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diff --git a/Master/tlpkg/tlperl0/lib/perlpod.pod b/Master/tlpkg/tlperl0/lib/perlpod.pod new file mode 100755 index 00000000000..55ea57ea5a8 --- /dev/null +++ b/Master/tlpkg/tlperl0/lib/perlpod.pod @@ -0,0 +1,732 @@ + +=for comment +This document is in Pod format. To read this, use a Pod formatter, +like "perldoc perlpod". + +=head1 NAME +X<POD> X<plain old documentation> + +perlpod - the Plain Old Documentation format + +=head1 DESCRIPTION + +Pod is a simple-to-use markup language used for writing documentation +for Perl, Perl programs, and Perl modules. + +Translators are available for converting Pod to various formats +like plain text, HTML, man pages, and more. + +Pod markup consists of three basic kinds of paragraphs: +L<ordinary|/"Ordinary Paragraph">, +L<verbatim|/"Verbatim Paragraph">, and +L<command|/"Command Paragraph">. + + +=head2 Ordinary Paragraph +X<POD, ordinary paragraph> + +Most paragraphs in your documentation will be ordinary blocks +of text, like this one. You can simply type in your text without +any markup whatsoever, and with just a blank line before and +after. When it gets formatted, it will undergo minimal formatting, +like being rewrapped, probably put into a proportionally spaced +font, and maybe even justified. + +You can use formatting codes in ordinary paragraphs, for B<bold>, +I<italic>, C<code-style>, L<hyperlinks|perlfaq>, and more. Such +codes are explained in the "L<Formatting Codes|/"Formatting Codes">" +section, below. + + +=head2 Verbatim Paragraph +X<POD, verbatim paragraph> X<verbatim> + +Verbatim paragraphs are usually used for presenting a codeblock or +other text which does not require any special parsing or formatting, +and which shouldn't be wrapped. + +A verbatim paragraph is distinguished by having its first character +be a space or a tab. (And commonly, all its lines begin with spaces +and/or tabs.) It should be reproduced exactly, with tabs assumed to +be on 8-column boundaries. There are no special formatting codes, +so you can't italicize or anything like that. A \ means \, and +nothing else. + + +=head2 Command Paragraph +X<POD, command> + +A command paragraph is used for special treatment of whole chunks +of text, usually as headings or parts of lists. + +All command paragraphs (which are typically only one line long) start +with "=", followed by an identifier, followed by arbitrary text that +the command can use however it pleases. Currently recognized commands +are + + =pod + =head1 Heading Text + =head2 Heading Text + =head3 Heading Text + =head4 Heading Text + =over indentlevel + =item stuff + =back + =begin format + =end format + =for format text... + =encoding type + =cut + +To explain them each in detail: + +=over + +=item C<=head1 I<Heading Text>> +X<=head1> X<=head2> X<=head3> X<=head4> +X<head1> X<head2> X<head3> X<head4> + +=item C<=head2 I<Heading Text>> + +=item C<=head3 I<Heading Text>> + +=item C<=head4 I<Heading Text>> + +Head1 through head4 produce headings, head1 being the highest +level. The text in the rest of this paragraph is the content of the +heading. For example: + + =head2 Object Attributes + +The text "Object Attributes" comprises the heading there. (Note that +head3 and head4 are recent additions, not supported in older Pod +translators.) The text in these heading commands can use +formatting codes, as seen here: + + =head2 Possible Values for C<$/> + +Such commands are explained in the +"L<Formatting Codes|/"Formatting Codes">" section, below. + +=item C<=over I<indentlevel>> +X<=over> X<=item> X<=back> X<over> X<item> X<back> + +=item C<=item I<stuff...>> + +=item C<=back> + +Item, over, and back require a little more explanation: "=over" starts +a region specifically for the generation of a list using "=item" +commands, or for indenting (groups of) normal paragraphs. At the end +of your list, use "=back" to end it. The I<indentlevel> option to +"=over" indicates how far over to indent, generally in ems (where +one em is the width of an "M" in the document's base font) or roughly +comparable units; if there is no I<indentlevel> option, it defaults +to four. (And some formatters may just ignore whatever I<indentlevel> +you provide.) In the I<stuff> in C<=item I<stuff...