latex.py is a preprocessor for LaTeX source files.
It was originally written because a journal asked me not to have any
user-defined latex macro in the source file. Which was a problem, since
I had lots of them. Hence, a program was needed to process the file and
expand these macros to create a file to send to the publisher.
Since then, it has grown a bit. There are now three main use cases:
1) Write macros in python. Because it's simpler? More powerful libraries?
Use '@' instead of '\' as macro prefix. Typical build process:
python latex.py -i macros.py -o manuscript.pdf manuscript.tex
2) Expand user-defined macros in text, because some journals don't like these.
Uses '\' as macro prefix, but replaces as many as possible with their
expansions.
python latex.py -L -o manuscript.texp manuscript.tex
3) Parse a latex file to determine its dependencies, for use in makefiles etc.
deps=$(python latex.py -L \
-P includegraphics:1:%s.pdf \
-P input:1:%s.tex \
-P bibliography:1:%s.bib \
manuscript.tex)
In the .tex file, lines beginning with '%@', or between '{%@' and '}%@',
form a block of python code. As a simple case, the following can be put in
the .tex file,
---
{%@
def vec(x):
return r'\hat{%s}' % x
A = r'\mathrm{A}' [1]
}%@
---
and now \vec{\A} is expanded to \hat{\mathrm{A}} in the text (assuming
the -L flag is used).
There are various shortcuts to make this more pleasant to write. The
following are two equivalent ways to write the definitions above:
---
{%@
def vec(x):
return : \hat{#(x)} [2]
A =: \mathrm{A}
}%@
---
{%@
vec =: \hat{%s} [3]
A =: \mathrm{A}
}%@
---
\newcommand{\vec}[1]{\hat{#1}} [4]
\newcommand{\A}{\mathrm{A}}
(The ':' syntax is not pure python obviously. For the curious, line [2] is
converted to
return r"""\hat{%(x)s}""" % locals()
Furthermore, a macro can either be a string (as in lines [1] and [3]), or
a function (as in [2]). Strings are formatted using the arguments to the
macro.
[4]: Yes, latex.py understands \newcommand when the -L flag is given. It
can be used on an unmodified latex file to expand all user-defined macros.
Another short example:
---
%@eval = eval [5]
\title{Proving that $2+2=@eval{2+2}$
---
The line [5] is required to make the builtin function eval visible as a macro.
Note that these builtins may be shadowed by user variables, but are always
accessible as for example __builtin__.eval.
It is recommended that functions, variables and classes that should not be
visible as macros should contain the underscore character ('_'), since it is
not allowed in a macro name.
See the examples/ directory for other examples.
latex.py was written in 2010 by Joachim B Haga (jobh@simula.no).
It is licensed under GPL v2 (or later).