Editing WoW:Handling events (section)

===Hello World===
The two implementations below are functionally identical: they print "Hello World! Hello PLAYER_ENTERING_WORLD" to the default chat frame when the character zones into the world. Note that the event variable is implicit in the XML OnEvent handler: it is supplied by the OnEvent closure signature.

'''Using XML'''
 <Ui>
 <Frame name="FooAddonFrame">
  <Scripts>
    <OnLoad> self:RegisterEvent("PLAYER_ENTERING_WORLD"); </OnLoad>
    <OnEvent> print("Hello World! Hello " .. event); </OnEvent>
   </Scripts>
 </Frame>
 </Ui>

'''Using Lua'''
 local frame = CreateFrame("FRAME", "FooAddonFrame");
 frame:RegisterEvent("PLAYER_ENTERING_WORLD");
 local function eventHandler(self, event, ...)
  print("Hello World! Hello " .. event);
 end
 frame:SetScript("OnEvent", eventHandler);