Faster __repr__ with str.__add__ moved inside the f-string. For __eq__ comp;are field by field instead of building temporary tuples.
Co-authored-by: Shantanu <12621235+hauntsaninja@users.noreply.github.com>
This commit prefixes `__dataclass` to several things in the locals dict:
- Names like `_dflt_` (which cause trouble, see first test)
- Names like `_type_` (not known to be able to cause trouble)
- `_return_type` (not known to able to cause trouble)
- `_HAS_DEFAULT_FACTORY` (which causes trouble, see second test)
In addition, this removes `MISSING` from the locals dict. As far as I can tell, this wasn't needed even in the initial implementation of dataclasses.py (and tests on that version passed with it removed). This makes me wary :-)
This is basically a continuation of #96151, where fixing this was welcomed in https://github.com/python/cpython/pull/98143#issuecomment-1280306360
dataclass used to get the annotations on a class object using
cls.__dict__.get('__annotations__'). Now that it always imports
inspect, it can use inspect.get_annotations, which is modern
best practice for coping with annotations.
Previously, when using `functools.wrap` around them (and inherit their docstrings), sphinx renders the docstrings badly and raises warnings about wrong indent.
`@dataclass` in 3.10 prohibits using list, dict, or set as default values. It does this to avoid the mutable default problem. This test is both too strict, and not strict enough. Too strict, because some immutable subclasses should be safe, and not strict enough, because other mutable types should be prohibited. With this change applied, `@dataclass` now uses unhashability as a proxy for mutability: if objects aren't hashable, they're assumed to be mutable.
Special handling is needed, because for non-slots dataclasses the instance attributes are not set: reading from a field just references the class's attribute of the same name, which contains the default value. But this doesn't work for classes using __slots__: they don't read the class's attribute. So in that case (and that case only), initialize the instance attribute. Handle this for both normal defaults, and for fields using default_factory.
When a dataclass inherits from an empty base, all immutability checks are omitted. This PR fixes this and adds tests for it.
Automerge-Triggered-By: GH:ericvsmith
The hard part was making all the tests pass; there are some subtle issues here, because apparently the future import wasn't tested very thoroughly in previous Python versions.
For example, `inspect.signature()` returned type objects normally (except for forward references), but strings with the future import. We changed it to try and return type objects by calling `typing.get_type_hints()`, but fall back on returning strings if that function fails (which it may do if there are future references in the annotations that require passing in a specific namespace to resolve).
Raymond Hettinger
Alex Waygood
Nikita Sobolev
David Ellis
Shantanu
T
Ilya V. Schurov
Xuehai Pan
Carl Meyer
larryhastings
Roman Novak
Tom Fryers
Serhiy Storchaka
Bluenix
Eric V. Smith
Hugo van Kemenade
Arie Bovenberg
Landon Yarrington
Binbin
Sean Grady
Yurii Karabas
Pablo Galindo
Brandt Bucher
Iurii Kemaev
Zackery Spytz
Brandt Bucher
Batuhan Taskaya
Ben Avrahami