file.tell() returns Long usually, Int if subclassed #46864
Comments
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Compare: >>> class y(file):
... def __init__(self, name):
... file.__init__(self, name)
... def __len__(self):
... self.seek(0, 2)
... return self.tell()
...
>>> n = y('/tmp/longfile')
>>> len(n)
364773376Versus: >>> class z:
... def __init__(self, name):
... self.f = file(name, 'r')
... def __len__(self):
... self.f.seek(0, 2)
... return self.f.tell()
...
>>> x = z('/tmp/longfile')
>>> len(x)
Traceback (most recent call last):
File "<stdin>", line 1, in ?
TypeError: __len__() should return an intBecause: >>> x = file('/tmp/longfile')
>>> type(x.tell())
<type 'long'> |
esreverotua
mannequin
added
stdlib
|
This is because y is a new-style class (because file is) and z is not. >>> class z(object):
... def __init__(self, name):
... self.f = file(name, 'r')
... def __len__(self):
... self.f.seek(0, 2)
... return self.f.tell()
>>> x = z('/tmp/longfile')
>>> len(x)
[Whatever it is] |
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Thanks Benjamin, that is a very interesting feature that I can't find thanks, |
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The documentation is still not very good about documenting the |
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