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bug in documentation example code for subclassing ndarray #14386
Description
There seems to be a minor bug in the example code for subclassing ndarray in this section of the online documentation
The example for class C includes a call to object.__new__() with more than one argument:
class C(object):
def __new__(cls, *args):
print('Cls in __new__:', cls)
print('Args in __new__:', args)
return object.__new__(cls, *args)Calling this results in an error:
File "/home/jon/python/ndarray_testing.py", line 31, in __new__
return object.__new__(cls, *args)
TypeError: object.__new__() takes exactly one argument (the type to instantiate)
If the extra argument to object.__new__() is removed, the example works as expected.
Fixed example:
class C(object):
def __new__(cls, *args):
print('Cls in __new__:', cls)
print('Args in __new__:', args)
return object.__new__(cls)
def __init__(self, *args):
print('type(self) in __init__:', type(self))
print('Args in __init__:', args)Output of fixed example
In [129]: C('foo')
Cls in __new__: <class '__main__.C'>
Args in __new__: ('foo',)
type(self) in __init__: <class '__main__.C'>
Args in __init__: ('foo',)
Out[129]: <__main__.C at 0x7f27fb972710>
Numpy/Python version information:
1.16.2 3.7.3 (default, Mar 27 2019, 22:11:17)
[GCC 7.3.0]
Activity
DOC: fix issue with __new__ usage in subclassing doc.
rgommers commentedon Aug 28, 2019
thanks for the report @jonpovey. fix taken over in gh-14395
DOC: fix issue with __new__ usage in subclassing doc.