Tags are \directives embedded into the text stream, commanding how certain parts of the text should be interpreted. The general syntax is \<name\[{<options\>}][<body\>]>. Whether a part is optional or not depends on the tag (at least a tag name is required ;-).
A \tag name is made of a backslash and a number of alphanumeric characters (capitals):
\\TAGTag options can be optional (see the specific tags documentation). They follow the tag name immediately, enclosed by a pair of corresponding curly braces. Each option is a simple string assignment. The value should be quoted if \/^\\w+$/ does not match it. Option settings are separated by whitespace(s).
\\TAG\B<{par1=value1 par2="www.perl.com" par3="words and blanks"}>If a tag accepts options, it can be made \conditional which means it can be activated depending on the result of passed Perl code, which is evaluated as \REF{occasion=1 name="Active contents" type=linked}<Active Content>. This code is passed by option \_cnd_.
\\IMAGE{\B<_cnd_="$illustrate"> src="piegraph.gif"}If Active Contents is disabled, the condition defaults to be false.
The \tag body may be optional. If used, it is anything you want to make the tag valid for. It immediately follows the optional parameters, enclosed by angle brackets:
\\TAG\B<<body\>>
Tag bodies \\TAG<can
be multilined>.
\\TAG{par=value}\B<<body\>>Tags can be \nested.
\\TAG1<\\TAG2<body>>\Every PerlPoint translator defines its own tags, but usually all of them support \OTHER_BASIC_TAGS{current=showAll} as a base set. Additionally, there are a few reserved tags which are implemented by \every translator. See the next section for details.
* provide additional source control and
* allow target format specific source parts and
* implement structured formatting;
* can be used whereever tags in general are valid;
* currently are \\\INCLUDE, \\\EMBED and \\\END_EMBED, \\\TABLE and \\\END_TABLE;
==File inclusion
It is possible to include another file by \\\INCLUDE{file=\<filename\ type=\<type\>}>.
The mandatory base options are
@| option | description file | names the source to be included (should exist) type | determines how the file is handled
All types different from \"pp" or \"perl" make the included file be read but not evaluated. The read contents is usually passed to the generated output file directly, with exception of type \"example". This is useful to include target language specific, preformatted parts.
\\INCLUDE<type=html file=homepage>A certain translator typically supports the file types of its target language, see the translator specific documentation for details.
===Including nested PerlPoint sources
If the type of an included file is specified as \"PP", the file contents is made part of the presentation source.
// include PerlPoint
\\INCLUDE{\B<type=pp> file="nested.pp"}The nesting level is umlimited, but every file \in a nesting hierarchy is \read only once (to avoid confusion by circular nesting). (Including the same file multiply in different nesting hierarchies is possible without problems.)
A PerlPoint file can be included wherever a tag is allowed, but sometimes it has to be arranged slightly: if you place the inclusion directive at the beginning of a new paragraph \and your included PerlPoint starts by a paragraph of another type than text, you should begin the included file by an empty line to let the parser detect the correct paragraph type. Here is an example: if the inclusion directive is placed like
// include PerlPoint
\\INCLUDE{type=pp file="file.pp"}and \file.pp immediately starts with a verbatim block like
<<VERBATIM
verbatim
VERBATIM, \the inclusion directive already opens a new paragraph which is detected to be \text (because there is no special startup character). Now in the included file, from the parsers point of view the included PerlPoint is simply a continuation of this text, because a paragraph ends with an empty line. This trouble can be avoided by beginning such an included file by an empty line, so that its first paragraph can be detected correctly.
====Special option: headlinebase
When including nested PerlPoint, a special tag option \"headlinebase" can be specified to define a headline base level used as an offset to all headlines in the included document.
<<EOE If "\INCLUDE{type=PP file=file headlinebase=20}" is specified and "file" contains a one level headline like "=Main topic of special explanations" this headline is detected with a level of 21. EOE
Pass the special keyword \BCURRENT_LEVEL to this tag option if you want to set just the \current headline level as an offset. This results in "subchapters".
