summaryrefslogtreecommitdiff
path: root/docs/hooks.txt
blob: 286ed7e2a458babc39547f265f15b307765ea6ff (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
1050
1051
1052
1053
1054
1055
1056
1057
1058
1059
1060
1061
1062
1063
1064
1065
1066
1067
1068
1069
1070
1071
1072
1073
1074
1075
1076
1077
1078
1079
1080
1081
1082
1083
1084
1085
1086
1087
1088
1089
1090
1091
1092
1093
1094
1095
1096
1097
1098
1099
1100
1101
1102
1103
1104
1105
1106
1107
1108
1109
1110
1111
1112
1113
1114
1115
1116
1117
1118
1119
1120
1121
1122
1123
1124
1125
1126
1127
1128
1129
1130
1131
1132
1133
1134
1135
1136
1137
1138
1139
1140
1141
1142
1143
1144
1145
1146
1147
1148
1149
1150
1151
1152
1153
1154
1155
1156
1157
1158
1159
1160
1161
1162
1163
1164
1165
1166
1167
1168
1169
1170
1171
1172
1173
1174
1175
1176
1177
1178
1179
1180
1181
1182
1183
1184
1185
1186
1187
1188
1189
1190
1191
1192
1193
1194
1195
1196
1197
1198
1199
1200
1201
1202
1203
1204
1205
1206
1207
1208
1209
1210
1211
1212
1213
1214
1215
1216
1217
1218
1219
1220
1221
1222
1223
1224
1225
1226
1227
1228
1229
1230
1231
1232
1233
1234
1235
1236
1237
1238
1239
1240
1241
1242
1243
1244
1245
1246
1247
1248
1249
1250
1251
1252
1253
1254
1255
1256
1257
1258
1259
1260
1261
1262
1263
1264
1265
1266
1267
1268
1269
1270
1271
1272
1273
1274
1275
1276
1277
1278
1279
1280
1281
1282
1283
1284
1285
1286
1287
1288
1289
1290
1291
1292
1293
1294
1295
1296
1297
1298
1299
1300
1301
1302
1303
1304
1305
1306
1307
1308
1309
1310
1311
1312
1313
1314
1315
1316
1317
1318
1319
1320
1321
1322
1323
1324
1325
1326
1327
1328
1329
1330
1331
1332
1333
1334
1335
1336
1337
1338
1339
1340
1341
1342
1343
1344
1345
hooks.txt

This document describes how event hooks work in MediaWiki; how to add hooks for
an event; and how to run hooks for an event.

==Glossary==

event
     Something that happens with the wiki. For example: a user logs in. A wiki
     page is saved. A wiki page is deleted. Often there are two events
     associated with a single action: one before the code is run to make the
     event happen, and one after. Each event has a name, preferably in
     CamelCase. For example, 'UserLogin', 'ArticleSave', 'ArticleSaveComplete',
     'ArticleDelete'.

hook
     A clump of code and data that should be run when an event happens. This can
     be either a function and a chunk of data, or an object and a method.
     
hook function
     The function part of a hook.
     
==Rationale==

Hooks allow us to decouple optionally-run code from code that is run for
everyone. It allows MediaWiki hackers, third-party developers and local
administrators to define code that will be run at certain points in the mainline
code, and to modify the data run by that mainline code. Hooks can keep mainline
code simple, and make it easier to write extensions. Hooks are a principled
alternative to local patches.

Consider, for example, two options in MediaWiki. One reverses the order of a
title before displaying the article; the other converts the title to all
uppercase letters. Currently, in MediaWiki code, we would handle this as follows
(note: not real code, here):

	function showAnArticle($article) {
		global $wgReverseTitle, $wgCapitalizeTitle;

		if ($wgReverseTitle) {
			wfReverseTitle($article);
		}

		if ($wgCapitalizeTitle) {
			wfCapitalizeTitle($article);
		}

		# code to actually show the article goes here
	}

An extension writer, or a local admin, will often add custom code to the
function -- with or without a global variable. For example, someone wanting
email notification when an article is shown may add:

    function showAnArticle($article) {
        global $wgReverseTitle, $wgCapitalizeTitle, $wgNotifyArticle;
	
		if ($wgReverseTitle) {
			wfReverseTitle($article);
		}
	
		if ($wgCapitalizeTitle) {
			wfCapitalizeTitle($article);
		}

		# code to actually show the article goes here
	
		if ($wgNotifyArticle) {
			wfNotifyArticleShow($article));
		}
    }

Using a hook-running strategy, we can avoid having all this option-specific
stuff in our mainline code. Using hooks, the function becomes:

	function showAnArticle($article) {

		if (wfRunHooks('ArticleShow', array(&$article))) {

			# code to actually show the article goes here

			wfRunHooks('ArticleShowComplete', array(&$article));
		}
	}

We've cleaned up the code here by removing clumps of weird, infrequently used
code and moving them off somewhere else. It's much easier for someone working
with this code to see what's _really_ going on, and make changes or fix bugs.

In addition, we can take all the code that deals with the little-used 
title-reversing options (say) and put it in one place. Instead of having little
title-reversing if-blocks spread all over the codebase in showAnArticle,
deleteAnArticle, exportArticle, etc., we can concentrate it all in an extension
file:

	function reverseArticleTitle($article) {
		# ...
	}

	function reverseForExport($article) {
		# ...
	}

The setup function for the extension just has to add its hook functions to the
appropriate events:

	setupTitleReversingExtension() {
		global $wgHooks;

		$wgHooks['ArticleShow'][] = 'reverseArticleTitle';
		$wgHooks['ArticleDelete'][] = 'reverseArticleTitle';
		$wgHooks['ArticleExport'][] = 'reverseForExport';
	}

Having all this code related to the title-reversion option in one place means
that it's easier to read and understand; you don't have to do a grep-find to see
where the $wgReverseTitle variable is used, say.

If the code is well enough isolated, it can even be excluded when not used -- 
making for some slight savings in memory and load-up performance at runtime. 
Admins who want to have all the reversed titles can add:

	require_once('extensions/ReverseTitle.php');

...to their LocalSettings.php file; those of us who don't want or need it can
just leave it out.

The extensions don't even have to be shipped with MediaWiki; they could be
provided by a third-party developer or written by the admin him/herself.

