manual/luatex-introduction.tex

   1 % language=uk
   2
   3 \environment luatex-style
   4 \environment luatex-logos
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   6 \startcomponent luatex-introduction
   7
   8 \startchapter[title=Introduction]
   9
  10 This book will eventually become the reference manual of \LUATEX. At the moment,
  11 it simply reports the behaviour of the executable matching the snapshot or beta
  12 release date in the title page. We don't claim it is complete and we assume that
  13 the reader knows about \TEX\ as described in \quotation {The \TEX\ Book}, the
  14 \quotation {\ETEX\ manual}, the \quotation {\PDFTEX\ manual}, etc. Additional
  15 reference material is published in journals of user groups and \CONTEXT\ related
  16 documentation.
  17
  18 Successive versions brought new functionality, more control, some cleanup of
  19 internals and experimental features evolved into stable ones or were dropped.
  20 Already quite early \LUATEX\ could be used for production and it was used in
  21 production by the authors. Successive versions sometimes demanded a adaption to
  22 the \LUA\ interfacing, but the concepts were unchanged. The current version can
  23 be considered stable in functionality and there will be no fundamental changes
  24 between 0.90 and 1.00. Of course we then can decide to move towards version 2.00
  25 with different properties.
  26
  27 Don't expect \LUATEX\ to behave the same as \PDFTEX ! Although the core
  28 functionality of that 8 bit engine was starting point, it has been combined with
  29 the directional support of \OMEGA\ (\ALEPH). But, \LUATEX\ can behave different
  30 due to its wide (32 bit) characters, many registers and large memory support.
  31 There is native \UTF\ input, support for large (more that 8 bit) fonts, and the
  32 math machinery is tuned for \OPENTYPE\ math. There is support for directional
  33 typesetting too. The log output can differ from other engines and will likely
  34 differ more as we move forward. When you run plain \TEX\ for sure \LUATEX\ runs
  35 slower than \PDFTEX\ but when you run for instance \CONTEXT\ \MKIV\ it might be
  36 faster on more complex documents. But in any case: 32 bit all||over combined with
  37 more features has a price.
  38
  39 \LUATEX\ consists of a number of interrelated but (still) distinguishable parts.
  40 The organization of the source code is adapted so that it can glue all these
  41 components together. We continue cleaning up side effects of the accumulated
  42 code in \TEX\ engines (especially code that is not needed any longer).
  43
  44 \startitemize[packed]
  45     \startitem
  46         Most of \PDFTEX\ version 1.40.9, converted to C (with patches from later
  47         releases). Some experimental features have been removed and some utility
  48         macros are not inherited as their functionality can be done in \LUA. The
  49         number of backend interface commands has been reduced to a few. The
  50         extensions are separated from the core (which we keep close to the
  51         original \TEX\ core). Some mechanisms like expansion and protrusion can
  52         behave different from the original due to some cleanup and optimization.
  53         Some whatsit based functionality (image support and reusable content)
  54         is now core functionality.
  55     \stopitem
  56     \startitem
  57         The direction model and some other bits from \ALEPH\ RC4 (derived from
  58         \OMEGA) is included. The related primitives are part of core \LUATEX\ but
  59         at the node level directional support is no longer based on so called
  60         whatsits but on real nodes. In fact, whatsits are now only used for
  61         backend specific extensions.
  62     \stopitem
  63     \startitem
  64         Neither \ALEPH's I/O translation processes, nor tcx files, nor \ENCTEX\
  65         can be used, these encoding|-|related functions are superseded by a
  66         \LUA|-|based solution (reader callbacks). In a similar fashion all file
  67         \IO\ can be intercepted.
  68     \stopitem
  69     \startitem
  70         We currently use \LUA\ 5.2.*. At some point we might decide to move to
  71         5.3.* but that is yet to be decided. There are few \LUA\ libraries that
  72         we consider part of the core \LUA\ machinery, for instance \type {lpeg}.
  73         There are additional \LUA\ libraries that interface to the internals of
  74         \TEX.
  75     \stopitem
  76     \startitem
  77         There are various \TEX\ extensions but only those that cannot be done
  78         using the \LUA\ interfaces. The math machinery often has two code paths:
  79         one traditional and the other more suitable for wide \OPENTYPE\ fonts.
  80     \stopitem
  81     \startitem
  82         The fontloader uses parts of \FONTFORGE\ 2008.11.17 combined with
  83         additionaL code specific for usage in a \TEX\ engine. We try to minimize
  84         specific font support to what \TEX needs: character references and
  85         dimensions and delegate everything else to \LUA. That way we keep \TEX\
  86         open for extensions without touching the core.
  87     \stopitem
  88     \startitem
  89         The \METAPOST\ library is integral part of \LUATEX. This gives \TEX\ some
  90         graphical capabilities using a relative high speed graphical subsystem.
  91         Again \LUA\ is used as glue between the frontend and backend. Further
  92         development of \METAPOST\ is closely related to \LUATEX.
  93     \stopitem
  94 \stopitemize
  95
  96 The yearly \TEXLIVE\ version is the stable version, any version between them are
  97 to be considered beta. The beta releases are normally available via the \CONTEXT\
  98 distribution channels (the garden and so called minimals).
  99
 100 \blank[1*big]
 101
 102 Hans Hagen, Harmut Henkel, \crlf
 103 Taco Hoekwater \& Luigi Scarso
 104
 105 \blank[3*big]
 106
 107 \starttabulate
 108 \NC Version  \EQ \currentdate \NC \NR
 109 \NC \LUATEX  \EQ Snapshot \number\luatexversion.\luatexrevision \NC \NR
 110 \NC \CONTEXT \EQ \contextversion \NC \NR
 111 \stoptabulate
 112
 113 \stopchapter
 114
 115 \stopcomponent