The PDDLA Programming Language

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*
* PRODIDACT Language Auteur - PDDLA
*
* This is a sample of the PRODIDACT programming Language created
* to develope multi-media MS-DOS applications. The language was
* created by Frederic Torres in 1990 and used in numerous applications
* up to 1993. The run time was written in Turbo Pascal/Borland Pascal.
*
* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
*
* The PDDLA Programming Language
* ------------------------------
* The language was a simple structured programming language inspired by the
* PASCAL language. All the reserved keywords are in French.
* The language execution was based on an interpreter.
*
*
* Language
* - - - - -
*
* Though, it was inspired by PASCAL there was some differences.
*
* - No user function.
*
* - Variable Scope: Local variables were actually available to any sub
*   procedures called. This is bizarre and a probably not a good idea.
*   But this is how I implemented the variable/memory manager.
*   At the end of a procedure all local variables would be discarded.
*   It was also possible to declare global variables.
*
* - Array: There was no array, but array could be simulated using the
*   & macro concept as implemented in the dBASE language. See below in
*   this file.
*
* - Procedure Pointer/Delegate: It was possible to simulate procedure
*   pointer/delegate using the & macro concept.See below in this file.
*
* - Object Orientation: The language was not object oriented, but allowed
*   the char '.' in procedure and variable name. Therefore creating the
*   illusion of some kind of object orientation.
*
* - Debugger: There was no debugger, but a real time tracing mode at the
*   top of the screen.
*
* - Source code overlay:It was possible to load and un load dynamically
*   source code. The reason why is that we had only 640 Kb of memory.
*
* - String could has predefined max length to save memory.
*
*
* Multi media support: (Obvisouly in 2010 this sound lame, but it was in 1990).
* - - - - - - - - - -
*
* - Keyboard and mouse
* - 16 colors PCX image
* - Amimation (list of images displayed in loop)
* - Hypertext file (basically it was simple HTML file)
* - Special text display and menu in form of comic strip
* - Customizable font.
* - Virtual memory manager to save and restore screen area.
*
*
* Integrity
* - - - - -
*
* The source files can be encrypted before shipping. Applications shipped
* could not be altered all image files, hypertext files and dictionary
* definition files would be verified at the starting time. If a change was
* detected the application would not start.
*
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* Include the file Lib.EAO
$I Lib

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** Procedure Debug (AKA Main)
**
Procedure DEBUT;

    GlobalVariables.Initialize;
    Chemin("images",""); * Define the sub paths where to the pcx images

    Screen.Clear;
    Screen.PrintXY(0, 0, "Hello World - Press SPACE to continue");
    Image("VOITURE1", 200, 200);
    UserPause;

    Screen.Clear;
    Array.Demonstration;
    UserPause;

    Screen.Clear;
    ProcedurePointer.Demonstration;
    UserPause;

    Screen.Clear;
    RunModule("MyModule", "PrintThis");
    UserPause;

    HyperTexte("HyperText.HT", "Page1");
    UserPause;
Fin;

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**
**
Procedure Array.Demonstration;

    Chaine MSG_0 := "message 1"; * declare a string
    Chaine MSG_1 := "message 2";
    Chaine MSG_2 := "message 3";
    Entier i     := 0;

    TantQue i<=2 Faire * While loop

        Chaine s  := "MSG_" + Chaine(i);
        Chaine ss := &s;
        Screen.PrintXY(0, i * 14, ss);
        i := i + 1;
    Fin;
Fin;

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**
**
Procedure ProcedurePointer.Demonstration;

    Chaine s := "MyProcedure";
    &s; * Call procedure MyProcedure indirectly
Fin;

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**
**
Procedure MyProcedure;

    Screen.Clear;
    Screen.PrintXY(0,0,"My Procedure");
    UserPause;
Fin;

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**
**
Procedure RunModule(Chaine m,p)
  ChargeModule(m) * Load module
  &p;             * Execute procedure name contained in variable p
  DeChargeModule  * Unload module
FIN;

See file LIB.EAO