doctools_lang_intro(n) Documentation tools doctools_lang_intro(n)______________________________________________________________________________NAMEdoctools_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 speci‐
fication, i.e. the doctools language syntax specification and the doc‐
tools 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 white‐
space. 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 mul‐
tiple times, including none, and they can be used in any order. How‐
ever 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 con‐
figuration 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 high‐
light 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 every‐
thing 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 automati‐
cally 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 com‐
mand 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 docu‐
ment 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. How‐
ever their function is not the marking up of phrases as specific types
of things, but the insertion of characters, namely [ and ]. These com‐
mands, 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 docu‐
ment, 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 sim‐
ple 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 reg‐
ular 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 spe‐
cialized form of a term definition list where the term is a com‐
mand name.
definitions
(def and call) This opens a general term definition list. The
terms defined by the list items are specified through the argu‐
ment(s) of the list item commands, either general terms, possi‐
bly 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 spe‐
cialized 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 para‐
graph, 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 under‐
stand 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 recom‐
mended to familiarize oneself with one of the applications for the pro‐
cessing 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, doc‐
tools_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)
