Instead of calling `exec()` once for each function added to a dataclass, only call `exec()` once per dataclass. This can lead to speed improvements of up to 20%.
dataclasses.replace() now raises TypeError instead of ValueError if
specify keyword argument for a field declared with init=False or miss keyword
argument for required InitVar field.
It creates a modified copy of an object by calling the object's
__replace__() method.
It is a generalization of dataclasses.replace(), named tuple's _replace()
method and replace() methods in various classes, and supports all these
stdlib classes.
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.
Eric V. Smith
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