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% $Id$
% Enable and prefix LuaTeX primitives for LaTeX-based formats
% Assumes LuaTeX 0.39.x or greater.
% Manuel Pégourié-Gonnard, 2009. Public domain.
\begingroup
\catcode`\{=1
\catcode`\}=2
\directlua{
% etex and pdftex primitives are enabled without prefixing
tex.enableprimitives('',
tex.extraprimitives('etex', 'pdftex'))
% other primitives are prefixed with luatex (see below)
tex.enableprimitives('luatex',
tex.extraprimitives('core', 'omega', 'aleph', 'luatex'))
}
\endgroup
\endinput
% Rationale for primitives prefixing.
%
% 1. All current macro packages run smoothly on top of pdf(e)TeX, so those
% primitives are left untouched.
% 2. Other non-TeX82 primitives in LuaTeX may cause name clashes with existing
% macros in macro packages, especially when the use very "natural" names
% such as \outputbox, \mathstyle etc. Such a probability for name clashes is
% highly undesirable if LuaTeX is to replace pdfTeX as the default engine
% some day, and still undesirable even if it does not, anyway, since some
% level of compatibility never hurts.
% 3. The LuaTeX team doesn't want to apply a systematic prefixing policy, but
% kindly provided a tool allowing to apply it. So we chose to use it.
% Previously, we even disabled the extra primitives, but now we feel it's
% better to enable them with systematic prefexing, in order to avoid that
% each and every macro package (or user) enables them with various and
% inconsistent prefixes (including the empty prefix).
% 4. The 'luatex' prefix was chosen since it is already used as a prefix for
% some primitives, such as \luatexversion: since way, those promitive don't
% end up with a double prefix (see tex.enableprimitive in the luatex manual
% for details).
% 5. The \directlua primitive is provided both with its natural name (allowing
% to easily detect LuaTeX-besed formats) and a prefixed version
% \luatexdirectlua (for consistency with \luatexlatelua).
% 6. Various remarks
% (a) The obvious drawback of such a prefixing policy is that the names used
% by LaTeX or generic macro writer won't match the names used in the
% manual. We hope this is compensated by the gain in backwards
% compatibility.
% (b) All primitives dealing with Unicode math already begin with \U, and
% maybe will match the names of XeTeX primitives some day, so maybe
% prefixing was not necessary/desirable for them. However, we tried to
% make the prefixing rule as simple as possible, so that point (a) doesn't
% get too annoying.
% (c) The final name of some primitive may sound strange, namely those
% already containing the name of an engine, such as \luatexOmegaVersion.
% However, since LuaTeX is not a drop-in replacement for Omega/Aleph, we
% felt it wrong to provide \OmegaVersion.
% (d) Maybe some day we'll realise that it is better to provide all
% primitives without prefixing at all, after all. If this happens, it will
% be easy to add the unprefixed primitives in the format while keeping the
% prefixed names for compatibility. It wouldn't work the other way round
% (ie, realising that we should not provide the unprefixed primitives
% would cause huge compatibility problems for all LuaTeX-specific macro
% packages).
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