5 // Duncan Mak (duncan@ximian.com)
6 // Ben Maurer (bmaurer@users.sourceforge.net)
8 // (C) 2002 Ximian, Inc. http://www.ximian.com
13 // Copyright (C) 2004 Novell, Inc (http://www.novell.com)
15 // Permission is hereby granted, free of charge, to any person obtaining
16 // a copy of this software and associated documentation files (the
17 // "Software"), to deal in the Software without restriction, including
18 // without limitation the rights to use, copy, modify, merge, publish,
19 // distribute, sublicense, and/or sell copies of the Software, and to
20 // permit persons to whom the Software is furnished to do so, subject to
21 // the following conditions:
23 // The above copyright notice and this permission notice shall be
24 // included in all copies or substantial portions of the Software.
26 // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
27 // EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
28 // MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
29 // NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
30 // LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
31 // OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
32 // WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
35 using System.Runtime.Serialization;
40 public sealed class DBNull : ISerializable, IConvertible
43 public static readonly DBNull Value = new DBNull ();
45 // Private constructor
50 private DBNull (SerializationInfo info, StreamingContext context)
52 throw new NotSupportedException ();
56 public void GetObjectData (SerializationInfo info, StreamingContext context)
58 UnitySerializationHolder.GetDBNullData (this, info, context);
61 public TypeCode GetTypeCode ()
63 return TypeCode.DBNull;
66 bool IConvertible.ToBoolean (IFormatProvider provider)
68 throw new InvalidCastException ();
71 byte IConvertible.ToByte (IFormatProvider provider)
73 throw new InvalidCastException ();
76 char IConvertible.ToChar (IFormatProvider provider)
78 throw new InvalidCastException ();
81 DateTime IConvertible.ToDateTime (IFormatProvider provider)
83 throw new InvalidCastException ();
86 decimal IConvertible.ToDecimal (IFormatProvider provider)
88 throw new InvalidCastException ();
91 double IConvertible.ToDouble (IFormatProvider provider)
93 throw new InvalidCastException ();
96 short IConvertible.ToInt16 (IFormatProvider provider)
98 throw new InvalidCastException ();
101 int IConvertible.ToInt32 (IFormatProvider provider)
103 throw new InvalidCastException ();
106 long IConvertible.ToInt64 (IFormatProvider provider)
108 throw new InvalidCastException ();
111 sbyte IConvertible.ToSByte (IFormatProvider provider)
113 throw new InvalidCastException ();
116 float IConvertible.ToSingle (IFormatProvider provider)
118 throw new InvalidCastException ();
121 object IConvertible.ToType (Type type, IFormatProvider provider)
123 if (type == typeof (string))
125 throw new InvalidCastException ();
128 ushort IConvertible.ToUInt16 (IFormatProvider provider)
130 throw new InvalidCastException ();
133 uint IConvertible.ToUInt32 (IFormatProvider provider)
135 throw new InvalidCastException ();
138 ulong IConvertible.ToUInt64 (IFormatProvider provider)
140 throw new InvalidCastException ();
143 public override string ToString ()
148 public string ToString (IFormatProvider provider)