Thread - using wxPerl with threads |
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>.
Wx::PlThreadEvent
can be used to communicate between worker and
GUI threads. The event can carry a shared value between threads.
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::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.
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.
Thread - using wxPerl with threads |