Question: How can I restart Windows from ObjectPAL?

Answer: The following code sample demonstrates this:

   Uses User32
     ExitWindowsEx( uFlags CLONG, dwReserved CLONG ) CLONG
   endUses

   method pushButton( var eventInfo Event )
   var
     uFlags     longInt
     dwReserved longInt
   endvar

   uFlags = 2      ;// Reboot computer before restarting Windows
   dwReserved = 0  ;// Always set to zero;

   ExitWindowsEx( uFlags, dwReserved )

endMethod

How it works:

ExitWindowsEx shuts down or reboots the user's computer. This starts the process immediately, so should only be used after any required processing is performed. For example, if you use tCursors in the method that calls this function, be sure to close them before calling ExitWindowsEx; otherwise, unposted changes will be lost.

ExitWindowsEx returns non-zero values if successful or a zero (0) if there's an error. While it may seem odd this think of errors ocurring by restarting Windows, it can happen. For example, suppose you have a "dirty" form open in Paradox when you trigger this. Normally, Paradox prompts you to save your form. If you choose Cancel from that prompt, Paradox blocks the shutdown process. Windows considers this an "error" (because it didn't complete as expected). If you are working with something that returns a value, you should always check those values to ensure that something unexpected hasn't prevented your process from completing properly.

The uFlags parameter controls the type of restart that Windows performs and supports the following values:

• 0 (EWX_LOGOFF) logs the current user off the network.
• 1 (EWX_SHUTDOWN) shuts down the system (without powering it off).
• 2 (EWX_REBOOT) performs a full reboot of the system (aka a "cold" boot)
• 4 (EWX_FORCE) forces applications to simply quit, as opposed to running any built-in services designed to gracefully exit the application (such as prompting to save files, etc.).
• 8 (EWX_POWEROFF) shuts down the system and powers it off, if the system has power management features enabled.

The parentheses in the above list show the names of the corresponding Windows constants. Developers using languages with direct access to the Windows API should use these instead of the hard-coded values, in case Microsoft chooses to change the effects of specific values in a future version of Windows.

The dwReserved flag is reserved by Microsoft for future expansion; it should always be set to zero (0).