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Mailing list for the LaTeX3 project <[log in to unmask]>
Frank Mittelbach <[log in to unmask]>
Sun, 14 Nov 1999 19:48:23 +0100
Mailing list for the LaTeX3 project <[log in to unmask]>
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James Kilfiger writes:

 > What is your view of the aim in terms of compatiblity with 2e.  Should
 > there be source compatiblity or formatting compatiblity.  I'd say the
 > first is essential, if only in a compatiblty mode, the second may be
 > desirable, but only in a compatitblty mode.

i have very strong feelings on compatibility and several people have already
learned about it when i rejected a sensible change in the 2e kernel for
reasons of compatibility.

 my main argument for 2e is that LaTeX 2e is an exchange medium as well as a
 typesetting machinery. this means that even sensible change/enhancements have
 to be judged as to whether introducing an incompatibility between two
 maintenance releases of LaTeX2e is worth the price. many people argue that
 this is no problem because feature X is not there in previous releases so
 couldn't have been used, but the problem in fact lies in the other direction:
 once a new feature is introduced and people and package writer use it they
 produce documents and/or packages which only work with LaTeX <date> and since
 a lot of people are unable to upgrade on regular basis this introduces a
 situation comparable to the last days of LaTeX2.09 where half of the
 installations couldn't process the documents of the other half (unless one
 kept at least three or four different `LaTeXs' around and even then)

 This is our basic strategy for not changing article.cls to produce a more
 decent layout or for adding feature X to the kernel (see ltnews07.tex) even
 if we agree that it would be sensible

but this is all concerning 2e. James asked about 2e* and eventually ltx3.

for what i'm currently doing i have somewhat different views. first of all,
all the concepts and all the code that is currently being discussed and
produced is explicitly written as a package solution to run on top of
LaTeX2e. (this will change eventually but then we are going to call the beauty
not 2e* but 3 or 2000:-)

this means that a new class/package file that makes use of these concepts is

  a) something new that should run on every LaTeX2e installation that has
  installed the corresponding packages (and installing new packages is far
  easier than installing a new kernel)

  b) a document that uses a new class would not have any compatibility
  issues, other than with different versions of the 2e* package.
  the latter will certainly be a problem for a while which means hat it will
  take a while until something like a 2e* package can be reliably be used in
  production. But any document that uses the new classes or packages using the
  new concepts will also be "new", ie written with that information in mind.

but what about all the million documents aready written?

answer: as long as we are within 2e* and do not provide replacements for
things like article.cls then nothing is going to change their formatting since
they wouldn't even notice that there is additional stuff is around (since they
do not load it).

both together will allow us to thoroughly test the new concepts on a wider
scale without compromising the production environment that LaTeX2e provides.

in case we actually provide replacements for classes like article.cls there
should be no difference either in the sense that a replacement for article.cls
should of course keep the document command interface (100%) and as far as
possible (no guess for a percentage) the layout.

but i consider replacements for article.cls, report.cls and the like (within
2e*) more or less only as a test case for the templates (i.e., can we
reproduce the (wonderful :-) original LaTeX layout) and at that state it
should be done under different names to avoid any compatibility issues for the
production environments at all.

the moment we actually produce a kernel containing those concepts there is of
course the need to produce replacements of the standard classes (as well as of
a lot of packages that may benefit from the new concepts). As far as those
replacements are concerned i agree that they should at least provide source
compatibility and as far as possible also formatting compatibility. preferably
this should be achieved automatically. but i wouldn't get totally unhappy if
there is a need to automatically change 2e documents into ltx3 document via
some translation process. after all, if you do not allow for this you either
have to abandom any improvment (such as a better though perhaps not fully
compatible float mechansim) or you have to provide a very very elaborate
compatibility mode. what is more appropriate remains to be seen. right now i
would not like to make predictions on what is better.