Pod::Checker

Section: Perl Programmers Reference Guide (3perl)
Updated: 2019-04-20
Page Index

NAME

Pod::Checker - check pod documents for syntax errors

SYNOPSIS

  use Pod::Checker;

  $syntax_okay = podchecker($filepath, $outputpath, %options);

  my $checker = Pod::Checker->new(%options);
  $checker->parse_from_file($filepath, \*STDERR);

OPTIONS/ARGUMENTS

$filepath is the input POD to read and $outputpath is where to write POD syntax error messages. Either argument may be a scalar indicating a file-path, or else a reference to an open filehandle. If unspecified, the input-file it defaults to "\*STDIN", and the output-file defaults to "\*STDERR".

podchecker()

This function can take a hash of options:

-warnings => val: Turn warnings on/off. val is usually 1 for on, but higher values trigger additional warnings. See ``Warnings''.
-quiet => val: If "val" is true, do not print any errors/warnings.

DESCRIPTION

podchecker will perform syntax checking of Perl5 POD format documentation.

Curious/ambitious users are welcome to propose additional features they wish to see in Pod::Checker and podchecker and verify that the checks are consistent with perlpod.

The following checks are currently performed:

•: Unknown '=xxxx' commands, unknown 'X<...>' interior-sequences, and unterminated interior sequences.
•: Check for proper balancing of "=begin" and "=end". The contents of such a block are generally ignored, i.e. no syntax checks are performed.
•: Check for proper nesting and balancing of "=over", "=item" and "=back".
•: Check for same nested interior-sequences (e.g. "L<...L<...>...>").
•: Check for malformed or non-existing entities "E<...>".
•: Check for correct syntax of hyperlinks "L<...>". See perlpod for details.
•: Check for unresolved document-internal links. This check may also reveal misspelled links that seem to be internal links but should be links to something else.

DIAGNOSTICS

Errors

•: empty =headn
A heading ("=head1" or "=head2") without any text? That ain't no heading!
•: =over on line N without closing =back
•: You forgot a '=back' before '=headN'
•: =over is the last thing in the document?!
The "=over" command does not have a corresponding "=back" before the next heading ("=head1" or "=head2") or the end of the file.
•: '=item' outside of any '=over'
•: =back without =over
An "=item" or "=back" command has been found outside a "=over"/"=back" block.
•: Can't have a 0 in =over N
You need to indent a strictly positive number of spaces, not 0.
•: =over should be: '=over' or '=over positive_number'
Either have an argumentless =over, or have its argument a strictly positive number.
•: =begin TARGET without matching =end TARGET
A "=begin" command was found that has no matching =end command.
•: =begin without a target?
A "=begin" command was found that is not followed by the formatter specification.
•: =end TARGET without matching =begin.
A standalone "=end" command was found.
•: '=end' without a target?
'=end' directives need to have a target, just like =begin directives.
•: '=end TARGET' is invalid.
TARGET needs to be one word
•: =end CONTENT doesn't match =begin TARGET
CONTENT needs to match =begin's TARGET.
•: =for without a target?
There is no specification of the formatter after the "=for" command.
•: unresolved internal link NAME
The given link to NAME does not have a matching node in the current POD. This also happened when a single word node name is not enclosed in "".
•: Unknown directive: CMD
An invalid POD command has been found. Valid are "=head1", "=head2", "=head3", "=head4", "=over", "=item", "=back", "=begin", "=end", "=for", "=pod", "=cut"
•: Deleting unknown formatting code SEQ
An invalid markup command has been encountered. Valid are: "B<>", "C<>", "E<>", "F<>", "I<>", "L<>", "S<>", "X<>", "Z<>"
•: Unterminated SEQ<> sequence
An unclosed formatting code
•: An E<...> surrounding strange content
The STRING found cannot be interpreted as a character entity.
•: An empty E<>
•: An empty "L<>"
•: An empty X<>
There needs to be content inside E, L, and X formatting codes.
•: A non-empty Z<>
The "Z<>" sequence is supposed to be empty.
•: Spurious text after =pod / =cut
The commands "=pod" and "=cut" do not take any arguments.
•: =back doesn't take any parameters, but you said =back ARGUMENT
The "=back" command does not take any arguments.
•: =pod directives shouldn't be over one line long! Ignoring all N lines of content
Self explanatory
•: =cut found outside a pod block.
A '=cut' directive found in the middle of non-POD
•: Invalid =encoding syntax: CONTENT
Syntax error in =encoding directive

Warnings

These may not necessarily cause trouble, but indicate mediocre style.