<<EOE If "\INCLUDE{type=PP file=file headlinebase=CURRENT_LEVEL}" is specified in a chapter of level 4 and "file" contains a one level headline like "=Main topic of special explanations" this headline is detected with a level of 5. EOE
Similar to \CURRENT_LEVEL, \BBASE_LEVEL sets the current \base headline level as an offset. The "base level" is the level above the current one. Using \BASE_LEVEL results in parallel chapters.
<<EOE If "\INCLUDE{type=PP file=file headlinebase=BASE_LEVEL}" is specified in a chapter of level 4 and "file" contains a one level headline like "=Main topic of special explanations" this headline is detected with a level of 4 - similar to the level the nested source was included on. EOE
A given offset is reset when the included document is parsed completely.
The \"headlinebase" feature makes it easier to share partial documents with others, or to build complex documents by including seperately maintained parts, or to include one and the same part at different headline levels.
====Special option: smart
Option \Bsmart commands the parser to include the file only unless this was already done before. This is intended for inclusion of pure alias/macro definition or variable assignment files.
\\INCLUDE{type=PP file="common-macros.pp" \B<smart=1>}====Special option: localize
Nested sources may declare variables of their own, possibly overwriting already assigned values. Option \Blocalize works like Perls \local(): such changes will be reversed after the nested source will have been completely processed - so the original values will be restored. You can specify a comma separated list of variable names or the special string \__ALL__ which flags that the current settings shall be restored \completely.
\\INCLUDE{type=PP file="nested.pp" \B<localize=\I<myVar>>}
\\INCLUDE{type=PP file="nested.pp" \B<localize=\I<"var1, var2, var3>>"}
\\INCLUDE{type=PP file="nested.pp" \B<localize=\I<__ALL__>>}===Including Perl
The second special case of inclusion is a file type of \"Perl".
// include PerlPoint
\\INCLUDE{\B<type=perl> file="dynamicPP.pl"}\Inluded Perl is \active contents - see the special chapter about it.
\If active contents is enabled, included Perl code is evaluated. The code is expected to produce a PerlPoint string which then replaces the inclusion tag and is read like static PerlPoint.
If the included code fails, an error message is displayed and the result is ignored.
===Including Examples
Included files can be declared to be examples. This makes the file placed into the source as a \verbatim block, without need to copy its contents into the source.
// include an external script as an example
\\INCLUDE{\B<type=example> file=script}So, an example script of
#!perl -w
print "Geetings from outside!\\n";is made part of the source as if one would have written
<<EOE <<EOE #!perl -w
print "Greetings from outside!\n";
EOE
EOEAll lines of the example file are included unchanged. On request, they can be indented. To do so, just set the special option \"indent" to a positive numerical value equal to the number of spaces to be inserted before each line.
// external example source, indented by 3 spaces
\\INCLUDE{type=example file=script \B<indent=3>}Including external scripts can accelerate PerlPoint authoring significantly, especially if the included files are still subject to changes.
===Using input filters
Included files can be preprocessed by user defined \input filters, which is a generic way to make \any file a PerlPoint source. A filter is set up by using the special option \\.
Let's say you want to process a POD source.
This is simple:
\\INCLUDE{file="perlpod.pod" \B<ifilter="pod2pp"> type=pp}Oh, well, we need a \pod2pp() function to make this work. It could be defined in embedded or included Perl code above the example snippet, like this:
\\EMBED{lang=perl}
# load lib
use Pod::PerlPoint;
# process what we got and supply the result
sub pod2pp
{
my ($pod2pp, $perlpoint)=(new Pod::PerlPoint());
$pod2pp->output_string(\$perlpoint);
$pod2pp->parse_string_document(\I<@main::_ifilterText>);
$perlpoint;
}
\\END_EMBEDAs you can see, the source to be translated is provided in an array \\. (A second variable \\ provides the target language, if required.) The result should be supplied as a list.
Filters can be used for any file type, not only \pp. Just make sure that your code supplies whatever is appropriate for your \type option.
==Embedded code
Target format code does not necessarily need to be imported by file - it can be directly \embedded as well. This means that one can write target language code within the input stream using \\\EMBED, maybe because you miss a certain feature in the current translator version:
<<EOE
\EMBED{lang=HTML}
This is <i><b>embedded</b> HTML</i>. The parser detects <i>no</i>
Perl Point tag here, except of <b>END_EMBED</b>.
