En Fri, 14 Aug 2009 19:24:26 -0300, pinkisntwell <pinkisntw...@gmail.com>
escribió:
class Vertex(tuple):
pass
class Positioned_Vertex(Vertex):
def __init__(self, a, b):
Vertex.__init__(a)
a=Positioned_Vertex((0,0,0), 1)
This gives:
TypeError: tuple() takes at most 1 argument (2 given)
It looks like the explicit call to Vertex.__init__ is never made and
Vertex.__init__ is implicitly called when a Positioned_Vertex is
created. Is there a way to work around this and call the constructor
with the intended argument list?
The tuple constructor (like numbers, strings, and other immutable objects)
never calls __init__. You have to override __new__ instead:
py> class Point3D(tuple):
... def __new__(cls, x, y, z):
... obj = super(Point3D, cls).__new__(cls, (x,y,z))
... return obj
...
py> a = Point3D(10, 20, 30)
py> a
(10, 20, 30)
py> type(a)
<class '__main__.Point3D'>
See http://docs.python.org/reference/datamodel.html#basic-customization
--
Gabriel Genellina
--
http://mail.python.org/mailman/listinfo/python-list
