diff options
Diffstat (limited to 'Lib/dataclasses.py')
| -rw-r--r-- | Lib/dataclasses.py | 10 |
1 files changed, 9 insertions, 1 deletions
diff --git a/Lib/dataclasses.py b/Lib/dataclasses.py index 325b822..8c3d638 100644 --- a/Lib/dataclasses.py +++ b/Lib/dataclasses.py @@ -1202,7 +1202,7 @@ def make_dataclass(cls_name, fields, *, bases=(), namespace=None, init=True, unsafe_hash=unsafe_hash, frozen=frozen) -def replace(obj, **changes): +def replace(*args, **changes): """Return a new object replacing specified fields with new values. This is especially useful for frozen classes. Example usage: @@ -1216,6 +1216,14 @@ def replace(obj, **changes): c1 = replace(c, x=3) assert c1.x == 3 and c1.y == 2 """ + if len(args) > 1: + raise TypeError(f'replace() takes 1 positional argument but {len(args)} were given') + if args: + obj, = args + elif 'obj' in changes: + obj = changes.pop('obj') + else: + raise TypeError("replace() missing 1 required positional argument: 'obj'") # We're going to mutate 'changes', but that's okay because it's a # new dict, even if called with 'replace(obj, **my_changes)'. |