==Writing hooks==

A hook is a chunk of code run at some particular event. It consists of:

  * a function with some optional accompanying data, or
  * an object with a method and some optional accompanying data.

Hooks are registered by adding them to the global $wgHooks array for a given
event. All the following are valid ways to define hooks:

	$wgHooks['EventName'][] = 'someFunction'; # function, no data
	$wgHooks['EventName'][] = array('someFunction', $someData);
	$wgHooks['EventName'][] = array('someFunction'); # weird, but OK

	$wgHooks['EventName'][] = $object; # object only
	$wgHooks['EventName'][] = array($object, 'someMethod');
	$wgHooks['EventName'][] = array($object, 'someMethod', $someData);
	$wgHooks['EventName'][] = array($object); # weird but OK

When an event occurs, the function (or object method) will be called with the
optional data provided as well as event-specific parameters. The above examples
would result in the following code being executed when 'EventName' happened:

	# function, no data
	someFunction($param1, $param2)
	# function with data
	someFunction($someData, $param1, $param2)

	# object only
	$object->onEventName($param1, $param2)
	# object with method
	$object->someMethod($param1, $param2)
	# object with method and data
	$object->someMethod($someData, $param1, $param2)
      
Note that when an object is the hook, and there's no specified method, the
default method called is 'onEventName'. For different events this would be
different: 'onArticleSave', 'onUserLogin', etc.

The extra data is useful if we want to use the same function or object for
different purposes. For example:

	$wgHooks['ArticleSaveComplete'][] = array('ircNotify', 'TimStarling');
	$wgHooks['ArticleSaveComplete'][] = array('ircNotify', 'brion');

This code would result in ircNotify being run twice when an article is saved:
once for 'TimStarling', and once for 'brion'.

Hooks can return three possible values:

  * true: the hook has operated successfully
  * "some string": an error occurred; processing should stop and the error
                   should be shown to the user
  * false: the hook has successfully done the work necessary and the calling
           function should skip
	
The last result would be for cases where the hook function replaces the main
functionality. For example, if you wanted to authenticate users to a custom
system (LDAP, another PHP program, whatever), you could do:

	$wgHooks['UserLogin'][] = array('ldapLogin', $ldapServer);
  
	function ldapLogin($username, $password) {
		# log user into LDAP
		return false;
	}

Returning false makes less sense for events where the action is complete, and
will normally be ignored.

==Using hooks==

A calling function or method uses the wfRunHooks() function to run the hooks
related to a particular event, like so:

	class Article { 
		# ...
		function protect() {
			global $wgUser;
			if (wfRunHooks('ArticleProtect', array(&$this, &$wgUser))) {
				# protect the article
				wfRunHooks('ArticleProtectComplete', array(&$this, &$wgUser));
			}
		}
	}
						    
wfRunHooks() returns true if the calling function should continue processing
(the hooks ran OK, or there are no hooks to run), or false if it shouldn't (an
error occurred, or one of the hooks handled the action already). Checking the
return value matters more for "before" hooks than for "complete" hooks.

Note that hook parameters are passed in an array; this is a necessary
inconvenience to make it possible to pass reference values (that can be changed)
into the hook code. Also note that earlier versions of wfRunHooks took a
variable number of arguments; the array() calling protocol came about after
MediaWiki 1.4rc1.

==Events and parameters==

This is a list of known events and parameters; please add to it if you're going
to add events to the MediaWiki code.

'AbortAutoblock': Return false to cancel an autoblock.
$autoblockip: The IP going to be autoblocked.
$block: The block from which the autoblock is coming.

'AbortLogin': Return false to cancel account login.
$user: the User object being authenticated against
$password: the password being submitted, not yet checked for validity
&$retval: a LoginForm class constant to return from authenticateUserData();
          default is LoginForm::ABORTED. Note that the client may be using
          a machine API rather than the HTML user interface.

'AbortMove': allows to abort moving an article (title)
$old: old title
$nt: new title
$user: user who is doing the move
$err: error message
$reason: the reason for the move (added in 1.13)

'AbortNewAccount': Return false to cancel account creation.
$user: the User object about to be created (read-only, incomplete)
$message: out parameter: error message to display on abort

'AddNewAccount': after a user account is created
$user: the User object that was created. (Parameter added in 1.7)
$byEmail: true when account was created "by email" (added in 1.12)

'AjaxAddScript': Called in output page just before the initialisation
of the javascript ajax engine. The hook is only called when ajax
is enabled ( $wgUseAjax = true; ).

'AlternateEdit': before checking if an user can edit a page and
before showing the edit form ( EditPage::edit() ). This is triggered
on &action=edit.
$EditPage : the EditPage object

'APIEditBeforeSave': before saving a page with api.php?action=edit,
after processing request parameters. Return false to let the request
fail, returning an error message or an <edit result="Failure"> tag
if $resultArr was filled.
$EditPage : the EditPage object
$text : the new text of the article (has yet to be saved)
$resultArr : data in this array will be added to the API result

'APIQueryInfoTokens': use this hook to add custom tokens to prop=info.
Every token has an action, which will be used in the intoken parameter
and in the output (actiontoken="..."), and a callback function which
should return the token, or false if the user isn't allowed to obtain
it. The prototype of the callback function is func($pageid, $title)
where $pageid is the page ID of the page the token is requested for
and $title is the associated Title object. In the hook, just add
your callback to the $tokenFunctions array and return true (returning
false makes no sense)
$tokenFunctions: array(action => callback)

'APIQueryRevisionsTokens': use this hook to add custom tokens to prop=revisions.
Every token has an action, which will be used in the rvtoken parameter
and in the output (actiontoken="..."), and a callback function which
should return the token, or false if the user isn't allowed to obtain
it. The prototype of the callback function is func($pageid, $title, $rev)
where $pageid is the page ID of the page associated to the revision the
token is requested for, $title the associated Title object and $rev the
associated Revision object. In the hook, just add your callback to the
$tokenFunctions array and return true (returning false makes no sense)
$tokenFunctions: array(action => callback)

'ArticleAfterFetchContent': after fetching content of an article from the database
$article: the article (object) being loaded from the database
$content: the content (string) of the article

'ArticleDelete': before an article is deleted
$article: the article (object) being deleted
$user: the user (object) deleting the article
$reason: the reason (string) the article is being deleted
$error: if the deletion was prohibited, the (raw HTML) error message to display
  (added in 1.13)

