Wednesday, March 22, 2006

Process Handling with VBA

(Q) Whenever I shell out to another application, Access doesn't seem to wait before executing the next VBA statement. How do I make Access wait till I'm done with my other application.
(A) Paste the following code in a new module and use the Shell sub.


'***************** Code Start ******************
Private Const STARTF_USESHOWWINDOW& = &H1
Private Const NORMAL_PRIORITY_CLASS = &H20&
Private Const INFINITE = -1&

Private Type STARTUPINFO
cb As Long
lpReserved As String
lpDesktop As String
lpTitle As String
dwX As Long
dwY As Long
dwXSize As Long
dwYSize As Long
dwXCountChars As Long
dwYCountChars As Long
dwFillAttribute As Long
dwFlags As Long
wShowWindow As Integer
cbReserved2 As Integer
lpReserved2 As Long
hStdInput As Long
hStdOutput As Long
hStdError As Long
End Type

Private Type PROCESS_INFORMATION
hProcess As Long
hThread As Long
dwProcessID As Long
dwThreadID As Long
End Type

Private Declare Function WaitForSingleObject Lib "kernel32" (ByVal _
hHandle As Long, ByVal dwMilliseconds As Long) As Long

Private Declare Function CreateProcessA Lib "kernel32" (ByVal _
lpApplicationName As Long, ByVal lpCommandLine As String, ByVal _
lpProcessAttributes As Long, ByVal lpThreadAttributes As Long, _
ByVal bInheritHandles As Long, ByVal dwCreationFlags As Long, _
ByVal lpEnvironment As Long, ByVal lpCurrentDirectory As Long, _
lpStartupInfo As STARTUPINFO, lpProcessInformation As _
PROCESS_INFORMATION) As Long

Private Declare Function CloseHandle Lib "kernel32" (ByVal _
hObject As Long) As Long

Public Sub ShellWait(Pathname As String, Optional WindowStyle As Long)
Dim proc As PROCESS_INFORMATION
Dim start As STARTUPINFO
Dim ret As Long
' Initialize the STARTUPINFO structure:
With start
.cb = Len(start)
If Not IsMissing(WindowStyle) Then
.dwFlags = STARTF_USESHOWWINDOW
.wShowWindow = WindowStyle
End If
End With
' Start the shelled application:
ret& = CreateProcessA(0&, Pathname, 0&, 0&, 1&, _
NORMAL_PRIORITY_CLASS, 0&, 0&, start, proc)
' Wait for the shelled application to finish:
ret& = WaitForSingleObject(proc.hProcess, INFINITE)
ret& = CloseHandle(proc.hProcess)
End Sub
'***************** Code End ****************

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