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readme.html
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readme.html
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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<HTML>
<HEAD>
<TITLE>Lua 5.2 readme</TITLE>
<LINK REL="stylesheet" TYPE="text/css" HREF="lua.css">
<META HTTP-EQUIV="content-type" CONTENT="text/html; charset=iso-8859-1">
<STYLE TYPE="text/css">
blockquote, .display {
color: black ;
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</STYLE>
</HEAD>
<BODY>
<HR>
<H1>
<A HREF="http://www.lua.org/"><IMG SRC="logo.gif" ALT="Lua" BORDER=0></A>
Welcome to Lua 5.2 (alpha)
</H1>
<P>
<IMG SRC="alert.png" ALIGN="absbottom" ALT="[!]">
<EM>This is an alpha version of Lua 5.2.
Some details may change in the final version.</EM>
<P>
<A HREF="#about">about</A>
·
<A HREF="#install">installation</A>
·
<A HREF="#changes">changes</A>
·
<A HREF="#license">license</A>
·
<A HREF="contents.html">reference manual</A>
<HR>
<H2><A NAME="about">About Lua</A></H2>
<P>
Lua is a powerful, fast, lightweight, embeddable scripting language
developed by a
<A HREF="http://www.lua.org/authors.html">team</A>
at
<A HREF="http://www.puc-rio.br/">PUC-Rio</A>,
the Pontifical Catholic University of Rio de Janeiro in Brazil.
Lua is
<A HREF="#license">free software</A>
used in many products and projects around the world.
<P>
Lua's
<A HREF="http://www.lua.org/">official web site</A>
provides complete information
about Lua,
including
an
<A HREF="http://www.lua.org/about.html">executive summary</A>
and
updated
<A HREF="http://www.lua.org/docs.html">documentation</A>,
especially the
<A HREF="http://www.lua.org/manual/5.2/">reference manual</A>,
which may differ slightly from the
<A HREF="contents.html">local copy</A>
distributed in this package.
<H2><A NAME="install">Installing Lua</A></H2>
<P>
Lua is distributed in
<A HREF="ftp/">source</A>
form.
You need to build it before using it.
Building Lua should be straightforward
because
Lua is implemented in pure ANSI C, and compiles unmodified in all known
platforms that have an ANSI C compiler.
Lua also compiles unmodified as C++.
The instructions given below for building Lua are for Unix-like platforms.
See also
<A HREF="#other">instructions for other systems</A>
and
<A HREF="#customization">customization options</A>.
<P>
If you don't have the time or the inclination to compile Lua yourself,
get a binary from
<A HREF="http://lua-users.org/wiki/LuaBinaries">LuaBinaries</A>.
Try also
<A HREF="http://luaforwindows.luaforge.net/">Lua for Windows</A>,
an easy-to-use distribution of Lua that includes many useful libraries.
<!--
<P>
If you only want to try Lua,
try the
<A HREF="demo.html">live demo</A>.
<P>
-->
<H3>Building Lua</H3>
<P>
In most Unix-like platforms, simply do "<KBD>make</KBD>" with a suitable target.
Here are the details.
<OL>
<LI>
Open a terminal window and move to
the top-level directory, which is named lua-5.2.0.
The Makefile there controls both the build process and the installation process.
<P>
<LI>
Do "<KBD>make</KBD>" and see if your platform is listed.
The platforms currently supported are:
<BLOCKQUOTE>
aix ansi bsd freebsd generic linux macosx mingw posix solaris
</BLOCKQUOTE>
<P>
If your platform is listed, just do "<KBD>make xxx</KBD>", where xxx
is your platform name.
<P>
If your platform is not listed, try the closest one or posix, generic,
ansi, in this order.
<P>
<LI>
The compilation takes only a few moments
and produces three files in the src directory:
lua (the interpreter),
luac (the compiler),
and liblua.a (the library).
<P>
<LI>
To check that Lua has been built correctly, do "<KBD>make test</KBD>"
after building Lua. This will run the interpreter on a simple "Hello world"
Lua program from the test directory.
You may want to try other example programs in that directory.
</OL>
<H3>Installing Lua</H3>
<P>
Once you have built Lua, you may want to install it in an official
place in your system. In this case, do "<KBD>make install</KBD>". The official
place and the way to install files are defined in Makefile. You'll
probably need the right permissions to install files.
