Glib::Signal(3pm) User Contributed Perl Documentation Glib::Signal(3pm)NAME
Glib::Signal - Object customization and general purpose notification
DESCRIPTION
This page describes some functions related to signals in Glib. Since most things you can do with signals are tied to Glib::Object
instances, the majority of the signal functions are documented there.
Thread safety
Some libraries, most notably GStreamer, sometimes invoke signal handlers from a foreign thread that has no Perl interpreter associated with
it. When this happens, we have no choice but to hand the marshalling over to the main loop which in turn later wakes up the main thread
and lets it handle the request. We cannot invoke the signal handler from the foreign thread since the Perl interpreter may not be used
concurrently.
The downside to this approach is that the foreign thread is blocked until the main thread has finished executing the signal handler. This
might lead to deadlocks. It might help in this case to wrap the crucial parts of the signal handler inside a Glib::Idle callback so that
the signal handler can return directly.
METHODS
integer = Glib->install_exception_handler ($func, $data=undef)
o $func (subroutine)
o $data (scalar)
Install a subroutine to be executed when a signal emission traps an exception (a croak or die). $func should return boolean (true if the
handler should remain installed) and expect to receive a single scalar. This scalar will be a private copy of $@ which the handler can
mangle to its heart's content.
Returns an identifier that may be used with "remove_exception_handler".
See "gperl_install_exception_handler()" in Glib::xsapi.
Glib->remove_exception_handler ($tag)
o $tag (integer)
Remove the exception handler identified by $tag, as returned by "install_exception_handler". If $tag cannot be found, this does nothing.
WARNING: Do not call this function from within an exception handler. If you want to remove your handler during its execution just have it
return false.
See "gperl_remove_exception_handler()" in Glib::xsapi.
ENUMS AND FLAGS
flags Glib::SignalFlags
o 'run-first' / 'G_SIGNAL_RUN_FIRST'
o 'run-last' / 'G_SIGNAL_RUN_LAST'
o 'run-cleanup' / 'G_SIGNAL_RUN_CLEANUP'
o 'no-recurse' / 'G_SIGNAL_NO_RECURSE'
o 'detailed' / 'G_SIGNAL_DETAILED'
o 'action' / 'G_SIGNAL_ACTION'
o 'no-hooks' / 'G_SIGNAL_NO_HOOKS'
SEE ALSO
Glib, Glib::Object
COPYRIGHT
Copyright (C) 2003-2011 by the gtk2-perl team.
This software is licensed under the LGPL. See Glib for a full notice.
perl v5.14.2 2012-05-24 Glib::Signal(3pm)
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Glib::MainLoop(3pm) User Contributed Perl Documentation Glib::MainLoop(3pm)NAME
Glib::MainLoop - An event source manager
DESCRIPTION
Event-driven programs need some sort of loop which watches for events and launches the appropriate actions. Glib::MainLoop provides this
functionality.
Mainloops have context, provided by the MainContext object. For the most part you can use the default context (see "default"), but if you
want to create a subcontext for a nested loop which doesn't have the same event sources, etc, you can.
Event sources, attached to main contexts, watch for events to happen, and launch appropriate actions. Glib provides a few ready-made event
sources, the Glib::Timeout, Glib::Idle, and io watch ("Glib::IO->add_watch").
Under the hood, Gtk+ adds event sources for GdkEvents to dispatch events to your widgets. In fact, Gtk2 provides an abstraction of
Glib::MainLoop (See "Gtk2->main" and friends), so you may rarely have cause to use Glib::MainLoop directly.
Note: As of version 1.080, the Glib module uses a custom event source to ensure that perl's safe signal handling and the glib polling event
loop play nicely together. It is no longer necessary to install a timeout to ensure that async signals get handled in a timely manner.
CONSTANTS
"SOURCE_REMOVE" and "SOURCE_CONTINUE" are designed for use as the return values from timeout, idle and I/O watch source functions. They
return true to keep running or false to remove themselves. These constants can help you get that the right way around.
