[Python-ideas] Add recordlcass to collections module

[Zaur Shibzukhov]

---
*Zaur Shibzukhov*


2018-09-03 1:02 GMT+03:00 Wes Turner <wes.turner at gmail.com>:

>
> On Sunday, September 2, 2018, Zaur Shibzukhov <szport at gmail.com> wrote:
>
>>
>>
>> ---
>> *Zaur Shibzukhov*
>>
>>
>> 2018-09-02 22:11 GMT+03:00 Wes Turner <wes.turner at gmail.com>:
>>
>>> Does the value of __hash__ change when attributes of a recordclass
>>> change?
>>>
>>
>> Currently recordclass's __hash__ didn't implemented.
>>
>
> https://docs.python.org/3/glossary.html#term-hashable
>
> https://docs.python.org/3/reference/datamodel.html#object.__hash__
>
> http://www.attrs.org/en/stable/hashing.html
>

There is correction:
recordclass and it's base memoryslots didn't implement __hash__, but
memoryslots implement richcompare (almost as python's list).

>
>
>>
>>> On Sunday, September 2, 2018, Zaur Shibzukhov <szport at gmail.com> wrote:
>>>
>>>> As the author of `recordclass` I would like to shed some light...
>>>>
>>>> Recorclass originated as a response to the [question](
>>>> https://stackoverflow.com/questions/29290359/exis
>>>> tence-of-mutable-named-tuple-in-python/29419745#29419745) on
>>>> stackoverflow.
>>>>
>>>> `Recordclass` was conceived and implemented as a type that, by api,
>>>> memory and speed, would be completely identical to` namedtuple`, except
>>>> that it would support an assignment in which any element could be replaced
>>>> without creating a new instance, as in ` namedtuple`. Those. would be
>>>> almost identical to `namedtuple` and support the assignment (` __setitem__`
>>>> / `setslice__`).
>>>>
>>>> The effectiveness of namedtuple is based on the effectiveness of the
>>>> `tuple` type in python. In order to achieve the same efficiency it was
>>>> necessary to create a type `memoryslots`. Its structure
>>>> (`PyMemorySlotsObject`) is identical to the structure of` tuple`
>>>> (`PyTupleObject`) and therefore takes up the same amount of memory as`
>>>> tuple`.
>>>>
>>>> `Recordclass` is defined on top of` memoryslots` just like `namedtuple`
>>>> above` tuple`. Attributes are accessed via a descriptor
>>>> (`itemgetset`), which supports both` __get__` and `__set__` by the element
>>>> index.
>>>>
>>>> The class generated by `recordclass` is:
>>>>
>>>> `` `
>>>> from recordclass import memoryslots, itemgetset
>>>>
>>>> class C (memoryslots):
>>>>     __slots__ = ()
>>>>
>>>>     _fields = ('attr_1', ..., 'attr_m')
>>>>
>>>>     attr_1 = itemgetset (0)
>>>>     ...
>>>>     attr_m = itemgetset (m-1)
>>>>
>>>>     def __new __ (cls, attr_1, ..., attr_m):
>>>>         'Create new instance of {typename} ({arg_list})'
>>>>         return memoryslots .__ new __ (cls, attr_1, ..., attr_m)
>>>> `` `
>>>> etc. following the `namedtuple` definition scheme.
>>>>
>>>> As a result, `recordclass` takes up as much memory as` namedtuple`, it
>>>> supports quick access by `__getitem__` /` __setitem__` and by attribute
>>>> name via the protocol of the descriptors.
>>>>
>>>> Regards,
>>>>
>>>> Zaur
>>>>
>>>> суббота, 1 сентября 2018 г., 10:48:07 UTC+3 пользователь Martin Bammer
>>>> написал:
>>>>>
>>>>> Hi,
>>>>>
>>>>> what about adding recordclass
>>>>> (https://bitbucket.org/intellimath/recordclass) to the collections
>>>>> module
>>>>>
>>>>> It is like namedtuple, but elements are writable and it is written in
>>>>> C
>>>>> and thus much faster.
>>>>>
>>>>> And for convenience it could be named as namedlist.
>>>>>
>>>>> Regards,
>>>>>
>>>>> Martin
>>>>>
>>>>>
>>>>> _______________________________________________
>>>>> Python-ideas mailing list
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>>>>>
>>>>
>>
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