>>, you may +use formatting codes, as seen here: + + =item Using C<$|> to Control Buffering + +Such commands are explained in the +"L<Formatting Codes|/"Formatting Codes">" section, below. + +Note also that there are some basic rules to using "=over" ... +"=back" regions: + +=over + +=item * + +Don't use "=item"s outside of an "=over" ... "=back" region. + +=item * + +The first thing after the "=over" command should be an "=item", unless +there aren't going to be any items at all in this "=over" ... "=back" +region. + +=item * + +Don't put "=headI<n>" commands inside an "=over" ... "=back" region. + +=item * + +And perhaps most importantly, keep the items consistent: either use +"=item *" for all of them, to produce bullets; or use "=item 1.", +"=item 2.", etc., to produce numbered lists; or use "=item foo", +"=item bar", etc. -- namely, things that look nothing like bullets or +numbers. + +If you start with bullets or numbers, stick with them, as +formatters use the first "=item" type to decide how to format the +list. + +=back + +=item C<=cut> +X<=cut> X<cut> + +To end a Pod block, use a blank line, +then a line beginning with "=cut", and a blank +line after it. This lets Perl (and the Pod formatter) know that +this is where Perl code is resuming. (The blank line before the "=cut" +is not technically necessary, but many older Pod processors require it.) + +=item C<=pod> +X<=pod> X<pod> + +The "=pod" command by itself doesn't do much of anything, but it +signals to Perl (and Pod formatters) that a Pod block starts here. A +Pod block starts with I<any> command paragraph, so a "=pod" command is +usually used just when you want to start a Pod block with an ordinary +paragraph or a verbatim paragraph. For example: + + =item stuff() + + This function does stuff. + + =cut + + sub stuff { + ... + } + + =pod + + Remember to check its return value, as in: + + stuff() || die "Couldn't do stuff!"; + + =cut + +=item C<=begin I<formatname>> +X<=begin> X<=end> X<=for> X<begin> X<end> X<for> + +=item C<=end I<formatname>> + +=item C<=for I<formatname> I<text...>> + +For, begin, and end will let you have regions of text/code/data that +are not generally interpreted as normal Pod text, but are passed +directly to particular formatters, or are otherwise special. A +formatter that can use that format will use the region, otherwise it +will be completely ignored. + +A command "=begin I<formatname>", some paragraphs, and a +command "=end I<formatname>", mean that the text/data in between +is meant for formatters that understand the special format +called I<formatname>. For example, + + =begin html + + <hr> <img src="thang.png"> + <p> This is a raw HTML paragraph </p> + + =end html + +The command "=for I<formatname> I<text...>" +specifies that the remainder of just this paragraph (starting +right after I<formatname>) is in that special format. + + =for html <hr> <img src="thang.png"> + <p> This is a raw HTML paragraph </p> + +This means the same thing as the above "=begin html" ... "=end html" +region. + +That is, with "=for", you can have only one paragraph's worth +of text (i.e., the text in "=foo targetname text..."), but with +"=begin targetname" ... "=end targetname", you can have any amount +of stuff inbetween. (Note that there still must be a blank line +after the "=begin" command and a blank line before the "=end" +command. + +Here are some examples of how to use these: + + =begin html + + <br>Figure 1.<br><IMG SRC="figure1.png"><br> + + =end html + + =begin text + + --------------- + | foo | + | bar | + --------------- + + ^^^^ Figure 1. ^^^^ + + =end text + +Some format names that formatters currently are known to accept +include "roff", "man", "latex", "tex", "text", and "html". (Some +formatters will treat some of these as synonyms.) + +A format name of "comment" is common for just making notes (presumably +to yourself) that won't appear in any formatted version of the Pod +document: + + =for comment + Make sure that all the available options are documented! + +Some I<formatnames> will require a leading colon (as in +C<"=for :formatname">, or +C<"=begin :formatname" ... "=end :formatname">), +to signal that the text is not raw data, but instead I<is> Pod text +(i.e., possibly containing formatting codes) that's just not for +normal formatting (e.g., may not be a normal-use paragraph, but might +be for formatting as a footnote). + +=item C<=encoding I<encodingname>> +X<=encoding> X<encoding> + +This command is used for declaring the encoding of a document. Most +users won't need this; but if your encoding isn't US-ASCII or Latin-1, +then put a C<=encoding I<encodingname>> command early in the