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attr.evolve no longer supports setting an attr object as attribute #804
Description
Hi,
I don't know if this is an intentional side-effect of #759, but attr.evolve no longer works in the non-recursive recursive case if the argument is an attr class.
Here is a snippet to reproduce it:
import attr
@attr.s
class Cls1:
param1 = attr.ib()
@attr.s
class Cls2:
param2 = attr.ib()
obj2a = Cls2(param2="a")
obj2b = Cls2(param2="b")
obj1a = Cls1(param1=obj2a)
obj1b = attr.evolve(obj1a, param1=obj2b)
print(obj1b)Before fe6eb31, it printed this: Cls1(param1=Cls2(param2='b'))
But after this commit, it raises this error:
Traceback (most recent call last):
File "test.py", line 17, in <module>
obj1b = attr.evolve(obj1a, param1=obj2b)
File "/home/dev/.local/lib/python3.7/site-packages/attrs-21.2.0.dev0-py3.7.egg/attr/_funcs.py", line 347, in evolve
changes[init_name] = evolve(value, **changes[init_name])
TypeError: evolve() argument after ** must be a mapping, not Cls2
Thanks!
Activity
[-]`attr.evolve` no longer supports setting an attr class as attribute[/-][+]`attr.evolve` no longer supports setting an attr object as attribute[/+]staaam commentedon May 6, 2021
same here. Issue is in attr._funcs.evolve at:
value- is old value (param1 from example above)changes[init_name]- is new value (obj2b from above)but for recursive evolve it should be dict
probably the best way to make it backward compatible will be to check
elif has(value) and isinstance(changes[init_name], Mapping):hynek commentedon May 6, 2021
Yeah, we'll have to revert #759 and push out 21.2.
I'm gonna wait a bit with the release to see if there's other breakages that should be fixed.
Blacklist attr 21.1.0
hynek commentedon May 7, 2021
21.2 with the fix is on PyPI.