manual/luatex-introduction.tex

   1 % language=uk
   2
   3 \environment luatex-style
   4 \environment luatex-logos
   5
   6 \startcomponent luatex-introduction
   7
   8 \startchapter[title=Introduction]
   9
  10 This is the reference manual of \LUATEX. We don't claim it is complete and we
  11 assume that the reader knows about \TEX\ as described in \quotation {The \TEX\
  12 Book}, the \quotation {\ETEX\ manual}, the \quotation {\PDFTEX\ manual}, etc.
  13 Additional reference material is published in journals of user groups and
  14 \CONTEXT\ related documentation.
  15
  16 It took about a decade to reach stable version 1.0, but for good reason.
  17 Successive versions brought new functionality, more control, some cleanup of
  18 internals and experimental features evolved into stable ones or were dropped.
  19 Already quite early \LUATEX\ could be used for production and it was used on a
  20 daily basis by the authors. Successive versions sometimes demanded a adaption to
  21 the \LUA\ interfacing, but the concepts were unchanged. The current version can
  22 be considered stable in functionality and there will be no fundamental changes.
  23 Of course we then can decide to move towards version 2.00 with different
  24 properties.
  25
  26 Don't expect \LUATEX\ to behave the same as \PDFTEX ! Although the core
  27 functionality of that 8 bit engine was starting point, it has been combined with
  28 the directional support of \OMEGA\ (\ALEPH). But, \LUATEX\ can behave different
  29 due to its wide (32 bit) characters, many registers and large memory support.
  30 There is native \UTF\ input, support for large (more that 8 bit) fonts, and the
  31 math machinery is tuned for \OPENTYPE\ math. There is support for directional
  32 typesetting too. The log output can differ from other engines and will likely
  33 differ more as we move forward. When you run plain \TEX\ for sure \LUATEX\ runs
  34 slower than \PDFTEX\ but when you run for instance \CONTEXT\ \MKIV\ in many cases
  35 it runs faster, especially when you have a bit more complex documents or input.
  36 Anyway, 32 bit all||over combined with more features has a price, but on a modern
  37 machine this is no real problem.
  38
  39 Testing is done with \CONTEXT, but \LUATEX\ should work fine with other macro
  40 packages too. For that purpose we provide generic font handlers that are mostly
  41 the same as used in \CONTEXT. Discussing specific implementations is beyond this
  42 manual. Even when we keep \LUATEX\ lean and mean, we already have enough to
  43 discuss here.
  44
  45 \LUATEX\ consists of a number of interrelated but (still) distinguishable parts.
  46 The organization of the source code is adapted so that it can glue all these
  47 components together. We continue cleaning up side effects of the accumulated
  48 code in \TEX\ engines (especially code that is not needed any longer).
  49
  50 \startitemize[packed]
  51     \startitem
  52         Most of \PDFTEX\ version 1.40.9, converted to \CCODE. Some experimental
  53         features have been removed and some utility macros are not inherited as
  54         their functionality can be done in \LUA. The number of backend interface
  55         commands has been reduced to a few. The extensions are separated from the
  56         core (which we keep close to the original \TEX\ core). Some mechanisms
  57         like expansion and protrusion can behave different from the original due
  58         to some cleanup and optimization. Some whatsit based functionality (image
  59         support and reusable content) is now core functionality.
  60     \stopitem
  61     \startitem
  62         The direction model and some other bits from \ALEPH\ RC4 (derived from
  63         \OMEGA) is included. The related primitives are part of core \LUATEX\ but
  64         at the node level directional support is no longer based on so called
  65         whatsits but on real nodes. In fact, whatsits are now only used for
  66         backend specific extensions.
  67     \stopitem
  68     \startitem
  69         Neither \ALEPH's I/O translation processes, nor tcx files, nor \ENCTEX\
  70         can be used, these encoding|-|related functions are superseded by a
  71         \LUA|-|based solution (reader callbacks). In a similar fashion all file
  72         \IO\ can be intercepted.
  73     \stopitem
  74     \startitem
  75         We currently use \LUA\ 5.2.*. At some point we might decide to move to
  76         5.3.* but that is yet to be decided. There are few \LUA\ libraries that
  77         we consider part of the core \LUA\ machinery, for instance \type {lpeg}.
  78         There are additional \LUA\ libraries that interface to the internals of
  79         \TEX.
  80     \stopitem
  81     \startitem
  82         There are various \TEX\ extensions but only those that cannot be done
  83         using the \LUA\ interfaces. The math machinery often has two code paths:
  84         one traditional and the other more suitable for wide \OPENTYPE\ fonts.
  85     \stopitem
  86     \startitem
  87         The fontloader uses parts of \FONTFORGE\ 2008.11.17 combined with
  88         additional code specific for usage in a \TEX\ engine. We try to minimize
  89         specific font support to what \TEX\ needs: character references and
  90         dimensions and delegate everything else to \LUA. That way we keep \TEX\
  91         open for extensions without touching the core.
  92     \stopitem
  93     \startitem
  94         The \METAPOST\ library is integral part of \LUATEX. This gives \TEX\ some
  95         graphical capabilities using a relative high speed graphical subsystem.
  96         Again \LUA\ is used as glue between the frontend and backend. Further
  97         development of \METAPOST\ is closely related to \LUATEX.
  98     \stopitem
  99 \stopitemize
 100
 101 We try to keep upcoming versions compatible but intermediate releases can contain
 102 experimental features. A general rule is that versions that end up on \TEX live
 103 and|/|or are released around \CONTEXT\ meetings are stable. Future versions will
 104 probably become a bit leaner and meaner. Some libraries might become external as
 105 we don't want to bloat the binary and also don't want to add more hard coded
 106 solutions. After all, with \LUA\ you can extend the core functionality. The less
 107 dependencies, the better.
 108
 109 The \TEXLIVE\ version is to be considered the current stable version. Any version
 110 between the yearly \TEXLIVE\ releases are to be considered beta. The beta
 111 releases are normally available via the \CONTEXT\ distribution channels (the
 112 garden and so called minimals).
 113
 114 \blank[1*big]
 115
 116 Hans Hagen, Harmut Henkel, \crlf
 117 Taco Hoekwater \& Luigi Scarso
 118
 119 \blank[3*big]
 120
 121 \starttabulate
 122 \NC Version  \EQ \currentdate \NC \NR
 123 \NC \LUATEX  \EQ version  \cldcontext{status.luatex_version/100},
 124                  revision \cldcontext{status.luatex_revision},
 125                  number   \cldcontext{environment.luatexversion} \NC \NR
 126 \NC \CONTEXT \EQ MkIV \contextversion \NC \NR
 127 \stoptabulate
 128
 129 \stopchapter
 130
 131 \stopcomponent