Glib::SOURCE_CONTINUE # true
Glib::SOURCE_REMOVE # false
METHODS
maincontext thingamabob = Glib::MainContext->new
mainloop = Glib::MainLoop->new ($context=undef, $is_running=FALSE)
o $context (Glib::MainContext thingamabob)
o $is_running (boolean)
integer = Glib::Timeout->add ($interval, $callback, $data=undef, $priority=G_PRIORITY_DEFAULT)
o $interval (integer) number of milliseconds
o $callback (subroutine)
o $data (scalar)
o $priority (integer)
Run $callback every $interval milliseconds until $callback returns false. Returns a source id which may be used with
"Glib::Source->remove". Note that a mainloop must be active for the timeout to execute.
integer = Glib::Idle->add ($callback, $data=undef, $priority=G_PRIORITY_DEFAULT_IDLE)
o $callback (subroutine)
o $data (scalar)
o $priority (integer)
Run $callback when the mainloop is idle. If $callback returns false, it will uninstall itself, otherwise, it will run again at the next
idle iteration. Returns a source id which may be used with "Glib::Source->remove".
integer = Glib::Timeout->add_seconds ($interval, $callback, $data=undef, $priority=G_PRIORITY_DEFAULT)
o $interval (integer)
o $callback (scalar)
o $data (scalar)
o $priority (integer)
Since: glib 2.14
integer = Glib::IO->add_watch ($fd, $condition, $callback, $data=undef, $priority=G_PRIORITY_DEFAULT)
o $fd (integer) file descriptor, e.g. fileno($filehandle)
o $condition (Glib::IOCondition)
o $callback (subroutine)
o $data (scalar)
o $priority (integer)
Run $callback when there is an event on $fd that matches $condition. The watch uninstalls itself if $callback returns false. Returns a
source id that may be used with "Glib::Source->remove".
Glib's IO channels serve the same basic purpose as Perl's file handles, so for the most part you don't see GIOChannels in Perl. The IO
watch integrates IO operations with the main loop, which Perl file handles don't do. For various reasons, this function requires raw file
descriptors, not full file handles. See "fileno" in perlfunc.
maincontext thingamabob = $loop->get_context
maincontext thingamabob = Glib::MainContext->default
boolean = $context->is_owner
Since: glib 2.12
boolean = $loop->is_running
boolean = $context->iteration ($may_block)
o $may_block (boolean)
integer = Glib::main_depth
Find the current main loop recursion level. This is handy in fringe situations, but those are very rare; see the C API reference for a
more in-depth discussion.
Since: glib 2.4
boolean = $context->pending
$loop->quit
boolean = Glib::Source->remove ($tag)
o $tag (integer)
Remove an event source. $tag is the number returned by things like "Glib::Timeout->add", "Glib::Idle->add", and "Glib::IO->add_watch".
$loop->run
integer = Glib::Child->watch_add ($pid, $callback, $data=undef, $priority=G_PRIORITY_DEFAULT)
o $pid (integer) child process ID
o $callback (subroutine)
o $data (scalar)
o $priority (integer)
Add a source to the default main context which will call
&$callback ($pid, $waitstatus, $data)
when child process $pid terminates. The return value is a source id which can be used with "Glib::Source->remove". When the callback is
made the source is removed automatically.
In a non-threaded program Glib implements this source by installing a SIGCHLD handler. Don't change $SIG{CHLD} in Perl or the callback
will never run.
Since: glib 2.4
ENUMS AND FLAGS
flags Glib::IOCondition
o 'in' / 'G_IO_IN'
o 'out' / 'G_IO_OUT'
o 'pri' / 'G_IO_PRI'
o 'err' / 'G_IO_ERR'
o 'hup' / 'G_IO_HUP'
o 'nval' / 'G_IO_NVAL'
SEE ALSO
Glib
COPYRIGHT
Copyright (C) 2003-2011 by the gtk2-perl team.
This software is licensed under the LGPL. See Glib for a full notice.
perl v5.14.2 2012-05-24 Glib::MainLoop(3pm)