document so +that pod formatters will know how to decode the document. For +I<encodingname>, use a name recognized by the L<Encode::Supported> +module. Examples: + + =encoding utf8 + + =encoding koi8-r + + =encoding ShiftJIS + + =encoding big5 + +=back + +C<=encoding> affects the whole document, and must occur only once. + +And don't forget, when using any other command, that the command lasts up +until the end of its I<paragraph>, not its line. So in the +examples below, you can see that every command needs the blank +line after it, to end its paragraph. + +Some examples of lists include: + + =over + + =item * + + First item + + =item * + + Second item + + =back + + =over + + =item Foo() + + Description of Foo function + + =item Bar() + + Description of Bar function + + =back + + +=head2 Formatting Codes +X<POD, formatting code> X<formatting code> +X<POD, interior sequence> X<interior sequence> + +In ordinary paragraphs and in some command paragraphs, various +formatting codes (a.k.a. "interior sequences") can be used: + +=for comment + "interior sequences" is such an opaque term. + Prefer "formatting codes" instead. + +=over + +=item C<IE<lt>textE<gt>> -- italic text +X<I> X<< IZ<><> >> X<POD, formatting code, italic> X<italic> + +Used for emphasis ("C<be IE<lt>careful!E<gt>>") and parameters +("C<redo IE<lt>LABELE<gt>>") + +=item C<BE<lt>textE<gt>> -- bold text +X<B> X<< BZ<><> >> X<POD, formatting code, bold> X<bold> + +Used for switches ("C<perl's BE<lt>-nE<gt> switch>"), programs +("C<some systems provide a BE<lt>chfnE<gt> for that>"), +emphasis ("C<be BE<lt>careful!E<gt>>"), and so on +("C<and that feature is known as BE<lt>autovivificationE<gt>>"). + +=item C<CE<lt>codeE<gt>> -- code text +X<C> X<< CZ<><> >> X<POD, formatting code, code> X<code> + +Renders code in a typewriter font, or gives some other indication that +this represents program text ("C<CE<lt>gmtime($^T)E<gt>>") or some other +form of computerese ("C<CE<lt>drwxr-xr-xE<gt>>"). + +=item C<LE<lt>nameE<gt>> -- a hyperlink +X<L> X<< LZ<><> >> X<POD, formatting code, hyperlink> X<hyperlink> + +There are various syntaxes, listed below. In the syntaxes given, +C<text>, C<name>, and C<section> cannot contain the characters +'/' and '|'; and any '<' or '>' should be matched. + +=over + +=item * + +C<LE<lt>nameE<gt>> + +Link to a Perl manual page (e.g., C<LE<lt>Net::PingE<gt>>). Note +that C<name> should not contain spaces. This syntax +is also occasionally used for references to UNIX man pages, as in +C<LE<lt>crontab(5)E<gt>>. + +=item * + +C<LE<lt>name/"sec"E<gt>> or C<LE<lt>name/secE<gt>> + +Link to a section in other manual page. E.g., +C<LE<lt>perlsyn/"For Loops"E<gt>> + +=item * + +C<LE<lt>/"sec"E<gt>> or C<LE<lt>/secE<gt>> + +Link to a section in this manual page. E.g., +C<LE<lt>/"Object Methods"E<gt>> + +=back + +A section is started by the named heading or item. For +example, C<LE<lt>perlvar/$.E<gt>> or C<LE<lt>perlvar/"$."E<gt>> both +link to the section started by "C<=item $.>" in perlvar. And +C<LE<lt>perlsyn/For LoopsE<gt>> or C<LE<lt>perlsyn/"For Loops"E<gt>> +both link to the section started by "C<=head2 For Loops>" +in perlsyn. + +To control what text is used for display, you +use "C<LE<lt>text|...E<gt>>", as in: + +=over + +=item * + +C<LE<lt>text|nameE<gt>> + +Link this text to that manual page. E.g., +C<LE<lt>Perl Error Messages|perldiagE<gt>> + +=item * + +C<LE<lt>text|name/"sec"E<gt>> or C<LE<lt>text|name/secE<gt>> + +Link this text to that section in that manual page. E.g., +C<LE<lt>postfix "if"|perlsyn/"Statement Modifiers"E<gt>> + +=item * + +C<LE<lt>text|/"sec"E<gt>> or C<LE<lt>text|/secE<gt>> +or C<LE<lt>text|"sec"E<gt>> + +Link this text to that section in this manual page. E.g., +C<LE<lt>the various attributes|/"Member Data"E<gt>> + +=back + +Or you can link to a web page: + +=over + +=item * + +C<LE<lt>scheme:...E<gt>> + +C<LE<lt>text|scheme:...E<gt>> + +Links to an absolute URL. For example, C<LE<lt>http://www.perl.org/E<gt>> or +C<LE<lt>The Perl Home Page|http://www.perl.org/E<gt>>. + +=back + +=item C<EE<lt>escapeE<gt>> -- a character escape +X<E> X<< EZ<><> >> X<POD, formatting code, escape> X<escape> + +Very similar to HTML/XML C<&I<foo>;> "entity references": + +=over + +=item * + +C<EE<lt>ltE<gt>> -- a literal E<lt> (less than) + +=item * + +C<EE<lt>gtE<gt>> -- a literal E<gt> (greater than) + +=item * + +C<EE<lt>verbarE<gt>> -- a literal | (I<ver>tical I<bar>) + +=item * + +C<EE<lt>solE<gt>> = a