Unable to call base class draw method
In Pythonista I created a new script using the "Scene with Layers" template. I then attempted to define my own custom layer class using the below.
class MyLayer (Layer): def draw(self): super(MyLayer,self).draw()
My hope was to allow the base class to draw then add some custom rendering on top .
I changed the code in the template scene setup method so it created instances of MyLayer instead of Layer to test it.
When I run I get the following error.
"TypeError: draw() takes exactly 1 argument (2 given)"
Any idea what I'm doing wrong?
ccc I don't see any text in your reply. It appears to be empty :)
I thought I had a solution but it did not work :-(
I could not spot the problem but you might try looking at the draw() methods in:
import inspect, scene print(inspect.getsource(scene.Layer)) print(inspect.getsource(scene.Scene))
Strange ; I know I've called base class methods in other contexts but never draw and never derived from any scene classes .
I got it to work! The inspect code you posted helped. Looks like the Layer draw method takes a second optional arg, a (alpha). Adding that got rid of the error. Odd since it's optional though, but it worked!
Here's the working code.
class MyLayer (Layer): def draw(self, a=1.0): super(MyLayer,self).draw(a)
# The following only works with single inheritance classes like scene.Layer... super(self.__class__, self).draw(a)
What do you mean? I'm not following your last comment.
class MyLayer (Layer): def draw(self, a=1.0): # super(MyLayer,self).draw(a) super(self.__class__, self).draw(a) # Alternate syntax that does not hardcode the classname
Ah ok! Yes that is nicer. Thanks!
I ended up creating a function to make this even cleaner.
def _super(self): return super(self.__class__,self)
With this it makes it much cleaner when you want to invoke the base class.
class MyLayer (Layer): def draw(self,a=1.0): _super(self).draw(a)
A lot nicer if you're coding on an iPhone with the small display :)