CODEWITHSUNDEEP
pythonfunctiontkintertkinter-canvas
daniel mcgregor
daniel mcgregor

Reputation: 83

Get a variable from a function

In this code I am wondering how to get the rect variable and use it in the Delete method as I have tried to do. It currently comes up with an error.

from tkinter import *

def createRect(event):
    rect = w.create_rectangle(50, 25, 150, 75, fill="blue")
    return rect

def Start(event):
    print("Single Clicked")
    createRect(event)

def Delete(event):
    i = createRect(event)
    print("Double Clicked")
    w.delete(i.rect)

root = Tk()
w = Canvas(root, width=200, height=100)
w.pack()
frame = Button(root, text="delete/make")
frame.bind("<Double-1>", Delete)
frame.bind("<Button-1>", Start)
frame.pack()
root.mainloop()

Upvotes: 0

Views: 79

Answers (1)

cs95
cs95

Reputation: 402483

Generally, I would advise against using global variables since you have less control over who can modify them and how. But in this case, your Start and Delete functions are being called by the mainloop. You can create a container object and use this in your methods. 

class MyRect:
   def __init__(self):
       self.rect = None
       self.isSet = False

Then, inside your tkinter code, you can use it like this:

myrect = MyRect()

def Start(event):
    if not myrect.isSet:
        print("Single Clicked")
        myrect.rect = createRect(event)
        myrect.isSet = True

def Delete(event):
    if myrect.isSet:
       print("Double Clicked")
       w.delete(myrect.rect)
       myrect.rect = None
       myrect.isSet = False

You can also handle users double clicking or clicking button 1 more times than they should this way.

If you're feeling adventurous, you could add __setattr__ and __getattr__ methods that'll control what happens when you modify rect instances when you shouldn't.

Upvotes: 1

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