'ArticleDeleteComplete': after an article is deleted
$article: the article that was deleted
$user: the user that deleted the article
$reason: the reason the article was deleted
$id: id of the article that was deleted

'ArticleEditUpdateNewTalk': before updating user_newtalk when a user talk page was changed
$article: article (object) of the user talk page

'ArticleEditUpdatesDeleteFromRecentchanges': before deleting old entries from recentchanges table, return false to not delete old entries
$article: article (object) being modified

'ArticleFromTitle': when creating an article object from a title object using Wiki::articleFromTitle()
$title: title (object) used to create the article object
$article: article (object) that will be returned

'ArticleInsertComplete': After a new article is created
$article: Article created
$user: User creating the article
$text: New content
$summary: Edit summary/comment
$isMinor: Whether or not the edit was marked as minor
$isWatch: (No longer used)
$section: (No longer used)
$flags: Flags passed to Article::doEdit()
$revision: New Revision of the article

'ArticleMergeComplete': after merging to article using Special:Mergehistory
$targetTitle: target title (object)
$destTitle: destination title (object) 

'ArticlePageDataAfter': after loading data of an article from the database
$article: article (object) whose data were loaded
$row: row (object) returned from the database server

'ArticlePageDataBefore': before loading data of an article from the database
$article: article (object) that data will be loaded
$fields: fileds (array) to load from the database

'ArticleProtect': before an article is protected
$article: the article being protected
$user: the user doing the protection
$protect: boolean whether this is a protect or an unprotect
$reason: Reason for protect
$moveonly: boolean whether this is for move only or not

'ArticleProtectComplete': after an article is protected
$article: the article that was protected
$user: the user who did the protection
$protect: boolean whether it was a protect or an unprotect
$reason: Reason for protect
$moveonly: boolean whether it was for move only or not

'ArticlePurge': before executing "&action=purge" 
$article: article (object) to purge

'ArticleRevisionVisiblitySet': called when changing visibility of one or more
revision of an article
&$title: title object of the article

'ArticleRevisionUndeleted': after an article revision is restored
$title: the article title
$revision: the revision
$oldPageID: the page ID of the revision when archived (may be null)

'ArticleRollbackComplete': after an article rollback is completed
$article: the article that was edited
$user: the user who did the rollback
$revision: the revision the page was reverted back to

'ArticleSave': before an article is saved
$article: the article (object) being saved
$user: the user (object) saving the article
$text: the new article text
$summary: the article summary (comment)
$isminor: minor flag
$iswatch: watch flag
$section: section #

'ArticleSaveComplete': After an article has been updated
$article: Article modified
$user: User performing the modification
$text: New content
$summary: Edit summary/comment
$isMinor: Whether or not the edit was marked as minor
$isWatch: (No longer used)
$section: (No longer used)
$flags: Flags passed to Article::doEdit()
$revision: New Revision of the article

'ArticleSaveComplete': after an article is saved
$article: the article (object) saved
$user: the user (object) who saved the article
$text: the new article text
$summary: the article summary (comment)
$isminor: minor flag
$iswatch: watch flag
$section: section #

wfRunHooks( 'ArticleSaveComplete', array( &$this, &$wgUser, $text, $summary, $flags & EDIT_MINOR, null, null, &$flags, $revision ) );

'ArticleUndelete': When one or more revisions of an article are restored
$title: Title corresponding to the article restored
$create: Whether or not the restoration caused the page to be created
(i.e. it didn't exist before)

'ArticleUpdateBeforeRedirect': After a page is updated (usually on save), before the user is redirected back to the page
&$article: the article
&$sectionanchor: The section anchor link (e.g. "#overview" )
&$extraq: Extra query parameters which can be added via hooked functions

'ArticleViewHeader': Before the parser cache is about to be tried for article viewing.
&$article: the article
&$pcache: whether to try the parser cache or not
&$outputDone: whether the output for this page finished or not

'ArticleViewRedirect': before setting "Redirected from ..." subtitle when follwed an redirect
$article: target article (object)

'AuthPluginAutoCreate': Called when creating a local account for an user logged
in from an external authentication method
$user: User object created locally

'AuthPluginSetup': update or replace authentication plugin object ($wgAuth)
Gives a chance for an extension to set it programattically to a variable class.
&$auth: the $wgAuth object, probably a stub

'AutopromoteCondition': check autopromote condition for user.
$type: condition type
$args: arguments
$user: user
$result: result of checking autopromote condition

'BadImage': When checking against the bad image list
$name: Image name being checked
&$bad: Whether or not the image is "bad"

Change $bad and return false to override. If an image is "bad", it is not
rendered inline in wiki pages or galleries in category pages.

'BeforeGalleryFindFile': before an image is fetched for a gallery
&$gallery,: the gallery object
&$nt: the image title 
&$time: image timestamp

'BeforePageDisplay': Prior to outputting a page
&$out: OutputPage object
&$skin: Skin object

'BeforeParserFetchTemplateAndtitle': before a template is fetched by Parser
&$parser: Parser object
&$title: title of the template
&$skip: skip this template and link it?
&$id: the id of the revision being parsed

'BeforeParserMakeImageLinkObj': before an image is rendered by Parser
&$parser: Parser object
&$nt: the image title
&$skip: skip this image and link it?
&$time: the image timestamp

'BeforeParserrenderImageGallery': before an image gallery is rendered by Parser
&$parser: Parser object
&$ig: ImageGallery object

'BeforeWatchlist': Override watchlist display or add extra SQL clauses.
$nondefaults: Assoc array with the following keys:
              days, hideOwn, hideBots, hideMinor, namespace
$wgUser: wgUser.
&$hookSql: a string which will be inserted without sanitation into the SQL query
           used to get the watchlist, at the end of the WHERE part.

