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PDL::Doc - support for PDL online documentation |
PDL::Doc - support for PDL online documentation
use PDL::Doc;
$onlinedc = new PDL::Doc ($docfile);
@match = $onlinedc->search('m/slice|clump/');
An implementation of online docs for PDL.
For a package like PDL that has a lot of functions it is very desirable to have some form of online help to make it easy for the user to remind himself of names, calling conventions and typical usage of the multitude of functions at his disposal. To make it straightforward to extract the relevant information from the POD documentation in source files that make up the PDL distribution certain conventions have been adopted in formatting this documentation.
The first convention says that all documentation for PDL functions appears in the POD section introduced by
=head1 FUNCTIONS
Individual functions in this section are introduced by
=head2 funcname
where signature is the argumentlist for a PP defined function
as explained in the PDL::PP manpage. Generally, PDL documentation is in
valid POD format (see perlpod) but uses the =for directive
in a special way. The =for directive is used to flag to the
PDL Pod parser that information is following that will be used
to generate online help.
The PDL podparser is derived from the PDL::Pod::Parser class that had to be patched in a few places, partly to fix minor bugs, partly to enhance functionality for perusal by PDL::Doc. Since the PDL::Doc module is still experimental the patched Pod-Parser distribution is included with the current PDL-Doc distribution. Note that PDL::Doc will not work correctly with the released Pod-Parser distribution.
The PDL Pod parser recognises the following =for directives:
=for ref
Returns a piddle of lags to parent.
=for sig
Signature: (a(n), [o]b(), [t]tmp(n))
=for usage
wpic($pdl,$filename[,{ options... }])
=for options
CONVERTER => 'ppmtogif', # explicitly specify pbm converter
FLAGS => '-interlaced -transparent 0', # flags for converter
IFORM => 'PGM', # explicitly specify intermediate format
XTRAFLAGS => '-imagename iris', # additional flags to defaultflags
FORMAT => 'PCX', # explicitly specify output image format
COLOR => 'bw', # specify color conversion
LUT => $lut, # use color table information
=for example
wpic $pdl, $file;
$im->wpic('web.gif',{LUT => $lut});
for (@images) {
$_->wpic($name[0],{CONVERTER => 'ppmtogif'})
}
$PDL:Config{WITH_BADVAL} is set to 1). The intention is to
have this information automatically created for pp-compiled
functions, although it can be over-ridden.
The PDL podparser is implemented as a simple state machine. Any of
the above =for statements switches the podparser into a state
where the following paragraph is accepted as information for the
respective field (Ref, Usage, Opt, Example or Bad).
Only the text up to
the end of the current paragraph is accepted, for example:
=for example
($x,$y) = $a->func(1,3); # this is part of the accepted info
$x = func($a,0,1); # this as well
$x = func($a,$b); # but this isn't
To make the resulting pod documentation also easily digestible for the
existing pod filters (pod2man, pod2text, pod2html, etc) the actual
textblock of information must be separated from the =for directive
by at least one blank line. Otherwise, the textblock will be lost in
the translation process when the ``normal'' podformatters are used. The
general idea behind this format is that it should be easy to extract
the information for online documentation, automatic generation of a
reference card, etc but at the same time the documentation should be
translated by the standard podformatters without loss of contents
(and without requiring any changes in the existing POD format).
The preceding explanations should be further explained by the following example (extracted from PDL/IO/Misc/misc.pd):
=head2 rcols()
=for ref
Read ASCII whitespaced cols from file into piddles efficiently.
If no columns are specified all are assumed Will optionally only process lines matching a pattern. Can take file name or *HANDLE.
=for usage
Usage: ($x,$y,...) = rcols(*HANDLE|"filename", ["/pattern/",$col1, $col2,] ...)
e.g.,
=for example
($x,$y) = rcols 'file1'
($x,$y,$z) = rcols 'file2', "/foo/",3,4
$x = PDL->rcols 'file1';
Note: currently quotes are required on the pattern.
which is translated by, e.g, the standard pod2text converter into:
rcols()
Read ASCII whitespaced cols from file into piddles efficiently.
