#ifndef DEMODLL_H
#define DEMODLL_H
///////////////////////////////////////////////////////////////////
//  DemoDll.h   - Demonstrate Creation, use, and miss-use of     //
//                Dynamic Link Libraries (DLLs)                  //
//                                                               //
//  Language:    Visual C++, ver 7.0                             //
//  Platform:    Dell Dimension 8100, Windows 2000, SP 2.0       //
//  Application: Demonstration for CSE775 - Distributed Objects  //
//  Author:      Jim Fawcett, CST 2-187, Syracuse University     //
//               (315) 443-3948, jfawcett@twcny.rr.com           //
///////////////////////////////////////////////////////////////////
/*
    Operations:
    ===========
    This workspace contains six modules:
    1. DemoDll (implemented by this module)
       - demonstrates creation of basic dll, exporting a class
         and global functions
    2. RevisedDemoDll
       - changes the implementation of DemoDll but keeps its
         interface and semantics.
    3. dllClient
       - uses both DemoDll.dll and RevisedDemoDll.dll
       - use of DemoDll.dll is successful
       - use of RevisedDemoDll crashes because dll was modified
         but client was not, and client was welded to the dll's
         implementation.
    4. DemoInterface
       - demonstrates how to build a dll that does not require
         a client to bind to its implementation by providing
         an interface (abstract class) with a creational function.
    5. RevisedDemoInterface
       - changes the implementation of DemoInterface but keeps
         its interface and semantics.
    6. interfaceClient
       - uses both DemoInterface and RevisedDemoInterface
         successfully.

//

       Example of what does not work:
       
         DemoDll and RevisedDemoDll use the same class and 
         function syntax but different implementations.
         Since dllClient binds directly to CDemoDll, it
         cannont survive changes to the CDemoDll imple-
         mentation that result in different object sizes.

           +-----------+      +----------+
           | dllClient |----->| CDemoDll |
           +-----------+      +----------+

                           1st version in DemoDll
                           2nd version in RevisedDemoDll

       Example of what does work:

         DemoInterface and RevisedDemoInterface use the same
         class and function syntax.  Since only the CDemoDll
         implementing class changes the interfaceClient works 
         successfully with both.

           +-----------------+      +----------------+
           | interfaceClient |----->| CDemoInterface |
           +-----------------+      +----------------+
                                           / \
                                            |
                                            |
                                       +----------+      
                                       | CDemoDll |
                                       +----------+

                                   1st version in DemoInterface
                                   2nd version in RevisedDemoInterface

*/
//
/////////////////////////////////////////////////////////////////////////
//  Build Processes                                                    //
/////////////////////////////////////////////////////////////////////////
//  DemoDll:                                                           //
//    Required Files:                                                  //
//      DemoDll.h, DemoDll.cpp, stdafx.h, stdafx.cpp                   //
//    compiler command:                                                //
//      devenv DemoDll.vcproj /make /rebuild                           //
/////////////////////////////////////////////////////////////////////////
//  RevisedDemoDll:                                                    //
//    Required Files:                                                  //
//      RevisedDemoDll.h, RevisedDemoDll.cpp, stdafx.h, stdafx.cpp     //
//    compiler command:                                                //
//      devenv RevisedDemoDll.vcproj /make /rebuild                    //
/////////////////////////////////////////////////////////////////////////
//  dllClient     :                                                    //
//    Required Files:                                                  //
//      dllClient.cpp, stdafx.h, stdafx.cpp, DemoDll.dll, DemoDll.lib  //
//    compiler command:                                                //
//      devenv dllClient.vcproj /make /rebuild                         //
/////////////////////////////////////////////////////////////////////////

/////////////////////////////////////////////////////////////////////////
//  DemoInterface:                                                     //
//    Required Files:                                                  //
//      DemoInterface.h, DemoInterface.cpp, stdafx.h, stdafx.cpp       //
//    compiler command:                                                //
//      devenv DemoInterface.vcproj /make /rebuild                     //
/////////////////////////////////////////////////////////////////////////
//  RevisedDemoInterface:                                              //
//    Required Files:                                                  //
//      RevisedDemoInterface.h, RevisedDemoInterface.cpp,              //
//      stdafx.h, stdafx.cpp                                           //
//    compiler command:                                                //
//      devenv RevisedDemoInterface.vcproj /make /rebuild              //
/////////////////////////////////////////////////////////////////////////
//  interfaceClient:                                                   //
//    Required Files:                                                  //
//      interfaceClient.cpp, stdafx.h, stdafx.cpp,                     //
//      DemoInterface.dll, DemoInterface.lib                           //
//    compiler command:                                                //
//      devenv interfaceClient.vcproj /make /rebuild                   //
/////////////////////////////////////////////////////////////////////////

//
#ifdef DEMODLL_EXPORTS
#define DEMODLL_API __declspec(dllexport)
#else
#define DEMODLL_API __declspec(dllimport)
#endif

class DEMODLL_API CDemoDll {

public:
	CDemoDll(void);
  void setDir(const char *path);
  const char* getDir();
  void restore();
  bool changed();

private:
  friend DEMODLL_API const char* GetDir();
  bool _changed;

  /// _PATHSIZE change breaks dllClient
  /// but does not break interfaceClient
  
  static const size_t _PATHSIZE = 100;  // too small

  char _curPath[_PATHSIZE];
  char _oldPath[_PATHSIZE];
};

DEMODLL_API void SetDir(const char *path);

DEMODLL_API const char* GetDir();

#endif