On Tue, Aug 31, 2021 at 09:49:36AM -0400, Calvin Spealman wrote:
> I think the provenance of the "is None" rule comes from before None was a
> guaranteed singleton. In older versions of Python, it was *possible* to
> instantiate more instances of None.
I don't suppose you can show how that works? I've got Python 1.5 and
Python 0.9 (!) installed and I can't find any way to get a second
instance.
Python 0.9 doesn't even allow calling the type:
>>> type(None)()
Unhandled exception: type error: call of non-function
Stack backtrace (innermost last):
File "<stdin>", line 1
Comparison operators don't even work on their own, you need to put them
in an if statement:
>>> a = None
>>> b = eval('None')
>>> a is b
Parsing error: file <stdin>, line 1:
a is b
^
Unhandled exception: run-time error: syntax error
>>> if a is b:
... print 'true'
...
true
--
Steve
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