[Python-Dev] PEP 557: Data Classes

Gustavo Carneiro gjcarneiro at gmail.com
Thu Oct 12 09:16:21 EDT 2017

On 12 October 2017 at 11:20, Steve Holden <steve at holdenweb.com> wrote:

> On Thu, Oct 12, 2017 at 9:20 AM, Mike Miller <python-dev at mgmiller.net>
> wrote:
>> On 2017-10-12 00:36, Stéfane Fermigier wrote:
>>> "An object that is not defined by its attributes, but rather by a thread
>>> of continuity and its identity." (from https://en.wikipedia.org/wiki/
>>> Domain-driven_design#Building_blocks)
>> Not sure I follow all this, but Python objects do have identities once
>> instantiated.  e.g. >>> id('')
>> ​It seems to me that the quoted document is attempting to make a
> distinction ​similar to the one between classes (entities) and instances
> (value objects). The reason I liked "row" as a name is because it
> resembles  "vector" and hence is loosely assocaited with the concept of a
> tuple as well as being familiar to database users. In fact the answer to a
> relational query was, I believe, originally formally defined as a set of
> tuples.

But rows and tuples are usually immutable, at least in database terms.
These data classes are not immutable (by default).  If you want tuple-like
behaviour, you can continue to use tuples.

I see dataclasses as something closer to C `struct`.  Most likely someone
already considered `struct` as name; if not, please consider it.  Else
stick with dataclass, it's a good name IMHO.
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