1 files changed, 77 insertions, 0 deletions
diff --git a/apps/X11/VCL/property b/apps/X11/VCL/property
new file mode 100644
index 0000000..aee9eda
--- /dev/null
+++ b/apps/X11/VCL/property
@@ -0,0 +1,77 @@
+#ifndef PROPERTY_H
+#define PROPERTY_H
+
+#include <iostream>
+
+template<class Context, class T> struct Property_index;
+
+template<class Context, class T>
+class property {
+	Context* view;  // an Item needs to access values in its context
+	T (Context::*Getter)();
+	void (Context::*Setter)(T);
+
+protected:
+	T get() const { return (Getter) ? (view->*Getter)() : 0; }
+	void set(T val) { if (Setter) (view->*Setter)(val); }
+
+public:
+	property(Context* v,
+		T (Context::*G)() = &Context::get,
+		void (Context::*S)(T) = &Context::set)
+		:view(v), Getter(G), Setter(S) { }
+
+	operator T() const { return get(); } 
+	property& operator=(T val) { set(val); return *this; }
+	property& operator+=(T val) { set(get() + val); return *this; }
+	property& operator=(const property &other) { set(T(other)); return *this; }
+
+	// specialized operations:
+
+	T operator->() { return get(); }
+
+	// string specific
+	property<Property_index<Context,T>,char> operator[](int i);
+	int size()  { return (view->*Getter)().size(); }
+
+};
+
+template<class Context, class T>
+struct Property_index { // inefficient
+	property<Context,T>* p;
+	int i;
+	Property_index(property<Context,T>* pp, int ii) : p(pp), i(ii) { }
+	char get() const { return p->get()[i]; }
+	void set(char ch) { T v = p->get(); v[i] = ch; p->set(v); }
+};
+
+template<class Context, class T>
+property<Property_index<Context,T>,char> property<Context,T>::operator[](int i)
+{
+	return property<Property_index<Context,T>,char>(new Property_index<Context,T>(this,i));
+// leaks
+}
+
+template<class Context, class T>
+inline ostream& operator<<(ostream& s, property<Context,T> p)
+{
+	s << T(p);
+}
+
+template<class Context, class T>
+inline istream& operator>>(istream& s, property<Context,T>& p)
+{
+	T t;
+	s >> t;
+	p = t;
+}
+
+
+
+/* examples
+property<TTreeView,TTreeNodes*> Items;
+Items(this, &get, &set);
+*/
+
+
+#endif