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Changing notify to use xpcall with stacktrace on failure #230

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3a66f5c
Changing notify to use xpcall with stacktrace on failure
DasKeifer Jan 25, 2026
aca1b68
Making some fns available for other extensions and adding event/hook …
DasKeifer Feb 3, 2026
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88 changes: 72 additions & 16 deletions scripts/mod_loader/bootstrap/event.lua
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Original file line number Diff line number Diff line change
Expand Up @@ -50,14 +50,25 @@ end

function Subscription:notify(args)
if not self.listenerFn then
error("Subscription is closed")
end

return pcall(function()
return self.listenerFn(unpack2(args))
end)
error("Subscription is closed")
end

local ok, result = xpcall(
function()
return self.listenerFn(unpack2(args))
end,
function(e)
-- Capture and return the stack trace of the xpcall
-- 2 makes it start a frame higher so it doesn't include
-- this error handling fn
return debug.traceback(tostring(e), 2)
end
)

return ok, result
end


--- Unsubscribes this Subscription the next time the event passed in argument
--- is triggered.
function Subscription:openUntil(event)
Expand Down Expand Up @@ -117,6 +128,9 @@ function Event:new(options)
if options[Event.SHORTCIRCUIT] then
self.options[Event.SHORTCIRCUIT] = true
end
if options.eventName then
self.eventName = options.eventName
end
end
end

Expand Down Expand Up @@ -209,19 +223,66 @@ function Event:unsubscribeAll()
end
end

local function isStackOverflowError(err)
function Event.isStackOverflowError(err)
return string.find(err, "C stack overflow")
end

local function buildErrorMessage(headerMessage, subscriptionCaller, dispatchCaller)
function Event.splitTrace(trace)
local firstLine, rest = trace:match("([^\n]+)\n?(.*)")
return firstLine, rest
end

function Event.stripAfterXpcall(trace)
local out = {}
for line in trace:gmatch("[^\n]+") do
if line:find("%[C%]: in function 'xpcall'") then
break
end
out[#out+1] = line
end
return table.concat(out, "\n")
end

function Event.tryExtractFireXxxxHooks(line)
-- captures: fire + anything + Hooks
return line:match("in function '(fire.*Hooks)'")
end

function Event.findFireXxxxHooks(trace)
for line in trace:gmatch("[^\n]+") do
local fn = Event.tryExtractFireXxxxHooks(line)
if fn then
return fn
end
end
return nil
end

function Event.buildErrorMessage(headerMessage, errorOrResult, fireFnName, subscriptionCaller, dispatchCaller)
fireFnName = fireFnName or Event.findFireXxxxHooks(dispatchCaller) or "<unable to determine>"
local firstLine, rest = Event.splitTrace(errorOrResult)
return string.format(
"%s\n- Subscribed at: %s\n- Dispatched at: %s",
"%s%s\n- Event\\Hook: %s\n- Call trace: \n %s\n- Subscribed at: %s\n- Dispatched at: %s",
headerMessage,
firstLine,
fireFnName,
string.gsub(Event.stripAfterXpcall(rest), "\n", "\n "),
string.gsub(subscriptionCaller, "\n", "\n "),
string.gsub(dispatchCaller, "\n", "\n ")
)
end

function Event:handleFailure(errorOrResult, creator, caller)
errorOrResult = errorOrResult or "<unspecified error>"
local message = self.buildErrorMessage("An event callback failed: ", errorOrResult,
self.eventName, creator, caller)
if Event.isStackOverflowError(errorOrResult) then
error(message)
else
LOG(message)
end
end

--- Fires this event, notifying all subscribers and passing all arguments
--- that have been passed to this function to them.
--- Arguments are passed as-is without any cloning or protection, so if you
Expand All @@ -235,13 +296,8 @@ function Event:dispatch(...)
for _, sub in ipairs(snapshot) do
local ok, errorOrResult = sub:notify(args)

if not ok and errorOrResult then
local message = buildErrorMessage("An event callback failed: " .. errorOrResult, sub.creator, caller)
if isStackOverflowError(errorOrResult) then
error(message)
else
LOG(message)
end
if not ok then
self:handleFailure(errorOrResult, sub.creator, caller)
elseif ok then
if errorOrResult and self.options[Event.SHORTCIRCUIT] then
return true
Expand Down
263 changes: 138 additions & 125 deletions scripts/mod_loader/bootstrap/modApi.lua
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -16,132 +16,145 @@ modApi.events = {}
setmetatable(modApi.events, events_mt)

