Enabling COM Records as [out] method parameters

CHANGES.md

@@ -18,6 +18,7 @@ As of build 305, installation .exe files have been deprecated; see
 Coming in build 312, as yet unreleased
 --------------------------------------
 
+* Implement COM Records as [out] method parameters (mhammond#2708, [@geppi][geppi], [@the-snork][the-snork])
 * Implement multidimensional SAFEARRAY(COM Record) and SAFEARRAY(double) (mhammond#2655, [@geppi][geppi])
 * Added many missing license and copyright notice files (mhammond#2590, [@Avasam][Avasam])
 * Fixed missing version stamp on built `.dll` and `.exe` files (mhammond#2647, [@Avasam][Avasam])

com/TestSources/PyCOMTest/PyCOMImpl.cpp

@@ -626,6 +626,16 @@ HRESULT CPyCOMTest::GetStruct(TestStruct1 *ret)
     return S_OK;
 }
 
+HRESULT CPyCOMTest::GetOutStruct(TestStruct1 *pRecord)
+{
+    if (pRecord == NULL) {
+        return E_POINTER;
+    }
+    pRecord->int_value = 99;
+    pRecord->str_value = SysAllocString(L"Luftballons");
+    return S_OK;
+}
+
 HRESULT CPyCOMTest::ModifyStruct(TestStruct1 *prec)
 {
     prec->int_value = 100;

com/TestSources/PyCOMTest/PyCOMImpl.h

@@ -106,6 +106,7 @@ class CPyCOMTest : public IDispatchImpl<IPyCOMTest, &IID_IPyCOMTest, &LIBID_PyCO
     STDMETHOD(TestOptionals2)(double dval, BSTR strval, short sval, SAFEARRAY **pRet);
     STDMETHOD(TestOptionals3)(double dval, short sval, IPyCOMTest **outinterface2);
     STDMETHOD(GetStruct)(TestStruct1 *ret);
+    STDMETHOD(GetOutStruct)(TestStruct1 *pRecord);
     STDMETHOD(DoubleString)(BSTR inStr, BSTR *outStr);
     STDMETHOD(DoubleInOutString)(BSTR *str);
     STDMETHOD(TestMyInterface)(IUnknown *t);

com/TestSources/PyCOMTest/PyCOMTest.idl

@@ -269,6 +269,7 @@ library PyCOMTestLib
 							   [in, defaultvalue(1)] short sval,
 							   [out, retval] IPyCOMTest **ppout );
 		HRESULT GetStruct([out, retval]TestStruct1 *ret);
+        HRESULT GetOutStruct([out]TestStruct1 *pRecord);
 		HRESULT DoubleString([in] BSTR inStr, [out, retval] BSTR *outStr);
 		HRESULT DoubleInOutString([in,out] BSTR *str);
 		[restricted] HRESULT NotScriptable([in,out] int *val);

com/win32com/client/build.py

@@ -382,6 +382,22 @@ def MakeDispatchFuncMethod(self, entry, name, bMakeClass=1):
         if doc and doc[1]:
             ret.append(linePrefix + "\t" + _makeDocString(doc[1]))
 
+        for i, desc in enumerate(fdesc[2]):
+            if (
+                desc[0] & pythoncom.VT_RECORD
+                and desc[1] & (pythoncom.PARAMFLAG_FOUT | pythoncom.PARAMFLAG_FIN)
+                == pythoncom.PARAMFLAG_FOUT
+                and desc[3]
+                and desc[3].__class__.__name__ == "PyIID"
+            ):
+                outVal = f"pythoncom.GetRecordFromGuids(CLSID, MajorVersion, MinorVersion, LCID, {desc[3]!r})"
+                ret.extend(
+                    (
+                        f"{linePrefix}\tif {names[i + 1]} == {defOutArg}:",
+                        f"{linePrefix}\t\t{names[i + 1]} = {outVal}",
+                    )
+                )
+
         resclsid = entry.GetResultCLSID()
         if resclsid:
             resclsid = "'%s'" % resclsid
@@ -592,7 +608,7 @@ def _ResolveType(typerepr, itypeinfo):
                 return pythoncom.VT_UNKNOWN, clsid, retdoc
 
             elif typeKind == pythoncom.TKIND_RECORD:
-                return pythoncom.VT_RECORD, None, None
+                return pythoncom.VT_RECORD, resultAttr.iid, None
             raise NotSupportedException("Can not resolve alias or user-defined type")
     return typeSubstMap.get(typerepr, typerepr), None, None
 

com/win32com/test/testPyComTest.py

@@ -657,8 +657,14 @@ def TestGenerated():
 
     # Test plain pythoncom.com_record structs.
     progress("Testing baseclass pythoncom.com_record structs.")
+    # Test pythoncom.com_record as an [out] parameter.
+    r = o.GetOutStruct()
+    assert type(r) is pythoncom.com_record
+    assert r.int_value == 99 and str(r.str_value) == "Luftballons"
+    # Test pythoncom.com_record as a retval:
     r = o.GetStruct()
     assert type(r) is pythoncom.com_record
+    assert r.int_value == 99 and str(r.str_value) == "Hello from C++"
     TestStructByref(o, r)
     test_rec = Record("TestStruct2", o)
     assert type(test_rec) is pythoncom.com_record
@@ -701,6 +707,13 @@ def TestGenerated():
     retrieved_struct = parent_struct.a_struct_field
     assert retrieved_struct == member_struct
 
+    # Test a pythoncom.com_record subclass as an [out] parameter.
+    r = o.GetOutStruct()
+    # After 'TestStruct1' was registered as an instantiable subclass
+    # of pythoncom.com_record, the return value should have this type.
+    assert type(r) is TestStruct1
+    assert r.int_value == 99 and str(r.str_value) == "Luftballons"
+
     # Perform the 'Byref' and 'ArrayOfStruct tests using the registered subclasses.
     r = o.GetStruct()
     # After 'TestStruct1' was registered as an instantiable subclass