New Core Tutorial

git-svn-id: svn://ultimatepp.org/upp/trunk@10538 f0d560ea-af0d-0410-9eb7-867de7ffcac7

tutorial/CoreTutorial/CombineHash.cpp

@@ -0,0 +1,35 @@
+#include "Tutorial.h"
+
+void CombineHashTutorial()
+{
+	/// .CombineHash
+
+	/// To simplify providing of high quality hash codes for composite types, U++ provides
+	/// `CombineHash` utility class. This class uses `GetHashValue` function to gather hash
+	/// codes of all values and combines them to provide final hash value for composite type:
+
+	struct Foo {
+		String a;
+		int    b;
+		
+		unsigned GetHashValue() const { return CombineHash(a, b); }
+	};
+
+	/// Note that `GetHashValue` is defined as function template that calls `GetHashValue`
+	/// method of its argument, therefore defining `GetHashValue` method defines `GetHashValue`
+	/// function too:
+
+	Foo x;
+	x.a = "world";
+	x.b = 22;
+
+	DUMP(GetHashValue(x));
+	
+	///
+
+	x.a << '!';
+
+	DUMP(GetHashValue(x));
+	
+	///
+}