CODEWITHSUNDEEP
delphipropertiescomponentsdelphi-7
EProgrammerNotFound
EProgrammerNotFound

Reputation: 2461

Default property value of a component

I wonder if it is possible to define a default property value to a component.
In another words, I want to set, in design time, an unique name (maybe GUID) to each TDBGrid in the system, is it possible?
There is another way to control uniqueness of a component that works both in runtime and design time. Also it must persists after I close delphi; e.g combobox list values.

Thanks in advance!

edit

below is the code, that is not working:

type
  TMDBGrid = class(TDBGrid)
  private
    FUniqueName: String;
  protected
    function DefaultUniqueName: String;
    function GetUniqueName: String;
    procedure SetUniqueName(const AName: String);
  public
    constructor Create(AOwner: TComponent); override;
  published
    property UniqueName: String read GetUniqueName write SetUniqueName;
  end;

procedure Register;

implementation

uses uComponentUtils;

procedure Register;
begin
  RegisterComponents('MLStandard', [TMDBGrid]);
end;

{ TMDBGrid }

constructor TMDBGrid.Create(AOwner: TComponent);
begin
  inherited;
  FUniqueName := DefaultUniqueName;
end;

function TMDBGrid.DefaultUniqueName: String;
begin
  Result := GenerateGUID(True);
end;

function TMDBGrid.GetUniqueName: String;
begin
  Result := '';
end;

procedure TMDBGrid.SetUniqueName(const AName: String);
begin
  FUniqueName := AName;
  if FUniqueName = '' then
    FUniqueName := DefaultUniqueName;
end;

function GenerateGUID(PlainText: Boolean = False): String;
var G: TGUID;
begin
  CreateGUID(G);
  Result:= GUIDToString(G);
  if PlainText then
    Result := MultiStringReplace(Result, ['{','}','[',']','-','.',' ','(',')'],
                                         ['','','','','','','','',''],
                                         [rfReplaceAll, rfIgnoreCase]);
end;

"It's not working" means when a TDBGrid is added to any form, UNIQUENAME is empty. It should have a GUID.

Upvotes: 1

Views: 2275

Answers (1)

David Heffernan
David Heffernan

Reputation: 612993

Your implementation of GetUniqueName does not return anything. It needs to return FUniqueName.

function TMDBGrid.GetUniqueName: String;
begin
  Result := FUniqueName;
end;

Or you could delete the getter and change the property to be like so:

property UniqueName: String read FUniqueName write SetUniqueName;

Upvotes: 5

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