mirror of
https://github.com/lunarmodules/luasocket.git
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262 lines
7.5 KiB
HTML
262 lines
7.5 KiB
HTML
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN"
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"http://www.w3.org/TR/html4/strict.dtd">
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<html>
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<head>
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<title>LuaSocket: Network support for the Lua language</title>
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<link rel="stylesheet" href="reference.css" type="text/css">
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</head>
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<body>
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<!-- header +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ -->
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<div class=header>
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<hr>
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<center>
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<table summary="LuaSocket logo">
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<tr><td align=center><a href="http://www.lua.org">
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<img border=0 alt="LuaSocket" src="luasocket.png">
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</a></td></tr>
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<tr><td align=center valign=top>Network support for the Lua language
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</td></tr>
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</table>
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<p class=bar>
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<a href="home.html">home</a> ·
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<a href="home.html#download">download</a> ·
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<a href="introduction.html">introduction</a> ·
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<a href="reference.html">reference</a>
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</p>
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</center>
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<hr>
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</div>
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<!-- socket +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ -->
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<h2 id=socket>The socket namespace</h2>
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<p>
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The <tt>socket</tt> namespace contains the core functionality of LuaSocket.
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</p>
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<p>
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To obtain the <tt>socket</tt> namespace, run:
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</p>
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<pre class=example>
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-- loads the socket module
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local socket = require("socket")
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</pre>
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<!-- debug ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ -->
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<p class=name id=debug>
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socket.<b>DEBUG</b>
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</p>
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<p class=description>
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This constant is set to <tt><b>true</b></tt> if the library was compiled
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with debug support.
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</p>
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<!-- protect +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ -->
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<p class=name id=protect>
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socket.<b>protect(</b>func<b>)</b>
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</p>
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<p class=description>
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Converts a function that throws exceptions into a safe function.
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</p>
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<p class=parameters>
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<tt>Func</tt> is a function that calls
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<a href=#try><tt>try</tt></a> (or <tt>assert</tt>, or <tt>error</tt>)
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to throw exceptions.
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</p>
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<p class=return>
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Returns an equivalent function that instead of throwing exceptions,
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returns <tt><b>nil</b></tt> followed by an error message.
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</p>
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<p class=note>
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Note: Beware that if your function performs some illegal operation that
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raises an error, the protected function will catch the error and return it
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as a string. This is because the <a href=#try><tt>try</tt></a> function
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uses errors as the mechanism to throw exceptions.
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</p>
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<!-- select +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ -->
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<p class=name id=select>
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socket.<b>select(</b>recvt, sendt [, timeout]<b>)</b>
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</p>
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<p class=description>
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Waits for a number of sockets to change status.
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</p>
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<p class=parameters>
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<tt>Recvt</tt> is an array with the sockets to test for characters
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available for reading. Sockets in the <tt>sendt</tt> array are watched to
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see if it is OK to immediately write on them. <tt>Timeout</tt> is the
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maximum amount of time (in seconds) to wait for a change in status. A
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<tt><b>nil</b></tt>, negative or omitted <tt>timeout</tt> value allows the
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function to block indefinitely. <tt>Recvt</tt> and <tt>sendt</tt> can also
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be empty tables or <tt><b>nil</b></tt>. Non-socket values (or values with
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non-numeric indices) in the arrays will be silently ignored.
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</p>
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<p class=return> The function returns a table with the sockets ready for
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reading, a table with the sockets ready for writing and an error message.
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The error message is "<tt>timeout</tt>" if a timeout condition was met and
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<tt><b>nil</b></tt> otherwise. The returned tables are associative, to
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simplify the test if a specific socket has changed status.
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</p>
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<p class=note>
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<b>Important note</b>: a known bug in WinSock causes <tt>select</tt> to fail
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on non-blocking TCP sockets. The function may return a socket as
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writable even though the socket is <em>not</em> ready for sending.
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</p>
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<p class=note>
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<b>Another important note</b>: calling select with a server socket in the receive parameter before a call to accept does <em>not</em> guarantee
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<a href=tcp.html#accept><tt>accept</tt></a> will return immediately.
