None assigment

[Tim Peters]

[Peter Hansen]
> ...
> Why, I wonder, do some people think that just because
> something "shouldn't" happen, it must therefore
> never be allowed to happen?  If "we all agree that

[Clarence Gardner]
> I think, if there is a reason, it is probably that they want
> the language to prevent the programmer from *accidentally*
> doing bad things that happen to be possible.  But nobody
> types
> 	None = 3
> by accident.  And since, unlike some other languages, that
> is the only way to do it, there is no purpose in prohibiting it.

Actually, some people do write stuff like:

    for x, y, None in list_of_threetuples:
        print f(x, y)

when they don't care about the third tuple elements.  I know this because I
was one of them <wink>.  Got away with it for months, and just *assumed* the
language supported "None" as a "don't care" assignment target.  This is easy
to believe if you're coming from, say, Perl.

There's a bit of Deep Magic that makes this illusion hard to shake if you
fall under it:

>>> def f():
...     None = 42
>>> None = 66
>>> print f()
None
>>> type(f())
<type 'None'>
>>>

That is, rebinding None has no effect on that functions that fall off the
end still return "the old" value of None; the "intended" value of None is
hardcoded into the fall-off-the-end function return sequence.

In that respect, None is unique among non-keyword names, and for that reason
alone it should be a keyword instead of a global.  I expect that will happen
someday, too.  But it's a race between that and hell freezing over <wink>.

hard-to-get-excited-about-it-even-when-i-was-young-ly y'rs  - tim