On 9/4/2018 3:03 PM, Chris Barker via Python-ideas wrote:

Chiming in here:

dataclasses was just added to the stdlib.

I understand that record class is not the same thing, but the use cases do overlap a great deal.

So I think the cord goal for anyone that wants to see this in the stdlib is to demonstrate tbat recordclass Adds significant enough value to justify something so similar.

I've seen three things mentioned that might be different from dataclasses: - instance size - speed (not sure of what: instance creation? field access?) - iterating over fields But I've not seen concrete examples of the first two where dataclasses doesn't perform well enough. For the third one, there's already a thread on this mailing list: "Consider adding an iterable option to dataclass". I'm contemplating adding it.

Personally, I don’t see it.

I'm skeptical, too. Eric

-CHB

On Tue, Sep 4, 2018 at 2:04 PM Zaur Shibzukhov <szport@gmail.com <mailto:szport@gmail.com>> wrote:

--- /Zaur Shibzukhov/

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

On Sunday, September 2, 2018, Zaur Shibzukhov <szport@gmail.com <mailto:szport@gmail.com>> wrote:

--- /Zaur Shibzukhov/

2018-09-02 22:11 GMT+03:00 Wes Turner <wes.turner@gmail.com <mailto:wes.turner@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@gmail.com <mailto:szport@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/existence-of-mutable-named-tupl...) 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 Python...@python.org https://mail.python.org/mailman/listinfo/python-ideas

Code of Conduct: http://python.org/psf/codeofconduct/

_______________________________________________ Python-ideas mailing list Python-ideas@python.org <mailto:Python-ideas@python.org> https://mail.python.org/mailman/listinfo/python-ideas Code of Conduct: http://python.org/psf/codeofconduct/

--

Christopher Barker, Ph.D. Oceanographer

Emergency Response Division NOAA/NOS/OR&R            (206) 526-6959   voice 7600 Sand Point Way NE   (206) 526-6329   fax Seattle, WA  98115       (206) 526-6317   main reception

Chris.Barker@noaa.gov <mailto:Chris.Barker@noaa.gov>

_______________________________________________ Python-ideas mailing list Python-ideas@python.org https://mail.python.org/mailman/listinfo/python-ideas Code of Conduct: http://python.org/psf/codeofconduct/

On 9/4/2018 3:03 PM, Chris Barker via Python-ideas wrote:

Chiming in here:

dataclasses was just added to the stdlib.

I understand that record class is not the same thing, but the use cases do overlap a great deal.

So I think the cord goal for anyone that wants to see this in the stdlib is to demonstrate tbat recordclass Adds significant enough value to justify something so similar.

I've seen three things mentioned that might be different from dataclasses: - instance size - speed (not sure of what: instance creation? field access?) - iterating over fields But I've not seen concrete examples of the first two where dataclasses doesn't perform well enough. For the third one, there's already a thread on this mailing list: "Consider adding an iterable option to dataclass". I'm contemplating adding it.

Personally, I don’t see it.

I'm skeptical, too. Eric

-CHB

On Tue, Sep 4, 2018 at 2:04 PM Zaur Shibzukhov <szport@gmail.com <mailto:szport@gmail.com>> wrote:

--- /Zaur Shibzukhov/

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

On Sunday, September 2, 2018, Zaur Shibzukhov <szport@gmail.com <mailto:szport@gmail.com>> wrote:

--- /Zaur Shibzukhov/

2018-09-02 22:11 GMT+03:00 Wes Turner <wes.turner@gmail.com <mailto:wes.turner@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@gmail.com <mailto:szport@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/existence-of-mutable-named-tupl...) 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 Python...@python.org https://mail.python.org/mailman/listinfo/python-ideas

Code of Conduct: http://python.org/psf/codeofconduct/

_______________________________________________ Python-ideas mailing list Python-ideas@python.org <mailto:Python-ideas@python.org> https://mail.python.org/mailman/listinfo/python-ideas Code of Conduct: http://python.org/psf/codeofconduct/

--

Christopher Barker, Ph.D. Oceanographer

Emergency Response Division NOAA/NOS/OR&R            (206) 526-6959   voice 7600 Sand Point Way NE   (206) 526-6329   fax Seattle, WA  98115       (206) 526-6317   main reception

Chris.Barker@noaa.gov <mailto:Chris.Barker@noaa.gov>

_______________________________________________ Python-ideas mailing list Python-ideas@python.org https://mail.python.org/mailman/listinfo/python-ideas Code of Conduct: http://python.org/psf/codeofconduct/