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in order to find the corresponding IUnknown, BSTR, and SAFEARRAY, and VARIANT data types
You can useUse these programming techniques to enhance your everyday coding productivity by minimizingmaximizing code reuse
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CoRegisterClassObject and CoGetClassObject APIs to offerproffer your own application-level singleton objects
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enabling a host of Win32 API calls from with VB, AddressOf also enables
Page xxiii
if you try to interact with windows at the level of creation and window procedures.
Page 5
string conversion issues (see Chapter 14), weI recommend that you use
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'Equivalent to Long12 = Long21
Page 7
Dim String1 As String
Dim String2 As String
Dim pString1 As Long
String1 = "PowerVB"
String2 = String$(7, 0)
'These four operations all do the same thing
'Try one: this requires a typelib CopyMemory declare
CopyMemory ByVal String2, ByVal String1, 14
'Try two: Use StrPtr to guarantee no ANSI/UNICODE munging
CopyMemory ByVal StrPtr(String2), _
ByVal StrPtr(String1), 14
'Try three: Get the string's pointer from VarPtr
CopyMemory pString1, ByVal VarPtr(String1), 4
CopyMemory ByVal String2, ByVal pString1, 14
'Try four: Demonstrate VBoost.Assign instead
VBoost.Assign pString1, ByVal VarPtr(String1)
CopyMemory ByVal String2, ByVal pString1, 14
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This file registers with the name "VBoost Object Implementation (6.0)."
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appropriate descriptor to enable you to access array elements
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'Output (Intel uses biglittle-endian integer layout)
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.fFeatures = FADF_AUTO Or FADF_STATIC Or _
FADF_FIXEDSIZE
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Put your array in a structure and add a termination code to using lightweight objects.
The first blocksuses a lock count on the array
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You can also calculate the element countsize by using the formula VBoost.UDif(VarPtr(elem(1)), VarPtr(elem(0))).
SafeArrays use a rowcolumn-major layout, unlike C++, which uses a columnrow-major layout.
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SafeArrayCreate takes an array of SafeArrayBound elements in rowcolumn-major (VB) order, but the descriptor itself stores the list in reverse order, which is really columnrow-major (C++) order.
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In other words, VB makes your objects a persistable class, ActiveX control
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Second, if a reference supports an IID, the same IID must be supported by all references that the object returns.
The controlling IUnknown object then maps
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RHLS=LHS means that the type of the left-hand variable
Page 47
The QI that comes after the function call seems really bizarre because happens after the function returns. If the QI fails, then you will get a type mismatch error in the caller after the function has completed successfully. If the extra QI isn't enough to scare you away from such calls, the amount of code generated in order to handle them should be. In the case of ByVal calls, the AddRef/Release call happens in the callee, so there is no extra IUnknown work to be done by the caller. However, inIn the case of ByRef calls, the entire IUnknown burden falls on the caller, so theextra type checking code is generated everywhere the function is called with a mismatched type.
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Function GetDispatch(ByVal pUnkUR As IUnknownUnrestricted) _As
As Object
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The first member of any COM object is a pointer to the vtable
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IDispatch uses an ID based system, where each function
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Remember that using a With statement against an object is equivalent to assigning the object to a local variable.
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See the November 19991998 Visual Basic Programmer's Journal for the article "Inspect Dynamic Objects."
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section of Chapter 3,using a QueryInterface for IDispatch can have
lose a key feature ParamArray feature: the ability to pass a ByRef vVariant.
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registered it with regsvr32. (Or run Setup on the book's CD.)
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you can access the native function's event prototypes directly
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the type library the UDTs are contained in is the OCA back on
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By breaking this procedure in two, suddenly the code suddenly becomes reusable.
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By simply pointing a variable in each class to the same data, we you can eliminate the notification
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With delegation code that runs against any vtable entry, we you can use the same vtable
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An IUnknown hook is very similar to a blind delegator, but an IUnknown hook modifies
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VBoost releases the datareference and returns the E_NOINTERFACE error.
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You may want to toggle in the C++ version of the DLLVBoost objects during debugging
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so the earliest you can aggregate the object is in the Class_Initialize.
AggregateData is defined in VBoostTypes6.TlbOlb and has four members
this object is treated as a blind aggregate; a: A QI call is forwarded
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The native interfaces supported by Class2 are not wrapped, and the _Class1 interface supported by _Class1 is wrapped with a blind delegator that makes it act like a native part of Class12.
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with the DrawImpl class and adds a native method, or Area, that calculates the area
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There are no circular references in this system, but there are a couple big
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'long value
VBoost.AssignSwap pObj, Obj
.ItemData(.NewIndex) = pObj
End With
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Friend Property Get ChildInternal( _ByVal Index As Long) As
ByVal Index As Long) As Child Child
Set Child = InternalChildChildInternal(Index).GetExternalChild
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but the first instance in whichof each specific class of object you create a specific class of object.
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most-common values hidden in VBoostTypesObjCreate.
