frame):
frame = F(container, self)
self.frames[F] = frame
frame.grid(row = 0, column = 0, sticky = "nsew")
self.show_frame(welcome_frame)
def show_frame(self, cont):
frame = self.frames[cont]
frame.tkraise()
class welcome_frame(Frame):
def __init__(self, parent, controller):
Frame.__init__(self, parent)
welcome = Label(self, text="Hello, please use the menu above to navigate the interface")
welcome.grid(row=0, column=4, padx=10, pady=10)
class register_frame(Frame):
def __init__(self, parent, controller):
Frame.__init__(self, parent)
register_label = Label(self, text="New user - enter your details below to use the Collyer's car park.")
register_label.grid()
class booking_frame(Frame):
def __init__(self, parent, controller):
Frame.__init__(self, parent)
chosen_name = "Steve"
class calendar_frame(Frame):
def __init__(self, parent, controller):
Frame.__init__(self, parent)
print(booking_frame.chosen_name)
app = tkinterApp()
app.geometry("1000x800")
app.title("Collyer's Car Park")
app.mainloop()
First you need to change local variable chosen_name
to instance variable self.chosen_name
inside booking_frame
class, otherwise it cannot be accessed outside the class:首先需要在booking_frame class中将局部变量
chosen_name
改为实例变量self.chosen_name
,否则在booking_frame
之外无法访问:
class booking_frame(Frame):
def __init__(self, parent, controller):
Frame.__init__(self, parent)
self.chosen_name = "Steve" # changed to instance variable
Then you can access it via controller.frames[booking_frame].chosen_name
inside calendar_frame
class:然后你可以通过
controller.frames[booking_frame].chosen_name
在calendar_frame
class 中访问它:
class calendar_frame(Frame):
def __init__(self, parent, controller):
Frame.__init__(self, parent)
print(controller.frames[booking_frame].chosen_name)
Inheritance is to model relationships of objects which behave the same ("IS A" relationship). Inheritance 与行为相同的对象的 model 关系(“IS A”关系)。 It is not meant to share data between objects.
它并不意味着在对象之间共享数据。
A possible solution to your problem is to use a third object, that would be shared between booking_frame
and calendar_frame
.您的问题的一个可能解决方案是使用第三个 object,它将在
booking_frame
和calendar_frame
之间共享。
This object can be a Python dictionary for example;例如,这个 object 可以是 Python 字典; you can pass it to all your "frame" objects, or you can maybe decide to have it global (not very academic, for sure, but quick and dirty):
你可以将它传递给你所有的“框架”对象,或者你可以决定让它全局化(当然不是很学术,但又快又脏):
GLOBAL_STATE = {}
class booking_frame(Frame):
...
GLOBAL_STATE["chosen_name"] = "Steve"
class calendar_frame(Frame):
...
print(GLOBAL_STATE.get("chosen_name"))
I hope you can see now how you can refactor your code to share data between those objects.我希望您现在可以看到如何重构代码以在这些对象之间共享数据。
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