[Python-ideas] kwargs for return

[Wes Turner]

On Saturday, January 26, 2019, David Mertz <mertz at gnosis.cx> wrote:

> I was going to write exactly they're same idea Steven did.
>
> Right now you can simply design APIs to return dictionaries or, maybe
> better, namedtuples. Namedtuples are really nice since you can define new
> attributes when you upgrade an API without breaking any old coffee that
> used the prior attributes... Of course, you can only add more, not remove
> old ones, to assure compatibility. Unlike dictionaries, namedtuples cannot
> contain arbitrary "keywords" at runtime, which is either good or bad
> depending on your purposes.
>

Tuples are a dangerous (and classic, legacy) interface contract.

NamedTuples must be modified to allow additional (i.e. irrelevant to the
FUT) data through the return interface.


>
> Recently, dataclasses are also an option. They are cool, but I haven't yet
> had a reason to use them. They feel heavier than namedtuples though (as a
> programming construct, not talking about memory usage or speed or whatever).
>
> On Sat, Jan 26, 2019, 8:52 AM Steven D'Aprano <steve at pearwood.info wrote:
>
>> On Sat, Jan 26, 2019 at 02:04:12PM +0100, Thomas Güttler Lists wrote:
>>
>> > Example:
>> >
>> >     status = backend.transmit_data()
>> >
>> > But later you want to add something to the API.
>> [...]
>> > How could kwargs for return look like?
>>
>> return {'status': True, 'messages': []}
>>
>> Or perhaps better:
>>
>> return ResultObject(status=True, messages=[])
>>
>>
>> I don't see anything here that can't be done by returning a dict, a
>> namedtuple (possibly with optional fields), or some other object with
>> named fields. They can be optional, they can have defaults, and you can
>> extend the object by adding new fields without breaking backwards
>> compatibility.
>>
>>
>>
>>
>> --
>> Steve
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>
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