If no columns are specified all are assumed Will optionally only
process lines matching a pattern. Can take file name or *HANDLE.
Usage: ($x,$y,...) = rcols(*HANDLE|"filename", ["/pattern/",$col1, $col2,] ...)
e.g.,
($x,$y) = rcols 'file1'
($x,$y,$z) = rcols 'file2', "/foo/",3,4
$x = PDL->rcols 'file1';
Note: currently quotes are required on the pattern.
It should be clear from the preceding example that readable output
can be obtained from this format using the standard converters and
the reader will hopefully get a feeling how he can easily intersperse
the special =for directives with the normal POD documentation.
The module documentation should start with the
=head1 NAME
PDL::Modulename -- do something with piddles
section (as anyway required by pod2man) since the PDL podparser
extracts the name of the module this function belongs to from
that section.
Each function that is not only for internal use by the module
should be documented, introduced with the =head2 directive
in the =head1 FUNCTIONS section. The only field that every function
documented along these lines should have is the Ref field preceding
a one line description of its intended functionality (suitable for
inclusion in a concise reference card). PP defined functions (see the PDL::PP manpage)
should have a Sig field stating their signature. To facilitate
maintainance of this documentation for such functions the 'Doc' field
has been introduced into the definition of pp_def (see again the PDL::PP manpage)
which will take care that name and signature of the so defined function
are documented in this way (for examples of this usage see, for example,
the PDL::Slices module, especially slices.pd and the resulting
Slices.pm). Similarly, the 'BadDoc' field provides a means of
specifying information on how the routine handles the presence of
bad values: this will be autpmatically created if
BadDoc is not supplied, or set to undef.
Furthermore, the documentation for each function should contain at least one of the Usage or Examples fields. Depending on the calling conventions for the function under consideration presence of both fields may be warranted.
If a function has options that should be given as a hash reference in the form
{Option => Value, ...}
then the possible options (and aproppriate values) should be explained
in the textblock following the =for Opt directive (see example above
and, e.g., PDL::IO::Pic).
It is well possible that some of these conventions appear to be clumsy at times and the author is keen to hear of any suggestions for better alternatives.
$onlinedc = new PDL::Doc ('file.pdl',[more files]);
add another file to the online database associated with this object.
set the name of the output file for this online db
Make sure that the database is slurped in
save the database (i.e., the hash of PDL symbols) to the file associated with this object.
Return the PDL symhash (e.g. for custom search operations)
Search a PDL symhash
$onldc->search($regex, $fields [, $sort])
Searching is by default case insensitive. Other flags can be
given by specifying the regexp in the form m/regex/ismx
where / can be replaced with any other non-alphanumeric
character. $fields is an array reference for all hash fields
that should be matched against the regex. Valid fields are
Name, # name of the function Module, # module the function belongs to Ref, # the one-line reference description Example, # the example for this function Opt, # options File, # the path to the source file this docs have been extracted from
Scan a source file using the PDL podparser to extract information for online documentation
Scan whole directory trees for online documentation in
.pm (module definition) and *.pod (general
documentation) files (using the File::Find module).
extract the complete documentation about a function from its source file using the PDL::Pod::Parser filter.
Quite a few shortcomings which will hopefully be fixed following discussions on the pdl-porters mailing list.
Copyright 1997 Christian Soeller <c.soeller@auckland.ac.nz> and Karl Glazebrook <kgb@aaoepp.aao.gov.au> All rights reserved. There is no warranty. You are allowed to redistribute this software / documentation under certain conditions. For details, see the file COPYING in the PDL distribution. If this file is separated from the PDL distribution, the copyright notice should be included in the file.
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PDL::Doc - support for PDL online documentation |