'BlockIp': before an IP address or user is blocked
$block: the Block object about to be saved
$user: the user _doing_ the block (not the one being blocked)

'BlockIpComplete': after an IP address or user is blocked
$block: the Block object that was saved
$user: the user who did the block (not the one being blocked)

'BookInformation': Before information output on Special:Booksources
$isbn: ISBN to show information for
$output: OutputPage object in use

'BrokenLink': Before the HTML is created for a broken (i.e. red) link
&$linker: Linker instance
$nt: the page title
$query: the URL query string passed in
&$u: the URL of this link
&$style: the inline CSS style
&$prefix: a prefix prepended to the linked text
&$text: the text placed by the user in the wiki-link
&$inside: any additional alphanumeric characters placed after the wiki-link,
that are made part of the link text
&$trail: text placed immediately after the HTML link

'CategoryPageView': before viewing a categorypage in CategoryPage::view
$catpage: CategoryPage instance

'ChangesListInsertArticleLink': Override or augment link to article in RC list.
&$this:        ChangesList instance.
&$articlelink: HTML of link to article (already filled-in).
&$s:           HTML of row that is being constructed.
&$rc:          RecentChange instance.
$unpatrolled:  Whether or not we are showing unpatrolled changes.
$watched:      Whether or not the change is watched by the user.

'ContribsPager::getQueryInfo': Before the contributions query is about to run
&$pager: Pager object for contributions
&queryInfo: The query for the contribs Pager

'ContributionsLineEnding': Called before a contributions HTML line is finished
$page: SpecialPage object for contributions
$ret: the HTML line
$row: the DB row for this line

'ContributionsToolLinks': Change tool links above Special:Contributions
$id: User identifier
$title: User page title
&$tools: Array of tool links

'CustomEditor': When invoking the page editor
$article: Article being edited
$user: User performing the edit

Return true to allow the normal editor to be used, or false
if implementing a custom editor, e.g. for a special namespace,
etc.

'DiffViewHeader': called before diff display
$diff: DifferenceEngine object that's calling
$oldRev: Revision object of the "old" revision (may be null/invalid)
$newRev: Revision object of the "new" revision

'DisplayOldSubtitle': before creating subtitle when browsing old versions of an article
$article: article (object) being viewed
$oldid: oldid (int) being viewed

'EditFilter': Perform checks on an edit
$editor: Edit form (see includes/EditPage.php)
$text: Contents of the edit box
$section: Section being edited
&$error: Error message to return
$summary: Edit summary for page

'EditFilterMerged': Post-section-merge edit filter
$editor: EditPage instance (object)
$text: content of the edit box
$error: error message to return
$summary: Edit summary for page

'EditFormPreloadText': Allows population of the edit form when creating new pages
&$text: Text to preload with
&$title: Title object representing the page being created

'EditPage::attemptSave': called before an article is
saved, that is before insertNewArticle() is called
&$editpage_Obj: the current EditPage object

'EditPage::showEditForm:fields': allows injection of form field into edit form
&$editor: the EditPage instance for reference
&$out: an OutputPage instance to write to
return value is ignored (should always return true)

'EditPage::showEditForm:initial': before showing the edit form
$editor: EditPage instance (object)

Return false to halt editing; you'll need to handle error messages, etc. yourself.
Alternatively, modifying $error and returning true will cause the contents of $error
to be echoed at the top of the edit form as wikitext. Return true without altering
$error to allow the edit to proceed.

'EditPageBeforeConflictDiff': allows modifying the EditPage object and output
when there's an edit conflict.  Return false to halt normal diff output; in
this case you're responsible for computing and outputting the entire "conflict"
part, i.e., the "difference between revisions" and "your text" headers and
sections.
&$editor: EditPage instance
&$out: OutputPage instance

'EditPageBeforeEditButtons':  allows modifying the edit buttons below the textarea in the edit form
&$editpage: The current EditPage object
&$buttons: Array of edit buttons "Save", "Preview", "Live", and "Diff"

'EditSectionLink': Override the return value of Linker::editSectionLink()
$skin: Skin rendering the UI
$title: Title being linked to
$section: Section to link to
$link: Default link
$result: Result (alter this to override the generated links)

'EditSectionLinkForOther': Override the return value of Linker::editSectionLinkForOther()
$skin: Skin rendering the UI
$title: Title being linked to
$section: Section to link to
$hint: Anchor title/tooltip attributes
$link: Default link
$result: Result (alter this to override the generated links)

'EmailConfirmed': When checking that the user's email address is "confirmed"
$user: User being checked
$confirmed: Whether or not the email address is confirmed
This runs before the other checks, such as anonymity and the real check; return
true to allow those checks to occur, and false if checking is done.

'EmailUser': before sending email from one user to another
$to: address of receiving user
$from: address of sending user
$subject: subject of the mail
$text: text of the mail

'EmailUserComplete': after sending email from one user to another
$to: address of receiving user
$from: address of sending user
$subject: subject of the mail
$text: text of the mail

'FetchChangesList': When fetching the ChangesList derivative for a particular user
&$user: User the list is being fetched for
&$skin: Skin object to be used with the list
&$list: List object (defaults to NULL, change it to an object instance and return
false override the list derivative used)

'FileDeleteComplete': When a file is deleted
$file: reference to the deleted file
$oldimage: in case of the deletion of an old image, the name of the old file
$article: in case all revisions of the file are deleted a reference to the article 
	  associated with the file.
$user: user who performed the deletion
$reason: reason

'FileUpload': When a file upload occurs
$file : Image object representing the file that was uploaded

'FileUndeleteComplete': When a file is undeleted
$title: title object to the file
$fileVersions: array of undeleted versions. Empty if all versions were restored
$user: user who performed the undeletion
$reason: reason

'GetAutoPromoteGroups': When determining which autopromote groups a user is entitled to be in.
&$user: user to promote.
&$promote: groups that will be added.

'GetBlockedStatus': after loading blocking status of an user from the database
$user: user (object) being checked

'GetCacheVaryCookies': get cookies that should vary cache options
$out: OutputPage object
&$cookies: array of cookies name, add a value to it if you want to add a cookie
	that have to vary cache options

'GetFullURL': modify fully-qualified URLs used in redirects/export/offsite data
$title: Title object of page
$url: string value as output (out parameter, can modify)
$query: query options passed to Title::getFullURL()

'GetInternalURL': modify fully-qualified URLs used for squid cache purging
$title: Title object of page
$url: string value as output (out parameter, can modify)
$query: query options passed to Title::getInternalURL()

'GetLinkColours': modify the CSS class of an array of page links
$linkcolour_ids: array of prefixed DB keys of the pages linked to, indexed by page_id.
&$colours: (output) array of CSS classes, indexed by prefixed DB keys

'GetLocalURL': modify local URLs as output into page links
$title: Title object of page
$url: string value as output (out parameter, can modify)
$query: query options passed to Title::getLocalURL()

'getUserPermissionsErrors': Add a permissions error when permissions errors are
	checked for.  Use instead of userCan for most cases. Return false if the
	user can't do it, and populate $result with the reason in the form of
	array( messagename, param1, param2, ... ).  For consistency, error messages
	should be plain text with no special coloring, bolding, etc. to show that
	they're errors; presenting them properly to the user as errors is done by
	the caller.
$title: Title object being checked against
$user : Current user object
$action: Action being checked
$result: User permissions error to add. If none, return true.

