[AccessD] ShellExecute / Application.Quit

Maybe the problem is I'm trying to use the wrong method for my purposes?
This is not a situation where I need to shell out, perform a task, and
return.  My problem is that I'm using a .mdb as a launcher app.  I want to
shell out to launch another .mdb and immediately close the launcher app.
All of my code works...except if I try to run it from an AutoExec macro.  My
current work-around is to utilize a splash screen with a single OK
button...this works, but adds a few unnecessary seconds that I was trying to
avoid.  Ironically, it was because of this work-around that I found, in
testing, that 2-3% of the users drive mappings are not configured to
departmental standards....well actually they are, it's just that they are
technically in another department and on-loan to us.



Mark



-----Original Message-----
From: Gustav Brock [mailto:gustav at cactus.dk] 
Sent: Friday, May 07, 2004 8:24 AM
To: Access Developers discussion and problem solving
Subject: Re: [AccessD] ShellExecute / Application.Quit


Hi Mark

> The different versions of ShellWait utilize the API call CreateProcessA
> instead of ShellExecuteA.  I can't seem to get CreateProcessA to open
> anything...yet no errors are returned.  Is CreateProcessA like
ShellExecuteA
> in that as long as I pass a valid path/filename with a registered
extension,
> it will automagically do its thing?  ...because it isn't:(

It's hard to tell why it fails without knowing more.
But here's another approach - I can't remember where I got it:

<code>

Option Compare Database
Option Explicit

Private Const SYNCHRONIZE = &H100000
                                                
' Wait forever.
Private Const INFINITE = &HFFFF
' The state of the specified object is signaled.
Private Const WAIT_OBJECT_0 = 0
' The time-out interval elapsed and the object?s state is nonsignaled.
Private Const WAIT_TIMEOUT = &H102

Private Declare Function OpenProcess Lib "kernel32" ( _
  ByVal dwDesiredAccess As Long, _
  ByVal bInheritHandle As Long, _
  ByVal dwProcessId As Long) _
  As Long

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

Private Declare Function CloseHandle Lib "kernel32" ( _
  ByVal hObject As Long) _
  As Long
  
' The WaitForSingleObject function returns when one of the following occurs:
' - The specified object is in the signaled state.
' - The time-out interval elapses.
'
' The dwMilliseconds parameter specifies the time-out interval, in
milliseconds.
' The function returns if the interval elapses, even if the object?s state
is
' nonsignaled. If dwMilliseconds is zero, the function tests the object?s
state
' and returns immediately. If dwMilliseconds is INFINITE, the function?s
time-out
' interval never elapses.
'
' This example waits an INFINITE amount of time for the process to end. As a
' result this process will be frozen until the shelled process terminates.
The
' down side is that if the shelled process hangs, so will this one.
'
' A better approach is to wait a specific amount of time. Once the time-out
' interval expires, test the return value. If it is WAIT_TIMEOUT, the
process
' is still not signaled. Then you can either wait again or continue with
your
' processing.
'
' DOS Applications:
' Waiting for a DOS application is tricky because the DOS window never goes
' away when the application is done. To get around this, prefix the app that
' you are shelling to with "command.com /c".
'
' For example: lngPid = Shell("command.com /c " & strCommand.Text,
vbNormalFocus)

Function ShellWait( _
  ByVal strCommand As String) _
  As Boolean

  Dim lngPid      As Long
  Dim lngHnd      As Long
  Dim lngReturn   As Long
  Dim booSuccess  As Boolean
  
  If Len(Trim$(strCommand)) > 0 Then
    lngPid = Shell(strCommand, vbNormalFocus)
    If lngPid <> 0 Then
      ' Get a handle to the shelled process.
      lngHnd = OpenProcess(SYNCHRONIZE, 0, lngPid)
      ' If successful, wait for the application to end and close the handle.
      If lngHnd <> 0 Then
        lngReturn = WaitForSingleObject(lngHnd, INFINITE)
        CloseHandle (lngHnd)
        booSuccess = True
      End If
      MsgBox "Just terminated.", vbInformation, "Shelled Application"
    End If
  End If
  
  ShellWait = booSuccess

End Function

</code>

Beware of line breaks.

/gustav

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