用简单的Tracer类来为应用写入跟踪

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{       CodeMachine                 }
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{       版权所有 (C) 2004 nil   }
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{       2004-6-10                       }
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{
    通常将TTracer的实例存放于application级的Session中,在使用时,
    创建一个ITraceInfo,调用TTracer.Write(ITraceInfo)即可,
}

unit com.sunset.app.tracer;

interface

uses StrUtils,classes,SysUtils;

type

//==========================
// 接口声明
//==========================

    //跟踪信息的接口
    ITraceInfo = interface
        function ToString: string;
    end;
    //输出目标的接口
    IOutput = interface
        procedure Write(const aInfo: ITraceInfo); //写入跟踪信息
    end;

//==========================
// 跟踪信息类 ,实现 ITraceInfo
//==========================

    //string形式的跟踪记录
    TStringTI = class(TInterfacedObject, ITraceInfo)
    private
        FData: string;
    public
        constructor Create(data: string);
        function ToString: string;
    end;

//==========================
// 跟踪信息输出类,实现 IOutput
//==========================

[next]

    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;