Symbolic enums

By default, enums are treated as though they are integers. This works well for serialisation, but if the data is meant to be read by a human, it is desirable to display the enums in symbolic form.

In order to do this, classdesc will emit descriptors using Enum_handle<E>, where E is an enum, which wraps an enum variable. In particular, the Enum_handle will return a string symbolic representation of the enum, or assign the appropriate value to the enum variable when assigned a string constant representing the symbolic value of the enum:

  template <class T> //T is an enum
  class Enum_handle
  {
  public:
    Enum_handle(T& arg); // wrap enum arg
    operator std::string() const; //symbolic form of enum
    operator int() const; //integral value of the enum
    const Enum_handle& operator=(T x);
    const Enum_handle& operator=(int x);
    const Enum_handle& operator=(const std::string& x); //symbolic assignment  
  };

Classdesc handles writing the dictionaries needed to perform this conversion to and from symbolic constants. See the xml_pack descriptor for an example of its use.