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adding capabilities to thea main application
dependent DLLs starting with the DLL's directory, not in the directory
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a reference to ObjCreate.oOlb and include the OcxLoader.Bas, COMDllLoader.Bas, and FunctionDelegator.Bas files.
'OcxLoader.Bas
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'fTargetAbsolute: An optional flag indicating that the
' TargetOCX argument is an absolute, not a
' relative path.
'not have run, so the VBoost object hasmay not have been
'been created.
Set pCF = GetDllClassObject( _App.Path & "\" &
App.Path & "\" & TargetOcx, _
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HookData.pIIDs(0) = IIDFromString( _
strIIDI__IQuickActivate)
VBoost.AggregateUnknown _
Wrapper, HookData.AggData, _HookData.pIIDs,
HookData.pIIDs, LoadData.Hook
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If you havewant the form to support menus
The DynamicMDI sample also has sample code (contained in LookupCLSID.Bas) that registers a public context object (discussed in "Custom Class Objects" in this chapter) and code that determines a CLSID from an OCX or DLL based on a class name (contained in LookupCLSID.Bas).
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Once your project includes have a direct type-library reference
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publish the CLSID with which you registered instead.
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When you need a block of memory to create thean object, you call the heap's allocate function.
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If m_PrevCursor <> vbHourGlass Then
With Screen
'Don't touch if someone else changed it.
If MousePointer = vbHourGlass Then
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without turning the structure into a full-blown VB class.
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.pVTablem_pVTable = VarPtr(.VTable(0))
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StringFromGUID2 pguid, StrPtr(GuidString)
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the code in the calling function is approximately one-third the size of code for the non-HRESULT functions.
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If you specify adUseIIDs as one of the AggregateData flags, VBoost doesn't query
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ByVal Index As Integer) As Linked Point
Page 188 (occurs three times)
X As Single, Y As Single)
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(and the AutoRedraw solution doesn't go very far towards demonstrating lightweight objects.)).
Page 190 (occurs three times)
X As Single, Y As Single)
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you can only guarantee that you gotget the same item back
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that you can call from the immediate paneby calling. ClearROT calls HideObject on all
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Dim strGuid As String * 38
StringForromGUID2 _
Getting a reference to the object out of the ROT just became
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Errors in Figure 10.1: External Process should point to Mashaling Layer and ROT should point to ROTHook Object
hold strong references to the ROTHook objects, but the only
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Sample: DLLDllRegisterServer
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[uuid(8F633501-459A-11d3-AB5C-D4123C10000), odl]
Once you have a function pointer--pfnDllRegisterServer--you can callpass the pointer to InitDelegator (pfnDllRegisterServer) and assign
Page 235
I have rarely seenrarely see a sort routine written in straight VB that didn'tdoesn't make me cringe. Sort routines, regardless of the algorithm used, compare and swap
the elements in an array. Comparing elements in VB is straightforward, but itstraight VB requires a new sort routine for each type of array to be sorted. Having a new
routine for each data type wasn'tisn't quite enough to evoke a shudder; the shudder generally requires an examination of the swapping code. Although
swapping elements may seem straightforward, it iscan be extremely expensive for pointerString, Variant, and structure types because VB always performs a deep copy.
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QuickSort VarPtr(Strings(LBound(Strings)), _
UBound(Strings) - LBound(Strings) + 1, _
4, AddressOf CompareStrings
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'Assembly code we're using to make aread the stack pointer.
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stack pointerframe before prolog (ebp points here)
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VB cannot handle the misaligned stack and Y crashes.
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However, with the FunctionDelegator object, you can now come very close.
get away with writing C code and letting the C compiler generate assembly.
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displays an addressof 00401033
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Public Function InIDE() As Boolean
Debug.Assert Not TestIDE(InIDE)On Error Resume Next
End Function Debug.Assert 1 \ 0
Private Function TestIDE(Test As Boolean) As Boolean InIDE = Err
Test = TrueOn Error GoTo 0
End Function
Function First( ByVal Value As Double, _
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pushed on the stack whenever you call a function, so the address of the next instruction
Page 255 (footnote)
See http://www.jprobbins.comhttp://www.wintellect.com/robbins for other article references.
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pointer to a class instance coded into the function, and a pointer to that function.
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If you let the QueryInterface sequence readreach the primary object
Base object is both the controlling IUnknown and the delegator fordelegatee of the wrapped object.
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QS = Queue size, then number of tasks queued per thread
ART = QS * b (QS b + 1) / 2 * Slice * PCO * b (1 + b TO / QS b ) b
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using CreateObject to create a worker thread runs Sub Main a second time.
