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>