/*! \page perlmod Perl Module Output

\addindex perlmod

Since version 1.2.18, doxygen can generate a new output format we 

have called the "Perl Module output format".  It has been 

designed as an intermediate format that can be used to generate new 

and customized output without having to modify the doxygen source. 

Therefore, its purpose is similar to the XML output format that can be 

also generated by doxygen.  The XML output format is more standard, 

but the Perl Module output format is possibly simpler and easier to 

use.

The Perl Module output format is still experimental at the moment 

and could be changed in incompatible ways in future versions, although 

this should not be very probable.  It is also lacking some features of 

other doxygen backends.  However, it can be already used to generate 

useful output, as shown by the Perl Module-based \LaTeX generator.

Please report any bugs or problems you find in the Perl Module 

backend or the Perl Module-based \LaTeX generator to the 

doxygen-develop mailing list.  Suggestions are welcome as well.

\section using_perlmod_fmt Usage

When the \ref cfg_generate_perlmod "GENERATE_PERLMOD" tag is enabled in the Doxyfile, 

running doxygen generates a number of files in the `perlmod/` 

subdirectory of your output directory.  These files are the following:

`DoxyDocs.pm`:  This is the Perl module that actually

contains the documentation, in the Perl Module format described 

\ref doxydocs_format "below".

`DoxyModel.pm`:  This Perl module describes the structure of

`DoxyDocs.pm`, independently of the actual documentation.  See 

\ref doxymodel_format "below" for details.

`doxyrules.make`:  This file contains the make rules to build 

and clean the files that are generated from the Doxyfile.  Also 

contains the paths to those files and other relevant information. This 

file is intended to be included by your own Makefile.

`Makefile`:  This is a simple Makefile including 

`doxyrules.make`.

To make use of the documentation stored in DoxyDocs.pm you can use

one of the default Perl Module-based generators provided by doxygen

(at the moment this includes the Perl Module-based \LaTeX generator,

see \ref perlmod_latex "below") or write your own customized

generator.  This should not be too hard if you have some knowledge of

Perl and it's the main purpose of including the Perl Module backend in

doxygen.  See \ref doxydocs_format "below" for details on how

to do this.

<-- want to use \LaTeX but not possible in headings -->

\section perlmod_latex Using the LaTeX generator.

The Perl Module-based \LaTeX generator is pretty experimental and

incomplete at the moment, but you could find it useful nevertheless.

It can generate documentation for functions, typedefs and variables

within files and classes and can be customized quite a lot by

redefining \TeX macros.  However, there is still no documentation on

how to do this.

Setting the \ref cfg_perlmod_latex "PERLMOD_LATEX" tag to \c YES in the 

\c Doxyfile enables the creation of some additional files in the `perlmod/` 

subdirectory of your output directory.  These files contain the Perl 

scripts and \LaTeX code necessary to generate PDF and DVI output from 

the Perl Module output, using `pdflatex` and `latex` respectively.  Rules 

to automate the use of these files are also added to 

`doxyrules.make` and the `Makefile`.

The additional generated files are the following:

`doxylatex.pl`: This Perl script uses `DoxyDocs.pm` and 

DoxyModel.pm to generate `doxydocs.tex`, a \TeX file containing 

the documentation in a format that can be accessed by \LaTeX code. This 

file is not directly LaTeXable.

`doxyformat.tex`: This file contains the \LaTeX code that 

transforms the documentation from doxydocs.tex into \LaTeX text 

suitable to be \LaTeX'ed and presented to the user.

`doxylatex-template.pl`:  This Perl script uses `DoxyModel.pm` 

to generate `doxytemplate.tex`, a \TeX file defining default 

values for some macros.  doxytemplate.tex is included by 

doxyformat.tex to avoid the need of explicitly defining some macros.

`doxylatex.tex`:  This is a very simple \LaTeX document that 

loads some packages and includes doxyformat.tex and doxydocs.tex. This 

document is \LaTeX'ed to produce the PDF and DVI documentation by the 

rules added to `doxyrules.make`.

\subsection pm_pdf_gen Creation of PDF and DVI output 

To try this you need to have installed `latex`, `pdflatex` and the 

packages used by `doxylatex.tex`.

Update your `Doxyfile` to the latest version using:

doxygen -u Doxyfile

Set both \ref cfg_generate_perlmod "GENERATE_PERLMOD" and 

\ref cfg_perlmod_latex "PERLMOD_LATEX" tags to 

\c YES in your Doxyfile.

Run doxygen on your Doxyfile:

doxygen Doxyfile

A `perlmod/` subdirectory should have appeared in your output 

directory.  Enter the `perlmod/` subdirectory and run:

make pdf

This should generate a `doxylatex.pdf` with the documentation 

in PDF format.

Run:

make dvi

This should generate a `doxylatex.dvi` with the documentation 

in DVI format.

\section doxydocs_format Documentation format.

The Perl Module documentation generated by doxygen is stored in 

`DoxyDocs.pm`.  This is a very simple Perl module that contains 

only two statements: an assignment to the variable `$doxydocs` and 

the customary `1;` statement which usually ends Perl modules.  

The documentation is stored in the variable `$doxydocs`, which 

can then be accessed by a Perl script using `DoxyDocs.pm`.

`$doxydocs` contains a tree-like structure composed of three 

types of nodes: strings, hashes and lists.

`Strings`: These are normal Perl strings.  They can be of 

any length can contain any character.  Their semantics depends on 

their location within the tree.  This type of node has no children.

`Hashes`:  These are references to anonymous Perl hashes.  A 

hash can have multiple fields, each with a different key.  The value 

of a hash field can be a string, a hash or a list, and its semantics 

depends on the key of the hash field and the location of the hash 

within the tree.  The values of the hash fields are the children of 

the node.

`Lists`:  These are references to anonymous Perl lists.  A 

list has an undefined number of elements, which are the children of 

the node.  Each element has the same type (string, hash or list) and 

the same semantics, depending on the location of the list within the 

tree.

As you can see, the documentation contained in `$doxydocs`

does not present any special impediment to be processed by a simple

Perl script.  

To be able to generate meaningful output using the

documentation contained in `$doxydocs` you'll probably need to

know the semantics of the nodes of the documentation tree, which we

present in \ref perlmod_tree "this page".

-->

\section doxymodel_format Data structure

You might be interested in processing the documentation contained

in `DoxyDocs.pm` without needing to take into account the

semantics of each node of the documentation tree.  For this purpose,

doxygen generates a `DoxyModel.pm` file which contains a data

structure describing the type and children of each node in the

documentation tree.

The rest of this section is to be written yet, but in the meantime

you can look at the Perl scripts generated by doxygen (such as

`doxylatex.pl` or `doxytemplate-latex.pl`) to get an idea on

how to use `DoxyModel.pm`.

\htmlonly

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\endhtmlonly

*/