07.Delphi接口的生命周期

在Delphi的接口中，是不需要释放的，调用完之后，接口的生命周期就结束了，如下面的例子

unit mtReaper;

interface

type
  // 定义一个接口
  IBase = interface
    ['{F3E97960-3F35-11D7-B847-001060806215}']
  end;

  TSun = class(TInterfacedObject, IBase)
  private
    FObject: TObject;
  public
    constructor Create(AObject: TObject);
    destructor Destroy; override;
  end;

implementation

uses
  SysUtils;

constructor TSun.Create(AObject: TObject);
begin
  FObject := AObject;
end;

destructor TSun.Destroy;
begin
  // 销毁时，释放传入的对象
  FreeAndNil(FObject);
  inherited;
end;

end.

调用单元如下

unit frmMain;

// Download by http://www.codefans.net
interface

uses
  Windows,
  Messages,
  SysUtils,
  Variants,
  Classes,
  Graphics,
  Controls,
  Forms,
  Dialogs,
  StdCtrls;

type
  TDeath = class(TObject)
  public
    destructor Destroy; override;
  end;

  TForm1 = class(TForm)
    Button1: TButton;
    Button2: TButton;
    procedure Button1Click(Sender: TObject);
    procedure Button2Click(Sender: TObject);
  private
    procedure WaitAWhile;
  public
    {Public declarations}
  end;

var
  Form1: TForm1;

implementation

uses
  mtReaper;
{$R *.dfm}


destructor TDeath.Destroy;
begin
  showMessage('对象销毁了！');
  inherited;
end;

procedure TForm1.WaitAWhile;
var
  i: Integer;
begin
  for i := 0 to 5000 do
  begin
    Caption := Inttostr(i);
  end;
end;

procedure TForm1.Button1Click(Sender: TObject);
var
  m_Death: TDeath;
begin
  m_Death := TDeath.Create;
  try
    WaitAWhile;
  finally
    m_Death.Free;
  end;
end;

procedure TForm1.Button2Click(Sender: TObject);
var
  m_Death: TDeath;
  m_Base:  IBase;
begin
  m_Death := TDeath.Create;
  // interface接口，不用手动释放，调用完之后，生命就结束了
  m_Base := TSun.Create(m_Death);
  WaitAWhile;
end;

end.