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 Subject: Re: First experience with xr under L3PL From: Frank Mittelbach <[log in to unmask]> Reply To: Mailing list for the LaTeX3 project <[log in to unmask]> Date: Tue, 7 Jul 1998 22:51:08 +0200 Content-Type: text/plain Parts/Attachments: text/plain (221 lines)
sometime ago i think Javier Bezos remarked that typing with a baby on
your lap is probably more difficult than with a cat. i'd say there is
no comparison: just had one of my sons there (and was only trying to
read this message (or rather reread it more carefully) not to type
anything) and he managed with ease to put his hand on the keyboard and
guess what key he managed to press? d ... an omen? :-)

the times when working with them on my lap seem to be over

Richard  writes:

> On closer inpsection you also need this somewhere:
> \tlp_new:Nn \l_xr_line_tlp {}

true at least it would be consistent

> So as we have seen there is a Fortran-style implicit declaration of
> tlp's in certain circumstances, e.g. when used as the second argument
> of \ior_to:NN.  I'd like to suggest that the check' option used in
> the dtx files be changed into a package option, say checkdef' (you
> can think of a better name).  At the moment the decision of whether or
> not to check arguments is made once for all time when docstrip is
> invoked.

good idea, anybody willing to do this?

> Clearly we are still used to using \def in the same way as Lisp's
> setq, i.e. as a general definition mechanism that doesn't care about
> what you are defining (i.e. whether it has a previous definition).
> The new version of xr now has three declarations' that are evaluated
> when the package is loaded.  I can live with that; I (we) just need to
> remember that a new discipline is required.  I expect that a syntax
> checker for L3PL will find uses of seq's, tlp's, etc. without
> corresponding declarations.

right now it is mainly there as a help against unforseen later
errors. having such a checker would certainly be a help.

> Your algorithm is also subtly different.  The original version is
> careful to process \@input's in the order in which they are
> encountered, but your version uses a stack.  If there are no label
> conflicts, the net effect is the same.  But if there are multiple
> conflicts, the original version stops at the first conflict, whereas
> yours might even stop at the last first and the first last!

i don't deny that. i simply used this as an example to spawn further
discussion especially as you had taken the trouble to go through it i
thought i could add my share. actually i could have also produced
essentially the same algorithm by not using the stack commands but
instead using those other sequence commands.

>  >  > Tim's questions are really quite important for the average' package
>  >  > writer, because they will be programing in-the-small', and the xr
>  >  > example is quite a good one for that.  Even such a small package has
>  >  > needed a total re-think and re-writing.
>  >
>  > true but is it so much different from having to hunt through the LaTeX
>  > source to find you way in providing packages?
>
> Well . . . it's yet another layer of knowledge that has to be mastered
> before you can start doing non-trivial things.  Those of us who have
> been using TeX for ten years or more will shrug our shoulders and
> learn it anyway, but it might well serve as a deterrent to those who
> come to LaTeX3 as beginners.

i think i disagree here. what i meant is that you do need to learn
some layer whether it'll be current latex internal commands (by looking
at the latex source or other packages) or be something like the L3PL
language is not much different (except for those who already mastered
most of the mess of the current latex)

> If you are happy to release out-of-date and inconsistent documentation
> for incomplete packages then in fairness to us - your guinea pigs -
> _everything_ must be up for grabs.

i already said that this was a remark concerning latex2e --- and if
people are willing to help updating the documentation of the .dtx
files for 2e we are too willing to accept such help!!! just drop us a
-- sometimes fixes for the next release are already in) lock it in rcs
and put the updated documentation with your name on back in. certainly
we can make these sources better and it is still worth doing even

> Frank wrote elsewhere:
>  > just to change all the files to some new convention takes some effort
>  > which can be better spend. at the moment at least!
>
> Perhaps (the fewer inconsistencies in the original, the easier it will
> be), and I am not suggesting doing it on a whim; but if you try to
> close doors at this stage I - and I suspect others - will stubbornly
> stick in our arms and legs.  Even if you have already written five
> chapters of your next book :-)

we don't have the intention of closing doors at this stage. but at the
other hand we believe that there is not much gained if X suggests to
change the syntax slightly in this direction, then we have a long
discussion on whether or not this is how other people see this, then Y
suggest some other twist, ... and all of this gets implemented
straight away (by us) and changed over and over again instead of
providing new functionality within the framework as is and change it
completely on the surface later.

