[issue32977] added acts_like decorator to dataclasses module

[Eric V. Smith]

Eric V. Smith  added the comment:

Since this has to wait until 3.8 and I'm swamped with 3.7, this is going to 
have to wait for me to look at it.

Is there a reason it needs to be part of dataclasses itself? I'd suggest 
separating it out, putting it on PyPI, and getting some traction there, first.

--
versions: +Python 3.8 -Python 3.7

___
Python tracker 

___
___
Python-bugs-list mailing list
Unsubscribe: 
https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com

[issue32977] added acts_like decorator to dataclasses module

[Aaron Christianson]

New submission from Aaron Christianson :

I'm always writting these wrapper classes where I want to selectively want to 
expose the interface of some of the methods of certain attributes to co the 
containing object. This can mean I spend a lot of time implementing wrapper 
methods. That's no good. I wrote a class decorator to make this easy, and I 
realized it's a perfect complement to the new dataclasses module, though it can 
also be used with normal classes. I figured I'd check if you're interested in 
that. The interface looks like this:

>>> from dataclasses import dataclass, acts_like
>>> @acts_like('weight', ['__add__'])
... @acts_like('still_fresh', ['__bool__'])
... @dataclass
... class Spam:
... weight: int
... still_fresh: bool
>>> s = Spam(42, False)
>>> s + 3
45
>>> if not s:
... print('the spam is bad')
the spam is bad

It's a handy way to build objects with composition, but still get some of the 
benefits of inheritance in a *selective* and *explicite* way.

Here's the code: 
https://github.com/ninjaaron/cpython/blob/acts_like/Lib/dataclasses.py#L978

May require some addtional twiddling to make it work with frozen dataclasses, 
but I don't think it should be a problem.

--
components: Library (Lib)
messages: 313096
nosy: eric.smith, ninjaaron
priority: normal
severity: normal
status: open
title: added acts_like decorator to dataclasses module
type: enhancement
versions: Python 3.7

___
Python tracker 

___
___
Python-bugs-list mailing list
Unsubscribe: 
https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com