How To Use Interfaces

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Revision as of 16:24, 5 October 2021 by Thaddy (talk | contribs)
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Copy the text below and it will demonstrate how to use Interfaces to write less code, avoid code repetition,..., this is a fully working program.

program interfacesygenerics;
{$mode objfpc}{$H+}
type
  ITestInterface = interface
    ['{3FB19775-F5FA-464C-B10C-D8137D742088}']
    procedure DoSomething;
    procedure DoItAll;
  end;

  TBaseObject = class(TInterfacedObject,ITestInterface)
    procedure DoSomething;
    procedure DoItAll;
  end;

  TderivedObect = class(TBaseObject)
  end;
  
  procedure TBaseObject.DoSomething;
  begin
    Writeln('TBaseObject DoSomething !');
  end;

  procedure TBaseObject.DoItAll;
  begin
    Writeln('TBaseObject DoItAll !');
  end;
var
  I: ITestInterface;
begin
  Writeln('Using regular interfaces');
  I := TderivedObect.Create as ITestInterface;
  if I <> nil then
    Writeln('Got interface OK. Calling it');
  I.DoSomething;
  I.DoItAll;
end.

See also