Doc(3) User Contributed Perl Documentation Doc(3)NAMEPDL::Doc - support for PDL online documentation
SYNOPSIS
use PDL::Doc;
$onlinedc = new PDL::Doc ($docfile);
@match = $onlinedc->search('m/slice|clump/');
DESCRIPTION
An implementation of online docs for PDL.
Using PDL documentation
PDL::Doc's main use is in the "help" (synonym "?") and "apropos"
(synonym "??") commands in the perldl shell. PDL:Doc provides the
infrastrucure to index and access PDL's documentation through these
commands. There is also an API for direct access to the documentation
database (see below).
The PDL doc system is built on Perl's pod (Plain Old Documentation),
included inline with each module. The PDL core modules are
automatically indexed when PDL is built and installed, and there is
provision for indexing external modules as well.
To include your module's pod into the Perl::Doc index, you should
follow the documentation conventions below.
PDL documentation conventions
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 one of the following:
=head1 FUNCTIONS
=head1 OPERATORS
=head1 METHODS
=head1 CONSTRUCTORS
If you're documenting an object-oriented interface to a class that your
module defines, you should use METHODS and CONSTRUCTORS as appropriate.
If you are simply adding functions to PDL, use FUNCTIONS and OPERATORS
as appropriate.
Individual functions or methods in these section are introduced by
=head2 funcname
where signature is the argumentlist for a PP defined function as
explained in PDL::PP. 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 Pod parser recognises the following "=for" directives:
Ref indicates that the one line reference for this function follows,
e.g.,
=for ref
Returns a piddle of lags to parent.
Sig the signature for the current function follows, e.g.,
=for sig
Signature: (a(n), [o]b(), [t]tmp(n))
Usage
an indication of the possible calling conventions for the current
function, e.g.,
=for usage
wpic($pdl,$filename[,{ options... }])
Opt lists options for the current function, e.g.,
=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
Example
gives examples of typical usage for the current function:
=for example
wpic $pdl, $file;
$im->wpic('web.gif',{LUT => $lut});
for (@images) {
$_->wpic($name[0],{CONVERTER => 'ppmtogif'})
}
Bad provides information on how the function handles bad values (if
$PDL:Config{WITH_BADVAL} is set to 1). The documentation under
this directive should indicate if this function accepts piddles
with bad values and under what circumstances this function might
return piddles with bad values.
The PDL podparser is implemented as a simple state machine. Any of the
above "=for" statements switches the podparser into a state where the
following paragraph is accepted as information for the respective field
("Ref", "Usage", "Opt", "Example" or "Bad"). Only the text up to the
end of the current paragraph is accepted, for example:
=for example
($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.
Which directives should be contained in the 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 PDL::PP) 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 PDL::PP) 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.
INSTANCE METHODS
new
$onlinedc = new PDL::Doc ('file.pdl',[more files]);
addfiles
add another file to the online database associated with this object.
outfile
set the name of the output file for this online db
ensuredb
Make sure that the database is slurped in
savedb
save the database (i.e., the hash of PDL symbols) to the file
associated with this object.
gethash
Return the PDL symhash (e.g. for custom search operations)
The symhash is a multiply nested hash with the following structure:
$symhash = {
function_name => {
Module => 'module::name',
Sig => 'signature string',
Bad => 'bad documentation string',
...
},
function_name => {
Module => 'module::name',
Sig => 'signature string',
Bad => 'bad documentation string',
...
},
};
The possible keys for each function include:
Module - module name
Sig - signature
Crossref - the function name for the documentation, if it has multiple
names (ex: the documentation for zeros is under zeroes)
Names - a comma-separated string of the all the function's names
Example - example text (optional)
Ref - one-line reference string
Opt - options
Usage - short usage explanation
Bad - explanation of behavior when it encounters bad values
search
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 (or simply a string if you only want to
search one field) 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 these docs have been extracted from
If you wish to have your results sorted by function name, pass a true
value for $sort.
The results will be returned as an array of pairs in the form
@results = (
[funcname, {SYMHASH_ENTRY}],
[funcname, {SYMHASH_ENTRY}],
...
);
See the example at the end of the documentation to see how you might
use this.
scan
Scan a source file using the PDL podparser to extract information for
online documentation
scantree
Scan whole directory trees for online documentation in ".pm" (module
definition) and "*.pod" (general documentation) files (using the
File::Find module).
funcdocs
extract the complete documentation about a function from its
source file using the PDL::Pod::Parser filter.
FUNCTIONS
add_module
use PDL::Doc; PDL::Doc::add_module("my::module");
The "add_module" function allows you to add POD from a particular Perl
module that you've installed somewhere in @INC. It searches for the
active PDL document database and the module's .pod and .pm files, and
scans and indexes the module into the database.
"add_module" is meant to be added to your module's Makefile as part of
the installation script.
PDL::DOC EXAMPLE
Here's an example of how you might use the PDL Doc database in your own
code.
use PDL::Doc;
# Find the pdl documentation
my ($dir,$file,$pdldoc);
DIRECTORY: for $dir (@INC) {
$file = $dir."/PDL/pdldoc.db";
if (-f $file) {
print "Found docs database $file\n";
$pdldoc = new PDL::Doc ($file);
last DIRECTORY;
}
}
die ("Unable to find docs database!\n") unless $pdldoc;
# Print the reference line for zeroes:
print $pdldoc->gethash->{zeroes}->{Ref};
# See which examples use zeroes
$pdldoc->search('zeroes', 'Example', 1);
# All the functions that use zeroes in their example:
my @entries = $pdldoc->search('zeroes', 'Example', 1);
print "Functions that use 'zeroes' in their examples include:\n";
foreach my $entry (@entries) {
# Unpack the entry
my ($func_name, $sym_hash) = @$entry;
print "$func_name\n";
}
print "\n";
# Let's look at the function 'mpdl'
@entries = $pdldoc->search('mpdl', 'Name');
# I know there's only one:
my $entry = $entries[0];
my ($func_name, $sym_hash) = @$entry;
print "mpdl info:\n";
foreach my $key (keys %$sym_hash) {
# Unpack the entry
print "---$key---\n$sym_hash->{$key}\n";
}
Finding Modules
How can you tell if you've gotten a module for one of your entries?
The Ref entry will begin with 'Module:' if it's a module. In code:
# Prints:
# Module: fundamental PDL functionality
my $sym_hash = $pdldoc->gethash;
print $pdldoc->gethash->{'PDL::Core'}->{Ref}, "\n"
BUGS
Quite a few shortcomings which will hopefully be fixed following
discussions on the pdl-porters mailing list.
AUTHOR
Copyright 1997 Christian Soeller <c.soeller@auckland.ac.nz> and Karl
Glazebrook <kgb@aaoepp.aao.gov.au>
Further contributions copyright 2010 David Mertens
<dcmertens.perl@gmail.com>
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.
perl v5.18.1 2013-05-12 Doc(3)
