Delphi merkt nicht wenn ein case-Statement vollständig ist, oder?

[Uwe Raabe]

Das hat eigentlich ganz andere Gründe. Nehmen wir z.B. einen Enum-Typ, der positive und negative Elemente enthält. Bei positiven bzw. negativen Werten sind spezifische Code-Teile auszuführen, die teilweise vom genauen Wert unabhängig sind, während andere Teile vom exakten Wert abhängen:

Delphi-Quellcode:

type
{$SCOPEDENUMS ON}
  TRating = (undefined, Perfect, OK, Acceptable, NotGoodEnough, Bad, TotalShit);

  TRatingHelper = record helper for TRating
    procedure HandleIncompleteCase(Rating: TRating);
  end;

procedure TRatingHelper.HandleIncompleteCase(Rating: TRating);
begin
  raise EProgrammerNotFound.Create('unhandled case for TRating: ' + TRttiEnumerationType.GetName(Rating));
end;

const
  cRatingPositive = [TRating.Perfect, TRating.OK, TRating.Acceptable];
  cRatingNegative = [TRating.NotGoodEnough, TRating.Bad, TRating.TotalShit];

procedure HandleRating(Rating: TRating);
begin
  if Rating in cRatingPositive then begin
    // Handle positive rating part 1
    ...
    // Handle specific rating
    case Rating of
      TRating.Perfect: ...;
      TRating.OK: ...;
      TRating.Acceptable: ...;
    else
      HandleIncompleteCase(Rating);
    end;
    // Handle positive rating part 2
    ...
  end
  else if Rating in cRatingNegative begin
    // Handle negative rating part 1
    ...
    // Handle specific rating
    case Rating of
      TRating.NotGoodEnough: ...;
      TRating.Bad: ...;
      TRating.TotalShit: ...;
    else
      HandleIncompleteCase(Rating);
    end;
    // Handle negative rating part 2
    ...
  end
  else begin
    // Handle undefined rating
    ...
  end;
end;