Attribute.Match-Methode

using System;
using System.Reflection;

namespace MatchCS {
	// A custom attribute to allow 2 authors per method.
	public class AuthorsAttribute : Attribute {
		public AuthorsAttribute(string name1, string name2) {
			authorName1 = name1;
			authorName2 = name2;
		}

		protected string authorName1;
		protected string authorName2;
	
		public string AuthorName1 {
			get { return authorName1; }
			set { authorName1 = AuthorName1; }
		}

		public string AuthorName2 {
			get { return authorName2; }
			set { authorName2 = AuthorName2; }
		}

		// Use the hash code of the string objects and xor them together.
		public override int GetHashCode() {
			return authorName1.GetHashCode() ^ authorName2.GetHashCode();
		}

		// Determine if the object is a match to this one.
		public override bool Match(object obj) {
			// Obviously a match.
			if (obj == this)
				return true;

			// Obviously we're not null, so no.
			if (obj == null)
				return false;

			if (obj is AuthorsAttribute)
				// Combine the hash codes and see if they're unchanged.
				return (((AuthorsAttribute)obj).GetHashCode() & GetHashCode())
					== GetHashCode();
			else
				return false;
		}
	}

	// Add some authors to methods of a class.
	public class TestClass1 {
		[Authors("William Shakespeare", "Herman Melville")]
		public void Method1()
		{}

		[Authors("Leo Tolstoy", "John Milton")]
		public void Method2()
		{}
	}

	// Add authors to a second class's methods.
	public class TestClass2 {
		[Authors("William Shakespeare", "Herman Melville")]
		public void Method1()
		{}

		[Authors("Leo Tolstoy", "John Milton")]
		public void Method2()
		{}

		[Authors("William Shakespeare", "John Milton")]
		public void Method3()
		{}
	}

	class DemoClass {
		static void Main(string[] args) {
			// Get the type for both classes to access their metadata.
			Type clsType1 = typeof(TestClass1);
			Type clsType2 = typeof(TestClass2);

			// Iterate through each method of the first class.
			foreach(MethodInfo mInfo1 in clsType1.GetMethods()) {
				// Check each method for the Authors attribute.
				AuthorsAttribute authAttr1 = (AuthorsAttribute)
					Attribute.GetCustomAttribute(mInfo1, 
					typeof(AuthorsAttribute));
				if (authAttr1 != null) {
					// Display the authors.
					Console.WriteLine("Method {0} was authored by {1} " +
										"and {2}.", mInfo1.Name, 
										authAttr1.AuthorName1, 
										authAttr1.AuthorName2);
					// Iterate through each method of the second class.
					foreach(MethodInfo mInfo2 in clsType2.GetMethods()) {
						// Check each method for the Authors attribute.
						AuthorsAttribute authAttr2 = (AuthorsAttribute)
							Attribute.GetCustomAttribute(mInfo2, 
							typeof(AuthorsAttribute));
						// Compare with the authors in the first class.
						if (authAttr2 != null && authAttr2.Match(authAttr1))
							Console.WriteLine("Method {0} in class {1} " +
								"was authored by the same team.",
								mInfo2.Name, clsType2.Name);
					}
					Console.WriteLine("");
				}
			}
		}
	}
}

/*
 * Output:
 * Method Method1 was authored by William Shakespeare and Herman Melville.
 * Method Method1 in class TestClass2 was authored by the same team.
 *
 * Method Method2 was authored by Leo Tolstoy and John Milton.
 * Method Method2 in class TestClass2 was authored by the same team.
 */