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CopyMemory WD, CacheWD, LenB(CacheWD)
CacheWDm_Workers.Remove strKey
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ByVal ReturnDataPtr As Long) As Long
If fDoIncrement Then
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TheAccessing m_ReturnDataPtr access is safe if the ThreadData class
If Not IsEmpty(m_ReturnData) Then
T:If Not IsEmpty(m_ReturnData) Then
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T:If Not IsEmpty(m_ReturnData) Then
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Public Function DoStuff(Data As Variant, _
Data As Variant, ByVal ProgressPtr As Long, ByVal ReturnDataPtr As Long, _
ByVal ReturnDataPtr As Long, ByVal CritSectPtr As Long) As Long
LeaveCriticalSection m_pCritSect
End Sub
'ThreadData class., also pass Parent.CritSect to DoStuff
If Not IsEmpty(m_ReturnData) Then
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T:If Not IsEmpty(m_ReturnData) Then
T:If Not IsEmpty(m_ReturnData) Then
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Second, it owns a handle to the callingworker thread.
providing an efficient mechanism for signaling- completion.
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Optional ByVal fReturnThreadHandle As Boolean = False) _
As Long
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'The new thread should not own the controlling thread
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allocate the data in a memory block that lives longer than theCreateWorkerThread's stack.
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Error in Figure 13.4: The long dotted line should be extended to more clearly go from GetWorkerOutput to OutputData.
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'ThreadLaunch interface definition, ThreadLaunch.cls
'Called to create a new worker thread
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'ThreadStart procedure, ThreadProc.bas
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'ThreadControl class, in ThreadControl.cls
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Optional ByVal fReturnThreadHandle As Boolean = False) _
As Long
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fSignaled As Boolean '*TB.ThreadSignalPtr changed (CT:RW)
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'Frees any leftover Variant information and
'the controller.
Erase .pSA
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For iFields = 0 To _
.TokenizeLines(strLine, iStoppedAt, strFields) - 1
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extensive discussion of methods that don't return in an HRESULT.
Page 387
three pronged approach to gain this low-level of control of the typelibs
greater range of function and interface thatthan it can produce.
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These flags are primarily for marshaling interfaces,. Any ByRef type
Page 393
If you want to explicitly unload a DLL, either for memory reasons or to upgrade it dynamically
enable upgrading it without closing your application, you need to perform
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End Type
'Typelib equivalent, UNICODE
} TLibFLStringField;
'Calling code, UNICODE
If cBytes > 3876 Then cBytes = 3876
CopyMemory FLSF.TheString(0), ByVal strData, cBytes
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} TLibFLStringField;
'Calling code, ANSI
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Private Sub IPersistHistory_SetPositionCookie ( _
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Private Sub UserControl_ReadProperties( _
(PropBag As PropertyBag)
Page 406
You must be very careful not to not use the oleautomation or dual
You have to worry about registry settings not only when you marshal
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Although the IRecordInfo is needed only for marshaling, thereto store a record in a Variant and to marshal an array. There is no way to know if marshaling will be required an array will be marshalled when the array or Variant it is created.
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The interface identifier is used during thea Set statement to verify that thea running objects supports the IID promised by its design-time typelib description.
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You can make VB register movemore (or less) typelib information
Page 420 (add as third bulleted paragraph)
You can add help information to enums, records, public properties, and other places where the VB IDE does not accept help text. You can also provide an external program
that allows you to provide custom help information for every help field in the type library. This includes the ability to create localized satellite DLLs for your
ActiveX components. See the CD for more information on implementing the IModifyHelpData interface.
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you have to replace only a single function instead of an entire multi-function entire vtable.
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Frozen events are generally not a problem with modal forms in a compiled application.
If you subclass using a control, you can actually hitsafely stop at a breakpoint while debugging.
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Case WM_GETMINMAXINFO
With g_DerefMinMaxInfo
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You don't need to show a fully functional control at design time.
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the HasDC property. ThisUse this property tellsto tell VB to borrow device contexts as needed instead of caching them
Page 443
HasDC includesis one of the two properties added to controls in VB6 to reduce resource usage.
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Objects to facilitate aggregating VB objects.
However, you are not freedo not need to redistribute the OLB
(unless you send a gift copy of the book along with it).with the DLL. The OLB is needed at compile-time only.
Page 453
Dim pDst As Long, pSrc As Long
'(void*)pDst = (void*)pDstpSrc
Page 454
AssignZero is used to zero out a pointer.
One underhanded but highly convenient use of AssignAddRef is possible withapplicable to UserControl variables.
Page 455
VB's compiler does not allow you to assign the private base class to a variable or pass it to a normal parameter.
Page 459
Changing BufferBlocks does not automatically trigger a compaction; you must explicitly call Compact
Page 461
You can redirect IID_IDispatch with adPrimaryDispatch, with adMapIIDs, or in the QIHookMapIID function on the IQIHook interface.
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adDelayDontCacheResolved stops the aggregator from keeping the resolved reference, so IDelayCreation_Create iscan be
called multiple times for multiple requests for the same IID. No request is made even
if a reference for thisthe IID is currently in use.
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Dim AggData(0) As AggregateData
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IQIARHook adds uhAddRef and uhRelease. As you can with HookQI, you can use the Flags property
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