Key Binding Problem
Terry Reedy
tjreedy at udel.edu
Wed Mar 23 02:47:47 EDT 2016
On 3/23/2016 12:28 AM, Wildman via Python-list wrote:
> On Wed, 23 Mar 2016 03:02:51 +0000, MRAB wrote:
>
>> On 2016-03-23 02:46, Wildman via Python-list wrote:
>>> My question is how do I coax bind into executing the
>>> button procedures? Or is there a way to generate the
>>> button click event from the binding?
>>>
>> It won't let you bind to a function called "load_image" because there
>> isn't a function called "load_image"!
>>
>> The "Window" class, however, does have a method with that name.
>>
>> Try binding the keys in Window.__init__ or Window.init_window:
>>
>> def init_window(self):
>> ...
>> root.bind("<l>", self.load_image)
>
> Here is what I tried:
>
> class Window(tk.Frame):
>
> def __init__(self, master = None):
> tk.Frame.__init__(self,master)
> self.master = master
> root.bind("l", self.load_image)
>
> I get this error and it doesn't make any sense to me:
>
> Exception in Tkinter callback
> Traceback (most recent call last):
> File "/usr/lib/python2.7/lib-tk/Tkinter.py", line 1535, in __call__
> return self.func(*args)
> TypeError: load_image() takes exactly 1 argument (2 given)
Event handlers must have one parameter (other than 'self' for methods),
the event, as that is what they will be passed. You defined load_image
like this.
def load_image(self):
# load image file
It should be this
def load_image(self, event):
# load image file
You are free to ignore the event object and some people then name the
parameter '_' (or dummy) to signify that it will be ignored.
def load_image(self, _):
# load image file
You must pass the bound method, as you did, and not the function itself
(which has two parameters).
--
Terry Jan Reedy
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