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Glib::MainLoop - An event source manager
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.
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
$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.
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.
Since: glib 2.14
$fd (integer) file descriptor, e.g. fileno($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.
Since: glib 2.12
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
Remove an event source. $tag is the number returned by things like
Glib::Timeout->add, Glib::Idle->add, and
Glib::IO->add_watch.
Add a source to the default main context which will call
&$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
'in' / 'G_IO_IN'
'out' / 'G_IO_OUT'
'pri' / 'G_IO_PRI'
'err' / 'G_IO_ERR'
'hup' / 'G_IO_HUP'
'nval' / 'G_IO_NVAL'
Copyright (C) 2003-2009 by the gtk2-perl team.
This software is licensed under the LGPL. See Glib for a full notice.