The Simons     Component Library

           

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ObjectID.h

//
//  SCL : Simons Component Library
//
//
//  Filename:   ObjectID.h
//  Contents:   ObjectID pointer
//  Author:     Anthony J H Simons
//  Revised:    31 October 2005

// This software is distributed free in the hope that others will
// find it useful.  However, it comes WITHOUT ANY WARRANTY.  No
// liability can be accepted for software failure, merchantability
// or fitness for a particular purpose.  You can redistribute this
// software in its original form, or in a modified form, provided
// that this disclaimer is retained in the file banner.

#ifndef SCL_OBJECT_ID
#define SCL_OBJECT_ID

#include "Basic.h"

class Null;
class Object;


class ObjectID {
private:
        static ObjectID nullReference;  // Ensures that null's refcount >= 1
protected:
        Object* basicPointer;           
        Void assign(const Object*);
        Void assign(const ObjectID&);
        Void nullPointer(ObjectID) const;
        Void typeFailure(ObjectID) const;
public:
        ObjectID();
        ~ObjectID();
        ObjectID(const Null*);
        ObjectID(const Object*);
        ObjectID(const ObjectID&);
        ObjectID& operator=(const Object*);
        ObjectID& operator=(const ObjectID&);
        Object* operator->() const;
        const Object* pointer() const;
        friend bool operator==(const ObjectID&, const ObjectID&);
        friend bool operator!=(const ObjectID&, const ObjectID&);
        template<class T> friend T* toType(const ObjectID&);
        template<class T> friend T* tryType(const ObjectID&);
};

#endif

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