UNIT_SPELLCAST_START behavior?

Guides UI and Macro
1

Got a problem that may be a bug. But I’ve been burned enough to know that bugs often turn out to be my own error. So, here goes.

I have an addon that uses UNIT_SPELLCAST_START to notify a player when a mob begins a cast. If the spell is interruptible the addon displays a notification to the screen so the player can interrupt the mob. This works fine … sort of.

Curiously, when I test the addon against the rogue wizards (at the Stone Cairn lake in Elwynn Forest) the UNIT_SPELLCAST_START event fires twice! When I test it against other caster mobs (e.g., the geomancers near the Jasperlode mine) the event fires only once … as expected.

Any thoughts?

2

Which game version? In retail you get the event re-occuring because they chain cast their spell.

If not that, is the duplicate comming from the same unit?

3

Thanks, Fizz. The version is retail and I took care to eliminate any other casters in the vicinity. I’ve tested this against other casters and the addon works as I would expect.

Cheers,

4

My test (below ), single frame, single event, simple print, shows they appear to be working as intended so it’s a bit hard to try and diagnose without any code.

local f = CreateFrame("Frame")
f:RegisterEvent("UNIT_SPELLCAST_START")
f:SetScript("OnEvent", function(self, event, ...)
	local unit, spellGUID, spellID = ...
	print("|cffffff00frame|r", self, "\n|cffffff00unit|r", unit, "\n|cffffff00unitGUID|r", spellGUID, "\n|cffffff00unitspellID|r", spellID)
end)
5

Here’s my code that exhibits the behavior described above:

if event == "UNIT_SPELLCAST_START" then
        local casterId = arg1      
        local targetId = nil
        local playerName = UnitName("Player")
        local targetName = nil

        if casterId ~= nil then
            targetId = casterId .. "target"
            casterName = UnitName( casterId )
            targetName = UnitName( targetId )
            if targetName == playerName then
                targetName = "you!"
            end
        end

        local interruptible = false
        local spellName, _, _, _, _, _, _, notInterruptible, spellId = UnitCastingInfo( casterId )
        if interruptible then
            local s = nil
            if targetName == nil then
                s = sprintf("%s, %s\n", casterName, spellName )
            else        
                s = sprintf("%s, %s, %s\n", casterName, spellName, targetName )
            end
            UIErrorsFrame:AddMessage(s, 1.0, 1.0, 0.0, 1, 10 )
        end
        return
    end

FYI, the event (UNIT_SPELLCAST_START) only fires twice when caster is a rogue wizard at stone cairn lake. There is another rogue wizard in a camp near the Jasperlode mine that, when casting, only triggers the event once - as it should.

Cheers,

6

It looks to me like you might have an easier time of it parsing the Combat Log Event Unfiltered (called the CLEU).

https://wowpedia.fandom.com/wiki/COMBAT_LOG_EVENT

That carries a payload that has much of what you’re looking for in it - should simplify the code a bit and make it easier to find the problem.

7

I’m wondering if this code is what’s actually triggering whatever you’re seeing:

local interruptible = false
local spellName, _, _, _, _, _, _, notInterruptible, spellId = UnitCastingInfo( casterId )
if interruptible then
    ...
end

you’re assigning/checking interruptible but using notInterruptible as the return value of UnitCastingInfo() ie. interruptible will always be false!

My testing has been on the island at Stone Cairn.

8

you’re assigning/checking interruptible but using notInterruptible as the return value of UnitCastingInfo() ie. interruptible will always be false!

Good catch. Off to stone cairn to see if it fixes things.

Cheers,

9

The code provided should never report an interruptable spell so I imagine a duplicate would be out of the question. Which leads to the probablility of the problem being elsewhere (in your code or another addon entirely??).

Maybe a test addon still active?

10

Well, I’ve given up for now. Instead, I added a flag that prevents the code from executing the handler twice in the “same” interrupt. I will get back to it, however.

As to other addons, the code is developed and tested with no other addons active.

Thanks and I’m sure I’ll have more issues once I get some other tasks accomplished.