工作记录

ADOQuery override 的 iprovidersupport

吃得很胖的虾 — 2004-12-03 20:21:00Z

该死的DBISAM不支持iprovider ,去论坛上看,居然说早就知道这个问题,但最近太忙,没时间实现,faint...

正好要用到clientdataset 只好仿照ADOQuery 来实现接口的部分过程.

adoQuery override 的接口函数

procedure PSEndTransaction(Commit: Boolean); override;
procedure PSExecute; override;
function PSExecuteStatement(const ASQL: string; AParams: TParams; ResultSet: Pointer = nil): Integer; override;
procedure PSGetAttributes(List: TList); override;
function PSGetDefaultOrder: TIndexDef; override;
function PSGetKeyFields: string; override;
function PSGetParams: TParams; override;
function PSGetQuoteChar: string; override;
function PSGetTableName: string; override;
function PSGetIndexDefs(IndexTypes: TIndexOptions = [ixPrimary..ixNonMaintained]): TIndexDefs; override;
function PSGetUpdateException(E: Exception; Prev: EUpdateError): EUpdateError; override;
function PSInTransaction: Boolean; override;
function PSIsSQLBased: Boolean; override;
function PSIsSQLSupported: Boolean; override;
procedure PSReset; override;
procedure PSSetParams(AParams: TParams); override;
procedure PSSetCommandText(const CommandText: string); override;
procedure PSStartTransaction; override;
function PSUpdateRecord(UpdateKind: TUpdateKind; Delta: TDataSet): Boolean; override;

解决intraweb7.x在delphi 7下安装帮助文件后无法按F1导向的问题．

吃得很胖的虾 — 2004-12-03 12:38:00Z

其实很简单，安装完index content link后，记得把borland delphi help目录下的d7.gid删除掉．

webserver的错误捕捉和类型

吃得很胖的虾 — 2004-11-20 16:49:00Z

异常类型:

1.前台导向类

程序可通过try except块来捕捉,根据异常handle来判断程序处理.通过生成错误导向页面来引导用户处理.

2.后台异常类

后台程序出现可预知的错误,通过try except块来捕捉,根据异常handle来判断程序处理,运行时log到指定文件.

3.后台无法预料的错误

用madshiExcept捕捉后让用户选择处理方式.

delphi 下用assert 来完成错误的捕捉.

吃得很胖的虾 — 2004-11-20 16:18:00Z

Assert 过程原形
[code]procedure Assert (expr :Boolean [; const msg: string]);[/code]
在system.pas 里 Assert 的实现是:

procedure _Assert(const Message, Filename: AnsiString; LineNumber: Integer);
{$IFDEF PUREPASCAL}
begin
  if Assigned(AssertErrorProc) then
    AssertErrorProc(Message, Filename, LineNumber, Pointer(-1))
  else
    Error(reAssertionFailed);  // loses return address
end;
{$ELSE}
asm
        PUSH    EBX
{$IFDEF PIC}
        PUSH    EAX
        PUSH    ECX
        CALL    GetGOT
        MOV     EBX, EAX
        MOV     EAX, [EBX].AssertErrorProc
        CMP     [EAX], 0
        POP     ECX
        POP     EAX
{$ELSE}
        CMP     AssertErrorProc,0
{$ENDIF}
        JNZ     @@1
        MOV     AL,reAssertionFailed
        CALL    Error
        JMP     @@exit
@@1:    PUSH    [ESP+4].Pointer
{$IFDEF PIC}
        MOV     EBX, [EBX].AssertErrorProc
        CALL    [EBX]
{$ELSE}
        CALL    AssertErrorProc
{$ENDIF}
@@exit:
        POP     EBX
end;
{$ENDIF}

可以看出AssertErrorProc() 是没有初值的,通过对其赋值可以定义自己的Assert处理过程,另如果未对AssertErrorProc赋值,将调用Error()处理过程来做为异常处理.

TAssertErrorProc = procedure (const Message, Filename: string;
LineNumber: Integer; ErrorAddr: Pointer);

{$ASSERTIONS OFF/ON} 开关来决定Assert是否被调用.可以在project-option-complier里设置.

这样就可以在beta或debug版本是打开,而最终发布时关闭调试输出了.

一个简单的AssertErrorProc 例程:

unit AssertLogs;

interface

implementation
uses
Windows,
SysUtils;

var
runErrMsg : String;
oldAssertErrorProc : TAssertErrorProc;

procedure LogAssert(const Message, Filename: string; LineNumber: Integer; ErrorAddr: Pointer);
begin
runErrMsg := format('Error: %s, Addr: %p, in file(%d): %s ',
                      [Message, ErrorAddr, LineNumber, FileName]);
if IsConsole then
    Writeln(runErrMsg)
else
    MessageBox(0, pChar(runErrMsg), 'Error Log by AssertLogs', 0);
end;

initialization
oldAssertErrorProc := AssertErrorProc;
AssertErrorProc := @LogAssert;

finalization
AssertErrorProc := oldAssertErrorProc;
end.

*************************************
那么在output debug信息时只需要:

Assert(false,outputstring);

我的开发环境

吃得很胖的虾 — 2004-11-19 15:11:00Z