local t = modApi.events
t.onModMetadataDone = Event()
t.onModsMetadataDone = Event()
t.onModInitialized = Event()
t.onModsInitialized = Event()
t.onModLoaded = Event()
t.onModsLoaded = Event()
t.onModsFirstLoaded = Event()
t.onInitialLoadingFinished = Event()
t.onFtldatFinalized = Event()
t.onModContentReset = Event()
t.onTestsuitesCreated = Event()

t.onBoardClassInitialized = Event()
t.onPawnClassInitialized = Event()
t.onGameClassInitialized = Event()

t.onUiRootCreating = Event()
t.onUiRootCreated = Event()
t.onGameWindowResized = Event()
t.onConsoleToggled = Event()
t.onFrameDrawStart = Event()
t.onFrameDrawn = Event()
t.onWindowVisible = Event()

t.onMainMenuEntered = Event()
t.onMainMenuExited = Event()
t.onMainMenuLeaving = Event()
t.onHangarEntered = Event()
t.onHangarExited = Event()
t.onHangarLeaving = Event()
t.onHangarMechsSelected = Event()
t.onHangarMechsCleared = Event()
t.onHangarSquadSelected = Event()
t.onHangarSquadCleared = Event()
t.onGameEntered = Event()
t.onGameExited = Event()
t.onNewGameClicked = Event()
t.onContinueClicked = Event()
t.onSettingsChanged = Event()
t.onSettingsInitialized = Event()
t.onProfileChanged = Event()
t.onProfileCreated = Event()
t.onProfileDeleted = Event()
t.onDifficultyChanged = Event()
t.onLanguageChanged = Event()

t.onHangarUiShown = Event()
t.onHangarUiHidden = Event()
t.onEscapeMenuWindowShown = Event()
t.onEscapeMenuWindowHidden = Event()
t.onSquadSelectionWindowShown = Event()
modApi.eventNames = {
"onModMetadataDone",
"onModsMetadataDone",
"onModInitialized",
"onModsInitialized",
"onModLoaded",
"onModsLoaded",
"onModsFirstLoaded",
"onInitialLoadingFinished",
"onFtldatFinalized",
"onModContentReset",
"onTestsuitesCreated",

"onBoardClassInitialized",
"onPawnClassInitialized",
"onGameClassInitialized",

"onUiRootCreating",
"onUiRootCreated",
"onGameWindowResized",
"onConsoleToggled",
"onFrameDrawStart",
"onFrameDrawn",
"onWindowVisible",

"onMainMenuEntered",
"onMainMenuExited",
"onMainMenuLeaving",
"onHangarEntered",
"onHangarExited",
"onHangarLeaving",
"onHangarMechsSelected",
"onHangarMechsCleared",
"onHangarSquadSelected",
"onHangarSquadCleared",
"onGameEntered",
"onGameExited",
"onNewGameClicked",
"onContinueClicked",
"onSettingsChanged",
"onSettingsInitialized",
"onProfileChanged",
"onProfileCreated",
"onProfileDeleted",
"onDifficultyChanged",
"onLanguageChanged",

"onHangarUiShown",
"onHangarUiHidden",
"onEscapeMenuWindowShown",
"onEscapeMenuWindowHidden",
"onSquadSelectionWindowShown",
-- arguments: newPage, lastPage, wasOpen
t.onSquadSelectionPageChanged = Event()
t.onSquadSelectionWindowHidden = Event()
t.onCustomizeSquadWindowShown = Event()
t.onCustomizeSquadWindowHidden = Event()
t.onPilotSelectionWindowShown = Event()
t.onPilotSelectionWindowHidden = Event()
t.onDifficultySettingsWindowShown = Event()
t.onDifficultySettingsWindowHidden = Event()
t.onMechColorWindowShown = Event()
t.onMechColorWindowHidden = Event()
t.onAchievementsWindowShown = Event()
t.onAchievementsWindowHidden = Event()
t.onOptionsWindowShown = Event()
t.onOptionsWindowHidden = Event()
t.onLanguageSelectionWindowShown = Event()
t.onLanguageSelectionWindowHidden = Event()
t.onHotkeyConfigurationWindowShown = Event()
t.onHotkeyConfigurationWindowHidden = Event()
t.onProfileSelectionWindowShown = Event()
t.onProfileSelectionWindowHidden = Event()
t.onCreateProfileConfirmationWindowShown = Event()
t.onCreateProfileConfirmationWindowHidden = Event()
t.onDeleteProfileConfirmationWindowShown = Event()
t.onDeleteProfileConfirmationWindowHidden = Event()
t.onStatisticsWindowShown = Event()
t.onStatisticsWindowHidden = Event()
t.onNewGameWindowShown = Event()
t.onNewGameWindowHidden = Event()
t.onAbandonTimelineWindowShown = Event()
t.onAbandonTimelineWindowHidden = Event()
t.onStatusTooltipWindowShown = Event()
t.onStatusTooltipWindowHidden = Event()
t.onMapEditorTestEntered = Event()
t.onMapEditorTestExited = Event()
t.onPodWindowShown = Event()
t.onPodWindowHidden = Event()
t.onPerfectIslandWindowShown = Event()
t.onPerfectIslandWindowHidden = Event()
t.onWindowShown = Event()
t.onWindowHidden = Event()

