View Source: Lua - Waikato Linux Users Group

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[Lua | http://www.lua.org] is a lightweight ProgrammingLanguage designed for extending applications, but also frequently used as a stand-alone language. It is implemented as a small library of [ANSI] [C] functions that compiles unmodified on all known platforms. The [API] that allows an application to exchange data with [Lua] programs and also to extend Lua with [C] functions. In this sense, [Lua] can be regarded as a language framework for building domain-specific languages. [Lua] programs are compiled to ByteCode. [Lua]'s implementation goals are simplicity, efficiency, portability, and low embedding cost. The result is a fast language engine with small footprint, making it ideal in embedded systems too. It is FreeSoftware,  designed and implemented by a team at Tecgraf, the Computer Graphics Technology Group of PUC-Rio (the Pontifical Catholic University of Rio de Janeiro in Brazil). Tecgraf is a laboratory of theDepartment of ComputerScience.

The language combines simple procedural syntax with powerful data description constructs based on associative arrays, is dynamically typed, and has automatic memory management with GarbageCollection, making it ideal for configuration, scripting, and rapid prototyping. A fundamental concept in the design of [Lua] is to provide meta-mechanisms for implementing features, instead of providing a host of features directly in the language. For example, although [Lua] does not contain ObjectOrientation, it does provide mechanisms for implementing classes and inheritance. This philosophy brings an economy of concepts and keeps the language small, while allowing unconventional extensions to its semantics.

It is used as a scripting language for game engines by Lucas Soft, MicrosoftCorporation, etc (watch the conference at http://ll3.ai.mit.edu/).

See also:
* [The Lua-Users wiki | http://lua-users.org/wiki]
* <tt>#lua</tt> on the [FreeNode] [IRC] network

----

!! Sample [Lua] program

SourceCode::
    <verbatim>
    -- simple program that reads a config file in the format "a = b" and
    -- prints them to the output as "a is b"

    function fileexists( file )
        local f = io.open( file, "r" )
        if f then
            io.close( f )
            return true
        else
            return false
        end
    end

    function loadconfig( file )
        print( "+ reading config file " .. file )
        if fileexists( file ) then
            local cline = 1
            for line in io.lines( file ) do
                if string.sub( line, 0, 2 ) ~= "--" and line ~= "" then
                    local _,_,var, val = string.find( line, "(%S+)%s?=%s?(.*)" ) ;
                    if var == nil or val == nil then
                        print( "! malformed line on line " .. cline .. ", ignoring" )
                    else
                        print( var .. " is ".. val )
                    end
                end
                cline = cline + 1
            end
        else
            print( "! " .. file .. " does not exist !" )
            print( "! exiting.." )
            os.exit()
        end
    end

    loadconfig( "blah.conf" )
    </verbatim>

Output::
    <verbatim>
    $ lua blah.lua
    + reading config file blah.conf
    a is b
    var is val
    ! malformed line on line 3, ignoring
    nick is scope
    </verbatim>

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CategoryProgrammingLanguages
3 pages link to Lua:
Last edited on Sunday, November 21, 2004 2:54:26 pm by AristotlePagaltzis
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