'getUserPermissionsErrorsExpensive': Absolutely the same, but is called only
	if expensive checks are enabled.

'ImageBeforeProduceHTML': Called before producing the HTML created by a wiki
	image insertion.  You can skip the default logic entirely by returning
	false, or just modify a	few things using call-by-reference.
&$this: Skin object
&$title: Title object of the image
&$file: File object, or false if it doesn't exist
&$frameParams: Various parameters with special meanings; see documentation in
	includes/Linker.php for Linker::makeImageLink2
&$handlerParams: Various parameters with special meanings; see documentation in
	includes/Linker.php for Linker::makeImageLink2
&$time: Timestamp of file in 'YYYYMMDDHHIISS' string form, or false for current
&$res: Final HTML output, used if you return false


'ImageOpenShowImageInlineBefore': Call potential extension just before showing
	the image on an image page
$imagePage: ImagePage object ($this)
$output: $wgOut

'ImagePageFileHistoryLine': called when a file history line is contructed
$file: the file
$line: the HTML of the history line
$css: the line CSS class

'ImagePageFindFile': called when fetching the file associated with an image page
$page: ImagePage object
&$file: File object
&$displayFile: displayed File object

'InitializeArticleMaybeRedirect': MediaWiki check to see if title is a redirect
$title: Title object ($wgTitle)
$request: WebRequest
$ignoreRedirect: boolean to skip redirect check
$target: Title/string of redirect target

'InitPreferencesForm': called at the end of PreferencesForm's constructor
$form: the PreferencesForm
$request: the web request to initialized from

'InternalParseBeforeLinks': during Parser's internalParse method before links but
after noinclude/includeonly/onlyinclude and other processing.
&$this: Parser object
&$text: string containing partially parsed text
&$this->mStripState: Parser's internal StripState object

'IsFileCacheable': Override the result of Article::isFileCacheable() (if true)
$article: article (object) being checked

'IsTrustedProxy': Override the result of wfIsTrustedProxy()
$ip: IP being check
$result: Change this value to override the result of wfIsTrustedProxy()

'isValidEmailAddr': Override the result of User::isValidEmailAddr(), for ins-
tance to return false if the domain name doesn't match your organization
$addr: The e-mail address entered by the user
&$result: Set this and return false to override the internal checks

'isValidPassword': Override the result of User::isValidPassword()
$password: The password entered by the user
&$result: Set this and return false to override the internal checks
$user: User the password is being validated for

'LanguageGetMagic': Use this to define synonyms of magic words depending of the language
$magicExtensions: associative array of magic words synonyms
$lang: laguage code (string)

'LanguageGetSpecialPageAliases': Use to define aliases of special pages names depending of the language
$specialPageAliases: associative array of magic words synonyms
$lang: laguage code (string)

'LinkerMakeExternalImage': At the end of Linker::makeExternalImage() just before the return
&$url: the image url
&$alt: the image's alt text
&$img: the new image HTML (if returning false)

'LinkerMakeExternalLink': At the end of Linker::makeExternalLink() just before the return
&$url: the link url
&$text: the link text
&$link: the new link HTML (if returning false)

'LinksUpdate': At the beginning of LinksUpdate::doUpdate() just before the actual update
&$linksUpdate: the LinkUpdate object

'LinksUpdateComplete': At the end of LinksUpdate::doUpdate() when updating has completed
&$linksUpdate: the LinkUpdate object

'LinksUpdateConstructed': At the end of LinksUpdate() is contruction.
&$linksUpdate: the LinkUpdate object

'LoadAllMessages': called by MessageCache::loadAllMessages() to load extensions messages

'LoadExtensionSchemaUpdates': called by maintenance/updaters.inc when upgrading database schema

'LocalFile::getHistory': called before file history query performed
$file: the file
$tables: tables
$fields: select fields
$conds: conditions
$opts: query options
$join_conds: JOIN conditions

'LoginAuthenticateAudit': a login attempt for a valid user account either succeeded or failed.
                          No return data is accepted; this hook is for auditing only.
$user: the User object being authenticated against
$password: the password being submitted and found wanting
$retval: a LoginForm class constant with authenticateUserData() return value (SUCCESS, WRONG_PASS, etc)

'LogLine': Processes a single log entry on Special:Log
$log_type: string for the type of log entry (e.g. 'move'). Corresponds to logging.log_type 
    database field.
$log_action: string for the type of log action (e.g. 'delete', 'block', 'create2'). Corresponds
    to logging.log_action database field.
$title: Title object that corresponds to logging.log_namespace and logging.log_title database fields.
$paramArray: Array of parameters that corresponds to logging.log_params field. Note that only $paramArray[0]
    appears to contain anything.
&$comment: string that corresponds to logging.log_comment database field, and which is displayed in the UI.
&$revert: string that is displayed in the UI, similar to $comment.
$time: timestamp of the log entry (added in 1.12) 

'LogPageValidTypes': action being logged. DEPRECATED: Use $wgLogTypes
&$type: array of strings

'LogPageLogName': name of the logging page(s). DEPRECATED: Use $wgLogNames
&$typeText: array of strings

'LogPageLogHeader': strings used by wfMsg as a header. DEPRECATED: Use $wgLogHeaders
&$headerText: array of strings

'LogPageActionText': strings used by wfMsg as a header. DEPRECATED: Use $wgLogActions
&$actionText: array of strings

'MagicWordMagicWords': When defining new magic word. DEPRECATED: Use LanguageGetMagic hook instead
$magicWords: array of strings

'MagicWordwgVariableIDs': When definig new magic words IDs. DEPRECATED: Use LanguageGetMagic hook instead
$variableIDs: array of strings

