Re: lilypond-book: treat iffalse sections in latex as block comments (issue 6584073)

[Reinhold Kainhofer]

On 2012-10-06 06:33, address@hidden wrote:
> http://codereview.appspot.com/6584073/diff/1/python/book_latex.py
> File python/book_latex.py (right):
>
> http://codereview.appspot.com/6584073/diff/1/python/book_latex.py#newcode88
> python/book_latex.py:88: \\iffalse.*\\fi))''',
> On 2012/10/06 02:12:41, Julien Rioux wrote:
> > .* should be replaced by the non-greedy .*?
>
> Yes :-)

Absolutely, was my mistake.

> http://codereview.appspot.com/6584073/diff/1/python/book_latex.py#newcode88
> python/book_latex.py:88: \\iffalse.*\\fi))''',
> As David has commented on the list, I would prefer if you replaced the
> \iffalse ... \fi with a higher-level command, namely \begin{comment} ...
> \end{comment} (from the `comment' package).

So, your opinion is that lilypond-book SHOULD process the \lilypond{...} 
code inside the \iffalse  section and spectacularly fail. If users are 
using \iffalse -- I am for example one of those who use \iffalse to 
quickly comment out some parts temporarily -- then lilypond-book would 
still require everything between \iffalse and \fi to be in correct 
lilypond syntax and will create snippet images for all those snippets:

\documentclass[a4paper, 12pt]{article}
\begin{document}
TODO

\iffalse
This is a template for my future snippets:
\lilypond{Code comes here}
\fi

\end{document}



Shall lilypond-book really fail for (and process) snippets that will NOT 
be included by latex???


> First of all, this syntax
> suits LaTeX better since it resembles normal environments.  Second, it
> is a bad idea in general to expose \ifXXX to the top level; in other
> words, users should never do that.

But fact is, people ARE using \iffalse to temporarily comment out larger 
parts of latex files. With my colleagues, I have never seen 
\begin{comment} for comments, all the researchers I have worked with so 
far were using \iffalse.

Also, this is not about advocating what latex users should use, but 
handling whare users are using currently. So, I will add \begin{comment} 
to the pattern, too, but I still think that lilypond-book SHOULD ignore 
everything inside \iffalse.

> Reason is that \ifXXX is handled
> very special in TeX since you can define, say, \ifFoo which also pairs
> with the next \fi, making correct balancing of nested \ifXXX commands
> quite delicate and very hard to debug.

Sure, it's not the perfect way, but it's the quick-and-dirty way.
I'm also aware that lilypond-book will not be able to handle nested 
\ifXXX correctly. However, in the worst case, it will process some code 
after the first \fi and before the final \fi of the \iffalse. But that's 
still better than the current situation, where it processes everything 
between \iffalse and \fi.

Cheers,
Reinhold
--
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Reinhold Kainhofer, address@hidden, http://www.kainhofer.com
 * Financial & Actuarial Math., Vienna Univ. of Technology, Austria
 * http://www.fam.tuwien.ac.at/, DVR: 0005886
 * Edition Kainhofer, Music Publisher, http://www.edition-kainhofer.com