Pod::Checker(3p) | Perl Programmers Reference Guide | Pod::Checker(3p)

# 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.

- 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".

- A non-empty Z<>

  The "Z<>" sequence is supposed to be empty. Caveat: this issue is detected in Pod::Simple and will be flagged as an ERROR by any client code; any contents of "Z<...>" will be disregarded, anyway.

## 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.

The following list documents the overrides to Pod::Simple, primarily to make Pod::Coverage happy:

end_B
end_C
end_Document
end_F
end_I
end_L
end_Para
end_S
end_X
end_fcode
end_for
end_head
end_head1
end_head2
end_head3
end_head4
end_item
end_item_bullet
end_item_number
end_item_text
handle_pod_and_cut
handle_text
handle_whiteline
hyperlink
scream
start_B
start_C
start_Data
start_F
start_I
start_L
start_Para
start_S
start_Verbatim
start_X
start_fcode
start_for
start_head
start_head1
start_head2
start_head3
start_head4
start_item_bullet
start_item_number
start_item_text
start_over
start_over_block
start_over_bullet
start_over_empty
start_over_number
start_over_text
whine
"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>

2025-01-28 | perl v5.40.1