Difference between revisions of "How To Use Interfaces"

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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.
 
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.
<syntaxhighlight>{$mode objfpc}{$H+}{$interfaces com} // which is the default
+
<syntaxhighlight>program interfacesygenerics;
 +
{$mode objfpc}{$H+}
 
type
 
type
 
   ITestInterface = interface
 
   ITestInterface = interface
Line 13: Line 14:
 
   end;
 
   end;
  
 +
  TderivedObect = class(TBaseObject)
 +
  end;
 +
 
 
   procedure TBaseObject.DoSomething;
 
   procedure TBaseObject.DoSomething;
 
   begin
 
   begin
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begin
 
begin
 
   Writeln('Using regular interfaces');
 
   Writeln('Using regular interfaces');
   I := TBaseObject.Create as ITestInterface;
+
   I := TderivedObect.Create as ITestInterface;
 
   if I <> nil then
 
   if I <> nil then
 
     Writeln('Got interface OK. Calling it');
 
     Writeln('Got interface OK. Calling it');
 
   I.DoSomething;
 
   I.DoSomething;
 
   I.DoItAll;
 
   I.DoItAll;
end.
+
end.</syntaxhighlight>
</syntaxhighlight>
 
 
== See also ==
 
== See also ==
  

Revision as of 16:24, 5 October 2021

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