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Simulation of Variant type property

Posted on 1997-08-23
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Last Modified: 2013-11-23
Do you know how to simulate a VARIANT Type on published property ?
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Question by:dsam
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by:sassas081597
ID: 1342302
via Pointer
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mirek071497 earned 200 total points
ID: 1342303
Yes i know how.

but full implementation is for you.
This is template only and with new button which have variant property. You must decide which variants you need (integer, string, float ...).
You must write own GetValue and SetValue to do conversion from and to string which will shown in Object Inspector.

unit Varcomp;

interface

uses
  Windows, Messages, SysUtils, Classes, Graphics, Controls, Forms, Dialogs,
  StdCtrls;

type
  TTestVariant = class(TButton)
  private
    fVariant : Variant;
  protected {}
  public {}
  published {}
    property TestPropVariant : variant read fVariant write fVariant;
  end;

procedure Register;

implementation

uses
  DsgnIntf;

type
  TVarRecProperty = class(TPropertyEditor)
  public
    function AllEqual: Boolean; override;
    function GetValue: string; override;
    procedure SetValue(const Value: string); override;
  end;

procedure Register;
begin
  RegisterComponents('Samples', [TTestVariant]);
  RegisterPropertyEditor( TypeInfo(Variant), TComponent, '', TVarRecProperty );
end;

function TVarRecProperty.AllEqual: Boolean;
var
  I: Integer;
  V: Variant;
begin
  Result := False;
  if PropCount > 1 then
  begin
    V := GetVarValue;
    for I := 1 to PropCount - 1 do
      if GetVarValueAt(I) <> V then Exit;
  end;
  Result := True;
end;

function TVarRecProperty.GetValue: string;
var Vv : Variant;
begin
  Vv := GetVarValue;
  Result := '12.12';  { here you must change Variant Vv to string }
end;

procedure TVarRecProperty.SetValue(const Value: string);
var V : Variant;
begin
  Vv := 12.12; { here you must change String to Vv Variant Value }
  SetVarValue( Vv );
end;

end.
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by:mirek071497
ID: 1342304
Hi
What happened ? Any questions ?
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Expert Comment

by:mirek071497
ID: 1342305
another man on holliday.
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