'MarkPatrolled': before an edit is marked patrolled
$rcid: ID of the revision to be marked patrolled
$user: the user (object) marking the revision as patrolled
$wcOnlySysopsCanPatrol: config setting indicating whether the user
 needs to be a sysop in order to mark an edit patrolled

'MarkPatrolledComplete': after an edit is marked patrolled
$rcid: ID of the revision marked as patrolled
$user: user (object) who marked the edit patrolled
$wcOnlySysopsCanPatrol: config setting indicating whether the user
 must be a sysop to patrol the edit

'MathAfterTexvc': after texvc is executed when rendering mathematics
$mathRenderer: instance of MathRenderer
$errmsg: error message, in HTML (string). Nonempty indicates failure
 of rendering the formula

'MediaWikiPerformAction': Override MediaWiki::performAction().
Use this to do something completely different, after the basic
globals have been set up, but before ordinary actions take place.
$output:  $wgOut
$article: $wgArticle
$title:   $wgTitle
$user:    $wgUser
$request: $wgRequest
$this:    The $mediawiki object

'MessagesPreLoad': When loading a message from the database
$title: title of the message (string)
$message: value (string), change it to the message you want to define

'MonoBookTemplateToolboxEnd': Called by Monobook skin after toolbox links have been rendered (useful for adding more)
Note: this is only run for the Monobook skin.  To add items to the toolbox
for all 'SkinTemplate'-type skins, use the SkinTemplateToolboxEnd hook
instead.
$tools: array of tools

'NewRevisionFromEditComplete': called when a revision was inserted due to an edit
$article: the article edited
$rev: the new revision
$baseID: the revision ID this was based off, if any

'NormalizeMessageKey': Called before the software gets the text of a message
  (stuff in the MediaWiki: namespace), useful for changing WHAT message gets displayed
&$key: the message being looked up. Change this to something else to change what message gets displayed (string)
&$useDB: whether or not to look up the message in the database (bool)
&$langCode: the language code to get the message for (string) - or -
  whether to use the content language (true) or site language (false) (bool)
&$transform: whether or not to expand variables and templates in the message (bool)

'OpenSearchUrls': Called when constructing the OpenSearch description XML.
Hooks can alter or append to the array of URLs for search & suggestion formats.
&$urls: array of associative arrays with Url element attributes

'OutputPageBeforeHTML': a page has been processed by the parser and
the resulting HTML is about to be displayed.  
$parserOutput: the parserOutput (object) that corresponds to the page 
$text: the text that will be displayed, in HTML (string)

'OutputPageParserOutput': after adding a parserOutput to $wgOut
$out: OutputPage instance (object)
$parserOutput: parserOutput instance being added in $out

'OutputPageMakeCategoryLinks': links are about to be generated for the page's categories.
  Implementations should return false if they generate the category links, so the default link generation is skipped.
$out: OutputPage instance (object)
$categories: associative array, keys are category names, values are category types ("normal" or "hidden")
$links: array, intended to hold the result. Must be an associative array with category types as keys and arrays of HTML links as values.

'PageHistoryBeforeList': When a history page list is about to be constructed.
$article: the article that the history is loading for

'PageHistoryLineEnding' : right before the end <li> is added to a history line
$row: the revision row for this line
$s: the string representing this parsed line

'PageHistoryPager::getQueryInfo': when a history pager query parameter set is constructed
$pager: the pager
$queryInfo: the query parameters

'PageRenderingHash': alter the parser cache option hash key
  A parser extension which depends on user options should install
  this hook and append its values to the key.
$hash: reference to a hash key string which can be modified

'ParserAfterStrip': Same as ParserBeforeStrip

'ParserAfterTidy': Called after Parser::tidy() in Parser::parse()
$parser: Parser object being used 
$text: text that'll be returned

'ParserBeforeInternalParse': called at the beginning of Parser::internalParse()
$parser: Parser object
$text: text to parse
$stripState: StripState instance being used

'ParserBeforeStrip': Called at start of parsing time (no more strip, deprecated ?)
$parser: parser object
$text: text being parsed
$stripState: stripState used (object)

'ParserBeforeTidy': called before tidy and custom tags replacements
$parser: Parser object being used 
$text: actual text

'ParserClearState': called at the end of Parser::clearState()
$parser: Parser object being cleared

'ParserFirstCallInit': called when the parser initialises for the first time
&$parser: Parser object being cleared

'ParserGetVariableValueSwitch': called when the parser need the value of a custom magic word
$parser: Parser object
$varCache: array to store the value in case of multiples calls of the same magic word
$index: index (string) of the magic
$ret: value of the magic word (the hook should set it)

'ParserGetVariableValueTs': use this to change the value of the time for the {{LOCAL...}} magic word
$parser: Parser object
$time: actual time (timestamp)

'ParserGetVariableValueVarCache': use this to change the value of the variable cache or return false to not use it
$parser: Parser object
$varCache: varaiable cache (array)

'ParserLimitReport': called at the end of Parser:parse() when the parser will include comments about size of the text parsed
$parser: Parser object
$limitReport: text that will be included (without comment tags)

'ParserMakeImageParams': Called before the parser make an image link, use this to modify the parameters of the image.
$title: title object representing the file
$file: file object that will be used to create the image
&$params: 2-D array of parameters

'ParserTestParser': called when creating a new instance of Parser in maintenance/parserTests.inc
$parser: Parser object created

'ParserTestTables': alter the list of tables to duplicate when parser tests
are run. Use when page save hooks require the presence of custom tables
to ensure that tests continue to run properly.
&$tables: array of table names

'PersonalUrls': Alter the user-specific navigation links (e.g. "my page,
my talk page, my contributions" etc).

&$personal_urls: Array of link specifiers (see SkinTemplate.php)
&$title: Title object representing the current page

'PingLimiter': Allows extensions to override the results of User::pingLimiter()
&$user : User performing the action
$action : Action being performed
&$result : Whether or not the action should be prevented
Change $result and return false to give a definitive answer, otherwise
the built-in rate limiting checks are used, if enabled.

