Was kann man beim Entwurf dieser Klasse besser machen?

[Luckie]

Hier die Klasse und deren Implementation:

Delphi-Quellcode:

type
  TSplitStrArray = array of String;

type TSplitString = class
 private
   FString2Split : String;
   FSepChar      : Char;
   FStrings      : TSplitStrArray;
   FStringsCount : Integer;
   FSepPos       : array of Integer;
   procedure SetSplitString(SplitStr: String);
   procedure SetSepChar(sep: Char);
   procedure SetSepPos;
   procedure SplitString;
 public
   constructor create(SplitStr: String; sep: Char);
   function StringsCount: Integer;
   property String2Split: String read FString2Split write SetSplitString;
   property SepChar: Char read FSepChar write SetSepChar;
   function ReturnSepStrings: TSplitStrArray;
end;

constructor TSplitString.create(SplitStr: String; sep: Char);
var
  i : Integer;
begin
  FStringsCount := 0;
  if SplitStr = '' then
  begin
    Messagebox(0, 'Die Zeichenfolge ist leer.', 'Hinweis - TSplitString', MB_ICONSTOP);
    exit;
  end;
  if SplitStr[length(SplitStr)] <> sep then
    SplitStr := SplitStr+sep;
  for i := 0 to length(SplitStr) do
  begin
    if SplitStr[i] = sep then Inc(FStringsCount);
  end;
  SetSplitString(SplitStr);
  SetSepChar(sep);
  SetSepPos;
end;

procedure TSplitString.SetSepPos;
var
  i, j : Integer;
begin
  j := 0;
  setlength(FSepPos, FStringsCount+1);
  FSepPos[0] := 0;
  for i := 0 to length(FString2Split) do
  begin
    if FString2Split[i] = FSepChar then
    begin
      Inc(j);
      FSepPos[j] := i;
    end;
  end;
end;

procedure TSplitString.SetSplitString(SplitStr: String);
begin
  if SplitStr = '' then
    Messagebox(0, 'Die Zeichenfolge ist leer.', 'Hinweis - TSplitString', MB_ICONINFORMATION);
  FString2Split := SplitStr;
end;

procedure TSplitString.SetSepChar(sep: Char);
begin
  if sep = '' then
    Messagebox(0, 'Das Trennzeichen ist leer.', 'Hinweis - TSpliString', MB_ICONINFORMATION);
  FSepChar := sep;
end;

function TSplitString.StringsCount: Integer;
begin
  result := FStringsCount;
end;

procedure TSplitString.SplitString;
var
  i   : Integer;
begin
  setlength(FStrings, FStringsCount);
  for i := 0 to FStringsCount-1 do
  begin
    FStrings[i] := copy(FString2Split, FSepPos[i]+1, FsepPos[i+1]-FSepPos[i]-1);
  end;
end;

function TSplitString.ReturnSepStrings: TSplitStrArray;
begin
  result := FStrings;
end;

procedure TForm1.Button1Click(Sender: TObject);
var
  ObjSplitString: TSplitString;
  i : Integer;
begin
  ObjSplitString := TSplitString.create(Edit1.Text, ';');
  try
    Label1.Caption := IntToStr(ObjSplitString.StringsCount);
    for i := 0 to ObjSplitString.FStringsCount do
    begin
      Listbox1.Items.Add(IntToStr(ObjSplitString.FSepPos[i]));
    end;
    ObjSplitString.SplitString;
    for i := 0 to ObjSplitString.FStringsCount-1 do
    begin
      Listbox2.Items.Add(ObjSplitString.FStrings[i]);
    end;
  finally
    ObjSplitString.Free;
  end;
end;

Es geht mir um den reinen Entwurf der Klasse nicht um die Implementation der Methoden der Klasse.
Vorallem wie man Fehler Abfangen kann, wenn die zeichenfolge leer ist oder der Separator '' ist.