I would like to use .cancel() without a warning.

[DavidSM64]

Is your feature request related to a problem? Please describe.
I have a slider for my gui, but I don't want it to fire immediately until it stops moving. My quick solution to this is to have the app wait half a second before executing it, and cancel that request if a new one comes in. The downside to doing this method is that the console will spit out the warning Could not cancel function - it doesnt exist, it may have already run every time I start moving the slider.

def slider_changed_for_real():
    print('The new value is: ' + str(slider.value))

def slider_changed():
    slider.cancel(slider_changed_for_real) # Throws a warning if `slider_changed_for_real` isn't scheduled.
    slider.after(500, slider_changed_for_real)

Describe the solution you'd like
I'd like an optional parameter to cancel that would not print the warning if set to True (defaults to False).

    def cancel(self, function, ignoreWarning=False):
        """Cancel the scheduled `function` calls."""
        if function in self._callback.keys():
            callback_id = self._callback[function][0]
            self.tk.after_cancel(callback_id)
            self._callback.pop(function)
        elif not ignoreWarning:
            utils.error_format("Could not cancel function - it doesnt exist, it may have already run")

Either that or introduce a new method that returns a boolean if a function is scheduled or not.

    def is_scheduled(self, function):
        """Returns True if the function has been scheduled."""
        return function in self._callback.keys()

---

So as I'm writing this I figured out I can just do this to "solve" my problem:

def slider_changed():
    # Only cancel if the function is scheduled. Avoids the warning.
    if slider_changed_for_real in slider._callback.keys():
        slider.cancel(slider_changed_for_real)
    slider.after(500, slider_changed_for_real)

Not a fan of having to use a variable that is supposed to be private, so I'm still gonna advocate for an official solution. :)

[lawsie]

I feel like adding a suppression parameter seems perfectly reasonable, I'll try to get something added on dev.

[lawsie]

#522