X11::Protocol::GrabServer(3pm)

1X11::Protocol::GrabServUesre(r3)Contributed Perl DocumenXt1a1t:i:oPnrotocol::GrabServer(3)
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NAME

6       X11::Protocol::GrabServer -- object-oriented server grabbing
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SYNOPSIS

9        use X11::Protocol::GrabServer;
10        {
11          my $grab = X11::Protocol::GrabServer->new ($X);
12          do_some_things();
13          # UngrabServer when $grab destroyed
14        }
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DESCRIPTION

17       This is an object-oriented approach to GrabServer / UngrabServer on an
18       "X11::Protocol" connection.  A grab object represents a desired server
19       grab and destroying it ungrabs.
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21       The first grab object on a connection does a "GrabServer()" and the
22       last destroyed does an "UngrabServer()".  The idea is that it's easier
23       to manage the lifespan of a grabbing object in a block etc than to be
24       sure of catching all exits.
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26       Multiple grab objects can overlap or nest.  A single "GrabServer()" is
27       done and it remains until the last object is destroyed.  This is good
28       in a library or sub-function where an "UngrabServer()" should wait
29       until the end of outermost desired grab.
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31       A server grab is usually to make a few operations atomic, for instance
32       something global like root window properties.  A block-based temporary
33       object like the synopsis above is typical.  It's also possible to hold
34       a grab object for an extended time, perhaps for some state driven
35       interaction with the server.
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37       Care must be taken not to grab for too long since other client programs
38       are locked out.  Also if a grabbing program hangs then the server will
39       be unusable until the program is killed, or its TCP etc server
40       connection is broken.
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42   Weak $X
43       If Perl weak references are available (which means Perl 5.6 and up and
44       "Scalar::Util" with its usual XS code), then a grab object holds only a
45       weak reference to the target $X connection.  This means the grab
46       doesn't keep the connection alive once nothing else is interested.
47       When a connection is destroyed the server ungrabs automatically and so
48       there's no need for an explicit "UngrabServer()" in that case.
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50       The main effect of the weakening is that $X can be garbage collected
51       anywhere within a grabbing block, the same as if there was no grab.
52       Without the weakening it would wait until the end of the block.  In
53       practice this only rarely makes a difference.
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55       In the future if an "X11::Protocol" connection gets a notion of an
56       explicit close then the intention would be to skip any "UngrabServer()"
57       in that case too, ie. treat a closed connection the same as a weakened
58       away connection.
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60       Currently no attention is paid to whether the server has disconnected
61       the link.  A "UngrabServer()" is done on destroy in the usual way.  If
62       the server has disconnected then a "SIGPIPE" or "EPIPE" occurs the same
63       as for any other request sent to the $X.
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FUNCTIONS

66       "$g = X11::Protocol::GrabServer->new ($X)"
67           $X is an "X11::Protocol" object.  Create and return a $g object
68           representing a grab of the $X server.
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70           If this new $g is the first new grab on $X then an "$X->GrabServer"
71           is done.
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73       "$g->ungrab ()"
74           Ungrab the $g object explicitly.  An ungrab is done automatically
75           when $g is destroyed, but "$g->ungrab()" can do it sooner.
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77           If $g is already ungrabbed then do nothing.
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79       "$g->grab ()"
80           Re-grab with the $g object.  This can be used after a
81           "$g->ungrab()" to grab again with the same object, the same as if
82           newly created.
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84           If $g is already grabbing then do nothing.
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86       "$bool = $g->is_grabbed ()"
87           Return true if $g is grabbing.  This is true when first created, or
88           false after a "$g->ungrab()".
89
90           This function is only the state of $g.  There might be other
91           "GrabServer" objects which grabbing the server.
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HOME PAGE

97       <http://user42.tuxfamily.org/x11-protocol-other/index.html>
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LICENSE

100       Copyright 2010, 2011, 2012, 2013, 2014, 2017 Kevin Ryde
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102       X11-Protocol-Other is free software; you can redistribute it and/or
103       modify it under the terms of the GNU General Public License as
104       published by the Free Software Foundation; either version 3, or (at
105       your option) any later version.
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107       X11-Protocol-Other is distributed in the hope that it will be useful,
108       but WITHOUT ANY WARRANTY; without even the implied warranty of
109       MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
110       General Public License for more details.
111
112       You should have received a copy of the GNU General Public License along
113       with X11-Protocol-Other.  If not, see <http://www.gnu.org/licenses/>.
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117perl v5.32.0                      2020-07-28      X11::Protocol::GrabServer(3)

NAME

SYNOPSIS

DESCRIPTION

FUNCTIONS

SEE ALSO

HOME PAGE

LICENSE