gh-108751: Add copy.replace() function #108752
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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.
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merwok
reviewed
Sep 1, 2023
Doc/library/copy.rst
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| single: __replace__() (replace protocol) | ||
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| Function :func:`replace` is more limited than :func:`copy` and :func:`deepcopy`, | ||
| and only supports named tuples, dataclasses, and other classes which |
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Suggested change
| and only supports named tuples, dataclasses, and other classes which | |
| and only supports :term:`named tuples <named tuple>`, :mod:`dataclasses`, and other classes which |
(I haven鈥檛 double checked if named tuple or namedtuple is the right key)
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Actually, it does not support named tuples in general. It currently only supports named tuples created by collections.namedtuple().
merwok
reviewed
Sep 1, 2023
| func = getattr(cls, '__replace__', None) | ||
| if func is None: | ||
| raise TypeError(f"replace() does not support {cls.__name__} objects") | ||
| return func(obj, **changes) |
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This is a cool feature for very little code!
rhettinger
approved these changes
Sep 1, 2023
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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.
馃摎 Documentation preview 馃摎: https://cpython-previews--108752.org.readthedocs.build/