[Numpy-discussion] subclassing float64 (and friends)
eric jones
eric at enthought.com
Wed Jan 3 05:29:10 EST 2007
Hey all,
I am playing around with sub-classing the new-fangled float64 objects
and friends. I really like the new ndarray subclassing features
(__array_finalize__, etc.), and was exploring whether or not the scalars
worked the same way. I've stubbed my toe right out of the blocks
though. I can sub-class from standard python floats just fine, but when
I try to do the same from float64, I get a traceback. (examples below)
Anyone have ideas on how to do this correctly?
thanks,
eric
class MyFloat(float):
def __new__(cls, data, my_attr=None):
obj = float.__new__(cls, data)
obj.my_attr = my_attr
return obj
a = MyFloat(1.2,my_attr="hello")
print a, a.my_attr
output:
1.2 hello
from numpy import float64
class MyFloat2(float64):
def __new__(cls, data, my_attr=None):
obj = float64.__new__(cls, data)
obj.my_attr = my_attr
return obj
a = MyFloat2(1.2,my_attr="hello")
print a, a.my_attr
output:
Traceback (most recent call last):
File "C:\wrk\eric\trunk\src\lib\geo\examples\scalar_subtype.py",
line 33, in ?
a = MyFloat2(1.2,my_attr="hello")
File "C:\wrk\eric\trunk\src\lib\geo\examples\scalar_subtype.py",
line 30, in __new__
obj.my_attr = my_attr
AttributeError: 'numpy.float64' object has no attribute 'my_attr'
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