So you've written a masterpiece, a class in a class of its own, and
you'd like to share it with the world. But, being a responsible
developer, you feel the need to document your creation. What do you
do? The simplest solution is to use Ruby's built-in documentation
format, RD, and rdtool, a Ruby utility suite that converts this
documentation into a variety of output formats.
rdtool scans a file for =begin and =end{=begin...=end@{=begin
pairs, and
extracts the text between them all. This text is assumed to be
documentation in RD format. The text is then processed according to a
simple set of rules:
Lines of text flush to the left margin are converted to
paragraphs.
Lines starting with one to four equals signs are headings. ``=''
is a first-level heading, ``=='' a second-level heading, and so
on. ``+'' and ``++'' can be used to signal fifth- and sixth-level
headings if you really want to go that deep.
= Top Level Heading
== Second Level Heading
...
Lines in which the first nonspace is an asterisk indicate the
beginnings of bullet lists. Continuation lines for each bullet item
should line up with the text on the first line. Lists may be nested.
This is normal text
* start of a
multiline bullet item
* and another
* nested item
* second nested
* third item at top level
Lines where the first nonspace characters are digits between
parentheses indicate numbered lists. The actual digits used are
ignored. Again, lists may be nested.
(1) A numbered item
* subitem in a bulleted list
* subitem
(2) Second numbered item
(9) This will actually be labeled '3.'
Lines starting with a colon indicate labeled lists. The text on
the colon line is the label. The immediately following text (which
may not be indented less than the label) is the descriptive
text. Again, each type of list may be nested.
: red
when the light is red, you
must stop
: amber
the amber light means that things are about to change. Either:
* step on the gas, or
* slam on the brakes
: green
green means GO
Lines starting with three minus signs are a special kind of
labeled list, when the labels are method names and signatures. The
source in Figure A.1 on page 512 shows a handful of these in
action.
Indented text that isn't part of a list is set verbatim (such as the
stuff under ``Synopsis'' in Figures A.1 and A.2).
Within blocks of text and headings, you can use special inline
sequences to control text formatting. All sequences are nested
within a set of double parentheses.
Sequence
Example
Intended Use
((*emphasis*))
emphasis
Emphasis (normally italic)
(({code stuff}))
code stuff
Code
((|variable|))
variable
Variable name
((%type me%))
type me
Keyboard input
((:index term:))
index term
Something to be indexed
((<reference>))
reference
Hyperlink reference
((-footnote-))
text.4
Footnote text. A reference is placed
inline, and the text of the footnote appears at the bottom of the
page.
The content of headings, the labels of labeled lists, and the names of
methods are automatically
made into potential cross reference targets. You make links to these
targets from elsewhere in the document by citing their contents in the
((<...>)) construct.
= Synopsis
...
See ((<Return Codes>)) for details.
..
== Instance Methods
--- Tempfile.open( filename )
Opens the file...
== Return Codes
..
The method ((<Tempfile.open>)) raises an (({IOException}))...
If a reference starts with ``URL:'', rdtool attempts to format it as an
external hyperlink.
The reference ((<display part|label>)) generates a link to
label but places the text ``display part'' in the output
document. This is used in the description section of the example in
Figure A.1 on page 512 to generate references to the method names:
perspective, apart from the unusual ((<(({new}))|Tempfile.new>)),
...
This construct displays the word ``new'' in code font but uses it as
a hyperlink to the method Tempfile.new.
rdtool makes certain assumptions about the format of method
names. Class or module methods should appear as Class.method,
instance methods as Class#method, and class or module
constants as Class::Const.
--- Tempfile::IOWRITE
Open the file write-only.
...
--- Tempfile.new( filename )
Constructs a temporary file in the given directory. The file
...
--- Tempfile#open
Reopens ((|aTempfile|)) using mode ``r+'', which allows reading
..
The contents of filename will be inserted wherever the
document contains
<<< filename
If the file is specified with an .rd or .rb extension, it
will be interpreted as RD documentation.
If the filename has no extension, rdtool will look for a file with an
extension that matches the type of output being produced (.html
for HTML files, .man for man files, and so on) and interpolate
that file's contents in the output stream. Thus, a line such as:
<<< header
could be used to add an output-dependent header to a document.
RD documentation can be included directly in a Ruby source program or
written into a separate file (which by convention will have the
extension .rd). These files are processed using the rd2
command to produce appropriately formatted output.
rd2 [options]inputfile[ >outputfile]
Some common options include:
-rformat
Select an output
format. -rrd/rd2html-lib.rb produces HTML output (the
default). -rrd/rd2man-lib.rb produces Unix man page output.
As we are writing this, RD and rdtool are undergoing continuous
development. It is likely that some of the details we give here will
be out of date (or just plain wrong) by the time you read this.
Included with the rdtool distribution is the file README.rd. We
suggest you do so, as it will give you the current scoop on producing
Ruby documentation.
