doctools_lang_intro(n)        Documentation tools       doctools_lang_intro(n)



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NAME
       doctools_lang_intro - doctools language introduction

DESCRIPTION
       This document is an informal introduction to version 1 of the doctools
       markup language based on a multitude of examples. After reading this a
       writer should be ready to understand the two parts of the formal
       specification, i.e. the doctools language syntax specification and the
       doctools language command reference.

   FUNDAMENTALS
       In the broadest terms possible the doctools markup language is LaTeX-
       like, instead of like SGML and similar languages. A document written in
       this language consists primarily of text, with markup commands embedded
       into it.

       Each markup command is a Tcl command surrounded by a matching pair of [
       and ]. Inside of these delimiters the usual rules for a Tcl command
       apply with regard to word quotation, nested commands, continuation
       lines, etc. I.e.

                ... [list_begin enumerated] ...


                ... [call [cmd foo] \\
                        [arg bar]] ...


                ... [term {complex concept}] ...


                ... [opt "[arg key] [arg value]"] ...


   BASIC STRUCTURE
       The most simple document which can be written in doctools is

                  [manpage_begin NAME SECTION VERSION]
                  [description]
                  [manpage_end]

       This also shows us that all doctools documents are split into two
       parts, the header and the body. Everything coming before [description]
       belongs to the header, and everything coming after belongs to the body,
       with the whole document bracketed by the two manpage_* commands. Before
       and after these opening and closing commands we have only whitespace.

       In the remainder of this section we will discuss only the contents of
       the header, the structure of the body will be discussed in the section
       Text structure.

       The header section can be empty, and otherwise may contain only an
       arbitrary sequence of the four so-called header commands, plus
       whitespace. These commands are

       titledesc

       moddesc

       require

       copyright

       They provide, through their arguments, additional information about the
       document, like its title, the title of the larger group the document
       belongs to (if applicable), the requirements of the documented packages
       (if applicable), and copyright assignments. All of them can occur
       multiple times, including none, and they can be used in any order.
       However for titledesc and moddesc only the last occurrence is taken.
       For the other two the specified information is accumulated, in the
       given order. Regular text is not allowed within the header.

       Given the above a less minimal example of a document is

              [manpage_begin NAME SECTION VERSION]
              [copyright {YEAR AUTHOR}]
              [titledesc TITLE]
              [moddesc   MODULE_TITLE]
              [require   PACKAGE VERSION]
              [require   PACKAGE]
              [description]
              [manpage_end]

       Remember that the whitespace is optional. The document

                  [manpage_begin NAME SECTION VERSION]
                  [copyright {YEAR AUTHOR}][titledesc TITLE][moddesc MODULE_TITLE]
                  [require PACKAGE VERSION][require PACKAGE][description]
                  [manpage_end]

       has the same meaning as the example before.

       On the other hand, if whitespace is present it consists not only of any
       sequence of characters containing the space character, horizontal and
       vertical tabs, carriage return, and newline, but it may contain comment
       markup as well, in the form of the comment command.

              [comment { ... }]
              [manpage_begin NAME SECTION VERSION]
              [copyright {YEAR AUTHOR}]
              [titledesc TITLE]
              [moddesc   MODULE_TITLE][comment { ... }]
              [require   PACKAGE VERSION]
              [require   PACKAGE]
              [description]
              [manpage_end]
              [comment { ... }]


   ADVANCED STRUCTURE
       In the simple examples of the last section we fudged a bit regarding
       the markup actually allowed to be used before the manpage_begin command
       opening the document.

       Instead of only whitespace the two templating commands include and vset
       are also allowed, to enable the writer to either set and/or import
       configuration settings relevant to the document. I.e. it is possible to
       write

              [include FILE]
              [vset VAR VALUE]
              [manpage_begin NAME SECTION VERSION]
              [description]
              [manpage_end]

       Even more important, these two commands are allowed anywhere where a
       markup command is allowed, without regard for any other structure. I.e.
       for example in the header as well.

              [manpage_begin NAME SECTION VERSION]
              [include FILE]
              [vset VAR VALUE]
              [description]
              [manpage_end]

       The only restriction include has to obey is that the contents of the
       included file must be valid at the place of the inclusion. I.e. a file
       included before manpage_begin may contain only the templating commands
       vset and include, a file included in the header may contain only header
       commands, etc.

   TEXT STRUCTURE
       The body of the document consists mainly of text, possibly split into
       sections, subsections, and paragraphs, with parts marked up to
       highlight various semantic categories of text, and additional structure
       through the use of examples and (nested) lists.

       This section explains the high-level structural commands, with
       everything else deferred to the following sections.

       The simplest way of structuring the body is through the introduction of
       paragraphs. The command for doing so is para. Each occurrence of this
       command closes the previous paragraph and automatically opens the next.
       The first paragraph is automatically opened at the beginning of the
       body, by description. In the same manner the last paragraph
       automatically ends at manpage_end.

              [manpage_begin NAME SECTION VERSION]
              [description]
               ...
              [para]
               ...
              [para]
               ...
              [manpage_end]

       Empty paragraphs are ignored.

