Thread - using wxPerl with threads
# the order of these use()s is important use threads; use threads::shared; use Wx; my $DONE_EVENT : shared = Wx::NewEventType; my $worker = threads->create( \&work ); # create frames, etc my $frame = Wx::Frame->new( ... ); EVT_COMMAND( $frame, -1, $DONE_EVENT, \&done ); $app->MainLoop; sub done { my( $frame, $event ) = @_; print $event->GetData; } sub work { # ... do stuff, create a shared $result value my $threvent = new Wx::PlThreadEvent( -1, $DONE_EVENT, $result ); Wx::PostEvent( $frame, $threvent ); } # event handler sub OnCreateThread { # @_ = () is necessary to avoid "Scalars leaked" my( $self, $event ) = @_; @_ = (); threads->create( ... ); }
Threaded GUI application are somewhat different from non-GUI threaded applications in that the main thread (which runs the GUI) must never block. Also, in wxWidgets, no thread other than the main thread can manipulate GUI objects. This leads to a hybrid model where worker threads must send events to the main thread in order to change the GUI state or signal their termination.
It's necessary for use Wx to happen after <use threads::shared>.
use Wx
Wx::PlThreadEvent can be used to communicate between worker and GUI threads. The event can carry a shared value between threads.
Wx::PlThreadEvent
my $DONE_EVENT : shared = Wx::NewEventType; sub work { # ... do some stuff my $progress = new Wx::PlThreadEvent( -1, $DONE_EVENT, $progress ); Wx::PostEvent( $frame, $progress ); # ... do stuff, create a shared $result value my $end = new Wx::PlThreadEvent( -1, $DONE_EVENT, $result ); Wx::PostEvent( $frame, $end ); }
The target of the event can be any Wx::EvtHandler
Wx::EvtHandler
Wx::PlThreadEvent is a command event and can be handled as such. The ->GetData method can be used to retrieve the shared data contained inside the event.
->GetData
my $DONE_EVENT : shared = Wx::NewEventType; EVT_COMMAND( $frame, -1, $DONE_EVENT, \&done ); sub done { my( $frame, $event ) = @_; print $event->GetData; }
Creating new threads from event handlers works without problems except from a little snag. In order not to trigger a bug in the Perl interpreter, all event handler that directly or indirectly cause a thread creation must clean @_ before starting the thread.
@_
For example:
sub OnCreateThread { my( $self, $event ) = @_; @_ = (); threads->create( ... ); }
failure to do that will cause "scalars leaked" warnings from the Perl interpreter.
To install Wx, copy and paste the appropriate command in to your terminal.
cpanm
cpanm Wx
CPAN shell
perl -MCPAN -e shell install Wx
For more information on module installation, please visit the detailed CPAN module installation guide.