'PreferencesUserInformationPanel': Add HTML bits to user information list in preferences form
$form : PreferencesForm object
&$html : HTML to append to

'PrefixSearchBackend': Override the title prefix search used for OpenSearch and
AJAX search suggestions. Put results into &$results outparam and return false.
$ns : array of int namespace keys to search in
$search : search term (not guaranteed to be conveniently normalized)
$limit : maximum number of results to return
&$results : out param: array of page names (strings)

'PrefsEmailAudit': called when user changes his email address
$user: User (object) changing his email address
$oldaddr: old email address (string)
$newaddr: new email address (string)

'PrefsPasswordAudit': called when user changes his password
$user: User (object) changing his passoword
$newPass: new password
$error: error (string) 'badretype', 'wrongpassword', 'error' or 'success'

'RawPageViewBeforeOutput': Right before the text is blown out in action=raw
&$obj: RawPage object
&$text: The text that's going to be the output

'RecentChange_save': called at the end of RecenChange::save()
$recentChange: RecentChange object

'RenderPreferencesForm': called at the end of PreferencesForm::mainPrefsForm
$form: the PreferencesForm
$out: output page to render to, probably $wgOut

'ResetPreferences': called at the end of PreferencesForm::resetPrefs
$form: the PreferencesForm
$user: the User object to load preferences from

'RevisionInsertComplete': called after a revision is inserted into the DB
&$revision: the Revision
$data: the data stored in old_text.  The meaning depends on $flags: if external
  is set, it's the URL of the revision text in external storage; otherwise,
  it's the revision text itself.  In either case, if gzip is set, the revision
  text is gzipped.
$flags: a comma-delimited list of strings representing the options used.  May
  include: utf8 (this will always be set for new revisions); gzip; external.

'SavePreferences': called at the end of PreferencesForm::savePreferences; 
                   returning false prevents the preferences from being saved.
$form: the PreferencesForm
$user: the User object to save preferences to
$message: change this to set an error message (ignored if the hook does not return false)
$old: old preferences of the user

'SearchUpdate': Prior to search update completion
$id : Page id
$namespace : Page namespace
$title : Page title
$text : Current text being indexed

'SearchGetNearMatch': An extra chance for exact-title-matches in "go" searches
$term : Search term string
&$title : Outparam; set to $title object and return false for a match

'ShowRawCssJs': Customise the output of raw CSS and JavaScript in page views
$text: Text being shown
$title: Title of the custom script/stylesheet page
$output: Current OutputPage object

'SiteNoticeBefore': Before the sitenotice/anonnotice is composed
&$siteNotice: HTML returned as the sitenotice
Return true to allow the normal method of notice selection/rendering to work,
or change the value of $siteNotice and return false to alter it.

'SiteNoticeAfter': After the sitenotice/anonnotice is composed
&$siteNotice: HTML sitenotice
Alter the contents of $siteNotice to add to/alter the sitenotice/anonnotice.

'SkinAfterBottomScripts': At the end of Skin::bottomScripts()
$skin: Skin object
&$text: bottomScripts Text
Append to $text to add additional text/scripts after the stock bottom scripts.

'SkinSubPageSubtitle': At the beginning of Skin::subPageSubtitle()
$skin: Skin object
&$subpages: Subpage links HTML
If false is returned $subpages will be used instead of the HTML subPageSubtitle() generates.
If true is returned, $subpages will be ignored and the rest of subPageSubtitle() will run.

'SkinTemplateBuildContentActionUrlsAfterSpecialPage': after the single tab  when showing a special page
$sktemplate: SkinTemplate object
$content_actions: array of tabs

'SkinTemplateBuildNavUrlsNav_urlsAfterPermalink': after creating the "permanent link" tab
$sktemplate: SkinTemplate object
$nav_urls: array of tabs

'SkinTemplateContentActions': Alter the "content action" links in SkinTemplates
&$content_actions: Content actions
[See http://svn.wikimedia.org/viewvc/mediawiki/trunk/extensions/examples/Content_action.php
for an example]

'SkinTemplateOutputPageBeforeExec': Before SkinTemplate::outputPage() starts page output
&$sktemplate: SkinTemplate object
&$tpl: Template engine object

'SkinTemplatePreventOtherActiveTabs': use this to prevent showing active tabs
$sktemplate: SkinTemplate object
$res: set to true to prevent active tabs

'SkinTemplateSetupPageCss': use this to provide per-page CSS
$out: Css to return

'SkinTemplateTabAction': Override SkinTemplate::tabAction().
       You can either create your own array, or alter the parameters for the normal one.
&$this:     The SkinTemplate instance.
$title:     Title instance for the page.
$message:   Visible label of tab.
$selected:  Whether this is a selected tab.
$checkEdit: Whether or not the action=edit query should be added if appropriate.
&$classes:  Array of CSS classes to apply.
&$query:    Query string to add to link.
&$text:     Link text.
&$result:   Complete assoc. array if you want to return true.

'SkinTemplateTabs': called when finished to build the actions tabs
$sktemplate: SkinTemplate object
$content_actions: array of tabs

'SkinTemplateToolboxEnd': Called by SkinTemplate skins after toolbox links have been rendered (useful for adding more)
$tools: array of tools

'SpecialContributionsBeforeMainOutput': Before the form on Special:Contributions
$id: User identifier

'SpecialListusersDefaultQuery': called right before the end of UsersPager::getDefaultQuery()
$pager: The UsersPager instance
$query: The query array to be returned

'SpecialListusersFormatRow': called right before the end of UsersPager::formatRow()
$item: HTML to be returned. Will be wrapped in <li></li> after the hook finishes
$row: Database row object

'SpecialListusersHeader': called before closing the <fieldset> in UsersPager::getPageHeader()
$pager: The UsersPager instance
$out: The header HTML

'SpecialListusersHeaderForm': called before adding the submit button in UsersPager::getPageHeader()
$pager: The UsersPager instance
$out: The header HTML

'SpecialListusersQueryInfo': called right before the end of UsersPager::getQueryInfo()
$pager: The UsersPager instance
$query: The query array to be returned

'SpecialMovepageAfterMove': called after moving a page
$movePage: MovePageForm object
$oldTitle: old title (object)
$newTitle: new title (object)

'SpecialPageExecuteAfterPage': called after executing a special page
Warning: Not all the special pages call this hook
$specialPage: SpecialPage object
$par: paramter passed to the special page (string)
$funct: function called to execute the special page

'SpecialPageExecuteBeforeHeader': called before setting the header text of the special page
Warning: Not all the special pages call this hook
$specialPage: SpecialPage object
$par: paramter passed to the special page (string)
$funct: function called to execute the special page

