Antoon Pardon wrote:
> But '', {}, [] and () are not nothing. They are empty containers.
> And 0 is not nothing either it is a number. Suppose I have
> a variable that is either None if I'm not registered and a
> registration number if I am. In this case 0 should be treated
> as any other number.
This is why None is a singleton::
if registration_number is None:
# do one thing
else:
# do another
In the OP's case, if file.read() had happened to return None instead of
the empty string, he probably would've wanted to do the same thing.
OTOH, people on python-dev have said that the file.read() idiom of
returning '' when it's done should be replaced by a true iterator, i.e.
using StopIteration. (I don't know the details of exactly how things
would change, but I suspect this is something that will happen in Python
3.0.)
STeVe
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