This is a brief overview of the new design.
More thorough and up-to-date information is available on the documentation
wiki at http://www.mediawiki.org/
Encapsulates the state of the user viewing/using the site. Can be queried
for things like the user's settings, name, etc. Handles the details of
getting and saving to the "user" table of the database, and dealing with
sessions and cookies.
Encapsulates the entire HTML page that will be sent in response to any
server request. It is used by calling its functions to add text, headers,
etc., in any order, and then calling output() to send it all. It could be
easily changed to send incrementally if that becomes useful, but I prefer
the flexibility. This should also do the output encoding. The system
allocates a global one in $wgOut.
Represents the title of an article, and does all the work of translating
among various forms such as plain text, URL, database key, etc. For
convenience, and for historical reasons, it also represents a few features
of articles that don't involve their text, such as access rights.
See also title.txt.
Encapsulates access to the "page" table of the database. The object
represents a an article, and maintains state such as text (in Wikitext
format), flags, etc.
Encapsulates individual page revision data and access to the
revision/text/blobs storage system. Higher-level code should never touch
text storage directly; this class mediates it.
Encapsulates a "look and feel" for the wiki. All of the functions that
render HTML, and make choices about how to render it, are here, and are
called from various other places when needed (most notably,
OutputPage::addWikiText()). The StandardSkin object is a complete
implementation, and is meant to be subclassed with other skins that may
override some of its functions. The User object contains a reference to a
skin (according to that user's preference), and so rather than having a
global skin object we just rely on the global User and get the skin with
See also skin.txt.
Represents the language used for incidental text, and also has some
character encoding functions and other locale stuff. The current user
interface language is instantiated as $wgLang, and the local content
language as $wgContLang; be sure to use the *correct* language object
depending upon the circumstances.
See also language.txt.
Class used to transform wikitext to html.
Keeps information on existence of articles. See linkcache.txt.
These are meant to be descriptive, not dictatorial; I won't presume to tell
you how to program, I'm just describing the methods I chose to use for myself.
If you do choose to follow these guidelines, it will probably be easier for
you to collaborate with others on the project, but if you want to contribute
without bothering, by all means do so (and don't be surprised if I reformat
- I have the code indented with tabs to save file size and so that users can
set their tab stops to any depth they like. I use 4-space tab stops, which
work well. I also use K&R brace matching style. I know that's a religious
issue for some, so if you want to use a style that puts opening braces on
the next line, that's OK too, but please don't use a style where closing
braces don't align with either the opening brace on its own line or the
statement that opened the block--that's confusing as hell.
- Certain functions and class members are marked with /* private */, rather
than being marked as such. This is a hold-over from PHP 4, which didn't
support proper visibilities. You should not access things marked in this
manner outside the class/inheritance line as this code is subjected to be
updated in a manner that enforces this at some time in the near future, and
things will break. New code should use the standard method of setting
visibilities as normal.
- Member variables are generally "mXxx" to distinguish them. This should make
it easier to spot errors of forgetting the required "$this->", which PHP
will happily accept by creating a new local variable rather than complaining.
- Globals are particularly evil in PHP; it sets a lot of them automatically
from cookies, query strings, and such, leading to namespace conflicts; when
a variable name is used in a function, it is silently declared as a new
local masking the global, so you'll get weird error because you forgot the
global declaration; lack of static class member variables means you have to
use globals for them, etc. Evil, evil.
I think I've managed to pare down the number of globals we use to a scant
few dozen or so, and I've prefixed them all with "wg" so you can spot errors
better (odds are, if you see a "wg" variable being used in a function that
doesn't declare it global, that's probably an error).
Other conventions: Top-level functions are wfFuncname(), names of session
variables are wsName, cookies wcName, and form field values wpName ("p" for