[Ketho]

This time Blizzard wasn't so lazy and properly updated the TOC on the PTRs to 40200 which is less of a hassle
I'm interested in the solutions for forwards compatibility, and I want to share some myself

• Quoting the forwards compatible fix of Omegal:

  -- fix for 4.2 which introduces some new argument
  -- this is a temporary work-around which just drops the new argument for a quick and easy fix that is compatible with 4.2
  if tonumber((select(4, GetBuildInfo()))) >= 40200 then
  	local oldHandler = mod.COMBAT_LOG_EVENT_UNFILTERED
  	function mod:COMBAT_LOG_EVENT_UNFILTERED(timestamp, event, hideCaster, sourceGUID, sourceName, sourceFlags, mysteryArgument, destGUID, destName, destFlags, anotherMysteryArgument, ...)
  		return oldHandler(self, timestamp, event, hideCaster, sourceGUID, sourceName, sourceFlags, destGUID, destName, destFlags, ...)
  	end
  end

• Here is my own (Ace3) fowards compatible fix:

  local toc = select(4, GetBuildInfo())
   
  function MyAddOn:COMBAT_LOG_EVENT_UNFILTERED(event, ...)
      local timestamp, subevent, hideCaster, sourceGUID, sourceName, sourceFlags, sourceRaidFlags, destGUID, destName, destFlags, destRaidFlags
      local spellID, spellName, spellSchool
      local SuffixParam1, SuffixParam2, SuffixParam3, SuffixParam4, SuffixParam5, SuffixParam6, SuffixParam7, SuffixParam8, SuffixParam9
   
      local suffixPos
      if toc >= 40200 then
          timestamp, subevent, hideCaster, sourceGUID, sourceName, sourceFlags, sourceRaidFlags, destGUID, destName, destFlags, destRaidFlags = ...
          suffixPos = 12
      else
          timestamp, subevent, hideCaster, sourceGUID, sourceName, sourceFlags, destGUID, destName, destFlags = ...
          suffixPos = 10
      end
   
      local prefix = strsub(subevent, 1, 5)
      if prefix == "SWING" then
          SuffixParam1, SuffixParam2, SuffixParam3, SuffixParam4, SuffixParam5, SuffixParam6, SuffixParam7, SuffixParam8, SuffixParam9 = select(suffixPos, ...)
      elseif prefix == "SPELL" or prefix == "RANGE" then
          spellID, spellName, spellSchool, SuffixParam1, SuffixParam2, SuffixParam3, SuffixParam4, SuffixParam5, SuffixParam6, SuffixParam7, SuffixParam8, SuffixParam9 = select(suffixPos, ...)
      end
   
      -- do stuff
  end

I've also seen some addons use a "tail call" solution for patch 4.1.0,
but I'm not sure how it would be done now for patch 4.2.0

Edit:
Myself I still don't really understand the mod stuff/solution though, but somehow it looks like a way better solution .. (><)