t.onMissionChanged = Event()
t.onMissionDismissed = Event()
t.onIslandLeft = Event()
t.onGameStateChanged = Event()
t.onGameVictory = Event()
t.onSquadEnteredGame = Event()
t.onSquadExitedGame = Event()
t.onTilesetChanged = Event()
t.onFinalIslandHighlighted = Event()
t.onFinalIslandUnhighlighted = Event()
t.onFinalIslandSelected = Event()
t.onFinalIslandDeselected = Event()

t.onDeploymentPhaseStart = Event()
t.onLandingPhaseStart = Event()
t.onDeploymentPhaseEnd = Event()
t.onPawnUnselectedForDeployment = Event()
t.onPawnSelectedForDeployment = Event()
t.onPawnDeployed = Event()
t.onPawnUndeployed = Event()
t.onPawnLanding = Event()
t.onPawnLanded = Event()

t.onBoardAddEffect = Event()
t.onBoardDamageSpace = Event()

t.onShiftToggled = Event()
t.onAltToggled = Event()
t.onCtrlToggled = Event()
t.onKeyPressing = Event({ [Event.SHORTCIRCUIT] = true })
t.onKeyPressed = Event({ [Event.SHORTCIRCUIT] = true })
t.onKeyReleasing = Event({ [Event.SHORTCIRCUIT] = true })
t.onKeyReleased = Event({ [Event.SHORTCIRCUIT] = true })
"onSquadSelectionPageChanged",
"onSquadSelectionWindowHidden",
"onCustomizeSquadWindowShown",
"onCustomizeSquadWindowHidden",
"onPilotSelectionWindowShown",
"onPilotSelectionWindowHidden",
"onDifficultySettingsWindowShown",
"onDifficultySettingsWindowHidden",
"onMechColorWindowShown",
"onMechColorWindowHidden",
"onAchievementsWindowShown",
"onAchievementsWindowHidden",
"onOptionsWindowShown",
"onOptionsWindowHidden",
"onLanguageSelectionWindowShown",
"onLanguageSelectionWindowHidden",
"onHotkeyConfigurationWindowShown",
"onHotkeyConfigurationWindowHidden",
"onProfileSelectionWindowShown",
"onProfileSelectionWindowHidden",
"onCreateProfileConfirmationWindowShown",
"onCreateProfileConfirmationWindowHidden",
"onDeleteProfileConfirmationWindowShown",
"onDeleteProfileConfirmationWindowHidden",
"onStatisticsWindowShown",
"onStatisticsWindowHidden",
"onNewGameWindowShown",
"onNewGameWindowHidden",
"onAbandonTimelineWindowShown",
"onAbandonTimelineWindowHidden",
"onStatusTooltipWindowShown",
"onStatusTooltipWindowHidden",
"onMapEditorTestEntered",
"onMapEditorTestExited",
"onPodWindowShown",
"onPodWindowHidden",
"onPerfectIslandWindowShown",
"onPerfectIslandWindowHidden",
"onWindowShown",
"onWindowHidden",

"onMissionChanged",
"onMissionDismissed",
"onIslandLeft",
"onGameStateChanged",
"onGameVictory",
"onSquadEnteredGame",
"onSquadExitedGame",
"onTilesetChanged",
"onFinalIslandHighlighted",
"onFinalIslandUnhighlighted",
"onFinalIslandSelected",
"onFinalIslandDeselected",

"onDeploymentPhaseStart",
"onLandingPhaseStart",
"onDeploymentPhaseEnd",
"onPawnUnselectedForDeployment",
"onPawnSelectedForDeployment",
"onPawnDeployed",
"onPawnUndeployed",
"onPawnLanding",
"onPawnLanded",

"onBoardAddEffect",
"onBoardDamageSpace",

"onShiftToggled",
"onAltToggled",
"onCtrlToggled",
}

for _, event in ipairs(modApi.eventNames) do
t[event] = Event({ eventName = event })
end

modApi.shortcutEventNames = {
"onKeyPressing",
"onKeyPressed",
"onKeyReleasing",
"onKeyReleased",
}

for _, event in ipairs(modApi.shortcutEventNames) do
t[event] = Event({ eventName = event, [Event.SHORTCIRCUIT] = true })
end

-- //////////////////////////////////////////////////////////////////////////////
-- Hooks
Expand Down