On 18/05/2018 12:22, Ken Hilton wrote:
Hi all,
Yes, this is another idea for avoiding breaking existing code when
introducing new keywords. I'm not sure if this is too similar to
Guido's previous "allow keywords in certain places" idea, but here goes:
Only treat keywords as having any special meaning when they are in
places with syntactical significance.
So, currently, let's say someone set the variable "and_" to some
value. The following lines are both SyntaxErrors:
True and_ False
obj.and = value
And the following are both correct:
True and False
obj.and_ = value
My idea is to only treat keywords as having special meaning when
they're in the right place. So the following would all be legal:
>>> from operator import and
>>> var = and(True, False)
>>> var
False
>>> var = True and False
>>> var
False
>>> def except(exc, def):
... try:
... return def()
... except exc as e:
... return e
...
>>> except(ZeroDivisionError, lambda: 1/0)
ZeroDivisionError('division by zero',)
>>> except(ZeroDivisionError, lambda: 0/1)
0.0
>>> import asyncio as await #this is already currently legal, but
will not be in the __future__
>>> async def async(def):
... return await await.get_event_loop().run_in_executor(None, def)
...
>>>
And so on.
What are your thoughts?
Sharing,
Ken Hilton
;
Great idea, but why restrict it to keywords? Why not also allow
operators to be variable names:
>>> + = 23
>>> + + + + +
69
>>> - = 21
>>> - -
>>> -21
There would be some minor ambiguities, e.g. would
- - - -
evaluate to
(- -) - (-) # -42
or
(-) - (- -) # +42
or
- ( - ( - ( - ))) # -21
or
- (- - -) # 0
and indeed
+ + + + +
could *in theory* evaluate to
+ ( + ( + ( + ( +)))) # 23
or
(++) + (++) # 46
but I'm sure we could formulate some sensible rules to always get the
intended meaning. :-)
Rob Cliffe
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