I can see that similar questions has been asked, however I'm not really that familiar with lua coding.
I'm trying to fix an old World of Warcraft vanilla addon, to run in the Classic client.
The code is as follows:
function FHH_OnLoad()
this:RegisterEvent("PLAYER_ENTERING_WORLD");
this:RegisterEvent("UPDATE_MOUSEOVER_UNIT");
-- Register Slash Commands
SLASH_FHH1 = "/huntershelper";
SLASH_FHH2 = "/hh";
SlashCmdList["FHH"] = function(msg)
FHH_ChatCommandHandler(msg);
end
local version = GetAddOnMetadata("GFW_HuntersHelper", "Version");
GFWUtils.Print("Fizzwidget Hunter's Helper "..version.." initialized!");
end
And it throws the following errors;
Message: Interface\AddOns\GFW_HuntersHelper\HuntersHelper.lua:27: attempt to index global 'this' (a nil value)
Time: Tue Jun 30 09:25:14 2020
Count: 1
Stack: Interface\AddOns\GFW_HuntersHelper\HuntersHelper.lua:27: attempt to index global 'this' (a nil value)
Interface\AddOns\GFW_HuntersHelper\HuntersHelper.lua:27: in function `FHH_OnLoad'
[string "*:OnLoad"]:1: in function <[string "*:OnLoad"]:1>
Locals: (*temporary) = nil
(*temporary) = nil
(*temporary) = nil
(*temporary) = nil
(*temporary) = nil
(*temporary) = "attempt to index global 'this' (a nil value)"
I've tried playing around with the "this" statement but I'm not really sure what to do, and thought I'd see if anyone of you bright people in here would know what's going on
If the addon in question is quite old, then at some point in the past (2010?) the Addon API has moved from global variables to locals.
Frames are defined in XML files, like the one you posted in the comment:
<Frame name="HuntersHelperFrame">
<Scripts>
<OnLoad>FHH_OnLoad();</OnLoad>
<OnEvent>
FHH_OnEvent(event, arg1, arg2, arg3, arg4, arg5, arg6, arg7, arg8, arg9);
</OnEvent>
</Scripts>
</Frame>
The elements in <Scripts> are actually called as functions with their content as function body. They are called with some arguments. You can find out what arguments using World of Warcraft API as a reference. It's not official, but it's the closest thing to reference manual there is.
For now, you are interested in Widget handlers.
Now then, the first steps you should take are:
Change the XML:
<Frame name="HuntersHelperFrame">
<Scripts>
<OnLoad>FHH_OnLoad(self)</OnLoad>
<OnEvent>
FHH_OnEvent(self, event, ...)
</OnEvent>
</Scripts>
</Frame>
Change the lua to reflect that:
function FHH_OnLoad(self)
self:RegisterEvent("PLAYER_ENTERING_WORLD")
-- and so on, change all occurrences of `this` to `self`
-- or simply name the first argument `this` instead of `self`:
-- function FHH_OnLoad(this)
end
-- Change all of the functions:
function FHH_OnEvent(self, event, ...)
-- function body
end
Depending on the size of the addon it might become a big chunk of work. Sadly, that's not the end to it; be wary as the script could rely directly on the presence of global variables and do some tricks.
I guess you could try to work around it with tricks like local this = self and similar, but that might not be applicable in all cases, and may cause some problems due to how framework may parse the XML.
One final note; the API changed a lot over the years and you will most likely run into even more problems. Good luck!
Related
I'm using Sysdig to capture some events and have a small chisel (LUA script) to capture and format the events as necessary. On the on_init() I'm requesting fields like so :
f_field = chisel.request_field("<field>")
My question is how can I check if a field exists before requesting it? I'm going to use a new field only just released on 0.24.1 but ideally I'd like my chisel to continue to work on older versions of sysdig without this field. I've tried wrapping the call to chisel.request_field in a pcall() like so :
ok, f_field = pcall(chisel.request_field("<field>"))
and even implementing my own "get_field" function :
function get_field(field)
ok, f = pcall(chisel.request_field(field))
if ok then return f else return nil end
end
f_field = get_field("<field>")
if f_field ~= nil then
-- do something
end
but the error ("chisel requesting nonexistent field <field>") persists.
I can't see a way to check if a field exists but I can't seem to handle the error either. I really don't want multiple versions of my scripts if possible.
Thanks
Steve H
You're almost there. Your issue is in how you're using pcall. Pcall takes a function value and any arguments you wish to call that function with. In your example you're passing the result of the request_field function call to pcall. Try this instead..
ok, f = pcall(chisel.request_field, "field")
pcall will call the chisel method with your args in a protected mode and catch any subsequent errors.
Actually I am writting a programming language in Lua. It was quite fun. I've wrote a bit of standard library (stack op and simple io). Then I've thought about labels. It would look like in assembly. While and for loop aren't funny in any bit so programming in that language can be quite challenging. Here are some requirements for this system:
Label stack (or array, dictionary) must be accessible from global context.