<P>
To build and install Lua in one step, do "<KBD>make xxx install</KBD>",
where xxx is your platform name.
<P>
To install Lua locally, then do "<KBD>make local</KBD>".
This will create a directory <TT>install</TT> with subdirectories
<TT>bin</TT>, <TT>include</TT>, <TT>lib</TT>, <TT>man</TT>,
and install Lua as listed below.
To install Lua locally, but in some other directory, do
"<KBD>make install INSTALL_TOP=xxx</KBD>", where xxx is your chosen directory.
<DL CLASS="display">
<DT>
bin:
<DD>
lua luac
<DT>
include:
<DD>
lua.h luaconf.h lualib.h lauxlib.h lua.hpp
<DT>
lib:
<DD>
liblua.a
<DT>
man/man1:
<DD>
lua.1 luac.1
</DL>
<P>
These are the only directories you need for development.
If you only want to run Lua programs,
you only need the files in bin and man.
The files in include and lib are needed for
embedding Lua in C or C++ programs.
<H3><A NAME="customization">Customization</A></H3>
<P>
Three kinds of things can be customized by editing a file:
<UL>
<LI> Where and how to install Lua — edit Makefile.
<LI> How to build Lua — edit src/Makefile.
<LI> Lua features — edit src/luaconf.h.
</UL>
<P>
You don't actually need to edit the Makefiles because you may set the
relevant variables in the command line when invoking make.
Nevertheless, it's probably best to edit and save the Makefiles to
record the changes you need.
<P>
On the other hand, if you need to customize some Lua features, you'll need
to edit src/luaconf.h before building and installing Lua.
The edited file will be the one installed, and
it will be used by any Lua clients that you build, to ensure consistency.
Further customization is available to experts by editing the Lua sources.
<P>
We strongly recommend that you enable dynamic loading in src/luaconf.h.
This is done automatically for all platforms listed above that have
this feature and also for Windows.
<H3><A NAME="other">Building Lua on other systems</A></H3>
<P>
If you're not using the usual Unix tools, then the instructions for
building Lua depend on the compiler you use. You'll need to create
projects (or whatever your compiler uses) for building the library,
the interpreter, and the compiler, as follows:
<DL CLASS="display">
<DT>
library:
<DD>
lapi.c lcode.c lctype.c ldebug.c ldo.c ldump.c lfunc.c lgc.c llex.c
lmem.c lobject.c lopcodes.c lparser.c lstate.c lstring.c ltable.c
ltm.c lundump.c lvm.c lzio.c
lauxlib.c lbaselib.c lbitlib.c lcorolib.c ldblib.c liolib.c
lmathlib.c loslib.c lstrlib.c ltablib.c loadlib.c linit.c
<DT>
interpreter:
<DD>
library, lua.c
<DT>
compiler:
<DD>
library, luac.c
</DL>
<P>
To use Lua as a library in your own programs you'll need to know how to
create and use libraries with your compiler. Moreover, to dynamically load
C libraries for Lua you'll need to know how to create dynamic libraries
and you'll need to make sure that the Lua API functions are accessible to
those dynamic libraries — but <EM>don't</EM> link the Lua library
into each dynamic library. For Unix, we recommend that the Lua library
be linked statically into the host program and its symbols exported for
dynamic linking; src/Makefile does this for the Lua interpreter.
For Windows, we recommend that the Lua library be a DLL.
<P>
As mentioned above, you may edit src/luaconf.h to customize
some features before building Lua.
<H2><A NAME="changes">Changes since Lua 5.1</A></H2>
<P>
Here are the main changes introduced in Lua 5.2.
The
<A HREF="contents.html">reference manual</A>
lists the
<A HREF="manual.html#8">incompatibilities</A> that had to be introduced.
