Win32::GUI

Hi,

Threading in Perl is arguably the weakest part of the language. I do know of
successful implementations of a threaded win32::gui app, where one thread
handles GUI interaction, while the other does all the "work". I think if you
search the list you might be able to come across a couple of examples.

As an example of problems of a threaded perl application. Imagine you had an
object that encapsulated logic to process a text file. The initial
processing of this file takes a significant amount of time, so you want to
use a threaded model where the GUI is handled in one thread while the
processing of the object is in the other. All works well - however you can't
share perl objects between threads (only scalars)...Our newly processed text
file, is in one thread but can not be access directly - you have to use a
storable to serialise the data and copy it across...which can make the whole
exercise rather futile!

Hope that is of some help...

Cheers,

jez.

----- Original Message ----- 
From: "Brad Smith" <mata@...>
To: <perl-win32-gui-users@...>
Sent: Wednesday, June 23, 2004 11:49 AM
Subject: [perl-win32-gui-users] Working with threads


> Yesterday, after finishing a gui, I started reading some old list postings
> on threads.  I looked over my application and found a part of the code
> where I could test the threading (perl 5.8.x).  Best part, it worked!
>
> I have been programming in Perl steadily for the past five years, and it
> has quickly become my language of choice.  Up until now, I have
> proceeded in the linear fashion in which Perl works on win32, each task
> performed must be performed sequentially.  Of course, I have always
> sacrificed speed and responsivity for versatility.
>
> Now, I would like to begin retrofitting some of my code to a threaded
> model, in part.  I thought a good solution would be to try it with a gui,
> but I am stuck in my thinking, and have a few questions to ask, to gain
> clarity:
>
> 1.  When using threading with win32::gui, would/could I create a thread
> for each gui component/object?  For example, from my Master loop,
> could I create a thread that held a Window and every button, textfield,
> etc. contained inside the Window, while another thread held a Dialog
> Box with all of it's components (textfields, buttons, etc.)?
>
> 2.  If I can, from where do I control the Show() method?  I tried
> performing this from the Master Loop, but it said, of course, that my
> $Window didn't exist.  Then, I tried passing the Show() through the
> thread (e.g. $sample_thread->$Window->Show();), but that didn't work
> either.
>
> 3.  Instead of placing the $Window in threading, do I place the functions
> of $Window in the threading?
>
> 4.  Does anyone have an example of threading with Win32::gui?
>
> If anyone is old enough to remember seeing their first Walkman (circa
> 1980), that is the similar feeling I am having with win32::gui and
> threads!  For five years, I have used Perl for database processing, and
> cgi.  Two years ago, I discovered the power of OLE.  Now, I am
> revisiting GUI, and contemplating threads.  Next, I might begin
> considering myself to be a programmer! :)
>
> Brad Smith
>
>
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This model works quite well: - 

use win32::GUI;
use threads;
use Thread::Queue; 

# contruct GUI here --> 

my $commandQueue = Thread::Queue->new; 

threads->new(sub {
	while (my $command = $commandQueue->dequeue) {
		eval $command; warn $@ if $@;
	}
}); 

Win32::GUI::Dialog; 

sub SomeButton_Click {
	$commandQueue->enqueue("&somefunction(\$with_vars_as_refs)");
} 

__END 

You will have access in the thread to any variable created before. You may 
want to use a Timer to start the thread etc.. 

Blair. 


> 1.  When using threading with win32::gui, would/could I create a thread 
> for each gui component/object?  For example, from my Master loop, 
> could I create a thread that held a Window and every button, textfield, 
> etc. contained inside the Window, while another thread held a Dialog 
> Box with all of it"s components (textfields, buttons, etc.)?
> 2.  If I can, from where do I control the Show() method?  I tried 
> performing this from the Master Loop, but it said, of course, that my 
> $Window didn"t exist.  Then, I tried passing the Show() through the 
> thread (e.g. $sample_thread->$Window->Show();), but that didn"t work 
> either.