let's go back to this module stuff once more: i firmly believe that
the ideas brought forward would not be reasonably implementable at the
level we talked about (most of us do think that some of these ideas
are very helpful for a different level) and for that reason i'm not
really eager to change the syntax now just because Hans claimed he
needs this before he could seriously talk about these ideas
again. instead i proposed a way to try his ideas even within the
current syntax. *and i'm willing to listen to reason* which means if
he or somebody else would come forward with a practical trial
implementation that shows that i'm wrong i would be the first one to
admit this. in fact if the current syntax would indeed prevent doing
this trial i would be prepared to do that change (or any change that
would take away such a restriction) but as i explained there is no
such restriction technically with the current syntax so, saying that
one can only test or try things after one of us has change the surface
look of the language to somebody's liking is something that i can only
interpret as a refusal to take up my challenge (whatever the real
reason)

i also have nothing whatsoever against the idea that somebody sits
down and takes apart all the packages we have put together and does
some global replace and produces a version more to his or her liking.
we can certainly put such a version on CTAN as well.

but what i'm not going to do (me personally) is to do that type of
work just because some people think that _ are bad or the colon should
be a . or Modula2 type of syntax is better. that would drag on forever
without anything gained because there are probably as many opinions on
this subject as we had emails on it. if somebody wants to, please do
so, but don't ask us to do it for you now.

let me also say that i *DON'T* like the language as it is on many
special points (not the last are the many _) but just like here on the
list with perhaps 4-6 people commenting on the look of it we had
internally also very different opinions what looks best or works
best. and at one point we decided to stop and just pick one to
actually get functionality provided.

what i like about the language and this is what for me counts is its
support for the very important things of TeX namely expansion by the
general mechanism of the arg spec and that alone already proved to be
a big step forward when working in it. it also brought some better
orthogonality.

and yes i like programming in TeX as weird as it is some times :-)

>  > what i mean is, you need to have got a feeling for it but that it true
>  > right now as well except that right now because of nearly no
>  > conventions people are forced to reinvent the wheel over and over just
>  > because they don't know that some command or datatype or whatever
>
> Agreed.  A good example from the internals of LaTeX is the \@for and
> \@tfor constructs.  Unless you read the old lplain.tex or the new
> ltcntrl.dtx you would probably have no idea that these constructs
> existed.  The problem here is not one of consistency, but rather (a)
> these constructs have never really been official' and advertised, and
> (b) there is still no proper documentation.  \@for, \@tfor, and many
> other internal macros of LaTeX deserve promotion' to L3PL.  Much
> of this reinvention will then be avoided.

yes things like this should be part of the language and what we have
put out is not meant to be L3PL it is meant to be a start for
commenting and for those people interested helping us to provide
additional basic modules that would finally form a base kernel.

btw (a) above: those commands have never been really official because
in many cases they where originally only onetime hooks; \@for and
friends being an exception here and one of the main reasons for
something like L3PL is to provide exactly this: a consistent official
low-level interface that is described and advertised.

you also need a higher-level interface (or set of interfaces) which
are also official to avoid all the situations that people because of
nothing being put into such a status hooked into any layer with
disastrous effects when something was reprogrammed (or just fixed or
optimized :-)

>  > so yes you need a re-think, you probably don't need much of a
>  > rewriting for an existing package if you just mainly do a manual
>  > translation but you can gain a lot once you start replacing all you
>  > low-level private code by already provided solutions for many of the
>  > basic functionality which right now is often repeated over and over
>  > again in packages.
>
> It sounds as though it must be true, but let's see.  As I said
> earlier, we will go anywhere you take us, but let's enjoy the journey
> and learn from it.

i hope so. a good way would be to think about additionally needed
functionality and perhaps doing some suggested implementation.

loops would be such a slightly higher level thing and that was in fact
never properly written so far. we could those then put on ctan

> Frank also writes:
>  > . . . the
>  > solution is that you provide a replacement book for the TeX book.
>
> So this is your next book . . . my hand is creeping up . . . pick me!
> :-) I would be happy to contribute a chapter or two or proof-read or
> . . . Eine deutsche Uebersetzung waere auch moeglich . . . :-)

well it will not be the next one i guess :-)

in fact i've once have written roughly a 100 page manual on some
earlier version of the L3PL language which we then discarded---some of
the documentation you now got in an updated form (as far as convention
and code is concerned) in the current set of experimental stuff.

frank

ps don't be too surprised if i drop out of this discussion for a while
i might be offline a few days
`