(Default) module

The (Default) module --- known internally as _HiddenModule --- gathers together the unqualified intrinsic procedures that the compiler emits calls into and that are also callable directly: raw-memory helpers, atomic operations, compile-time reflection, codegen and stack-inspection primitives, and a long tail of runtime utilities. Members of this module are referenced without a qualifier, the same way MsgBox and CStr are.

Most of these procedures are deliberately hidden from IntelliSense and exist for advanced or low-level use; use them only when the higher-level alternatives in Math, Strings, Information, or Interaction don't cover the case. Several have additional internal-only members that are not listed here at all.

The pointer functions ObjPtr, StrPtr, and VarPtr and the Array constructor are documented under the Information module; Input, InputB, and Width under FileSystem.

Reading and writing memory

Memory at a known address is read and written one machine word at a time with the GetMem* / PutMem* family --- GetMem1, GetMem2, GetMem4, GetMem8, and GetMemPtr for reads, with matching PutMem1, PutMem2, PutMem4, PutMem8, and PutMemPtr. vbaCopyBytes and vbaCopyBytesZero move blocks; AllocMem and FreeMem manage heap allocations. The pointer constructors that feed these helpers --- ObjPtr, StrPtr, VarPtr --- live in Information.

Dim Buffer As LongPtr = AllocMem(16)
PutMem4 Buffer, &HDEADBEEF
Dim Magic As Long
GetMem4 Buffer, Magic
FreeMem Buffer

vbaRefVarAry and vbaAryMove are lower-level helpers used when interfacing with C-side array layouts.

Object references and casting

vbaObjAddref, vbaObjSet, and vbaObjSetAddref manipulate COM reference counts directly. vbaCastObj returns the object reinterpreted as another COM interface, given its IID. CreateGUID generates a fresh GUID and returns it as a registry-formatted string.

Atomic operations

The Interlocked* family wraps the corresponding Windows kernel atomics --- building blocks for lock-free counters and pointer swaps: InterlockedExchangePointer, InterlockedCompareExchangePointer, InterlockedCompareExchange32, InterlockedCompareExchange64, InterlockedIncrement32, and InterlockedDecrement32.

Compile-time reflection

A few intrinsics ask questions about the surrounding type without running anything; they are resolved by the compiler and embedded as constants. GetDeclaredTypeProgId, GetDeclaredTypeClsid, GetDeclaredTypeIid, and GetDeclaredTypeEventIid report a type's COM identifiers. GetDeclaredMinEnumValue and GetDeclaredMaxEnumValue return the minimum and maximum value of a declared enumeration.

Codegen injection and stack inspection

Emit and EmitAny splice raw bytes or typed literals into the codegen output of the enclosing procedure --- the vehicle for inline assembly. StackOffset and StackArgsSize report layout information at the current call site; UnprotectedAccess returns an object reference that bypasses the usual access checks on private members.

Runtime expression evaluation

Eval compiles and evaluates a twinBASIC expression supplied as a string, using a freshly built TbExpressionService configured with the standard library binder.

Pictures, bitmaps, and icons

PictureToByteArray serialises an IPicture to a byte array; CreateStdPictureFromHandle wraps a GDI handle in an stdole.StdPicture; ConvertIconToBitmap does the obvious.

Other helpers

GetInheritedOwner returns the inherited owner object of a control. GetShortcutTextByEnum returns the localised display text for a built-in keyboard shortcut. SetThreadGlobalErrorTrap registers a callback that fires when an unhandled run-time error escapes the active error handler chain on the calling thread.