       A structure coarser than paragraphs are sections, which allow the
       writer to split a document into larger, and labeled, pieces. The
       command for doing so is section. Each occurrence of this command closes
       the previous section and automatically opens the next, including its
       first paragraph. The first section is automatically opened at the
       beginning of the body, by description (This section is labeled
       "DESCRIPTION"). In the same manner the last section automatically ends
       at manpage_end.

       Empty sections are not ignored. We are free to (not) use paragraphs
       within sections.

              [manpage_begin NAME SECTION VERSION]
              [description]
               ...
              [section {Section A}]
               ...
              [para]
               ...
              [section {Section B}]
               ...
              [manpage_end]

       Between sections and paragraphs we have subsections, to split sections.
       The command for doing so is subsection. Each occurrence of this command
       closes the previous subsection and automatically opens the next,
       including its first paragraph. A subsection is automatically opened at
       the beginning of the body, by description, and at the beginning of each
       section. In the same manner the last subsection automatically ends at
       manpage_end.

       Empty subsections are not ignored. We are free to (not) use paragraphs
       within subsections.

              [manpage_begin NAME SECTION VERSION]
              [description]
               ...
              [section {Section A}]
               ...
              [subsection {Sub 1}]
               ...
              [para]
               ...
              [subsection {Sub 2}]
               ...
              [section {Section B}]
               ...
              [manpage_end]


   TEXT MARKUP
       Having handled the overall structure a writer can impose on the
       document we now take a closer at the text in a paragraph.

       While most often this is just the unadorned content of the document we
       do have situations where we wish to highlight parts of it as some type
       of thing or other, like command arguments, command names, concepts,
       uris, etc.

       For this we have a series of markup commands which take the text to
       highlight as their single argument. It should be noted that while their
       predominant use is the highlighting of parts of a paragraph they can
       also be used to mark up the arguments of list item commands, and of
       other markup commands.

       The commands available to us are

       arg    Its argument is a the name of a command argument.

       class  Its argument is a class name.

       cmd    Its argument is a command name (Tcl command).

       const  Its argument is a constant.

       emph   General, non-semantic emphasis.

       file   Its argument is a filename / path.

       fun    Its argument is a function name.

       method Its argument is a method name

       namespace
              Its argument is namespace name.

       opt    Its argument is some optional syntax element.

       option Its argument is a command line switch / widget option.

       package
              Its argument is a package name.

       sectref
              Its argument is the title of a section or subsection, i.e. a
              section reference.

       syscmd Its argument is a command name (external, system command).

       term   Its argument is a concept, or general terminology.

       type   Its argument is a type name.

       uri    Its argument is a uniform resource identifier, i.e an external
              reference. A second argument can be used to specify an explicit
              label for the reference in question.

       usage  The arguments describe the syntax of a Tcl command.

       var    Its argument is a variable.

       widget Its argument is a widget name.

       The example demonstrating the use of text markup is an excerpt from the
       doctools language command reference, with some highlighting added.  It
       shows their use within a block of text, as the arguments of a list item
       command (call), and our ability to nest them.

                ...
                [call [cmd arg_def] [arg type] [arg name]] [opt [arg mode]]]

                Text structure. List element. Argument list. Automatically closes the
                previous list element. Specifies the data-[arg type] of the described
                argument of a command, its [arg name] and its i/o-[arg mode]. The
                latter is optional.
                ...


   ESCAPES
       Beyond the 20 commands for simple markup shown in the previous section
       we have two more available which are technically simple markup.
       However their function is not the marking up of phrases as specific
       types of things, but the insertion of characters, namely [ and ].
       These commands, lb and rb respectively, are required because our use of
       [ and ] to bracket markup commands makes it impossible to directly use
       [ and ] within the text.

       Our example of their use are the sources of the last sentence in the
       previous paragraph, with some highlighting added.

                ...
                These commands, [cmd lb] and [cmd lb] respectively, are required
                because our use of [lb] and [rb] to bracket markup commands makes it
                impossible to directly use [lb] and [rb] within the text.
                ...


   CROSS-REFERENCES
       The last two commands we have to discuss are for the declaration of
       cross-references between documents, explicit and implicit. They are
       keywords and see_also. Both take an arbitrary number of arguments, all
       of which have to be plain unmarked text. I.e. it is not allowed to use
       markup on them. Both commands can be used multiple times in a document.
       If that is done all arguments of all occurrences of one of them are put
       together into a single set.

       keywords
              The arguments of this command are interpreted as keywords
              describing the document. A processor can use this information to
              create an index indirectly linking the containing document to
              all documents with the same keywords.

       see_also
              The arguments of this command are interpreted as references to
              other documents. A processor can format them as direct links to
              these documents.

       All the cross-reference commands can occur anywhere in the document
       between manpage_begin and manpage_end. As such the writer can choose
       whether she wants to have them at the beginning of the body, or at its
       end, maybe near the place a keyword is actually defined by the main
       content, or considers them as meta data which should be in the header,
       etc.

