COM对象和不同版本的DLL

Question

我对DLL对象非常陌生，我到处寻找都找不到正确的答案。我对Microsoft RMS做了一些附加操作，它会自动从我的动态链接库调用函数进程，并使用IDispach参数传递当前会话的详细信息。

我使用的是来自QSRules.dll的接口(组件>导入>组件>类型库...添加到项目)。它创建包含所有引用的TLB文件等。

procedure TRefreshScreenRefreshScreen.Process(const Session: IDispatch);
begin

  CodeSite.Send( csmLevel1, '(Session as SessionClass).Cashier.Name', (Session as SessionClass).Cashier.Name );
  CodeSite.Send( csmLevel1, '(Session as SessionClass).Cashier.Number', (Session as SessionClass).Cashier.Number );

end;

这在2.01版本的软件上工作得很好，但当试图在2.02版本上使用相同的功能时，它会崩溃，并显示“不支持的接口”。QSRules.dll已更新版本，所有类的GUID都不同。

我用code代码试过了：

procedure TRefreshScreenRefreshScreen.Process(const Session: IDispatch);
begin

  if Supports(Session, QSRules_TLB_2_0_0_151.SessionClass) then
    Begin
      CodeSite.Send( csmLevel1, '(Session as SessionClass).Cashier.Name', (Session as QSRules_TLB_2_0_0_151.SessionClass).Cashier.Name );
      CodeSite.Send( csmLevel1, '(Session as SessionClass).Cashier.Number', (Session as QSRules_TLB_2_0_0_151.SessionClass).Cashier.Number );
    end else

  if Supports(Session, QSRules_TLB_2_0_0_105.SessionClass) then
    Begin
      CodeSite.Send( csmLevel1, '(Session as SessionClass).Cashier.Name', (Session as QSRules_TLB_2_0_0_105.SessionClass).Cashier.Name );
      CodeSite.Send( csmLevel1, '(Session as SessionClass).Cashier.Number', (Session as QSRules_TLB_2_0_0_151.SessionClass).Cashier.Number );
    end

end;

有4到5个不同版本的dll，它们都有不同的GUID，但它们之间98%的代码是相同的。这样做是不必要的代码倍增。

有什么办法可以缩短吗？

我也试过了

procedure TRefreshScreenRefreshScreen.Process(const Session: IDispatch);
var
 _Session: SessionClass;
begin

  if Supports(Session, QSRules_TLB_2_0_0_151.SessionClass) then
    _Session = (Session as QSRules_TLB_2_0_0_151.SessionClass)

  else if Supports(Session, QSRules_TLB_2_0_0_105.SessionClass) then
      _Session = (Session as QSRules_TLB_2_0_0_105.SessionClass);

  with _Session do
  Begin
      CodeSite.Send( csmLevel1, '_Session.Cashier.Name', Cashier.Name );
      CodeSite.Send( csmLevel1, '_Session..Cashier.Number', Cashier.Number );
  End;

end;

但这不起作用，因为变量类型只能从单位赋值。

感谢任何人的帮助！

Answer 1

终于把它整理好了！只要分享答案，以防其他人在寻找它。

成功的关键是“后期绑定”，这意味着你不需要使用接口。

procedure TRefreshScreenRefreshScreen.Process(const Session: IDispatch);
var
 _Session: Variant;
begin

  _Session := Session;

  CodeSite.Send( csmLevel1, '_Session.Cashier.Name', _Session.Cashier.Name );
  CodeSite.Send( csmLevel1, '_Session.Cashier.Number', _Session.Cashier.Number );

end;

对于可变变量，函数不是由编译器检查的，而是在运行时检查的，因此您必须确保拼写正确，因为intellisense不会检查它。

像做梦一样工作！

无论如何，谢谢你们所有人！

Answer 2

您说接口在不同的版本中有不同的guids。只要新的接口是从旧的接口派生出来的，这就完全没问题了。真的是这样吗？如果是这样，那么您可以通过将Session对象转换为实际定义收银员成员的任何接口来简化代码。您不需要将其强制转换为每个单独的接口类型，除非这些接口不是彼此派生的。你能展示实际的接口声明吗？

