[Python-3000] parameter lists [was: Type Expressions]

[Ron Adam]

Giovanni Bajo wrote:
> Ron Adam <rrr at ronadam.com> wrote:
> 
>> This *may* relate to None being an object which isn't the same as
>> "not a value".  There currently isn't a way (that I know of) to
>> specify a generally null object outside of sequences.
>>
>>     def f(a, b, c=Null, d=x):     # Using None here wouldn't work.
>>
>>
>> Recently I found a case where I wanted to return something that was
>> more literally *nothing* than a None is.  So maybe a null symbol of
>> some sort might be useful in other cases as well?
> 
> And what's wrong with:
> 
> class Null: pass
> def f(a, b, c=Null, d=x):
>     [...]
> 
> Giovanni Bajo

That would only be part way there.  The interpreter would need to know 
about the Null object so it could treat it as a missing value in the 
case of a function definition.

And Guido already said NULL wouldn't be part of the language.

Cheers,
    Ron