CanSubclass() private method

private CanSubclass ( ) : bool
return bool
Ejemplo n.º 1
0
        //====================================================================
        // Metatype __new__ implementation. This is called to create a new
        // class / type when a reflected class is subclassed.
        //====================================================================

        public static IntPtr tp_new(IntPtr tp, IntPtr args, IntPtr kw)
        {
            int len = Runtime.PyTuple_Size(args);

            if (len < 3)
            {
                return(Exceptions.RaiseTypeError("invalid argument list"));
            }

            IntPtr name  = Runtime.PyTuple_GetItem(args, 0);
            IntPtr bases = Runtime.PyTuple_GetItem(args, 1);
            IntPtr dict  = Runtime.PyTuple_GetItem(args, 2);

            // We do not support multiple inheritance, so the bases argument
            // should be a 1-item tuple containing the type we are subtyping.
            // That type must itself have a managed implementation. We check
            // that by making sure its metatype is the CLR metatype.

            if (Runtime.PyTuple_Size(bases) != 1)
            {
                return(Exceptions.RaiseTypeError(
                           "cannot use multiple inheritance with managed classes"
                           ));
            }

            IntPtr base_type = Runtime.PyTuple_GetItem(bases, 0);
            IntPtr mt        = Runtime.PyObject_TYPE(base_type);

            if (!((mt == PyCLRMetaType) || (mt == Runtime.PyTypeType)))
            {
                return(Exceptions.RaiseTypeError("invalid metatype"));
            }

            // Ensure that the reflected type is appropriate for subclassing,
            // disallowing subclassing of delegates, enums and array types.

            ClassBase cb = GetManagedObject(base_type) as ClassBase;

            if (cb != null)
            {
                if (!cb.CanSubclass())
                {
                    return(Exceptions.RaiseTypeError(
                               "delegates, enums and array types cannot be subclassed"
                               ));
                }
            }

            IntPtr slots = Runtime.PyDict_GetItemString(dict, "__slots__");

            if (slots != IntPtr.Zero)
            {
                return(Exceptions.RaiseTypeError(
                           "subclasses of managed classes do not support __slots__"
                           ));
            }

            return(TypeManager.CreateSubType(name, base_type, dict));
        }
Ejemplo n.º 2
0
        public static IntPtr tp_new(IntPtr tp, IntPtr args, IntPtr kw)
        {
            int len = Runtime.PyTuple_Size(args);

            if (len < 3)
            {
                return(Exceptions.RaiseTypeError("invalid argument list"));
            }

            IntPtr name  = Runtime.PyTuple_GetItem(args, 0);
            IntPtr bases = Runtime.PyTuple_GetItem(args, 1);
            IntPtr dict  = Runtime.PyTuple_GetItem(args, 2);

            // We do not support multiple inheritance, so the bases argument
            // should be a 1-item tuple containing the type we are subtyping.
            // That type must itself have a managed implementation. We check
            // that by making sure its metatype is the CLR metatype.

            if (Runtime.PyTuple_Size(bases) != 1)
            {
                return(Exceptions.RaiseTypeError(
                           "cannot use multiple inheritance with managed classes"
                           ));
            }

            IntPtr base_type = Runtime.PyTuple_GetItem(bases, 0);
            IntPtr mt        = Runtime.PyObject_TYPE(base_type);

            if (!((mt == PyCLRMetaType) || (mt == Runtime.PyTypeType)))
            {
                return(Exceptions.RaiseTypeError("invalid metatype"));
            }

            // Ensure that the reflected type is appropriate for subclassing,
            // disallowing subclassing of delegates, enums and array types.

            ClassBase cb = GetManagedObject(base_type) as ClassBase;

            if (cb != null)
            {
                if (!cb.CanSubclass())
                {
                    return(Exceptions.RaiseTypeError(
                               "delegates, enums and array types cannot be subclassed"
                               ));
                }
            }

            IntPtr slots = Runtime.PyDict_GetItemString(dict, "__slots__");

            if (slots != IntPtr.Zero)
            {
                return(Exceptions.RaiseTypeError(
                           "subclasses of managed classes do not support __slots__"
                           ));
            }

            // hack for now... fix for 1.0
            //return TypeManager.CreateSubType(args);


            // right way

            IntPtr func = Marshal.ReadIntPtr(Runtime.PyTypeType,
                                             TypeOffset.tp_new);
            IntPtr type = NativeCall.Call_3(func, tp, args, kw);

            if (type == IntPtr.Zero)
            {
                return(IntPtr.Zero);
            }

            int flags = TypeFlags.Default;

            flags |= TypeFlags.Managed;
            flags |= TypeFlags.HeapType;
            flags |= TypeFlags.BaseType;
            flags |= TypeFlags.Subclass;
            flags |= TypeFlags.HaveGC;
            Marshal.WriteIntPtr(type, TypeOffset.tp_flags, (IntPtr)flags);

            TypeManager.CopySlot(base_type, type, TypeOffset.tp_dealloc);

            // Hmm - the standard subtype_traverse, clear look at ob_size to
            // do things, so to allow gc to work correctly we need to move
            // our hidden handle out of ob_size. Then, in theory we can
            // comment this out and still not crash.
            TypeManager.CopySlot(base_type, type, TypeOffset.tp_traverse);
            TypeManager.CopySlot(base_type, type, TypeOffset.tp_clear);


            // for now, move up hidden handle...
            IntPtr gc = Marshal.ReadIntPtr(base_type, TypeOffset.magic());

            Marshal.WriteIntPtr(type, TypeOffset.magic(), gc);

            //DebugUtil.DumpType(base_type);
            //DebugUtil.DumpType(type);

            return(type);
        }