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184 lines
9.3 KiB
184 lines
9.3 KiB
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<title>TQSocketNotifier Class</title>
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<td align="right" valign="center"><img src="logo32.png" align="right" width="64" height="32" border="0"></td></tr></table><h1 align=center>TQSocketNotifier Class Reference</h1>
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<p>The TQSocketNotifier class provides support for socket callbacks.
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<a href="#details">More...</a>
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<p><tt>#include <<a href="qsocketnotifier-h.html">ntqsocketnotifier.h</a>></tt>
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<p>Inherits <a href="ntqobject.html">TQObject</a>.
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<p><a href="qsocketnotifier-members.html">List of all member functions.</a>
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<h2>Public Members</h2>
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<ul>
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<li class=fn>enum <a href="#Type-enum"><b>Type</b></a> { Read, Write, Exception }</li>
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<li class=fn><a href="#TQSocketNotifier"><b>TQSocketNotifier</b></a> ( int socket, Type type, TQObject * parent = 0, const char * name = 0 )</li>
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<li class=fn><a href="#~TQSocketNotifier"><b>~TQSocketNotifier</b></a> ()</li>
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<li class=fn>int <a href="#socket"><b>socket</b></a> () const</li>
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<li class=fn>Type <a href="#type"><b>type</b></a> () const</li>
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<li class=fn>bool <a href="#isEnabled"><b>isEnabled</b></a> () const</li>
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<li class=fn>virtual void <a href="#setEnabled"><b>setEnabled</b></a> ( bool enable )</li>
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</ul>
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<h2>Signals</h2>
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<ul>
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<li class=fn>void <a href="#activated"><b>activated</b></a> ( int socket )</li>
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</ul>
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<hr><a name="details"></a><h2>Detailed Description</h2>
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The TQSocketNotifier class provides support for socket callbacks.
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<p>
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<p> This class makes it possible to write asynchronous socket-based
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code in TQt. Using synchronous socket operations blocks the
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program, which is clearly not acceptable for an event-driven GUI
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program.
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<p> Once you have opened a non-blocking socket (whether for TCP, UDP,
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a UNIX-domain socket, or any other protocol family your operating
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system supports), you can create a socket notifier to monitor the
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socket. Then you connect the <a href="#activated">activated</a>() signal to the slot you
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want to be called when a socket event occurs.
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<p> Note for Windows users: the socket passed to TQSocketNotifier will
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become non-blocking, even if it was created as a blocking socket.
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<p> There are three types of socket notifiers (read, write and
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exception); you must specify one of these in the constructor.
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<p> The type specifies when the activated() signal is to be emitted:
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<ol type=1>
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<li> TQSocketNotifier::Read - There is data to be read (socket read event).
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<li> TQSocketNotifier::Write - Data can be written (socket write event).
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<li> TQSocketNofifier::Exception - An exception has occurred (socket
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exception event). We recommend against using this.
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</ol>
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<p> For example, if you need to monitor both reads and writes for the
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same socket you must create two socket notifiers.
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<p> For read notifiers it makes little sense to connect the
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activated() signal to more than one slot because the data can be
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read from the socket only once.
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<p> Also observe that if you do not read all the available data when
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the read notifier fires, it fires again and again.
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<p> For write notifiers, immediately disable the notifier after the
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<a href="#activated">activated</a>() signal has been received and you have sent the data to
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be written on the socket. When you have more data to be written,
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enable it again to get a new activated() signal. The exception is
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if the socket data writing operation (send() or equivalent) fails
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with a "would block" error, which means that some buffer is full
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and you must wait before sending more data. In that case you do
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not need to disable and re-enable the write notifier; it will fire
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again as soon as the system allows more data to be sent.
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<p> The behavior of a write notifier that is left in enabled state
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after having emitting the first activated() signal (and no "would
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block" error has occurred) is undefined. Depending on the
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operating system, it may fire on every pass of the event loop or
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not at all.
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<p> If you need a time-out for your sockets you can use either <a href="ntqobject.html#startTimer">timer events</a> or the <a href="ntqtimer.html">TQTimer</a> class.
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<p> Socket action is detected in the <a href="ntqapplication.html#exec">main
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event loop</a> of TQt. The X11 version of TQt has a single UNIX
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select() call that incorporates all socket notifiers and the X
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socket.
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<p> Note that on XFree86 for OS/2, select() works only in the thread
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in which main() is running; you should therefore use that thread
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for GUI operations.
