I personally don't know how a built in function can be indexed as "nil" butthis error appeared and it haulted my nextbot's movement. heres my code that is causing this
if (!self:GetPlayerVisible() and chasing_timer > chasing_time) then
self.stopchasing = true
self.enraged = false
print("Chase stopped")
print("Increasing escaped chases count, new:", self.escapedchases)
self.escapedchases = self.escapedchases + 1
end
I tried replacing the "!" with "not" but it did nothing.
I don't know what self is but that table does not contain an element GetPlayerVisible. Hece you may not call it. Calling nil values doesn't make sense.
Ask yourself why you think this function exists. Typical reasons are typos, indexing the wrong table or not having implemented a function yet.
To avoid this error you basically have two options. Make sure you call something that exists, or don't call it.
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.
I have a Lua function where I build a table of value and attempt to add it to a global table with a named key.
The key name is pulled from the function arguments. Basically, it's a filename, and I'm pairing it up with data about the file.
Unfortunately, the global table always comes back nil. Here's my code: (let me know if you need to see more)
(Commented parts are other attempts, although many attempts have been deleted already)
Animator = Class{}
function Animator:init(atlasfile, stringatlasfriendlyname, totalanimationstates, numberofframesperstate, booleanstatictilesize)
-- Define the Animator's operation mode. Either static tile size or variable.
if booleanstatictilesize ~= false then
self.isTileSizeStatic = true
else
self.isTileSizeStatic = false
end
-- Define the total animation states (walking left, walking right, up down, etc.)
-- And then the total frames per state.
self.numAnimationStates = totalanimationstates or 1
self.numAnimationFrames = numberofframesperstate or 2
-- Assign the actual atlas file and give it a programmer-friendly name.
self.atlasname = stringatlasfriendlyname or removeFileExtension(atlasfile, 'animation')
generateAnimationQuads(atlasfile, self.atlasname, self.numAnimationStates, self.numAnimationFrames)
end
function generateAnimationQuads(atlasfile, atlasfriendlyname, states, frames)
spriteWidthDivider = atlasfile:getWidth() / frames
spriteHeightDivider = atlasfile:getHeight() / states
animationQuadArray = generateQuads(atlasfile, spriteWidthDivider, spriteHeightDivider)
animationSetValues = {atlasarray = animationQuadArray, width = spriteWidthDivider, height = spriteHeightDivider}
--gAnimationSets[#gAnimationSets+1] = atlasfriendlyname
gAnimationSets[atlasfriendlyname] = animationSetValues
--table.insert(gAnimationSets, atlasfriendlyname)
end
Note: when using print(atlasfriendlyname) and print(animationSetValues), neither are empty or nil. They both contain values.
For some reason, the line(s) that assign the key pair to gAnimationSets does not work.
gAnimationSets is defined a single time at the top of the program in main.lua, using
gAnimationSets = {}
Animator class is called during the init() function of a character class called Bug. And the Bug class is initialized in the init() function of StartState, which extends from BaseState, which simply defines dummy init(), enter(), update() etc. functions.
StartState is invoked in main.lua using the StateMachine class, where it is passed into StateMachine as a value of a global table declared in main.lua.
gAnimationSets is declared after the table of states and before invoking the state.
This is using the Love2D engine.
Sorry that I came here for help, I've been picking away at this for hours.
Edit: more testing.
Trying to print the animationQuadArray at the index gTextures['buganimation'] always returns nil. Huh?
Here's gTextures in Main.lua
gTextures = {
['background'] = love.graphics.newImage('graphics/background.png'),
['main'] = love.graphics.newImage('graphics/breakout.png'),
['arrows'] = love.graphics.newImage('graphics/arrows.png'),
['hearts'] = love.graphics.newImage('graphics/hearts.png'),
['particle'] = love.graphics.newImage('graphics/particle.png'),
['buganimation'] = love.graphics.newImage('graphics/buganimation.png')
}
Attempting to return gTextures['buganimation'] returns a file value as normal. It's not empty.
My brain is so fried right now I can't even remember why I came to edit this. I can't remember.
