Custom Constructor /DI bei factory-basierter Objekterstellung

[Stevie]

Hier mal ein kleines Beispiel:

Delphi-Quellcode:

program Simple_DI;

{$APPTYPE CONSOLE}

uses
  System.SysUtils,
  SimpleContainer in 'SimpleContainer.pas';

type
  IX = interface
    ['{E2D88E1C-AE7D-491A-B456-84B134749890}']
  end;

  IY = interface
    ['{3D1256AB-CDDE-49B2-94CF-E9FA82314206}']
  end;

  IZ = interface
    ['{4F51DE5D-B65B-4776-B25B-5B2868DC34AC}']
  end;

  TX = class(TInterfacedObject, IX)
  private
    fy: IY;
    fz: IZ;
  public
    constructor Create(const y: IY; const z: IZ);
  end;

  TY = class(TInterfacedObject, IY)
    constructor Create;
  end;

  TZ = class(TInterfacedObject, IZ)
    constructor Create;
  end;

{ TX }

constructor TX.Create(const y: IY; const z: IZ);
begin
  Writeln('creating ', ClassName);
  Writeln('injected ', (y as TObject).ClassName, ' for y');
  Writeln('injected ', (z as TObject).ClassName, ' for z');

  fy := y;
  fz := z;
end;

{ TY }

constructor TY.Create;
begin
  Writeln('creating ', ClassName);
end;

{ TZ }

constructor TZ.Create;
begin
  Writeln('creating ', ClassName);
end;

var
  container: TSimpleContainer;
  x: IX;
begin
  // showing the so called register, resole, release (RRR) pattern
  // see http://blog.ploeh.dk/2010/09/29/TheRegisterResolveReleasepattern/

  container := TSimpleContainer.Create;
  try
    // register
    container.Add<IX, TX>;
    container.Add<IY, TY>;
    container.Add<IZ, TZ>;

    // resolve
    x := container.Get<IX>;
  finally
    // release
    x := nil;
    container.Free;
  end;
end.