\END_EMBEDEOE
The mandatory \lang option specifies which language the embedded code is of. Usually a translator only supports its own target format to be embedded. (You will not be surprised that language values of \"perl" and \"pp" are special cases - see the related subsections.)
Please note that the \\\EMBED tag does not accept a tag body to avoid ambiguities. Use \\\END_EMBED to flag where the embedded code is completed. \It is the only recognized tag therein.
Because embedding is not implemented by a paragraph but by a \tag, \\EMBED can be placed \directly in a text like this:
<<EOE These \EMBED{lang=HTML}<i>italics</i>\END_EMBED are formatted by HTML code. EOE
===Embedding PerlPoint into PerlPoint
This is just for fun. Set the \"lang" option to \"pp" to try it:
<<EOE Perl Point \EMBED{lang=pp}can \EMBED{lang=pp}be \EMBED{lang=pp}nested\END_EMBED\END_EMBED\END_EMBED. EOE
===Embedding Perl
This feature offers dynamic PerlPoint generation at \translation time.
\\EMBED{lang=perl}hello\\END_EMBED\Embedded Perl is \active contents - see the special chapter about it.
\If active contents is enabled, embedded Perl code is evaluated. The code is expected to produce a PerlPoint string which then replaces the inclusion tag and is read like static PerlPoint.
If the included code fails, an error message is displayed and the result is ignored.
Here's another example:
<<EOE
\EMBED{lang=PERL}
# build a message
my $msg="Perl may be embedded as well.";
# and supply it
$msg;
\END_EMBEDEOE
The feature is of course more powerful. You may generate images at translation time and include them, scan the disk and include a formatted listing, download data from a webserver and make it part of your presentation, autoformat complex data, include formatted source code, keep your presentation up to date in any way and so on.
===Using input filters
Embedded code can be preprocessed by a user defined \input filter. A filter is set up by using the special option \\.
Let's say you want to process a piece of POD.
\\EMBED{\B<ifilter="pod2pp"> lang=pp}Again, we need a \pod2pp() function to make this work. Fortunately, as the function interface is the same, we can use the same filter that we defined to translate POD \files \REF{name="Special purpose tags | File inclusion | Using input filters" type=linked}<above>.
Filters can be used for any target language, not only \pp. Just make sure that your code supplies whatever is appropriate for your \type option.
==Tables by tag
It was mentioned in the \paragraph chapter that tables can be built by table paragraphs. Well, there is a tag variant of this:
<<EOE
\TABLE{bg=blue separator="|" border=2}
\B<column 1> | \B<column 2> | \B<column 3>
aaaa | bbbb | cccc
uuuu | vvvv | wwww
\END_TABLEEOE
\\\TABLE opens the table, while \\\END_TABLE closes it.
These tags are sligthly more powerfull than the paragraph syntax: you can set up several table features like the border width yourself, and you can format the headlines as you like.
All enclosed lines are evaluated as table rows by default, which means that each source line between \\\TABLE and \\\END_TABLE is treated as a table row. PerlPoint as well allows you to specify a string of your own choice to separate rows by option \rowseparator. This allows to specify a table \inlined into a paragraph.
<<EOE
\TABLE{bg=blue separator="|" border=2 rowseparator="+++"}
\B<column 1> | \B<column 2> | \B<column 3> +++ aaaa
| bbbb | cccc +++ uuuu | vvvv| wwww \END_TABLEEOE
This is exactly the same table as above.
As in all tables, leading and trailing whitespaces of a cell are automatically removed, so you can use as many of them as you want to improve the readability of your source.
Tables built by tag are normalized the same way as table paragraphs are.
Here is a list of basically supported tag options (by table):
@| option | description \separator | a string separating the table \columns (can contain more than one character) \rowseparator | a string separating the table \rows (can contain more than one character) \gracecr | usually set correctly by default, this specifies the number of row separators to be ignored before they are treated as separators - which usually allows to start the table contents in a subsequent line \after the line containing the \\\TABLE tag
More options may be supported by your PerlPoint translator software.
2 POD Errors
The following errors were encountered while parsing the POD:
- Around line 9:
Unknown directive: =Tags
- Around line 57:
Unknown directive: =Special