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From: rouben@math13.math.umbc.edu (Rouben Rostamian)
Newsgroups: comp.text.tex
Subject: Re: How do I comment-out a block of TeX
Message-ID: <4881@umbc3.UMBC.EDU>
Date: 24 Jan 91 03:54:36 GMT
References: <29555@usc>
Sender: newspost@umbc3.UMBC.EDU
Reply-To: rouben@math13.math.umbc.edu.UUCP (Rouben Rostamian)
Distribution: comp
Organization: Mathematics Department University of Maryland, Baltimore County
Lines: 62

In article <29555@usc> siemsen@sol.usc.edu (Pete Siemsen) writes:
>Is there some way to comment out a block of TeX code?  Yes, I can
>insert a percent sign at the front of every line, but I want something
>simpler, like C's "#if 0" and "#endif" preprocessor directives.  I
>tried \ifnum0>1 ... \fi, but TeX barfed with "missing \fi" after 2000
>or so lines.

I do not know off hand how to define an \comment macro in TeX, but
I recall a discussion of this issue in TeXHaX or someplace like that,
and that there were some people who offered solutions which I did not
save.

I cannot imagine why you should want to comment-out 2000 lines of 
text out of a file.  Two thousand lines of text should never be
placed in one file to begin with.

I have two suggestion regarding your query:

    1. The longer a TeX file, the more unwieldy it gets, not
only for debugging, but for editing, TeXing, updating, revising,
spell-checking, and so on.  I always advise beginners to break up
their TeX files into as many logically separate components as
possible.  For instance, when writing a journal article, it is a good
idea to place each section, not matter how short, into a separate
file.  Then have a master file \input the individual sections for
processing.  The same method applies to chapters and subsections of
books and monographs.  After all, "modular programming" is the
standard practice in writing programs, and a TeX documents is not
much different from a program.

Once you have modularized your text, you can comment and
uncomment selected \input commands in the master file to process
individual sections.

    2.  If you are on a machine with a C compiler, you may use C
preprocessor's #ifdef construct to comment out sections of a TeX
document.  Just enclose the selected text within an "#ifdef DEBUG"
and "#endif", and run your TeX document through the C preprocessor
before feeding it to TeX.  The C preprocesor is accessed differently
depending on the particular machine you are on.  Consult the manual.
In ultrix, you may do:

/lib/ccp -P -DDEBUG file.tex >file_new.tex

End of suggestions.
-----------------------------------------------------------------------
\begin{wishlist}
I wish that the unix implementation of TeX would accepts files form
standard in, as most other unix utilities do.  In that case I could
by-pass the creation of the intermediate file_new.tex in the example
above and do:

/lib/ccp -P -DDEBUG file.tex |latex

Alas, ...
\end{wishlist}

--
Rouben Rostamian                          Telephone: (301) 455-2458
Department of Mathematics and Statistics  e-mail:
University of Maryland Baltimore County   bitnet: rostamian@umbc.bitnet
Baltimore, MD 21228,  U.S.A.              internet: rouben@math9.math.umbc.edu