literal / (I<sol>idus) + +The above four are optional except in other formatting codes, +notably C<LE<lt>...E<gt>>, and when preceded by a +capital letter. + +=item * + +C<EE<lt>htmlnameE<gt>> + +Some non-numeric HTML entity name, such as C<EE<lt>eacuteE<gt>>, +meaning the same thing as C<é> in HTML -- i.e., a lowercase +e with an acute (/-shaped) accent. + +=item * + +C<EE<lt>numberE<gt>> + +The ASCII/Latin-1/Unicode character with that number. A +leading "0x" means that I<number> is hex, as in +C<EE<lt>0x201EE<gt>>. A leading "0" means that I<number> is octal, +as in C<EE<lt>075E<gt>>. Otherwise I<number> is interpreted as being +in decimal, as in C<EE<lt>181E<gt>>. + +Note that older Pod formatters might not recognize octal or +hex numeric escapes, and that many formatters cannot reliably +render characters above 255. (Some formatters may even have +to use compromised renderings of Latin-1 characters, like +rendering C<EE<lt>eacuteE<gt>> as just a plain "e".) + +=back + +=item C<FE<lt>filenameE<gt>> -- used for filenames +X<F> X<< FZ<><> >> X<POD, formatting code, filename> X<filename> + +Typically displayed in italics. Example: "C<FE<lt>.cshrcE<gt>>" + +=item C<SE<lt>textE<gt>> -- text contains non-breaking spaces +X<S> X<< SZ<><> >> X<POD, formatting code, non-breaking space> +X<non-breaking space> + +This means that the words in I<text> should not be broken +across lines. Example: S<C<SE<lt>$x ? $y : $zE<gt>>>. + +=item C<XE<lt>topic nameE<gt>> -- an index entry +X<X> X<< XZ<><> >> X<POD, formatting code, index entry> X<index entry> + +This is ignored by most formatters, but some may use it for building +indexes. It always renders as empty-string. +Example: C<XE<lt>absolutizing relative URLsE<gt>> + +=item C<ZE<lt>E<gt>> -- a null (zero-effect) formatting code +X<Z> X<< ZZ<><> >> X<POD, formatting code, null> X<null> + +This is rarely used. It's one way to get around using an +EE<lt>...E<gt> code sometimes. For example, instead of +"C<NEE<lt>ltE<gt>3>" (for "NE<lt>3") you could write +"C<NZE<lt>E<gt>E<lt>3>" (the "ZE<lt>E<gt>" breaks up the "N" and +the "E<lt>" so they can't be considered +the part of a (fictitious) "NE<lt>...E<gt>" code. + +=for comment + This was formerly explained as a "zero-width character". But it in + most parser models, it parses to nothing at all, as opposed to parsing + as if it were a E<zwnj> or E<zwj>, which are REAL zero-width characters. + So "width" and "character" are exactly the wrong words. + +=back + +Most of the time, you will need only a single set of angle brackets to +delimit the beginning and end of formatting codes. However, +sometimes you will want to put a real right angle bracket (a +greater-than sign, '>') inside of a formatting code. This is particularly +common when using a formatting code to provide a different font-type for a +snippet of code. As with all things in Perl, there is more than +one way to do it. One way is to simply escape the closing bracket +using an C<E> code: + + C<$a E<lt>=E<gt> $b> + +This will produce: "C<$a E<lt>=E<gt> $b>" + +A more readable, and perhaps more "plain" way is to use an alternate +set of delimiters that doesn't require a single ">" to be escaped. With +the Pod formatters that are standard starting with perl5.5.660, doubled +angle brackets ("<<" and ">>") may be used I<if and only if there is +whitespace right after the opening delimiter and whitespace right +before the closing delimiter!> For example, the following will +do the trick: +X<POD, formatting code, escaping with multiple brackets> + + C<< $a <=> $b >> + +In fact, you can use as many repeated angle-brackets as you like so +long as you have the same number of them in the opening and closing +delimiters, and make sure that whitespace immediately follows the last +'<' of the opening delimiter, and immediately precedes the first '>' +of the closing delimiter. (The whitespace is ignored.) So the +following will also work: +X<POD, formatting code, escaping with multiple brackets> + + C<<< $a <=> $b >>> + C<<<< $a <=> $b >>>> + +And they all mean exactly the same as this: + + C<$a E<lt>=E<gt> $b> + +As a further example, this means that if you wanted to put these bits of +code in C<C> (code) style: + + open(X, ">>thing.dat") || die $! + $foo->bar(); + +you could do it like so: + + C<<< open(X, ">>thing.dat") || die $! >>> + C<< $foo->bar(); >> + +which is presumably easier to read than the old way: + + C<open(X, "E<gt>E<gt>thing.dat") || die $!