Create True Windows DLL's From Clipper/FiveWin Code!

FiveDLL allows you create a Windows DLL with Clipper code and run this from a FiveWin application. Clipper Functions and Public Variables can be called from both Executable and DLL. Also C Code can be placed into the DLL that calls documented and undocumented api functions linked into the Executable.

With FiveDLL, you can:

• If you have to modify code which has been placed in this library, you only have to update one file (the DLL) instead of each and every .exe file.
• Your code cannot be DE-Compiled
• You can dynamically upgrade Applications by simply adding DLL-Modules. Clients can buy new modules which are then automatically "linked in" to the Main Application.
• FiveDLL comes with a Norton guide that describes the internal structure of clipper and lists lots of undocumented low level functions and pointers.
• FiveDLL decreases your Applications Memory footprint by dynamically loading only those modules that are required.

FiveDll Usage

To create a DLL with FiveDB, first compile all your modules that are to be included in the DLL. Include the NODEFLIB command in the Link script, because otherwise the standard \ clipper libraries will be linked into your DLL, which will make a dead sure GPF generator of your DLL. Clipper libraries have to be linked inot the main executable; they are unfortunately not programmed to work in a DLL, where the Stack and the DGROUP are in different segments. Some of the functions may work, while others definately will not, so make sure that the libs stay out of your DLL. The only LIB that is linked to the DLL ( beside FiveDLL.LIB ) is FiveWins Implib WINAPI.LIB.

Include EXPORTS DLLSymInit in the link script, and EXPORTS any other functions in the DLL that you want to call from outside the DLL (namely your exe) .Run your make/link script, and your DLL will be created, you might now add your resources to this DLL.

There are two ways you can use your DLL from the Executable:

• You can do it statically, which means that you add the DLLs ImpLib to the list of libraries in the executables link script. The fortune of doing so is, that the DLL is loaded automatically, and every EXPORTED function in the DLL will be resolved by the linker.

  The Drawback is, that the application will not run, if the DLL is not found. You also need to create an IMPLIB to inform the linker about where to find the functions that are inside the DLL, this is done with Blinker's BLILIB, Microsofts IMPLIB, Watcom WLIB or Borlands DEFLIB Tools.

• The second way is to load the DLL at runtime.This means that the executable at startup does not know which functions are in the DLL, and you load the DLL later with LoadLibrary(). The benefit of this is that you can have different DLLs for different environments / tasks, and then decide at runtime which one to use. The drawback is that you have to manage the DLL manually like this IF ABS( hDLL := LoadLibrary( "Test.Dll" )) <= 32
  CallDLL( GetProcAddress( hDll, "DLLSYMINIT", .T., 4 ))
  ENDIF

System Requirements:

• 386 or faster processor, Windows 3.11, Windows 95/98 or Windows NT 4.0
• Clipper 5.2 or 5.3, and FiveWin/Vampire 1.9x or higher
• An Import Librarian like Blinker BLILIB or Microsoft IMPLIB is recommended