Editing WoW:Identifying buffs using textures (section)

== Iterating buff / debuffs ==
While we could write separate functions for buffs and debuffs, it's easier to write a single ''iterator'' function and pass the desired spell effect type as an argument - effectively cutting down the amount of code required for the whole routine. We can get the buff's texture from [[API UnitBuff|UnitBuff]] and debuffs from [[API UnitDebuff|UnitDebuff]]:
 name, rank, iconTexture, count, duration, timeLeft =  UnitBuff(unit, buffIndex [, castable]);
 name, rank, texture, count, debuffType, duration, timeLeft  =  UnitDebuff(unitID, debuffIndex [, removable]);
The effect's texture is the third return value of both functions, but UnitDebuff has one more return value - which means that we'll need to store all seven return values in order to return them. ''Castable'' and ''removable'' arguments allow us to save iterations of the loop if we're only interested in buffs/debuffs the player can cast/remove, so we should allow access to those from the iterator function. For both functions, index starts at 1 and goes up until the function returns nil -- while a while loop is ideal, we can use an infinite loop, and call break; when nil is encountered to save iterator calls. So far, our inner iterator loop would look something like:
 qFunc, unit, castable, id, match = UnitBuff, "player", 1, nil, "SomeEffectTexture"; --
 while true do
  local name, rank, texture, count, type, duration, timeleft = qFunc(unit, id, castable); -- note UnitDebuff returns; we simply don't care about the names at this point, but we need all seven.
  if not name then
   break; -- There are no more buffs / debuffs, exit infinite loop
  end
  if string.match(texture, match) then
   return name, rank, texture, count, type, duration, timeleft; -- We've found a match
  end
  i = i + 1; -- Go for the next index
 end
This would tell return the proper UnitBuff/UnitDebuff returns if the target is affected by a matching buff/debuff, or nil if it's not. Stopping here is good enough; we can, however, make things even better by allowing you to detect multiple textures with the same texture by using another index argument, and then decrementing it on matching effects until we hit zero, returning the found buff entry. Everything combined, the iterator function is:
 function iterateQueriableEffect(qFunc, unit, matchTexture, id, castable)
  id = id or 1; -- default value, making id optional;
  while true do
   local name, rank, texture, count, type, duration, timeleft = qFunc(unit, id, castable);
   if not name then
    break;
   end
   if string.match(texture, matchTexture) then
    id = id - 1;
    if id == 0 then
     return name, rank, texture, count, type, duration, timeleft;
    end
   end
  end
 end