VB Forum / COM / November 2005

Serializing of VB-Types into ByteArrays per RtlMoveMemory is difficult, if
the type contains dynamic arrays or strings without Len-Def.
In both cases the VB-Type contains only Pointers to those members.

A solution for this problem is possible, if you work with VBs Put- and
Get-Statements against a NamedPipe.

'***Into a Form
Option Explicit

Private Declare Function CreateNamedPipe Lib "kernel32" Alias _
 "CreateNamedPipeA" (ByVal lpName As String, ByVal dwOpenMode&, _
  ByVal dwPipeMode As Long, ByVal nMaxInstances As Long, _
  ByVal nOutBufferSize As Long, ByVal nInBufferSize As Long, _
  ByVal nDefaultTimeOut As Long, lpSecurityAttributes As Any) As Long
Private Declare Function WriteFile Lib "kernel32" (ByVal hFile As Long, _
  lpBuffer As Any, ByVal nNumberOfBytesToWrite As Long, _
  lpNumberOfBytesWritten As Long, lpOverlapped As Any) As Long
Private Declare Function ReadFile Lib "kernel32" (ByVal hFile As Long, _
  lpBuffer As Any, ByVal nNumberOfBytesToRead As Long, _
  lpNumberOfBytesRead As Long, lpOverlapped As Any) As Long
Private Declare Function PeekNamedPipe Lib "kernel32" (ByVal hNmdPipe&, _
  lpBuffer As Any, ByVal nBufferSize As Long, lpBytesRead As Long, _
  lpTotalBytesAvail As Long, lpBytesLeftThisMessage As Long) As Long
Private Declare Function DisconnectNamedPipe& Lib "kernel32"(ByVal hPipe&)
Private Declare Function CloseHandle& Lib "kernel32" (ByVal hObject&)

Private Type Test
 L As Long
 S As String
 B() As Byte
End Type

Private Sub Form_Click()
Dim T1 As Test, T2 As Test, B() As Byte
  T1.L = 123
  T1.S = "ABC"
  ReDim T1.B(3): T1.B(1) = 1: T1.B(2) = 2: T1.B(3) = 3

  Type2Bytes T1, B
  Bytes2Type B, T2
  Print T2.L, T2.S, T2.B(1); T2.B(2); T2.B(3)
End Sub

'results with the Count of written Bytes
Private Function Type2Bytes(T As Test, B() As Byte) As Long
Dim hPipe&, FNr&, Bytes&: Const PName$ = "\\.\pipe\Type2Bytes"
 hPipe = CreateNamedPipe(PName, 3, 0, 255, -1, -1, 0, ByVal 0&)
 If hPipe = -1 Then Exit Function

 FNr = FreeFile
 Open PName For Binary As FNr
 Put FNr, , T
 Close FNr

 PeekNamedPipe hPipe, ByVal 0&, 0, ByVal 0&, Bytes, ByVal 0&
 If Bytes > 0 Then
   ReDim Preserve B(Bytes - 1)
   ReadFile hPipe, B(0), Bytes, Bytes, ByVal 0&
   Type2Bytes = Bytes
 End If
 DisconnectNamedPipe hPipe
 CloseHandle hPipe
End Function

Private Function Bytes2Type(B() As Byte, T As Test) As Long
Dim hPipe&, FNr&, Bytes&: Const PName$ = "\\.\pipe\Bytes2Type"
 hPipe = CreateNamedPipe(PName, 3, 0, 255, -1, -1, 0, ByVal 0&)
 If hPipe = -1 Then Exit Function

 FNr = FreeFile
 Open PName For Binary As FNr

 WriteFile hPipe, B(0), UBound(B) + 1, Bytes, ByVal 0&
 If Bytes = UBound(B) + 1 Then Get FNr, , T: Bytes2Type = Loc(FNr)

 Close FNr
 DisconnectNamedPipe hPipe
 CloseHandle hPipe
End Function

Olaf