Nick Keighley a écrit :
On 9 June, 10:35, Bruno Desthuilliers <bruno.
42.desthuilli...@websiteburo.invalid> wrote:
Nick Keighley a crit :
I'm trapping mouse clicks using
canvas.bind("<ButtonRelease-1>", mouse_clik_event)
def mouse_clik_event (event) :
stuff
What mouse_clik_event does is modify some data and trigger a redraw.
Is there any way to pass data to the callback function? Some GUIs give
you a user-data field in the event, does Tkinter?
Never used TkInter much, but if event is a regular Python object, you
don't need any "user-data field" - just set whatever attribute you want, ie:
[...]
>>> class Event(object): pass
...
>>> e = Event()
>>> e.user_data = "here are my data"
>>> e.user_data
'here are my data'
>>>
But I fail to see how this would solve your problem here - where would
you set this attribute ???
Those other GUIs also give you a mechanism to pass the data. Say
another parameter in the bind call
Ok, so my suggestion should work, as well as any equivalent (lambda,
closure, custom callable object etc).
>>> from functools import partial
>>> data = dict()
>>> def handle_event(event, data):
... data['foo'] = "bar"
... print event
...
>>> p = partial(handle_event, data=data)
ah! the first time I read this I didn't get this. But in the mean time
cobbled something together using lambda. Is "partial" doing the same
thing
Mostly, yes - in both cases you get a callable object that keeps a
reference on the data. You could also use a closure:
def make_handler(func, data):
def handler(event):
func(event, data)
return handler
def mouse_clik_event (event, data) :
dosomething (event.x, event.y, data)
draw_stuff (display, data)
display.canvas.bind(
"<ButtonRelease-1>",
make_handler(mouse_click_event, data)
)
but a little more elegantly?
Depending on your own definition for "elegantly"...
Note that the lambda trick you used is very idiomatic - functool.partial
being newer and probably not as used - so one could argue that the most
common way is also the most "elegant" !-)
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