•: nested commands CMD<...CMD<...>...>
Two nested identical markup commands have been found. Generally this does not make sense.
•: multiple occurrences (N) of link target name
The POD file has some "=item" and/or "=head" commands that have the same text. Potential hyperlinks to such a text cannot be unique then. This warning is printed only with warning level greater than one.
•: line containing nothing but whitespace in paragraph
There is some whitespace on a seemingly empty line. POD is very sensitive to such things, so this is flagged. vi users switch on the list option to avoid this problem.
•: =item has no contents
There is a list "=item" that has no text contents. You probably want to delete empty items.
•: You can't have =items (as at line N) unless the first thing after the =over is an =item
A list introduced by "=over" starts with a text or verbatim paragraph, but continues with "=item"s. Move the non-item paragraph out of the "=over"/"=back" block.
•: Expected '=item EXPECTED VALUE'
•: Expected '=item *'
•: Possible =item type mismatch: 'x' found leading a supposed definition =item
A list started with e.g. a bullet-like "=item" and continued with a numbered one. This is obviously inconsistent. For most translators the type of the first "=item" determines the type of the list.
•: You have '=item x' instead of the expected '=item N'
Erroneous numbering of =item numbers; they need to ascend consecutively.
•: Unknown E content in E<CONTENT>
A character entity was found that does not belong to the standard ISO set or the POD specials "verbar" and "sol". Currently, this warning only appears if a character entity was found that does not have a Unicode character. This should be fixed to adhere to the original warning.
•: empty =over/=back block
The list opened with "=over" does not contain anything.
•: empty section in previous paragraph
The previous section (introduced by a "=head" command) does not contain any valid content. This usually indicates that something is missing. Note: A "=head1" followed immediately by "=head2" does not trigger this warning.
•: Verbatim paragraph in NAME section
The NAME section ("=head1 NAME") should consist of a single paragraph with the script/module name, followed by a dash `-' and a very short description of what the thing is good for.
•: =headn without preceding higher level
For example if there is a "=head2" in the POD file prior to a "=head1".

Hyperlinks

There are some warnings with respect to malformed hyperlinks:

•

ignoring leading/trailing whitespace in link

There is whitespace at the beginning or the end of the contents of L<...>.

•

alternative text/node '%s' contains non-escaped | or /

The characters "|" and "/" are special in the L<...> context. Although the hyperlink parser does its best to determine which ``/'' is text and which is a delimiter in case of doubt, one ought to escape these literal characters like this:

  /     E<sol>
  |     E<verbar>

Note that the line number of the error/warning may refer to the line number of the start of the paragraph in which the error/warning exists, not the line number that the error/warning is on. This bug is present in errors/warnings related to formatting codes. This should be fixed.

RETURN VALUE

podchecker returns the number of POD syntax errors found or -1 if there were no POD commands at all found in the file.

EXAMPLES

See ``SYNOPSIS''

SCRIPTS

The podchecker script that comes with this distribution is a lean wrapper around this module. See the online manual with

  podchecker -help
  podchecker -man

INTERFACE

While checking, this module collects document properties, e.g. the nodes for hyperlinks ("=headX", "=item") and index entries ("X<>"). POD translators can use this feature to syntax-check and get the nodes in a first pass before actually starting to convert. This is expensive in terms of execution time, but allows for very robust conversions.

Since v1.24 the Pod::Checker module uses only the poderror method to print errors and warnings. The summary output (e.g. ``Pod syntax OK'') has been dropped from the module and has been included in podchecker (the script). This allows users of Pod::Checker to control completely the output behavior. Users of podchecker (the script) get the well-known behavior.

v1.45 inherits from Pod::Simple as opposed to all previous versions inheriting from Pod::Parser. Do not use Pod::Simple's interface when using Pod::Checker unless it is documented somewhere on this page. I repeat, DO NOT USE POD::SIMPLE'S INTERFACE.

"Pod::Checker->new( %options )"

Return a reference to a new Pod::Checker object that inherits from Pod::Simple and is used for calling the required methods later. The following options are recognized:

"-warnings => num"
Print warnings if "num" is true. The higher the value of "num", the more warnings are printed. Currently there are only levels 1 and 2.

"-quiet => num"
If "num" is true, do not print any errors/warnings. This is useful when Pod::Checker is used to munge POD code into plain text from within POD formatters.

"$checker->poderror( @args )"

"$checker->poderror( {%opts}, @args )"

Internal method for printing errors and warnings. If no options are given, simply prints ``@_''. The following options are recognized and used to form the output:

  -msg

A message to print prior to @args.

  -line

The line number the error occurred in.

  -file

The file (name) the error occurred in. Defaults to the name of the current file being processed.

  -severity

The error level, should be 'WARNING' or 'ERROR'.

"$checker->num_errors()"

Set (if argument specified) and retrieve the number of errors found.

"$checker->num_warnings()"

Set (if argument specified) and retrieve the number of warnings found.

"$checker->name()"

Set (if argument specified) and retrieve the canonical name of POD as found in the "=head1 NAME" section.

"$checker->node()"

Add (if argument specified) and retrieve the nodes (as defined by "=headX" and "=item") of the current POD. The nodes are returned in the order of their occurrence. They consist of plain text, each piece of whitespace is collapsed to a single blank.

"$checker->idx()"

Add (if argument specified) and retrieve the index entries (as defined by "X<>") of the current POD. They consist of plain text, each piece of whitespace is collapsed to a single blank.

"$checker->hyperlinks()"

Retrieve an array containing the hyperlinks to things outside the current POD (as defined by "L<>").

Each is an instance of a class with the following methods:

line()

Returns the approximate line number in which the link was encountered

type()

Returns the type of the link; one of: "url" for things like "http://www.foo", "man" for man pages, or "pod".

page()

Returns the linked-to page or url.

node()

Returns the anchor or node within the linked-to page, or an empty string ("") if none appears in the link.

AUTHOR

Please report bugs using <http://rt.cpan.org>.

Brad Appleton <bradapp@enteract.com> (initial version), Marek Rouchal <marekr@cpan.org>, Marc Green <marcgreen@cpan.org> (port to Pod::Simple) Ricardo Signes <rjbs@cpan.org> (more porting to Pod::Simple) Karl Williamson <khw@cpan.org> (more porting to Pod::Simple)

Based on code for Pod::Text::pod2text() written by Tom Christiansen <tchrist@mox.perl.com>