[Tutor] Tkinter class question

[Peter Otten]

Phil wrote:

> On Sat, 08 Apr 2017 09:12:17 +0200
> Peter Otten <__peter__ at web.de> wrote:
> 
> Thank you yet again Peter.
> 
> I realised what the answer is after taking a break for a couple of hours,
> however, I didn't know about:
> 
>>         ...
>>         self.check_button = Button(
>>             master,
>>             text="Check",
>>             command=self.check_2_2  # note there's no () -- the bound
>> method # is not invoked
>>         )
>>         ...
>> 
> 
> My working method uses the () 

This is unlikely unless you have found out about factory methods (functions 
that return functions).

> but I will remove them and see what
> difference it makes.

Make sure you understand the difference between calling a function and 
passing around a function as a value.

def f(): return 42

a = f
b = f()

You have understood the difference if you can predict the outcome of 
all four lines below:

print(a)
print(b)
print(a())
print(b())

Once you think you know the answer try it in the interactive interpreter.