SE450: Overriding: C++/C# [21/35]

C++ and C# default to static dispatch, for all functions, including member functions.

• Boxed entities are manipulated using references/pointers, live java objects. Unboxed entities are manipulated as values, like java base types.
  

  You can convert between them using wrapper objects.

    Integer box(int v) { return new Integer(v); }
    int unbox(Integer r) { return r.intValue(); }
  

  Java 1.5 does this automatically in most contexts.

• In C#, instances of a class are boxed; instances of a struct are unboxed --- structs generalize Java's base types.

  To get dynamic dispatch, use the keyword virtual, which is allowed only in classes (not structs).

  If you are interested in C#, see here: http://msdn.microsoft.com/library/default.asp?url=/library/en-us/csspec/html/vclrfcsharpspec_11_3.asp

• In C++, objects of any type may be boxed or unboxed. For example:

    string  v = string("cat");     // unboxed
    string* r = new string("dog"); // boxed
  
    int  v = 1;  // unboxed
    int* r = &v; // boxed
  

  To get dynamic dispatch, the receiving object must be boxed and the method must be virtual. See file:dynamicVersusStaticDispatch.cpp [source].