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Use the <a href=tcp.html#settimeout><tt>settimeout</tt></a>
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method or <tt>accept</tt> might block forever.
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</p>
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<p class=note>
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Interesting note: as mentioned in some Unix manuals, calling select with both
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sets empty and a non-null timeout is a fairly portable way to sleep with
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sub-second precision (<b>except it doesn't work on Windows</b>).
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</p>
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<!-- sink ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ -->
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<p class=name id=sink>
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socket.<b>sink(</b>mode, socket<b>)</b>
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</p>
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<p class=description>
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Creates an
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<a href="http://lua-users.org/wiki/FiltersSourcesAndSinks">LTN12</a>
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sink from a stream socket object.
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</p>
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<p class=parameters>
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<tt>Mode</tt> defines the behaviour of the sink. The following
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options are available:
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</p>
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<ul>
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<li> <tt>"http-chunked"</tt>: sends data through socket after applying the
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<em>chunked transfer coding</em>, closing the socket when done;
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<li> <tt>"close-when-done"</tt>: sends all received data through the
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socket, closing the socket when done;
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<li> <tt>"keep-open"</tt>: sends all received data through the
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socket, leaving it open when done.
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</ul>
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<p>
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<tt>Socket</tt> is the stream socket object used to send the data.
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</p>
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<p class=return>
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The function returns a sink with the appropriate behavior.
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</p>
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<!-- source +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ -->
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<p class=name id=source>
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socket.<b>source(</b>mode, socket [, length]<b>)</b>
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</p>
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<p class=description>
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Creates an
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<a href="http://lua-users.org/wiki/FiltersSourcesAndSinks">LTN12</a>
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source from a stream socket object.
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</p>
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<p class=parameters>
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<tt>Mode</tt> defines the behavior of the source. The following
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options are available:
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</p>
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<ul>
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<li> <tt>"http-chunked"</tt>: receives data from socket and removes the
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<em>chunked transfer coding</em> before returning the data;
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<li> <tt>"by-length"</tt>: receives a fixed number of bytes from the
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socket. This mode requires the extra argument <tt>length</tt>;
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<li> <tt>"until-closed"</tt>: receives data from a socket until the other
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side closes the connection.
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</ul>
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<p>
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<tt>Socket</tt> is the stream socket object used to receive the data.
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</p>
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<p class=return>
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The function returns a source with the appropriate behavior.
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</p>
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<!-- try ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ -->
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<p class=name id=try>
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socket.<b>try(</b>ret<sub>1</sub> [, ret<sub>2</sub> ... ret<sub>N</sub>]<b>)</b>
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</p>
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<p class=description>
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Throws an exception in case of error.
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</p>
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<p class=parameters>
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<tt>Ret</tt><sub>1</sub> to <tt>ret</tt><sub>N</sub> can be arbitrary
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arguments, but are usually the return values of a function call
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nested with <tt>try</tt>.
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</p>
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<p class=return>
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The function returns <tt>ret</tt><sub>1</sub> to <tt>ret</tt><sub>N</sub> if
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<tt>ret</tt><sub>1</sub> is not <tt><b>nil</b></tt>. Otherwise, it calls <tt>error</tt> passing <tt>ret</tt><sub>2</sub>.
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</p>
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<pre class=example>
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-- connects or throws an exception with the appropriate error message
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c = socket.try(socket.connect("localhost", 80))
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</pre>
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<!-- version ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ -->
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<p class=name id=version>
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socket.<b>VERSION</b>
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</p>
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<p class=description>
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This constant has a string describing the current LuaSocket version.
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</p>
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<!-- footer +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ -->
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<div class=footer>
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<hr>
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<center>
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<p class=bar>
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<a href="home.html">home</a> ·
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<a href="home.html#down">download</a> ·
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<a href="introduction.html">introduction</a> ·
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<a href="reference.html">reference</a>
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</p>
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<p>
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<small>
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Last modified by Diego Nehab on <br>
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Thu Jun 17 02:47:21 EDT 2004
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</small>
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</p>
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</center>
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</div>
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</body>
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</html>
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