Jump instruction handler will be in separate file.
This is how my label-handling function look like:
function handleLabel(name,currentLine)
end
I have no idea how to implement this kind of magic. First I've thought about that:
LabelLineIDS = {}
Labels = {}
Labelamount = 1;
function handleLabel(name,currentLine)
LabelLineIDS[Labelamount]=currentline
Labels[Labelamount]=name
Labelamount=Labelamount+1
end
-- In file "jump.lua":
local function has_value (tab, val)
for index, value in ipairs(tab) do
if value == val then
return index
end
end
print ("Error: Label not defined.") -- Bail out.
os.exit(1)
end
local function _onlabel()
local labelName = globalparams --Globalparams variable contain parameters to each function, at the moment
--this will contain label name. It _can_ be nil.
return LabelLineIDS[has_value(Labels, labelName)]
end
CurrLine = _onlabel() --Currline - current line that get's parsed.
--1 command per one line.
But I'm unsure is this well written or even work. Can you give me idea how to parse labels in my programming language (and write jump functions)? Or if my code is pretty ok at the moment, can you help me to improve it?
Using line counter in my parser I've decided to implement gotos like we can see in BASIC. Thanks everyone for help.
I'm trying to create an addon for World of Warcraft. I have created a function that checks whether a buff has been added to the current player.
Button:RegisterEvent("UNIT_AURA");
local function auraGained(self, event, ...)
if (UnitAura("player", "Heating Up")) then
if (heatingUpIsActive ~= 1) then
heatingUpIsActive = heatingUpIsActive + 1
print (heatingUpIsActive)
end
end
Button:SetScript("OnEvent", auraGained);
This works great, but how do I check if UnitAura is not "Heating Up"?
Also, I would prefer if heatingUpIsActive were a boolean, but it seems to not like when I do that. What is the correct way to create a boolean in Lua?
Your function isn't checking the aura that caused the event. It's looking for "Heating Up" any time any UNIT_AURA event comes by. In fact, it looks like the UNIT_AURA event doesn't actually tell you which aura triggered it. So you can't "check if UnitAura is not "Heating Up"", because you simply don't know what aura caused the event. Perhaps it was even several auras at once.
However, the event does tell you what unit got the aura. It's the first vararg. You should probably check to make sure it's player before doing something
local unitid = ...
if unitid ~= "player" then return end
Also, you didn't explain what problems you had with booleans. You should just be able to say something like
if not heatingUpIsActive then
heatingUpIsActive = true
-- do whatever you want
end
although I never saw any declaration of the variable in your code. It's a bad idea to use globals for things like this, so you should declare
local heatingUpIsActive
before the function declaration, e.g.
local heatingUpIsActive
local function auraGained(self, event, ...)
-- ...
I have a WoW/LUA script that I am attempting to start, but it seems to conflict with the Stubby addon, which is a part of the Auctioneer addon, I believe. Here is the message I receive:
Error occured in: Stubby Count: 1 Message: Error: Original call failed
after running hooks for: ChatFrame_OnEvent Usage:
SendChatMessage(text [,type] [,language] [,targetPlayer]) Debug:
(tail call): ? [string ":OnEvent"]:1:
[string ":OnEvent"]:1
Now, the only thing that's happening in the conflicting addon is:
ChatFrame_AddMessageEventFilter("CHAT_MSG_PARTY", partyMsg)
The code within partyMsg is very simple as well:
local function partyMsg(msg,author,language,lineID,senderGUID)
if (store ~= msg) then
SendChatMessage(msg,"SAY",nil,nil);
end
store = msg;
end
Is this error due to two addons both trying to filter the chat frame? If so, how can this be done? It seems odd to me that Blizzard would have such a simple and yet important concept limited to one addon.
I think I see what happened here.
The reference you were using, Events/Communication, shows only the specific parameters for a particular event, regardless of context.
The context is usually an OnEvent handler.
The ChatFrame_AddMessageEventFilter function lets you use the chat frame's OnEvent handler instead of your own for chat frame events, and has well defined parameters for filters you add.
An OnEvent handler might look like:
function Foo_OnEvent(self, event, ...)
A 'ChatFrame' filter must look like this, for the first two parameters:
function Foo_ChatFrameFilter(self, event, msg, ...)
The ChatFrame filter is specific. For OnEvent however, you can make a Lua 'handler' that doesnt care about what frame it came from:
<OnEvent>
MyEventHandler(event, ...)
</OnEvent>
For the sake of completion, I will include the entire source of this addon:
local function partyMsg(someTable,msgType,msg,user,language,...)
if (store ~= msg) then
SendChatMessage(user .. " just said: ".. msg .. " using that sneaky " .. language .. " language.");
end
store = msg;
return false;
end
ChatFrame_AddMessageEventFilter("CHAT_MSG_PARTY", partyMsg)
ChatFrame_AddMessageEventFilter("CHAT_MSG_PARTY_LEADER",partyMsg)
There were a couple issues with the original code:
1) I was using WoWWiki to get my information, and first, I read it incorrectly. lineID and senderGUID are not the 4th and 5th arguments. Then, beyond this, WoWWiki is incorrect on this page in general. The correct arguments are listed above in the source. The first argument, a table, I am unsure of its purpose. In any case, this code now works fully.
