[python] Fix Cluster objects datatypes on Python 3.11 (#26729)
* [python] Fix Cluster objects datatypes on Python 3.11
It seems that Python 3.11 requires the custom data type Nullable to
implement the __hash__() function, otherwise initializing dataclass
annotated objects fail with the following stack trace:
```
File "/home/sag/projects/project-chip/connectedhomeip-v1.1/.environment/pigweed-venv/lib/python3.11/site-packages/chip/clusters/Objects.py", line 385, in Commands
@dataclass
^^^^^^^^^
File "/usr/lib/python3.11/dataclasses.py", line 1223, in dataclass
return wrap(cls)
^^^^^^^^^
File "/usr/lib/python3.11/dataclasses.py", line 1213, in wrap
return _process_class(cls, init, repr, eq, order, unsafe_hash,
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "/usr/lib/python3.11/dataclasses.py", line 958, in _process_class
cls_fields.append(_get_field(cls, name, type, kw_only))
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "/usr/lib/python3.11/dataclasses.py", line 815, in _get_field
raise ValueError(f'mutable default {type(f.default)} for field '
ValueError: mutable default <class 'chip.clusters.Types.Nullable'> for field capacity is not allowed: use default_factory
```
Since all instances of Nullable are the same "value", we can return a
static 0 as hash value.
* [python] Mark Nullable type frozen
* address linter error
* Revert dataclass frozen
* Add commentdiff --git a/src/controller/python/chip/clusters/Types.py b/src/controller/python/chip/clusters/Types.py
index 2359705..cb420ee 100644
--- a/src/controller/python/chip/clusters/Types.py
+++ b/src/controller/python/chip/clusters/Types.py
@@ -15,7 +15,6 @@
# limitations under the License.
#
-
class Nullable():
def __repr__(self):
return 'Null'
@@ -32,5 +31,13 @@
def __lt__(self, other):
return True
+ def __hash__(self):
+ ''' Explicitly implement __hash__() to imply immutability when used in
+ dataclasses.
+
+ See also: https://docs.python.org/3/library/dataclasses.html#dataclasses.dataclass
+ '''
+ return 0
+
NullValue = Nullable()
