How to check if an object implements an interface

[shineworld 86]

Hi all,

I've many TFrame objects which can implement one or more interfaces, depends.

There is a Delphi way to check if a frame implements an interface?

E.g:
 

procedure UpdateTheme(Obj: TFrame);
begin
   if "Obj implements ITheme" then
      (Obj as ITheme).UpdateTheme;
end;

 

[Dalija Prasnikar 1525]

Use Supports function

 

var
  LTheme: ITheme;
begin
  if Supports(Obj, ITheme, LTheme) then
    LTheme.UpdateTheme;
end;

 

[Vincent Parrett 853]

procedure UpdateTheme(Obj: TFrame);
var
  objAsIThen : ITheme;
begin
  If Supports(Obj, ITheme, objAsIThen) then
      objAsITheme.UpdateTheme;
end;