[Python-ideas] Make keywords KEYwords only in places they would have syntactical meaning

[MRAB]

On 2018-05-18 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?
> 
This would be legal, but what would happen?

def yield(x):
     print('YIELD')

def foo():
     yield('FOO')

f = foo()