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Win32::GUI::Tutorial::Part9 - Some peripheral issues

Win32::GUI Tutorial - Part 9

What about that console window?

One thing I have glossed over in all of the above is precisely how we run our Win32::GUI Perl program. There are a number of possibilities you might have used.

  • Enter the command "perl MyApp.pl" from a Windows console window.

  • Enter the command "perl MyApp.pl" in the Windows "Run" box.

  • Double click on the file "MyApp.pl" (assuming you have .pl files associated with the perl.exe application).

In the first case, you will notice that the command prompt does not return until you close your GUI application's window. In the second and third case, it's worse - a console window opens and stays visible until the GUI application terminates.

This is ugly. Unfortunately, it's fairly inevitable, because of the way Windows works. Perl itself is a Windows "console" application, and so it behaves the way we see. You can't change this without changing Perl itself.

There is a fix for this, if you have Windows development tools available. Simply take a copy of perl.exe, call it perlw.exe, and change its "subsystem" setting from "console" to "windows". With Microsoft Visual Studio, the command to do this is

    editbin /subsystem:windows perlw.exe

ActiveState Perl comes with an executable called wperl.exe (you'll find it n the same place as your perl.exe). This is an executable with exactly this change already made to it.

If you can't (or don't want to) create a perlw.exe, then a compromise is to hide the console window while your application is running. This is reasonable for the second and third cases above, but less so for the first (where the application is run from an existing console window).

The code to do this is

    my ($DOS) = Win32::GUI::GetPerlWindow();
    Win32::GUI::Hide($DOS);

Note that GetPerlWindow() returns a windows handle, not a Win32::GUI::Window object, so we have to use the static call to Win32::GUI::Hide() as discussed in part 1 of the tutorial.

Do this as early as possible. Obviously, if we hide the console, we must show it when we finish (otherwise, someone who runs your program from a command prompt will be very cross with you!)

To do this, we need to put

    Win32::GUI::Show($DOS);

just before our program terminates. After the Win32::GUI::Dialog() call is usually the right place.

VERSION

Documentation for Win32::GUI v1.14 created 01 Jun 2017

This document is autogenerated by the build process. Edits made here will be lost. Edit docs/GUI/Tutorial/Part9.pod instead.

SUPPORT

Homepage: http://perl-win32-gui.sourceforge.net/.

For further support join the users mailing list from the website at http://lists.sourceforge.net/lists/listinfo/perl-win32-gui-users. There is a searchable list archive at http://sourceforge.net/p/perl-win32-gui/mailman/perl-win32-gui-users/.

COPYRIGHT and LICENCE

Copyright (c) 1997..2017 Aldo Calpini. All rights reserved.

This program is free software; you can redistribute it and/or modify it under the same terms as Perl itself.