Answer 3

v2.0.0.105中的收银员声明

_Cashier = interface(IDispatch)
    ['{AA84B4FB-AA41-4423-A763-59D0723ED52B}']
    function Get_Session: _SessionClass; safecall;
    function Get_CashDrawer: _CashDrawer; safecall;
    function Get_OverShortLimitType: overshortlimitEnum; safecall;
    function Get_MaxOverShortAmount: Currency; safecall;
    function Get_MaxOverShortPercent: Double; safecall;
    function Get_SecurityLevel: Smallint; safecall;
    function Get_HasPrivilege(var CashierPrivilege: cashierprivilegesEnum): WordBool; safecall;
    function Get_FailedLogOnAttempts: Integer; safecall;
    function Get_EmailAddress: WideString; safecall;
    function Get_Messages: _CashierMessages; safecall;
    function Get_UnreadMessageCount: Integer; safecall;
    function Get_Name: WideString; safecall;
    function Get_FirstName: WideString; safecall;
    function Get_LastName: WideString; safecall;
    function Get_ReturnLimit: Currency; safecall;
    function Get_FloorLimit: Currency; safecall;
    function Get_ID: Integer; safecall;
    function Get_CashDrawerNumber: Smallint; safecall;
    function Get_Loaded: WordBool; safecall;
    function Get_Number: WideString; safecall;
    property Session: _SessionClass read Get_Session;
    property CashDrawer: _CashDrawer read Get_CashDrawer;
    property OverShortLimitType: overshortlimitEnum read Get_OverShortLimitType;
    property MaxOverShortAmount: Currency read Get_MaxOverShortAmount;
    property MaxOverShortPercent: Double read Get_MaxOverShortPercent;
    property SecurityLevel: Smallint read Get_SecurityLevel;
    property HasPrivilege[var CashierPrivilege: cashierprivilegesEnum]: WordBool read Get_HasPrivilege;
    property FailedLogOnAttempts: Integer read Get_FailedLogOnAttempts;
    property EmailAddress: WideString read Get_EmailAddress;
    property Messages: _CashierMessages read Get_Messages;
    property UnreadMessageCount: Integer read Get_UnreadMessageCount;
    property Name: WideString read Get_Name;
    property FirstName: WideString read Get_FirstName;
    property LastName: WideString read Get_LastName;
    property ReturnLimit: Currency read Get_ReturnLimit;
    property FloorLimit: Currency read Get_FloorLimit;
    property ID: Integer read Get_ID;
    property CashDrawerNumber: Smallint read Get_CashDrawerNumber;
    property Loaded: WordBool read Get_Loaded;
    property Number: WideString read Get_Number;
  end;

v2.0.0.151中的收银员声明

_Cashier = interface(IDispatch)
    ['{39B2C128-00F1-4834-B1A4-05197C708BD9}']
    function Get_Session: _SessionClass; safecall;
    function Get_CashDrawer: _CashDrawer; safecall;
    function Get_OverShortLimitType: overshortlimitEnum; safecall;
    function Get_MaxOverShortAmount: Currency; safecall;
    function Get_MaxOverShortPercent: Double; safecall;
    function Get_SecurityLevel: Smallint; safecall;
    function Get_HasPrivilege(var CashierPrivilege: cashierprivilegesEnum): WordBool; safecall;
    function Get_FailedLogOnAttempts: Integer; safecall;
    function Get_EmailAddress: WideString; safecall;
    function Get_Messages: _CashierMessages; safecall;
    function Get_UnreadMessageCount: Integer; safecall;
    function Get_Name: WideString; safecall;
    function Get_FirstName: WideString; safecall;
    function Get_LastName: WideString; safecall;
    function Get_ReturnLimit: Currency; safecall;
    function Get_FloorLimit: Currency; safecall;
    function Get_ID: Integer; safecall;
    function Get_CashDrawerNumber: Smallint; safecall;
    function Get_Loaded: WordBool; safecall;
    function Get_Number: WideString; safecall;
    function Get_PasswordAge: Integer; safecall;
    function Get_ReminderPeriod: Integer; safecall;
    function Get_PasswordResetFlag: WordBool; safecall;
    function Get_IsPasswordChanged: WordBool; safecall;
    procedure Set_IsPasswordChanged(var Param1: WordBool); safecall;
    function Get_TimecardID: Integer; safecall;
    procedure Set_TimecardID(var Param1: Integer); safecall;
    function ValidatePassword(var Password: WideString): WordBool; safecall;
    function IsPwdDuplicated(var CashierNumber: Integer; var Password: WideString): WordBool; safecall;
    property Session: _SessionClass read Get_Session;
    property CashDrawer: _CashDrawer read Get_CashDrawer;
    property OverShortLimitType: overshortlimitEnum read Get_OverShortLimitType;
    property MaxOverShortAmount: Currency read Get_MaxOverShortAmount;
    property MaxOverShortPercent: Double read Get_MaxOverShortPercent;
    property SecurityLevel: Smallint read Get_SecurityLevel;
    property HasPrivilege[var CashierPrivilege: cashierprivilegesEnum]: WordBool read Get_HasPrivilege;
    property FailedLogOnAttempts: Integer read Get_FailedLogOnAttempts;
    property EmailAddress: WideString read Get_EmailAddress;
    property Messages: _CashierMessages read Get_Messages;
    property UnreadMessageCount: Integer read Get_UnreadMessageCount;
    property Name: WideString read Get_Name;
    property FirstName: WideString read Get_FirstName;
    property LastName: WideString read Get_LastName;
    property ReturnLimit: Currency read Get_ReturnLimit;
    property FloorLimit: Currency read Get_FloorLimit;
    property ID: Integer read Get_ID;
    property CashDrawerNumber: Smallint read Get_CashDrawerNumber;
    property Loaded: WordBool read Get_Loaded;
    property Number: WideString read Get_Number;
    property PasswordAge: Integer read Get_PasswordAge;
    property ReminderPeriod: Integer read Get_ReminderPeriod;
    property PasswordResetFlag: WordBool read Get_PasswordResetFlag;
    property IsPasswordChanged: WordBool read Get_IsPasswordChanged write Set_IsPasswordChanged;
    property TimecardID: Integer read Get_TimecardID write Set_TimecardID;
  end;

正如您所看到的，在较新的版本中添加了一些东西，但毫无疑问，我需要在调用它们的函数时检查软件版本。出纳员这只是25-30种类型中的一种，所以如果我必须为所有版本编写相同的基本实现...这是一项艰巨的任务，也是后期修改的可怕代码。