Members

• AllocMem -- allocates a block of native memory and returns its address
• ConvertIconToBitmap -- converts an icon picture to a bitmap picture
• CreateGUID -- generates a fresh GUID and returns it as a registry-formatted string
• CreateStdPictureFromHandle -- wraps a GDI bitmap or icon handle in an stdole.StdPicture
• Emit -- injects custom Byte values into the codegen stream of the enclosing procedure
• EmitAny -- injects custom typed values into the codegen stream of the enclosing procedure
• Eval -- compiles and evaluates a twinBASIC expression supplied as a string
• FreeMem -- frees memory allocated with AllocMem
• GetDeclaredMaxEnumValue -- returns the maximum value of a declared enumeration type, resolved at compile time
• GetDeclaredMinEnumValue -- returns the minimum value of a declared enumeration type, resolved at compile time
• GetDeclaredTypeClsid -- returns the COM CLSID associated with the declared type, resolved at compile time
• GetDeclaredTypeEventIid -- returns the COM event-interface IID associated with the declared type, resolved at compile time
• GetDeclaredTypeIid -- returns the COM interface IID associated with the declared type, resolved at compile time
• GetDeclaredTypeProgId -- returns the COM ProgID associated with the declared type, resolved at compile time
• GetInheritedOwner -- returns the inherited owner object of a control
• GetMem1 -- reads one byte from a memory address into a Byte variable
• GetMem2 -- reads two bytes from a memory address into an Integer variable
• GetMem4 -- reads four bytes from a memory address into a Long variable
• GetMem8 -- reads eight bytes from a memory address into a Currency variable
• GetMemPtr -- reads a pointer-sized value from a memory address into a LongPtr variable
• GetShortcutTextByEnum -- returns the localized text for a built-in keyboard shortcut by its enumeration ID
• InterlockedCompareExchange32 -- atomically compares and exchanges a 32-bit value
• InterlockedCompareExchange64 -- atomically compares and exchanges a 64-bit value
• InterlockedCompareExchangePointer -- atomically compares and exchanges a pointer-sized value
• InterlockedDecrement32 -- atomically decrements a 32-bit value and returns the new value
• InterlockedExchangePointer -- atomically exchanges a pointer-sized value and returns the previous value
• InterlockedIncrement32 -- atomically increments a 32-bit value and returns the new value
• PictureToByteArray -- serialises an IPicture into a Byte array
• PutMem1 -- writes one byte to a memory address
• PutMem2 -- writes two bytes to a memory address
• PutMem4 -- writes four bytes to a memory address
• PutMem8 -- writes eight bytes to a memory address
• PutMemPtr -- writes a pointer-sized value to a memory address
• RuntimeCreateGetMessageHook -- creates an IGetMessageHook for filtering window messages
• SetThreadGlobalErrorTrap -- registers a global callback invoked when an unhandled error is raised on the calling thread
• StackArgsSize -- returns the total size, in bytes, of the arguments on the current procedure's stack frame
• StackOffset -- returns the stack-frame offset of a variable
• UnprotectedAccess -- returns an object reference that bypasses access checks on private members
• vbaAryMove -- moves the contents of one array variable into another
• vbaCastObj -- returns an object reinterpreted as another COM interface
• vbaCopyBytes -- copies a block of bytes from one address to another
• vbaCopyBytesZero -- copies a block of bytes from one address to another, then zeros the source
• vbaObjAddref -- increments the COM reference count of an object at a given address
• vbaObjSet -- assigns an object pointer to an object variable, releasing any prior reference
• vbaObjSetAddref -- assigns an object pointer to an object variable, adding a reference and releasing any prior reference
• vbaRefVarAry -- returns a pointer to the SAFEARRAY descriptor inside a Variant array

IGetMessageHook interface

The IGetMessageHook interface hooks into the Windows message stream for a chosen window --- and optionally its descendants --- and forwards messages of a chosen type to a user-supplied callback. Obtain an instance with RuntimeCreateGetMessageHook; connect callbacks with RegisterMessage; then call Start to activate every registered subscription, and Stop to remove them.

The interface inherits directly from stdole.IUnknown (it is not dispatch-based), and the callbacks supplied to RegisterMessage are typed as GetMessageHookHelper.GetMessageHandler.

Const WM_LBUTTONDOWN = &H201

Sub Demo()
    Dim Hook As IGetMessageHook = RuntimeCreateGetMessageHook
    Hook.RegisterMessage Me.hWnd, AllDescendants, _
                         WM_LBUTTONDOWN, AddressOf OnLButtonDown
    Hook.Start
End Sub

Function OnLButtonDown(ByRef msg As GetMessageHookHelper.HookMSG) As LongPtr
    Debug.Print "Click at"; msg.pt.x, msg.pt.y
    ' Return zero to let the message continue normal processing.
End Function

Members

• RegisterMessage -- subscribes a callback to a single message type for a window and a chosen descendant scope
• Start -- activates every registered subscription
• Stop -- deactivates every registered subscription

EnumDescendantsModeFlags

Selects the window scope passed to RegisterMessage:

Constant	Value	Description
ExactWindow	1	Hook only the specified window.
AllDescendants	2	Hook the specified window and every descendant --- children, grandchildren, and so on.
DirectChildren	4	Hook the specified window and its immediate children only.

GetMessageHookHelper module

The GetMessageHookHelper module is a small companion to IGetMessageHook that holds the structures and the delegate type used by its callback. There is nothing to construct; the names exist only for use in declarations.

HookMSG

A copy of the Windows MSG structure, passed by reference into a GetMessageHandler callback.

Type HookMSG
    hwnd As LongPtr             ' Window the message is destined for.
    message As Long             ' The WM_* identifier.
    wParam As LongPtr           ' Message-specific parameter.
    lParam As LongPtr           ' Message-specific parameter.
    time As Long                ' Time the message was posted, in milliseconds since system start.
    pt As HookPOINT             ' Cursor position when the message was posted.
End Type

HookPOINT

A 2D point with Long coordinates, used by HookMSG to hold the cursor position.

Type HookPOINT
    x As Long
    y As Long
End Type

GetMessageHandler

The callback signature accepted by IGetMessageHook.RegisterMessage. Returning zero generally lets the message continue normal processing.

Public Delegate Function GetMessageHandler (ByRef msg As HookMSG) As LongPtr