Global table in Main.lua, all other functions can't access it.
print(gTextures['buganimation']) works inside the function in question. So gTextures is absolutely accessible.
Table isn't empty. AnimationSetValues is not empty.
I'm adding second answer because both are correct in context.
I ended up switching IDE's to VS Code and now the original one works.
I was originally using Eclipse LDT with a Love2D interpreter and in that environment, my original answer is correct, but in VS Code, the original is also correct.
So Dimitry was right, they are equivalent, but something about my actual Eclipse setup was not allowing that syntax to work.
I switched to VS Code after I had another strange syntax problem with the interpreter where goto syntax was not recognized and gave a persistent error. The interpreter thought goto was the name of a variable.
So I switched, and now both things are fixed. I guess I just won't use LDT for now.
Solution: Lua syntax. Brain Fry Syndrome
I wrote:
animationSetValues = {atlasarray = animationQuadArray, width = spriteWidthDivider, height = spriteHeightDivider}
Should be:
animationSetValues = {['atlasfile']=atlasfile, ['atlasarray']=animationQuadArray, ['width']=spriteWidthDivider, ['height']=spriteHeightDivider}
Edit: I'm fully aware of how to use answers. This was posted here to reserve my spot for an answer so I could edit it later when I returned back home, which is exactly what I'm doing right now. I'll keep the old post for archival purposes.
Original:
I solved it. I apologize for not posting the solution right now. My brain is melted into gravy.
I will post it tomorrow. Just wanted to "answer" saying no need to help. Solved it.
Solution is basically, "oh it's just one of those Lua things". Wonderful. I'm having so much fun with this language - you can tell by my blank expression.
From the language without line endings or brackets, but forced print parentheses... ugh. I'm going back to C# when this class is done.
I'm trying to make a gmod gamemode. In my init.lua I wanted it so that way team members can't hurt each other. So I used this code
function GM:EntityTakeDamage( target, dmginfo )
if ( target:IsPlayer() and dmginfo:IsPlayer() ) then
if (dmginfo:Team() == target:Team()) then
dmginfo:ScaleDamage( 0.0 ) // Sets damage to 0
end
end
end
However it's giving me the error telling me that IsPlayer() is a nil value even though it should be returning a boolean. It points to no other lines other then the line with IsPlayer() and it's saying it is IsPlayer()
you have a typo in line 3. dminfo
You should narrow down which of your multiple IsPlayer() calls actually is nil
dmgInfo is a CTakeDamageInfo which has no function IsPlayer()
single line Lua comments are opened with --, not //
https://wiki.garrysmod.com/page/Category:CTakeDamageInfo
If you call a function and it says its nil, then check if it even exists. Or even better, check this befor you use the function in the first place.
And to prevent you from coming back in a minute, CTtakeDamageInfo also does not have a function Team() as well.
Check out CTDamageInfo:GetAttacker()
I'm trying to get a handle on how OOP is done in Lua, and I thought I had a simple way to do it but it isn't working and I'm just not seeing the reason. Here's what I'm trying:
Person = { };
function Person:newPerson(inName)
print(inName);
p = { };
p.myName = inName;
function p:sayHello()
print ("Hello, my name is " .. self.myName);
end
return p;
end
Frank = Person.newPerson("Frank");
Frank:sayHello();
FYI, I'm working with the Corona SDK, although I am assuming that doesn't make a difference (except that's where print() comes from I believe). In any case, the part that's killing me is that inName is nil as reported by print(inName)... therefore, myName is obviously set to nil so calls to sayHello() fail (although they work fine if I hardcode a value for myName, which leads me to think the basic structure I'm trying is sound, but I've got to be missing something simple). It looks, as far as I can tell, like the value of inName is not being set when newPerson() is called, but I can't for the life of me figure out why; I don't see why it's not just like any other function call.
Any help would be appreciated. Thanks!
Remember that this:
function Person:newPerson(inName)
Is equivalent to this:
function Person.newPerson(self, inName)
Therefore, when you do this:
Person.newPerson("Frank");
You are passing one parameter to a function that expects two. You probably don't want newPerson to be created with :.
Try
Frank = Person:newPerson("Frank");