{
This post is just to demonstrate a very simple sorted collection using
non-Object Types With the collection.  If it is needed to store itself
to a stream, it will need additional over-ridden methods to do that.
I'm just posting this, because I wrote it several days ago to implement
a simple Variable system in a script language For a menu Program that I
wrote, and I was looking For an *easier* way to maintain the Variable
list than With a linked list.  To my astonishment, today, I needed a
similar structure, and (ohmygosh) I found that I could *re-use* this
code, by merely deriving a child class and adding another method or so.
This is the first time that I have ever *re-used* an Object Type that I
have modified.  Of course, I haven't been actually using TurboVision for
more than a month or so, so I haven't had much of a chance, but it is
very nice to see that when people talk about "Object oriented
Programming paradigm", they are not ONLY speaking in big Words, but that
they also (apparently) are telling the truth.

I'm not taking any responsibility if this overWrites your interrupt
vector table, so be carefull.  If you find any mistakes, or actually
modify this code to become more usefull, I'd appreciate it if you could
tell me- actually determining the best way to implement a new Object
class is kind of difficult For me since I've only been doing this for
about a month, trying to squeeze it in along With school and a job.

Here's the code...
{********* STARTS HERE **********}
{ Unit: STROBJ.PAS
  WRITTEN BY: Brian Pape
  DATE: 03/28/93
  Copyright 1993 by Brian Pape and Alphawave Technologies
  This Unit contains String Type Objects
}
{$P+}  { Enable open String parameters.  Replace by $V- For TP 6.0 or lower }
Unit strobj;

Interface

Uses
  Objects;

Type
  str20 = String[20];

  PVarType = ^TVarType;
  TVarType = Record
    name  : str20;
    value : String;
  end;  { TVarType }

  PVarCollection = ^TVarCollection;
  TVarCollection = Object(TSortedCollection)
    Constructor init(Alimit,Adelta:Integer);
    Function KeyOf(item:Pointer):Pointer; virtual;
    Function Compare(Key1,Key2:Pointer):Integer; virtual;
    Procedure freeitem(Item:Pointer); virtual;

    { This Function will return the value of a Variable in a TVarCollection }
    Function getVar(s:String):String;

    { Adds a PVarType Record to the collection, without having to manually
      create, and allocate memory for, a Record Type }
    Procedure add(aname:str20;avalue:String);
  end;  { TVarCollection }

Implementation

Constructor TVarCollection.init(ALimit,ADelta:Integer);
begin
  inherited init(ALimit,ADelta);
end;  { TVarCollection.init }

Function TVarCollection.KeyOf(item:Pointer):Pointer;
begin
  KeyOf := @(TVarType(item^).name);
end;  { TVarCollection.KeyOf }

Function TVarCollection.Compare(Key1,Key2:Pointer):Integer;
begin
  if String(Key1^) > String(Key2^) then
    Compare := 1
  else if String(Key1^) = String(Key2^) then
    Compare := 0
  else Compare := -1;
end;  { TVarCollection.Compare }

Procedure TVarCollection.freeitem(Item:Pointer);
begin
  dispose(Item);
end;  { freeitem }

Function TVarCollection.getVar(s:String):String;
Var
  t : TVarType;
  where : Integer;
begin
  t.name := s;
  if Search(@t,where) then
    getVar := TVarType(at(where)^).value
  else
    getVar := '';
end;  { getVar }


Procedure TVarCollection.add(aname:str20;avalue:String);
Var
  rec : PVarType;
begin
  rec := new(PVarType);
  rec^.name := aname;
  rec^.value := avalue;
  insert(rec);
end;  { add }

begin
end.  { strobj }
{*********** endS HERE *************}