For example, I have a table
table.insert( t, 1, function()
print ("rock");
end );
Is there any way to get function name from this table. I know that I can store name like a key, but what if I want to keep numeric index and also I want to know function name?
Is there any way to do it?
Thanks, on advance.
Say you have this code:
t = {}
x = 5
table.insert(t, 1, x)
t would then be {[1] = 5}. "5" is just a number - it has no name, and isn't associated with the variable "x"; it's a value.
In Lua, functions are treated exactly the same way, as values:
t = {}
x = function() print("test! :D") end
table.insert(t, 1, x)
The value of x is not associated with x in any way, shape, or form. If you want to manually name a function, you can do it by wrapping the function in a table, for example:
t = {}
x = function() print("test! :D") end
table.insert(t, 1, {
name = "MyFunctionName",
func = x
})
That is how you would do it!
...unless..
..you break the rules!
When Lua was developed, the developers realised that the anonymous nature of functions would make productive error messages difficult to produce, if not impossible.
The best thing you'd see would be:
stdin: some error!
stdin: in function 'unknown'
stdin: in function 'unknown'
So, they made it so that when Lua code was parsed, it would record some debug information, to make life easier. To access this information from Lua itself, the debug library is provided.
Be very careful with functions in this library.
You should exert care when using this library. The functions provided here should be used exclusively for debugging and similar tasks, such as profiling. Please resist the temptation to use them as a usual programming tool: they can be very slow. Moreover, several of these functions violate some assumptions about Lua code (e.g., that variables local to a function cannot be accessed from outside or that userdata metatables cannot be changed by Lua code) and therefore can compromise otherwise secure code.
To achieve your desired effect, you must use the debug.getinfo function; an example:
x = function()
print("test!")
print(debug.getinfo(1, "n").name)
end
x() -- prints "test!" followed by "x"
Unfortunately, the form of debug.getinfo that operates directly on a function doesn't fill the name argument (debug.getinfo(x, "n").name == nil) and the version above requires you to run the function.
It seems hopeless!
...unless..
..you really break the rules.
The debug.sethook function allows you to interrupt running Lua code at certain events, and even change things while it's all happening. This, combined with coroutines, allows you to do some interestingly hacky stuff.
Here is an implementation of debug.getfuncname:
function debug.getfuncname(f)
--[[If name found, returns
name source line
If name not found, returns
nil source line
If error, returns
nil nil error
]]
if type(f) == "function" then
local info = debug.getinfo(f, "S")
if not info or not info.what then
return nil, nil, "Invalid function"
elseif info.what == "C" then
-- cannot be called on C functions, as they would execute!
return nil, nil, "C function"
end
--[[Deep magic, look away!]]
local co = coroutine.create(f)
local name, source, linedefined
debug.sethook(co, function(event, line)
local info = debug.getinfo(2, "Sn")
name = info.namewhat ~= "" and info.name or nil
source, linedefined = info.short_src, info.linedefined
coroutine.yield() -- prevent function from executing code
end, "c")
coroutine.resume(co)
return name, source, linedefined
end
return nil, nil, "Not a function"
end
Example usage:
function test()
print("If this prints, stuff went really wrong!")
end
print("Name = ", debug.getfuncname(test))
This function isn't very reliable - it works sometimes, and doesn't others. The debug library is very touchy, so it's to be expected.
Note that you should never use this for actual release code! Only for debugging!
The most extreme case that is still acceptable is logging errors on piece of released software, to help the developer fix issues. No vital code should depend on functions from the debug library.
Good luck!
The function hasn't got any name. If you want you can assign it to a named variable:
theFunction = t[1]
-- Call it:
theFunction()
If what you want is storing a named function to the table, define it beforehand and use its name to store it:
theFunction = function()
print ("rock");
end
table.insert(t, 1, theFunction)
If this is not what you meant, give more details; for example how you would like to access the function. You're question is a bit misty.
The thing is table.insert considers the table as a sequence, only with numeric keys.
If you want to be able to call the function as t.fun() you'll have to use the table as an associative array and hence use a string as key. (BTW any type except nil or NaN are allowed as key)
t={}
t['MyFun']=function print'foo' end
t.myFun() -- uses syntactic sugar for string keys that are valid identifiers.
You might also notice that functions are passed by reference. So all functions are actually anonymous, and are just stored as a value to a certain key or variable.
You can store the names in a separate table.
functions = {}
functionNames = {}
function addFunction(f, name)
table.insert(functions, f)
functionNames[name] = f
end
To get the function, you can use the index. Once you have the function, you can get its name from function_names:
f = functions[3]
name = functionNames[f]
Good luck!