# [tex-live] Ignoring portion of LaTeX code; the \par problem.

Norbert Preining preining at logic.at
Mon Apr 5 18:23:06 CEST 2010

Dear Michaël,

and people much more knowledgable than you on this list!!!

On So, 04 Apr 2010, Michaël Cadilhac wrote:
> 1- The \par problem.  I do understand that a \par may break the system
> by which arguments are parsed.  But how come this gives me an error:
>
> \def\ignore#1{}
> \ignore{\string\par}
>
> or even
>
> \ignore{\let\par=\relax}

On Mo, 05 Apr 2010, Michaël Cadilhac wrote:
> You seem to have failed to read my preceding email.  Maybe you should
> consider working on understanding basics of good communication -- see:
> http://tools.ietf.org/html/rfc1855  (Netiquette)

I think *YOU* missed the point in:
is this a problem with TeX Live?Did you try MikTeX, any other TeX
implementation? You would have seen that it is always the same,
because you seem to miss some core points of TeX.

> Better hint, Robin, my post wasn't any try to get help on such matter,
> but to report an apparent bug.  Also, you may have had a look at the

There is no apparent bug, there is only a misconception of yours.

The error message of TeX when rrunning on your "\par problem" is
clear enough:
! Paragraph ended before \ignore was complete.
\par
l.2 \ignore{\string\par
}
?

You might look up how macro expansion in TeX works in the TeX book
or somewhere else.  But having \par in the argument unprotected
is not the best way.

And here Robin's remark comes in quite handy, even if you threw it away
with diguise: Look up code in other packages who have dealt with that

> some potential newbie out.  Also, you may have found that my main point
> was that the *parsing* (as in "mechanics") of the TeX file failed me.

Well, that is because TeX parsing is far from trivial.

I have myself no IDEA AT ALL how to write something like that, but I would
trust Robin's remark on where to look for a solution, instead of
bashing him.

> You'd be kind enough not to answer again without having a look at my
> first message.

And you could be so kind to excuse for your impoliteness, and check out
his suggestion.

Norbert
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Norbert Preining            preining@{jaist.ac.jp, logic.at, debian.org}
JAIST, Japan            TU Wien, Austria           Debian TeX Task Force
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