New Core Tutorial

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

tutorial/CoreTutorial/AsString.cpp

@@ -0,0 +1,82 @@
+#include "Tutorial.h"
+
+void AsStringTutorial()
+{
+	/// .`AsString`, `ToString` and `operator<<`
+
+	/// U++ Core provides simple yet effective standard schema for converting values to default
+	/// textual form. System is based on the combination of template functions (following code
+	/// is part of U++ library):
+
+#if 0
+namespace Upp {
+	template <class T>
+	inline String AsString(const T& x)
+	{
+		return x.ToString();
+	}
+	
+	template <class T>
+	inline Stream& operator<<(Stream& s, const T& x)
+	{
+		s << AsString(x);
+		return s;
+	}
+	
+	template <class T>
+	inline String& operator<<(String& s, const T& x)
+	{
+		s.Cat(AsString(x));
+		return s;
+	}
+};
+#endif
+
+	/// Client types have to either define `String ToString` method or specialize `AsString`
+	/// template in `Upp` namespace. Such types can be appended to Streams or Strings using
+	/// `operator<<`. Of course, U++ value types and primitive types have required items
+	/// predefined by U++:
+
+	FileOut fout(ConfigFile("test.txt"));
+	String  sout;
+	
+	fout << 1.23 << ' ' << GetSysDate() << ' ' << GetSysTime();
+	sout << 1.23 << ' ' << GetSysDate() << ' ' << GetSysTime();
+	
+	fout.Close();
+
+	DUMP(LoadFile(ConfigFile("test.txt")));
+	DUMP(sout);
+
+	/// Getting client types involved into this schema is not too difficult, all you need to do
+	/// is to add `ToString` method:
+
+	struct BinFoo {
+		int x;
+		
+		String ToString() const   { return FormatIntBase(x, 2); }
+	};
+	
+	BinFoo bf;
+	bf.x = 30;
+	
+	sout.Clear();
+	sout << bf;
+	DUMP(sout);
+	
+	/// If you cannot add `ToString`, you can still specialize template in Upp namespace:
+	
+	struct RomanFoo {
+		int x;
+		
+		RomanFoo(int x) : x(x) {}
+	};
+
+#if 0
+	namespace Upp {
+	template <> String Upp::AsString(const RomanFoo& a) { return FormatIntRoman(a.x); }
+	};
+#endif
+
+	///
+}