mw magic word

#--------------------------------------------------
# Step 1: choose a magic word id
#--------------------------------------------------
 
# storing the chosen id in a constant is not required
# but still good programming practice - it  makes 
# searching for all occurrences of the magic word id a
# bit easier - note that the the name of the constant
# and the value it is assigned don't have to have anthing
# to do with each other.
 
define('MAG_NIFTYVAR', 'mycustomvar1');
 
#---------------------------------------------------
# Step 2: define some words to use in wiki markup
#---------------------------------------------------
 
$wgHooks['LanguageGetMagic'][] = 'wfMyWikiWords';
function wfMyWikiWords(&$aWikiWords, &$langID) {
 
  #tell MediaWiki that all {{NiftyVar}}, {{NIFTYVAR}}, 
  #{{CoolVar}}, {{COOLVAR}} and all case variants found 
  #in wiki text should be mapped to magic id 'mycustomvar1'
  # (0 means case-insensitive)
  $aWikiWords[MAG_NIFTYVAR] = array(0, 'NiftyVar','CoolVar');
 
  #must do this or you will silence every LanguageGetMagic
  #hook after this!
  return true;
}
 
#---------------------------------------------------
# Step 3: assign a value to our variable
#---------------------------------------------------
 
$wgHooks['ParserGetVariableValueSwitch'][] = 'wfMyAssignAValue';
function wfMyAssignAValue(&$parser, &$cache, &$magicWordId, &$ret) {
  if (MAG_NIFTYVAR == $magicWordId) {
     // We found a value
     $ret='This is a really silly value';
  }
  // We must return true for two separate reasons:
  // 1. To permit further callbacks to run for this hook.
  //    They might override our value but that's life.
  //    Returning false would prevent these future callbacks from running.
  // 2. At the same time, "true" indicates we found a value.
  //    Returning false would the set variable value to null.
  //
  // In other words, true means "we found a value AND other 
  // callbacks will run," and false means "we didn't find a value
  // AND abort future callbacks." It's a shame these two meanings
  // are mixed in the same return value.  So as a rule, return
  // true whether we found a value or not.
  return true;
}
 
#---------------------------------------------------
# Step 4: register the custom variables so that it
#         shows up in Special:Version under the 
#         listing of custom variables
#---------------------------------------------------
 
$wgExtensionCredits['variable'][] = array(
       'name' => 'NiftyVar',
       'author' =>'John Doe', 
       'url' => 'http://www.mediawiki.org/wiki/Extension:NiftyVar', 
       'description' => 'This variable is an example and performs no discernable function'
       );
 
#---------------------------------------------------
# Step 5: register wiki markup words associated with
#         MAG_NIFTYVAR as a variable and not some 
#         other type of magic word
#---------------------------------------------------
 
$wgHooks['MagicWordwgVariableIDs'][] = 'wfMyDeclareVarIds';
function wfMyDeclareVarIds(&$aCustomVariableIds) {
 
  #aCustomVariableIds is where MediaWiki wants to store its
  #list of custom variable ids. We oblige by adding ours:
  $aCustomVariableIds[] = MAG_NIFTYVAR;
 
  #must do this or you will silence every MagicWordwgVariableIds
  #registered after this!
  return true;
}