Core: In dialog to add property only list types that can be instantiated

Fixes #15159: Dialog for adding properties allows property types that give exceptions

src/Base/BaseClass.h

@@ -128,7 +128,7 @@ private:
     TYPESYSTEM_SOURCE_ABSTRACT_P(_class_)                                                          \
     void _class_::init(void)                                                                       \
     {                                                                                              \
-        initSubclass(_class_::classTypeId, #_class_, #_parentclass_, &(_class_::create));          \
+        initSubclass(_class_::classTypeId, #_class_, #_parentclass_, nullptr);                     \
     }
 // NOLINTEND(cppcoreguidelines-macro-usage)
 

src/Base/Type.cpp

@@ -65,6 +65,11 @@ void* Type::createInstance()
     return method ? (*method)() : nullptr;
 }
 
+bool Type::canInstantiate() const
+{
+    instantiationMethod method = typedata[index]->instMethod;
+    return method != nullptr;
+}
 
 void* Type::createInstanceByName(const char* TypeName, bool bLoadModule)
 {

src/Base/Type.h

@@ -89,6 +89,8 @@ public:
 
     /// creates a instance of this type
     void* createInstance();
+    /// Checks whether this type can instantiate
+    bool canInstantiate() const;
     /// creates a instance of the named type
     static void* createInstanceByName(const char* TypeName, bool bLoadModule = false);
     static void importModule(const char* TypeName);