[vtkusers] ​SetClientData in python (David Gobbi)

[Oliver Natt]

Dear Andrew,

Davids proposal ist great. However, it appears a bit strange to most 
programmers. I prefer for this purpose to make a new class which is a 
callable. I think, this makes the code more readable for most 
programmers since the data attribute is already initialized within the 
class itself. Your example would look like this:

class DummyCallback:
     def __init__(self, data):
         self.data = data
     def __call__(self, obj, event):
         print(ev, self.data)

cb = DummyCallback(renwin)
interactor.AddObserver('LeftButtonPressEvent', cb)

The last two lines can, of course, be abbreviated to:
interactor.AddObserver('LeftButtonPressEvent', DummyCallback(renwin))

Best regards
Oliver


Am 11.11.2017 um 23:46 schrieb Andrew Maclean:
> Ok
> I have got it.
> This works:
>
> def DummyFunc(obj, ev):
>      print(ev, DummyFunc.data)
>
> DummyFunc.data = renwin
> # How do I pass my obj_2 ? interactor.AddObserver('LeftButtonPressEvent', DummyFunc)
>
> ​David, you may be able to explain this better than I can but I assume 
> this is what happens:​
>     Here we are adding a new attribute to DummyFunc. We can do this 
> because Python functions are in fact objects.
>
> ​This is something totally strange to C++ programmers!
>
> What a neat approach!​
>
>

-- 
Oliver Natt,

Jägerstraße 26b
90451 Nürnberg

Phone:   +49 (0)  9 11 - 71 58 71 40
Mobile   +49 (0)  1 76 - 20 82 27 38
E-Mail:  onatt at gmx.de

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