1Wx::Thread(3)         User Contributed Perl Documentation        Wx::Thread(3)
2
3
4

NAME

6       Thread - using wxPerl with threads
7

SYNOPSIS

9         # the order of these use()s is important
10         use threads;
11         use threads::shared;
12         use Wx;
13
14         my $DONE_EVENT : shared = Wx::NewEventType;
15
16         my $worker = threads->create( \&work );
17
18         # create frames, etc
19         my $frame = Wx::Frame->new( ... );
20         EVT_COMMAND( $frame, -1, $DONE_EVENT, \&done );
21         $app->MainLoop;
22
23         sub done {
24             my( $frame, $event ) = @_;
25
26             print $event->GetData;
27         }
28
29         sub work {
30             # ... do stuff, create a shared $result value
31
32             my $threvent = new Wx::PlThreadEvent( -1, $DONE_EVENT, $result );
33             Wx::PostEvent( $frame, $threvent );
34         }
35
36         # event handler
37         sub OnCreateThread {
38             # @_ = () is necessary to avoid "Scalars leaked"
39             my( $self, $event ) = @_; @_ = ();
40
41             threads->create( ... );
42         }
43

DESCRIPTION

45       Threaded GUI application are somewhat different from non-GUI threaded
46       applications in that the main thread (which runs the GUI) must never
47       block.  Also, in wxWidgets, no thread other than the main thread can
48       manipulate GUI objects.  This leads to a hybrid model where worker
49       threads must send events to the main thread in order to change the GUI
50       state or signal their termination.
51
52   Order of module loading
53       It's necessary for "use Wx" to happen after <use threads::shared>.
54
55   Sending events from worker threads
56       "Wx::PlThreadEvent" can be used to communicate between worker and GUI
57       threads.  The event can carry a shared value between threads.
58
59         my $DONE_EVENT : shared = Wx::NewEventType;
60
61         sub work {
62             # ... do some stuff
63             my $progress = new Wx::PlThreadEvent( -1, $DONE_EVENT, $progress );
64             Wx::PostEvent( $frame, $progress );
65
66             # ... do stuff, create a shared $result value
67             my $end = new Wx::PlThreadEvent( -1, $DONE_EVENT, $result );
68             Wx::PostEvent( $frame, $end );
69         }
70
71       The target of the event can be any "Wx::EvtHandler"
72
73   Receiving events from worker threads
74       "Wx::PlThreadEvent" is a command event and can be handled as such.  The
75       "->GetData" method can be used to retrieve the shared data contained
76       inside the event.
77
78         my $DONE_EVENT : shared = Wx::NewEventType;
79
80         EVT_COMMAND( $frame, -1, $DONE_EVENT, \&done );
81
82         sub done {
83             my( $frame, $event ) = @_;
84
85             print $event->GetData;
86         }
87
88   Creating new threads
89       Creating new threads from event handlers works without problems except
90       from a little snag.  In order not to trigger a bug in the Perl
91       interpreter, all event handler that directly or indirectly cause a
92       thread creation must clean @_ before starting the thread.
93
94       For example:
95
96         sub OnCreateThread {
97             my( $self, $event ) = @_; @_ = ();
98
99             threads->create( ... );
100         }
101
102       failure to do that will cause "scalars leaked" warnings from the Perl
103       interpreter.
104
105
106
107perl v5.32.1                      2021-01-27                     Wx::Thread(3)