New Core Tutorial

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

tutorial/CoreTutorial/One.cpp

@@ -0,0 +1,52 @@
+#include "Tutorial.h"
+
+void OneTutorial()
+{
+	/// .`One`
+
+	/// `One` is a container that can store none or one element of T or derived from T. It is
+	/// functionally quite similar to `std::unique_ptr`, but has some convenient features.
+
+	struct Base {
+		virtual String Get() = 0;
+		virtual ~Base() {}
+	};
+	
+	struct Derived1 : Base {
+		virtual String Get() { return "Derived1"; }
+	};
+	
+	struct Derived2 : Base {
+		virtual String Get() { return "Derived2"; }
+	};
+	
+	One<Base> s;
+	
+	/// `operator bool` of one returns true if it contains an element:
+	
+	DUMP((bool)s);
+	
+	///
+	
+	s.Create<Derived1>();
+	DUMP((bool)s);
+	DUMP(s->Get());
+
+	/// You can use `Is` to check if certain type is currently stored in `One`:
+	
+	DUMP(s.Is<Derived1>());
+	DUMP(s.Is<Base>());
+	DUMP(s.Is<Derived2>());
+	
+	/// To get a pointer to the contained instance, use `operator~`:
+	
+	Base *b = ~s;
+	DUMP(b->Get());
+
+	/// Clear method removes the element from One:
+
+	s.Clear();
+	DUMP((bool)s);
+	
+	///
+}