<H3>Main changes</H3>
<UL>
<LI> yieldable pcall and metamethods
<LI> new <CODE>_ENV</CODE> scheme
<LI> ephemeron tables
<LI> new library for bitwise operations
<LI> light C functions
<LI> emergency garbage collector
</UL>
Here are the other changes introduced in Lua 5.2:
<H3>Language</H3>
<UL>
<LI> no more fenv for threads or functions
<LI> tables honor the <CODE>__len</CODE> metamethod
<LI> hex and <CODE>\*</CODE> escapes in strings
<LI> order metamethods work for different types
<LI> no more verification of opcode consistency
<LI> hook event "tail return" replaced by "tail call"
<LI> empty statement
</UL>
<H3>Libraries</H3>
<UL>
<LI> new metamethods <CODE>__pairs</CODE> and <CODE>__ipairs</CODE>
<LI> arguments for function called through <CODE>xpcall</CODE>
<LI> optional 'mode' argument to load (to control binary x text)
<LI> new function <CODE>loadin</CODE>
<LI> <CODE>loadlib</CODE> may load libraries with global names (RTLD_GLOBAL)
<LI> new function <CODE>package.searchpath</CODE>
<LI> optional base in <CODE>math.log</CODE>
<LI> <CODE>file:write</CODE> returns <CODE>file</CODE>
<LI> closing a pipe returns exit status
<LI> <CODE>os.exit</CODE> may close state
<LI> new option 'isrunning' for <CODE>collectgarbage</CODE> and <CODE>lua_gc</CODE>
<LI> frontier patterns
<LI> <CODE>\0</CODE> in patterns
<LI> new option <CODE>*L</CODE> for <CODE>io.read</CODE>
<LI> options for <CODE>io.lines</CODE>
</UL>
<H3>C API</H3>
<UL>
<LI> main thread predefined in the registry
<LI> new constants <CODE>LUA_OK</CODE> and <CODE>LUA_ERRGCMM</CODE>
<LI> new <CODE>lua_compare</CODE>, <CODE>lua_arith</CODE>, and <CODE>lua_len</CODE>
<LI> new <CODE>lua_version</CODE> and <CODE>luaL_version</CODE>
<LI> <CODE>lua_pushstring</CODE> and <CODE>pushlstring</CODE> return string
<LI> new <CODE>luaL_testudata</CODE> and <CODE>luaL_setmetatable</CODE>
<LI> new <CODE>luaL_tolstring</CODE>
<LI> new <CODE>lua_copy</CODE>
<LI> new <CODE>lua_absindex</CODE>
<LI> new <CODE>lua_upvalueid</CODE> and <CODE>lua_upvaluejoin</CODE>
<LI> <CODE>nparams</CODE> and <CODE>isvarag</CODE> available in debug API
<LI> new <CODE>lua_Unsigned</CODE>
</UL>
<H3>Implementation</H3>
<UL>
<LI> max constants per function raised to 2<SUP>26</SUP>
<LI> internal (immutable) version of ctypes
<LI> simpler implementation for string buffers
<LI> udata with finalizers are kept in a separated list for the GC
<LI> <CODE>CallInfo</CODE> stack now is a linked list
<LI> parser uses much less C-stack space (no more auto arrays)
<LI> new hash for floats
<LI> handling of non-string error messages in the standalone interpreter
<LI> generational mode for garbage collection (experimental)
</UL>
<H2><A NAME="license">License</A></H2>
<A HREF="http://www.opensource.org/docs/definition.php">
<IMG SRC="osi-certified-72x60.png" ALIGN="right" BORDER="0" ALT="[osi certified]" STYLE="padding-left: 30px ;">
</A>
<P>
Lua is free software distributed under the terms of the
<A HREF="http://www.opensource.org/licenses/mit-license.html">MIT license</A>
reproduced below;
it can be used for any purpose, including commercial purposes,
at absolutely no cost without having to ask us.
The only requirement is that if you do use Lua,
then you should give us credit by including the appropriate copyright notice somewhere in your product or its documentation.
For details, see
<A HREF="http://www.lua.org/license.html">this</A>.
<BLOCKQUOTE>
Copyright © 1994–2010 Lua.org, PUC-Rio.
<P>
Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:
<P>
The above copyright notice and this permission notice shall be included in
all copies or substantial portions of the Software.
<P>
THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
THE SOFTWARE.
</BLOCKQUOTE>
<HR>
<SMALL>
Last update:
Thu Nov 11 15:16:22 BRST 2010
</SMALL>
<!--
Last change: revised for Lua 5.2.0 (alpha)
-->
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