用简单的Tracer类来为应用写入跟踪

    TFileLog = class(TInterfacedObject, IOutput) 
    private 
        FLogFile: string; 
    public 
        constructor Create(const FileName: string); 
        procedure Write(const aInfo: ITraceInfo); //写入跟踪信息 
    end;

    TProcStr = procedure(const value:string) of Object; 
    TDatabaseLog = class(TInterfacedObject, IOutput) 
    private 
        FWriteProc :TProcStr; 
    public 
        constructor Create(WriteProc: TProcStr); 
        procedure Write(const aInfo: ITraceInfo); //写入跟踪信息 
    end;

//========================== 
// 跟踪工具 
//==========================

{ TTracer } 
    //用来进行记录跟踪日志的类 
    TTracer = class(TObject) 
    private 
        FOutput: IOutput; //输出目标 
        procedure SetOutput(const Value: IOutput); 
    public 
        constructor Create; overload; 
        constructor Create(aOutput: IOutput); overload; 
        destructor Destroy; override; 
        property Output: IOutput read FOutput write SetOutput; 
        procedure Write(const aInfo: ITraceInfo); //写入跟踪信息 
    end;

implementation

{ TTracer }

constructor TTracer.Create; 
begin

end;

constructor TTracer.Create(aOutput: IOutput); 
begin 
    FOutput := aOutput; 
end;