widget.bind('<Button-1>',callback) # binding
def callback(self,event)
#do something
I need to pass an argument to callback() . The argument is a dictionary object.
How to pass an argument to event handler in tkinter?
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7 Answers
Here is an entry on this from the New Mexico Tech Tkinter 8.5 Reference (https://anzeljg.github.io/rin2/book2/2405/docs/tkinter/extra-args.html)
This way allows you to add as many arguments as you need:
54.7. The extra arguments trick
Sometimes you would like to pass other arguments to a handler besides the event.
Here is an example. Suppose your application has an array of ten checkbuttons whose >widgets are stored in a list self.cbList, indexed by the checkbutton number in >range(10).
Suppose further that you want to write one handler named .__cbHandler for >events in all ten of these checkbuttons. The handler can get the actual Checkbutton >widget that triggered it by referring to the .widget attribute of the Event object that >gets passed in, but how does it find out that checkbutton's index in self.cbList?
It would be nice to write our handler with an extra argument for the checkbutton number, >something like this:
def __cbHandler(self, event, cbNumber):
But event handlers are passed only one argument, the event. So we can't use the function >above because of a mismatch in the number of arguments.
Fortunately, Python's ability to provide default values for function arguments gives us >a way out. Have a look at this code:
def __createWidgets(self):
…
self.cbList = [] # Create the checkbutton list
for i in range(10):
cb = tk.Checkbutton(self, …)
self.cbList.append(cb)
cb.grid( row=1, column=i)
def handler(event, self=self, i=i): 1
return self.__cbHandler(event, i)
cb.bind('<Button-1>', handler)
…
def __cbHandler(self, event, cbNumber):
…
These lines define a new function handler that expects three arguments. The first >argument is the Event object passed to all event handlers, and the second and third >arguments will be set to their default values—the extra arguments we need to pass it.
This technique can be extended to supply any number of additional arguments to >handlers.
Pass the callback function to the instance and call it from the instance method.
from tkinter import *
class MyClass:
def __init__(self, my_callback, message):
self.my_callback = my_callback
self.message = message
def callback(self, event):
self.my_callback(self)
def my_callback(o):
print(o.message)
obj = MyClass(my_callback, "I am instance of MyClass")
root = Tk()
btn=Button(root, text="Click")
btn.bind('<Button-1>', obj.callback)
btn.pack()
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