Add an opt-in value view for WinRT Object-valued maps in Python

[leileizhang (lei9444)]

Problem

Code that reads and writes many values in PropertySet, ValueSet, DeviceInformation.properties or the map from retrieve_properties_async() has to wrap every access in unbox_object() or to_winrt_object() (#194).

Key changes

• dynwinrt.values.object_value_view(mapping, *, preserve_type=False) returns a live view:

  • a MutableObjectValueView (MutableMapping) for a generated IMap wrapper;
  • a read-only ObjectValueView (Mapping) for an IMapView wrapper.

  The view holds no WinRT reference of its own.

• Reads unbox with unbox_object(). WinRT null reads as None. A runtime object comes back as its DynWinRTValue. So does a box with no Python form: an unsupported PropertyType, or a DateTime outside datetime's range.

• Writes use to_winrt_object()'s default rules, and its errors propagate unchanged.

• view.raw is the generated map. Its values stay native and keep their COM identity.

• A QueryInterface check confirms IMap/IMapView<String or Guid, Object>. Any other map, such as StringMap, raises TypeError, and the typing overloads reject it too.

• Tests:

  • pytest over real PropertySet, ValueSet, StringMap and MediaPropertySet maps;
  • E2E checks with generated bindings, including device and file properties;
  • a mypy --strict consumer check.

Notes

• Stacked on Add explicit WinRT Object boxing and type-preserving unboxing to Python #194.
• Opt-in only. Generated code, unbox_object() and to_winrt_object() are unchanged, and there are no codegen or native changes.
• Generated IPropertySet wrappers, such as ApplicationDataContainer.values, are not Python mappings. Pass values.as_interface(IMap_String_Object) instead.
• JavaScript parity is a follow-up.