       Our example shows the sources for the cross-references of this
       document, with some highlighting added. Incidentally they are found at
       the end of the body.

                ...
                [see_also doctools_intro]
                [see_also doctools_lang_syntax]
                [see_also doctools_lang_cmdref]
                [keywords markup {semantic markup}]
                [keywords {doctools markup} {doctools language}]
                [keywords {doctools syntax} {doctools commands}]
                [manpage_end]


   EXAMPLES
       Where ever we can write plain text we can write examples too. For
       simple examples we have the command example which takes a single
       argument, the text of the argument. The example text must not contain
       markup. If we wish to have markup within an example we have to use the
       2-command combination example_begin / example_end instead.

       The first opens an example block, the other closes it, and in between
       we can write plain text and use all the regular text markup commands.
       Note that text structure commands are not allowed. This also means that
       it is not possible to embed examples and lists within an example.  On
       the other hand, we can use templating commands within example blocks to
       read their contents from a file (Remember section Advanced structure).

       The source for the very first example in this document (see section
       Fundamentals), with some highlighting added, is

                [example {
                  ... [list_begin enumerated] ...
                }]

       Using example_begin / example_end this would look like

                [example_begin]
                  ... [list_begin enumerated] ...
                [example_end]


   LISTS
       Where ever we can write plain text we can write lists too. The main
       commands are list_begin to start a list, and list_end to close one. The
       opening command takes an argument specifying the type of list started
       it, and this in turn determines which of the eight existing list item
       commands are allowed within the list to start list items.

       After the opening command only whitespace is allowed, until the first
       list item command opens the first item of the list. Each item is a
       regular series of paragraphs and is closed by either the next list item
       command, or the end of the list. If closed by a list item command this
       command automatically opens the next list item. A consequence of a list
       item being a series of paragraphs is that all regular text markup can
       be used within a list item, including examples and other lists.

       The list types recognized by list_begin and their associated list item
       commands are:

       arguments
              (arg_def) This opens an argument (declaration) list. It is a
              specialized form of a term definition list where the term is an
              argument name, with its type and i/o-mode.

       commands
              (cmd_def) This opens a command (declaration) list. It is a
              specialized form of a term definition list where the term is a
              command name.

       definitions
              (def and call) This opens a general term definition list. The
              terms defined by the list items are specified through the
              argument(s) of the list item commands, either general terms,
              possibly with markup (def), or Tcl commands with their syntax
              (call).

       enumerated
              (enum) This opens a general enumerated list.

       itemized
              (item) This opens a general itemized list.

       options
              (opt_def) This opens an option (declaration) list. It is a
              specialized form of a term definition list where the term is an
              option name, possibly with the option's arguments.

       tkoptions
              (tkoption_def) This opens a widget option (declaration) list. It
              is a specialized form of a term definition list where the term
              is the name of a configuration option for a widget, with its
              name and class in the option database.

       Our example is the source of the definition list in the previous
       paragraph, with most of the content in the middle removed.

                ...
                [list_begin definitions]
                [def [const arg]]

                ([cmd arg_def]) This opens an argument (declaration) list. It is a
                specialized form of a definition list where the term is an argument
                name, with its type and i/o-mode.

                [def [const itemized]]

                ([cmd item])
                This opens a general itemized list.

                ...
                [def [const tkoption]]

                ([cmd tkoption_def]) This opens a widget option (declaration) list. It
                is a specialized form of a definition list where the term is the name
                of a configuration option for a widget, with its name and class in the
                option database.

                [list_end]
                ...

       Note that a list cannot begin in one (sub)section and end in another.
       Differently said, (sub)section breaks are not allowed within lists and
       list items. An example of this illegal construct is

                ...
                [list_begin itemized]
                [item]
                ...
                [section {ILLEGAL WITHIN THE LIST}]
                ...
                [list_end]
                ...


FURTHER READING
       Now that this document has been digested the reader, assumed to be a
       writer of documentation should be fortified enough to be able to
       understand the formal doctools language syntax specification as well.
       From here on out the doctools language command reference will also
       serve as the detailed specification and cheat sheet for all available
       commands and their syntax.

       To be able to validate a document while writing it, it is also
       recommended to familiarize oneself with one of the applications for the
       processing and conversion of doctools documents, i.e. either Tcllib's
       easy and simple dtplite, or Tclapps' ultra-configurable dtp.

BUGS, IDEAS, FEEDBACK
       This document, will undoubtedly contain bugs and other problems.
       Please report such in the category doctools of the Tcllib SF Trackers
       [http://sourceforge.net/tracker/?group_id=12883].  Please also report
       any ideas for enhancements you may have.

SEE ALSO
       doctools_intro, doctools_lang_cmdref, doctools_lang_faq,
       doctools_lang_syntax

KEYWORDS
       doctools commands, doctools language, doctools markup, doctools syntax,
       markup, semantic markup

CATEGORY
       Documentation tools

COPYRIGHT
       Copyright (c) 2007 Andreas Kupries <andreas_kupries@users.sourceforge.net>




doctools                              1.0               doctools_lang_intro(n)