> + C<$foo-E<gt>bar();> + +This is currently supported by pod2text (Pod::Text), pod2man (Pod::Man), +and any other pod2xxx or Pod::Xxxx translators that use +Pod::Parser 1.093 or later, or Pod::Tree 1.02 or later. + +=head2 The Intent +X<POD, intent of> + +The intent is simplicity of use, not power of expression. Paragraphs +look like paragraphs (block format), so that they stand out +visually, and so that I could run them through C<fmt> easily to reformat +them (that's F7 in my version of B<vi>, or Esc Q in my version of +B<emacs>). I wanted the translator to always leave the C<'> and C<`> and +C<"> quotes alone, in verbatim mode, so I could slurp in a +working program, shift it over four spaces, and have it print out, er, +verbatim. And presumably in a monospace font. + +The Pod format is not necessarily sufficient for writing a book. Pod +is just meant to be an idiot-proof common source for nroff, HTML, +TeX, and other markup languages, as used for online +documentation. Translators exist for B<pod2text>, B<pod2html>, +B<pod2man> (that's for nroff(1) and troff(1)), B<pod2latex>, and +B<pod2fm>. Various others are available in CPAN. + + +=head2 Embedding Pods in Perl Modules +X<POD, embedding> + +You can embed Pod documentation in your Perl modules and scripts. +Start your documentation with an empty line, a "=head1" command at the +beginning, and end it with a "=cut" command and an empty line. Perl +will ignore the Pod text. See any of the supplied library modules for +examples. If you're going to put your Pod at the end of the file, and +you're using an __END__ or __DATA__ cut mark, make sure to put an +empty line there before the first Pod command. + + __END__ + + =head1 NAME + + Time::Local - efficiently compute time from local and GMT time + +Without that empty line before the "=head1", many translators wouldn't +have recognized the "=head1" as starting a Pod block. + +=head2 Hints for Writing Pod + +=over + +=item * +X<podchecker> X<POD, validating> + +The B<podchecker> command is provided for checking Pod syntax for errors +and warnings. For example, it checks for completely blank lines in +Pod blocks and for unknown commands and formatting codes. You should +still also pass your document through one or more translators and proofread +the result, or print out the result and proofread that. Some of the +problems found may be bugs in the translators, which you may or may not +wish to work around. + +=item * + +If you're more familiar with writing in HTML than with writing in Pod, you +can try your hand at writing documentation in simple HTML, and converting +it to Pod with the experimental L<Pod::HTML2Pod|Pod::HTML2Pod> module, +(available in CPAN), and looking at the resulting code. The experimental +L<Pod::PXML|Pod::PXML> module in CPAN might also be useful. + +=item * + +Many older Pod translators require the lines before every Pod +command and after every Pod command (including "=cut"!) to be a blank +line. Having something like this: + + # - - - - - - - - - - - - + =item $firecracker->boom() + + This noisily detonates the firecracker object. + =cut + sub boom { + ... + +...will make such Pod translators completely fail to see the Pod block +at all. + +Instead, have it like this: + + # - - - - - - - - - - - - + + =item $firecracker->boom() + + This noisily detonates the firecracker object. + + =cut + + sub boom { + ... + +=item * + +Some older Pod translators require paragraphs (including command +paragraphs like "=head2 Functions") to be separated by I<completely> +empty lines. If you have an apparently empty line with some spaces +on it, this might not count as a separator for those translators, and +that could cause odd formatting. + +=item * + +Older translators might add wording around an LE<lt>E<gt> link, so that +C<LE<lt>Foo::BarE<gt>> may become "the Foo::Bar manpage", for example. +So you shouldn't write things like C<the LE<lt>fooE<gt> +documentation>, if you want the translated document to read sensibly +-- instead write C<the LE<lt>Foo::Bar|Foo::BarE<gt> documentation> or +C<LE<lt>the Foo::Bar documentation|Foo::BarE<gt>>, to control how the +link comes out. + +=item * + +Going past the 70th column in a verbatim block might be ungracefully +wrapped by some formatters. + +=back + +=head1 SEE ALSO + +L<perlpodspec>, L<perlsyn/"PODs: Embedded Documentation">, +L<perlnewmod>, L<perldoc>, L<pod2html>, L<pod2man>, L<podchecker>. + +=head1 AUTHOR + +Larry Wall, Sean M. Burke + +=cut |