Delphi objects: shortcut for TObjectList iteration

user_13952888 0
Viewed 111

I'm starting to learn and actively use OOP in my projects. I've found that constructions like LDevices.Devices[i] look very cumbersome and make code hard to read.

So there's my question: is there any way to be able to make a shortcut for a field to access it like LDevices[i], not LDevices.Devices[i]? Devices is TObjectList<TDevice>.

Structure of my object, for reference:

TDeviceStorage = class (TObject)
    private
      DevicesByID: TDictionary<Integer,TDevice>;
    public
      Devices: TObjectList<TDevice>;
      Constructor Create;
      Destructor Destroy; override;
      procedure AddDevice(aID: Integer; aName, aShortName: String; aSubtype, aLocation: Integer; aSteamID: String);
      procedure Clear();
      function Count(): Integer;
      function DeviceByID(aID: Integer): TDevice;
      function DeviceIndex(aID: Integer): Integer;
  end;
delphi-10.4-sydney iteration object delphi oop
1 Answers

Yes, this is exactly what the default directive on an array property is used for:

TDeviceStorage = class(TObject)
private
  FDevicesByID: TDictionary<Integer, TDevice>;
  FDevices: TObjectList<TDevice>;
  function GetDeviceCount: Integer;
  function GetDevice(Index: Integer): TDevice;
  procedure SetDevice(Index: Integer; const Value: TDevice);
public
  constructor Create;
  destructor Destroy; override;
  procedure AddDevice(AID: Integer; const AName, AShortName: string;
    ASubtype, ALocation: Integer; const ASteamID: string);
  procedure Clear;
  function DeviceByID(AID: Integer): TDevice;
  function DeviceIndex(AID: Integer): Integer;
  property Devices[Index: Integer]: TDevice read GetDevice write SetDevice; default;
  property DeviceCount: Integer read GetDeviceCount;
end;

with

function TDeviceStorage.GetDevice(Index: Integer): TDevice;
begin
  Result := FDevices[Index];
end;

function TDeviceStorage.GetDeviceCount: Integer;
begin
  Result := FDevices.Count;
end;

procedure TDeviceStorage.SetDevice(Index: Integer; const Value: TDevice);
begin
  FDevices[Index] := Value;
end;

Now, if DS: TDeviceStorage, you can write DS[i] to access the ith device in FDevices.

user_2828480
Related