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<p> <p>See also <a href="ntqsocket.html">TQSocket</a>, <a href="ntqserversocket.html">TQServerSocket</a>, <a href="ntqsocketdevice.html">TQSocketDevice</a>, <a href="ntqfile.html#handle">TQFile::handle</a>(), and <a href="io.html">Input/Output and Networking</a>.
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<hr><h2>Member Type Documentation</h2>
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<h3 class=fn><a name="Type-enum"></a>TQSocketNotifier::Type</h3>
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<ul>
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<li><tt>TQSocketNotifier::Read</tt>
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<li><tt>TQSocketNotifier::Write</tt>
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<li><tt>TQSocketNotifier::Exception</tt>
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</ul>
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<hr><h2>Member Function Documentation</h2>
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<h3 class=fn><a name="TQSocketNotifier"></a>TQSocketNotifier::TQSocketNotifier ( int socket, <a href="ntqsocketnotifier.html#Type-enum">Type</a> type, <a href="ntqobject.html">TQObject</a> * parent = 0, const char * name = 0 )
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</h3>
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Constructs a socket notifier called <em>name</em>, with the parent, <em>parent</em>. It watches <em>socket</em> for <em>type</em> events, and enables it.
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<p> It is generally advisable to explicitly enable or disable the
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socket notifier, especially for write notifiers.
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<p> <p>See also <a href="#setEnabled">setEnabled</a>() and <a href="#isEnabled">isEnabled</a>().
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<h3 class=fn><a name="~TQSocketNotifier"></a>TQSocketNotifier::~TQSocketNotifier ()
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</h3>
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Destroys the socket notifier.
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<h3 class=fn>void <a name="activated"></a>TQSocketNotifier::activated ( int socket )<tt> [signal]</tt>
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</h3>
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<p> This signal is emitted under certain conditions specified by the
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notifier <a href="#type">type</a>():
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<ol type=1>
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<li> TQSocketNotifier::Read - There is data to be read (socket read event).
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<li> TQSocketNotifier::Write - Data can be written (socket write event).
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<li> TQSocketNofifier::Exception - An exception has occurred (socket
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exception event).
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</ol>
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<p> The <em>socket</em> argument is the <a href="#socket">socket</a> identifier.
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<p> <p>See also <a href="#type">type</a>() and <a href="#socket">socket</a>().
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<h3 class=fn>bool <a name="isEnabled"></a>TQSocketNotifier::isEnabled () const
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</h3>
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<p> Returns TRUE if the notifier is enabled; otherwise returns FALSE.
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<p> <p>See also <a href="#setEnabled">setEnabled</a>().
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<h3 class=fn>void <a name="setEnabled"></a>TQSocketNotifier::setEnabled ( bool enable )<tt> [virtual]</tt>
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</h3>
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Enables the notifier if <em>enable</em> is TRUE or disables it if <em>enable</em> is FALSE.
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<p> The notifier is enabled by default.
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<p> If the notifier is enabled, it emits the <a href="#activated">activated</a>() signal
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whenever a socket event corresponding to its <a href="#type">type</a> occurs. If it is disabled, it ignores socket events
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(the same effect as not creating the socket notifier).
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<p> Write notifiers should normally be disabled immediately after the
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activated() signal has been emitted; see discussion of write
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notifiers in the <a href="#details">class description</a> above.
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<p> <p>See also <a href="#isEnabled">isEnabled</a>() and <a href="#activated">activated</a>().
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<h3 class=fn>int <a name="socket"></a>TQSocketNotifier::socket () const
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</h3>
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<p> Returns the socket identifier specified to the constructor.
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<p> <p>See also <a href="#type">type</a>().
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<h3 class=fn><a href="ntqsocketnotifier.html#Type-enum">Type</a> <a name="type"></a>TQSocketNotifier::type () const
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</h3>
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<p> Returns the socket event type specified to the constructor: <a href="#Type-enum">TQSocketNotifier::Read</a>, <a href="#Type-enum">TQSocketNotifier::Write</a>, or <a href="#Type-enum">TQSocketNotifier::Exception</a>.
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<p> <p>See also <a href="#socket">socket</a>().
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<hr><p>
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This file is part of the <a href="index.html">TQt toolkit</a>.
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Copyright © 1995-2007
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<a href="http://www.trolltech.com/">Trolltech</a>. All Rights Reserved.<p><address><hr><div align=center>
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<table width=100% cellspacing=0 border=0><tr>
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<td>Copyright © 2007
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<a href="troll.html">Trolltech</a><td align=center><a href="trademarks.html">Trademarks</a>
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<td align=right><div align=right>TQt 3.3.8</div>
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