New submission from Aaron Christianson <ninjaa...@gmail.com>:
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
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Python tracker <rep...@bugs.python.org>
<https://bugs.python.org/issue32977>
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