Support wrapper generation with 4 parameter constructors for backward compat with swift wrappers.

Author: jmp75

.gitignore

@@ -1,3 +1,7 @@
+__pycache__/
+.vscode/
+
+
 *.gz
 *.zip
 *.pyc

refcount/interop.py

@@ -504,6 +504,8 @@ def create_wrapper(self, obj: Any, type_id: str, release_native: Optional[Callab
         else:
             s = signature(wrapper_type)
             n = len(s.parameters)
+            parameters = [v for k, v in s.parameters.items()]
+            # [<Parameter "handle: Any">, <Parameter "release_native: Callable[[Any], NoneType]">, <Parameter "type_id: Optional[str] = None">, <Parameter "prior_ref_count: int = 0">]
             if n == 0:
                 raise TypeError("Wrapper constructor must have at least one argument")
             elif n == 1:
@@ -516,8 +518,12 @@ def create_wrapper(self, obj: Any, type_id: str, release_native: Optional[Callab
                 if release_native is None:
                     raise ValueError(f"Wrapper class '{type(wrapper_type)}' has three constructor arguments; the argument 'release_native' cannot be None")
                 return wrapper_type(obj, release_native, type_id)
+            elif n == 4:
+                if parameters[3].default == parameters[3].empty:
+                    raise ValueError(f"Wrapper class '{type(wrapper_type)}' has four constructor arguments; the last argument 'prior_ref_count' must have a default value")
+                return wrapper_type(obj, release_native, type_id)
             else:
-                raise NotImplementedError("Wrapper constructors with more than 3 arguments are not yet supported")
+                raise NotImplementedError("Wrapper constructors with more than 4 arguments are not yet supported")
 
 
 WrapperCreationFunction = Callable[[Any, str, Callable], DeletableCffiNativeHandle]

tests/Readme.md

@@ -5,9 +5,9 @@ If you want to explore the unit tests e.g. in debug mode from your IDE, you can
 on Linux: 
 
 ```sh
-cd tests
-cd test_native_library
-cmake -Bbuild .
+cd $HOME/src/pyrefcount/tests/test_native_library
+# rm -rf CMakeFiles/ Makefile CMakeCache.txt cmake_install.cmake
+cmake -DCMAKE_BUILD_TYPE=DEBUG -Bbuild .
 cmake --build build
 ```