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 What is and how to use a DLL ?
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   In some aspects, you may think in a DLL (Dynamic Link Libraries) as the
   modern version of overlays. Though, of course, DLLs are much more powerful.

   A DLL contains code (functions that you may use from your application) and
   also data. This is why we use them in FiveWin as a way of external storing
   our application resources.

   The big advantages of DLLs are:

      * DLLs can be used by several applications at the same time
        (and just one DLL instance is loaded by Windows!).

      * DLLs are programming language independent (in those situations
        where DLLs have been properly designed keeping in mind that other
        programmers may use them!).

      * If you develop applications that support multiple languages:
        create a DLL for each language supported after translating the
        dialogs, strings and messages to the target language(s). Then
        supply the appropriate .DLL (and help file) for that language.

   Due to the possibility that the DLL is used by several applications
   at the same time, the DLL uses the variables data from the program that
   is using the DLL. This is something you don't have to worry about but
   it is convenient that you know if sometimes you decide to write a DLL.

   You may not use CA-Clipper and FiveWin to develop DLLs. Use C or C++ to
   develop DLLs in case you need it.

   There are two ways of using a function which it is stored inside a DLL:

      * Linking at run-time

      * Telling the linker to use it.

   The xBase commands that FiveWin offers are for using DLLs at run-time.
   This has the advantage that you may select any DLL at run-time, but
   a small inconvenience is that it is not as fast as if you tell the
   linker to automatically link it when it is necessary.

   If you use the second way, which is faster, it is essential that the DLL
   you are going to access exists on the computer and is accessible.
   If not, Windows will warn you and the application will not execute.

   If you plan to develop an application which extensively uses DLLs calls
   it is more convenient that you develop a C module that access that DLL.

   See the following DLLs management xBase commands for an explanation
   of these two ways.