[Python-Dev] PEP 362 Third Revision

[Terry Reedy]

On 6/14/2012 1:10 PM, Brett Cannon wrote:
>
>
> On Thu, Jun 14, 2012 at 12:39 PM, Yury Selivanov
> <yselivanov.ml at gmail.com <mailto:yselivanov.ml at gmail.com>> wrote:
>
>     On 2012-06-14, at 12:32 PM, Benjamin Peterson wrote:
>
>      > 2012/6/14 Yury Selivanov <yselivanov.ml at gmail.com
>     <mailto:yselivanov.ml at gmail.com>>:
>      >> On 2012-06-14, at 11:24 AM, Brett Cannon wrote:
>      >>> On Thu, Jun 14, 2012 at 9:50 AM, Yury Selivanov
>     <yselivanov.ml at gmail.com <mailto:yselivanov.ml at gmail.com>> wrote:
>      >>>
>      >>> [SNIP]
>      >>>
>      >>> Let's consider replacement of 'Parameter.is_*' set of
>     attributes with
>      >>> a single 'Parameter.kind' attribute, which will have the following
>      >>> possible values: 'positional', 'vararg', 'keyword-only',
>     'varkwarg'.
>      >>>
>      >>> (I think 'positional' is more intuitive than 'index'?)
>      >>>
>      >>>
>      >>> +1 if this change is made.
>      >>
>      >> How about adding 'kind' and keeping 'is_*' attributes,
>      >> but making them read-only dynamic properties, i.e.:
>      >>
>      >>   class Parameter:
>      >>       ...
>      >>
>      >>       @property
>      >>       def is_vararg(self):
>      >>           return self.kind == 'vararg'
>      >>
>      >>       ...
>      >>
>      >> ?
>      >
>      > Seems a bit bloatly to me. (One way to do it.)
>
>     Yes, but on the other hand it solves "strings are error prone"
>     argument, keeps all 'is_*' attributes in sync, and makes them
>     read-only.
>
>     'kind' property may do validation on set, to diminish mistakes
>     probability even further.
>
>
> I agree with Benjamin, it goes against TOOWTDI without enough of a
> justification to break the rule. Just make the strings constants on the
> Parameter class and you solve the lack of enum issue.

My opinion: I don't like the multiple radio-button attributes either. It 
is one attribute with multiple values. We use constants elsewhere. In 
the absence of an enum type that maps ints to a string, the constants 
should be strings for display and printing.

-- 
Terry Jan Reedy