Glib::MainLoop(3) User Contributed Perl Documentation Glib::MainLoop(3)NAMEGlib::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)
· $context (Glib::MainContext thingamabob)
· $is_running (boolean)
integer = Glib::Timeout->add ($interval, $callback, $data=undef,
$priority=G_PRIORITY_DEFAULT)
· $interval (integer) number of milliseconds
· $callback (subroutine)
· $data (scalar)
· $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)
· $callback (subroutine)
· $data (scalar)
· $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)
· $interval (integer)
· $callback (scalar)
· $data (scalar)
· $priority (integer)
Since: glib 2.14
integer = Glib::IO->add_watch ($fd, $condition, $callback, $data=undef,
$priority=G_PRIORITY_DEFAULT)
· $fd (integer) file descriptor, e.g. fileno($filehandle)
· $condition (Glib::IOCondition)
· $callback (subroutine)
· $data (scalar)
· $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)
· $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)
· $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)
· $pid (integer) child process ID
· $callback (subroutine)
· $data (scalar)
· $priority (integer)
Add a source to the default main context which will call
&$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
· 'in' / 'G_IO_IN'
· 'out' / 'G_IO_OUT'
· 'pri' / 'G_IO_PRI'
· 'err' / 'G_IO_ERR'
· 'hup' / 'G_IO_HUP'
· '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 2012-01-14 Glib::MainLoop(3)