'SpecialPageExecuteBeforePage': called after setting the special page header text but before the main execution
Warning: Not all the special pages call this hook
$specialPage: SpecialPage object
$par: paramter passed to the special page (string)
$funct: function called to execute the special page

'SpecialPage_initList': called when setting up SpecialPage::$mList, use this hook to remove a core special page
$list: list (array) of core special pages

'SpecialRecentChangesPanel': called when building form options in SpecialRecentChanges
&$extraOpts: array of added items, to which can be added
$opts: FormOptions for this request

'SpecialRecentChangesQuery': called when building sql query for SpecialRecentChanges
&$conds: array of where conditionals for query
&$tables: array of tables to be queried
&$join_conds: join conditions for the tables
$opts: FormOptions for this request

'SpecialSearchNogomatch': called when user clicked the "Go" button but the target doesn't exist
$title: title object generated from the text entred by the user

'SpecialSearchResults': called before search result display when there are matches
$term: string of search term
&$titleMatches: empty or SearchResultSet object
&$textMatches: empty or SearchResultSet object

'SpecialSearchNoResults': called before search result display when there are no matches
$term: string of search term

'SpecialVersionExtensionTypes': called when generating the extensions credits, use this to change the tables headers
$extTypes: associative array of extensions types

'TitleMoveComplete': after moving an article (title)
$old: old title
$nt: new title
$user: user who did the move
$pageid: database ID of the page that's been moved
$redirid: database ID of the created redirect

'UndeleteShowRevision': called when showing a revision in Special:Undelete
$title: title object related to the revision
$rev: revision (object) that will be viewed

'UnknownAction': An unknown "action" has occured (useful for defining
		 your own actions)
$action: action name
$article: article "acted on"

'UnwatchArticle': before a watch is removed from an article
$user: user watching
$article: article object to be removed

'UnwatchArticle': after a watch is removed from an article
$user: user that was watching
$article: article object removed

'UnwatchArticleComplete': after a watch is removed from an article
$user: user that watched
$article: article object that was watched

'UploadForm:initial': before the upload form is generated
$form: UploadForm object
You might set the member-variables $uploadFormTextTop and 
$uploadFormTextAfterSummary to inject text (HTML) either before
or after the editform.

'UploadForm:BeforeProcessing': at the beginning of processUpload()
$form: UploadForm object
Lets you poke at member variables like $mUploadDescription before the
file is saved.

'UploadVerification': additional chances to reject an uploaded file
string $saveName: destination file name
string $tempName: filesystem path to the temporary file for checks
string &$error: output: HTML error to show if upload canceled by returning false

'UploadComplete': Upon completion of a file upload
$uploadForm: Upload form object. File can be accessed by $uploadForm->mLocalFile.

'UserArrayFromResult': called when creating an UserArray object from a database result
&$userArray: set this to an object to override the default object returned
$res: database result used to create the object

'userCan': To interrupt/advise the "user can do X to Y article" check.
	If you want to display an error message, try getUserPermissionsErrors.
$title: Title object being checked against
$user : Current user object
$action: Action being checked
$result: Pointer to result returned if hook returns false. If null is returned,
 userCan checks are continued by internal code.

'UserCanSendEmail': To override User::canSendEmail() permission check
$user: User (object) whose permission is being checked
&$canSend: bool set on input, can override on output


'UserClearNewTalkNotification': called when clearing the "You have new messages!" message, return false to not delete it
$user: User (object) that'll clear the message

'UserCreateForm': change to manipulate the login form
$template: SimpleTemplate instance for the form

'UserEffectiveGroups': Called in User::getEffectiveGroups()
$user: User to get groups for
&$groups: Current effective groups

'UserGetAllRights': after calculating a list of all available rights
&$rights: Array of rights, which may be added to.

'UserGetEmail': called when getting an user email address
$user: User object
&$email: email, change this to override local email

'UserGetEmailAuthenticationTimestamp': called when getting the timestamp of email authentification
$user: User object
&$timestamp: timestamp, change this to override local email authentification timestamp

'UserGetImplicitGroups': Called in User::getImplicitGroups()
&$groups: List of implicit (automatically-assigned) groups

'UserGetRights': Called in User::getRights()
$user: User to get rights for
&$rights: Current rights

'UserLoadDefaults': called when loading a default user
$user: user object
$name: user name

'UserLoadFromSession': called to authenticate users on external/environmental means
$user: user object being loaded
&$result: set this to a boolean value to abort the normal authentification process

'UserLoginComplete': after a user has logged in
$user: the user object that was created on login
$inject_html: Any HTML to inject after the "logged in" message.
		    
'UserLoginForm': change to manipulate the login form
$template: SimpleTemplate instance for the form

'UserLogout': before a user logs out
$user: the user object that is about to be logged out
       
'UserLogoutComplete': after a user has logged out
$user: the user object _after_ logout (won't have name, ID, etc.)
$inject_html: Any HTML to inject after the "logged out" message.
$oldName: name of the user before logout (string)

'UserRights': After a user's group memberships are changed
$user  : User object that was changed
$add   : Array of strings corresponding to groups added
$remove: Array of strings corresponding to groups removed

'UserRetrieveNewTalks': called when retrieving "You have new messages!" message(s)
$user: user retrieving new talks messages
$talks: array of new talks page(s)

'UserSaveSettings': called when saving user settings
$user: User object

'UserSetCookies': called when setting user cookies
$user: User object
&$session: session array, will be added to $_SESSION
&$cookies: cookies array mapping cookie name to its value

'UserSetEmail': called when changing user email address
$user: User object
&$email: new email, change this to override new email address

'UserSetEmailAuthenticationTimestamp': called when setting the timestamp of email authentification
$user: User object
&$timestamp: new timestamp, change this to override local email authentification timestamp

'UserToggles': called when initialising User::$mToggles, use this to add new toggles
$toggles: array of toggles to add

'WatchArticle': before a watch is added to an article
$user: user that will watch
$article: article object to be watched

'WatchArticleComplete': after a watch is added to an article
$user: user that watched
$article: article object watched

'wgQueryPages': called when initialising $wgQueryPages, use this to add new query pages to be updated with maintenance/updateSpecialPages.php
$query: $wgQueryPages itself

More hooks might be available but undocumented, you can execute
./maintenance/findhooks.php to find hidden one.