Difference between revisions of "How To Use Interfaces"
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var | var | ||
− | I: ITestInterface; | + | I: ITestInterface = nil; |
begin | begin | ||
Writeln('Using regular interfaces'); | Writeln('Using regular interfaces'); |
Revision as of 18:47, 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. The default interface in FPC is COM, which makes that once a class with an interface is instantiated as that interface it will automatically be released. Note if you change the interface type to CORBA it WILL leak.
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,ITestInterface)
procedure DoSomething;
procedure DoItAll;
end;
procedure TBaseObject.DoSomething;
begin
Writeln('TBaseObject DoSomething !');
end;
procedure TBaseObject.DoItAll;
begin
Writeln('TBaseObject DoItAll !');
end;
procedure TderivedObect.DoSomething;
begin
Writeln('TderivedObect DoSomething !');
end;
procedure TderivedObect.DoItAll;
begin
Writeln('TderivedObect DoItAll !');
end;
var
I: ITestInterface = nil;
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.