usnapshot.pas

来自「Delphi面向对象编程思想附书源码 好用哦！」· PAS 代码 · 共 46 行

unit uSnapshot;

interface

uses SysUtils, mtReaper,classes;

type
  ISnapshot=interface
    ['{FA256FA8-211F-462D-890B-FC0EB6096AD8}']
    procedure Restore;
  end;

  TSnapshot=class(TInterfacedObject,ISnapshot)
  private
    FOriginal:TPersistent;
    FTarget:TPersistent;
    FReaper:ImtReaper;
  public
    constructor Create(Target:TPersistent);
    destructor Destroy;override;
    procedure Restore;
  end;

implementation

constructor TSnapshot.create(Target:TPersistent);
begin
  FOriginal:=TPersistent(Target.classType.create);
  FReaper:=TmtReaper.create(FOriginal);
  FTarget:=Target;
  FOriginal.Assign(Target);
end;

destructor TSnapshot.Destroy;
begin
  restore;
  Inherited;
end;

procedure TSnapshot.Restore;
begin
  if FTarget<>nil  then
    FTarget.Assign(FOriginal);
end;
end.