pre-PEP: Suite-Based Keywords

[Brian Sabbey]

Shane Hathaway wrote:
> Kent Johnson wrote:
>> Brian Sabbey wrote:
>>> Using suite-based keyword arguments, the code
>>>
>>> f(x = 1)
>>>
>>> is equivalent to
>>>
>>> f():
>>>    x = 1
>>
>>
>> ISTM the syntax is ambiguous. How do you interpret
>> if f():
>>   x = 1
>> ?
>>
>> Is a suite alllowed only when a block could not be introduced in the
>> current syntax?
>
> I like this PEP a lot, but your concern is valid.  Maybe Brian could
> modify the PEP slightly to disambiguate.  How about using an ellipsis in
> the argument list to signify suite-based keywords?  Examples:
>
> f(...):
>    x = 1
>
> class C(object):
>   x = property(...):
>      doc = "I'm the 'x' property."
>      def fget(self):
>         return self.__x
>      def fset(self, value):
>         self.__x = value
>      def fdel(self):
>         del self.__x
>
> d = dict(...):
>    a = 1
>    b = 2
>
> Using an ellipsis in a statement that would begin a different kind of
> block is illegal and generates a syntax error.  Note that this usage
> seems to fit well with the definition of "ellipsis".
>
> http://dictionary.reference.com/search?q=ellipsis
>
> Shane

Yes, my description of the syntax was ambiguous.  To clarify, I intended 
the syntax to be backwardly compatible.  That is, one would not be able to 
use a suite to define keywords if there already exists a suite for other 
reasons.  So, one would not be able to use a suite to pass keywords to 'f' 
in this situation:

if f():
      x = 1

This code should behave exactly as it does now.

I agree that the ellipsis idea probably makes the code more readable, and 
it may be a good idea to have them for that reason.  However, ellipses are 
not necessary as a way to disambiguate the syntax; all statements 
containing suites currently begin with a keyword, and keyword suites would 
not.

-Brian