问如何捕捉瞬间或施放咒语的事件？

EN

local myFrame = CreateFrame("Frame");
local myCurrentCast;
myFrame:RegisterEvent("UNIT_SPELLCAST_SENT");
myFrame:RegisterEvent("UNIT_SPELLCAST_SUCCEEDED");
myFrame:SetScript("OnEvent",
    function(self, event, arg1, arg2, arg3, arg4)
        if (event == "UNIT_SPELLCAST_SENT" and arg1 == "player") then
            print("I am casting something");
            myCurrentCast = arg3;
        elseif (event == "UNIT_SPELLCAST_SUCCEEDED" and arg2 == myCurrentCast) then
            if (arg3 == 196670) then
                print("I just finished casting Chaos Bolt!");
            elseif (arg3 == 589) then
                print("Look at my instant Shadow Word: Pain.  Isn't it cool?");
            end
        end
    end
);