--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/Source/Patterns/MustImplementAttribute.cs	Thu Mar 27 21:46:09 2014 +0400
@@ -0,0 +1,66 @@
+using System;
+
+namespace BLToolkit.Patterns
+{
+	[AttributeUsage(AttributeTargets.Interface | AttributeTargets.Method | AttributeTargets.Property)]
+	public sealed class MustImplementAttribute : Attribute
+	{
+		public MustImplementAttribute(bool implement, bool throwException, string exceptionMessage)
+		{
+			_implement        = implement;
+			_throwException   = throwException;
+			_exceptionMessage = exceptionMessage;
+		}
+
+		public MustImplementAttribute(bool implement, bool throwException)
+			: this(implement, throwException, null)
+		{
+		}
+
+		public MustImplementAttribute(bool implement, string exceptionMessage)
+			: this(implement, true, exceptionMessage)
+		{
+		}
+
+		public MustImplementAttribute(bool implement)
+			: this(implement, true, null)
+		{
+		}
+
+		public MustImplementAttribute()
+			: this(true, true, null)
+		{
+		}
+
+		private readonly bool _implement;
+		public           bool  Implement
+		{
+			get { return _implement;  }
+		}
+
+		private bool _throwException;
+		public  bool  ThrowException
+		{
+			get { return _throwException;  }
+			set { _throwException = value; }
+		}
+
+		private string _exceptionMessage;
+		public  string  ExceptionMessage
+		{
+			get { return _exceptionMessage;  }
+			set { _exceptionMessage = value; }
+		}
+
+		/// <summary>
+		/// All methods are optional and throws <see cref="NotImplementedException"/> at run tune.
+		/// </summary>
+		public static readonly MustImplementAttribute Default   = new MustImplementAttribute(false, true, null);
+
+		/// <summary>
+		/// All methods are optional and does nothing at run tune.
+		/// Return value and all output parameters will be set to appropriate default values.
+		/// </summary>
+		public static readonly MustImplementAttribute Aggregate = new MustImplementAttribute(false, false, null);
+	}
+}