写日志函数AppLog（记录程序中的错误或操作流程） Delphi

procedure AppLog(msg: string); 
var
  f: textfile;
begin
  try
    try
      AssignFile(f, ExtractFilePath(ParamStr(0)) + 'app.log');
      if not fileexists(ExtractFilePath(ParamStr(0)) + 'app.log') then
        rewrite(f)
      else
        append(f);
      writeln(f, FormatDateTime('yyyy-MM-dd HH:mm:ss', Now()) + ' ' + msg);
    finally
      try
        closefile(f);
      except
      end;
    end;
  except

  end;
end;