I got an EPS8226 on which I uploaded a main.lua file and some other configs. When I run main.lua with dofile() in the terminal, the print from the callback function prints only "sensorId" without "sent 0". Yet, if I run main.lua again, or I print() something before (either inside the function() that calls the callback, or inside the callback itself) it will print properly "sensorId sent 0". This also works if I do not use the local variable.
function registerReaders()
for key, value in pairs(sensorConfig.data)
do
gpio.mode(value.pin, gpio.INPUT)
value.timer:alarm(value.polling, tmr.ALARM_AUTO, function() callbacks.sendData(sensorConfig.sensorId[key]) end)
tmr.create():alarm(1000, tmr.ALARM_SINGLE, function() callbacks.sendData(sensorConfig.sensorId[key]) end)
end
end
Printing "[sensorId_value]"
callbacks.sendData = function(sensorId)
local data = 1
print(sensorId .. " sent " .. data)
end
Printing properly ("OK" then "[sensorId_value] sent 0")
callbacks.sendData = function(sensorId)
local data = 1
print("OK")
print(sensorId .. " sent " .. data)
end
Printing properly ("[sensorId_value] sent 1")
callbacks.sendData = function(sensorId)
print(sensorId .. " sent 0")
end
In all examples sensorId is a variable, not a string, so unless sensorId = "sensorId" none of them should be printing "sensorId sent 0".
In the first example (all of them, actually) " sent " is a literal, it should output regardless of the value of data.
Shouldn't the second example print "[...] sent 1"?
Try using a variable name other than data, maybe there's some forward value confusion.
Related
I'm very confused. I'm trying to make it so that if you hold E with Roblox's "ProximityPrompt", you will get a GUI on your screen with some text. Everything works except that the text won't work. I also am not writing a string on the client script. There is a variable for it on the server script that gets passed over. But I keep seeing this error in the output.
Players.ford200000.PlayerGui.BuyGui.Frame.TextInput.Text:2: attempt to concatenate nil with string - Client -
Here is what I'm doing in my script
local sp = script.Parent
sp.ProximityPrompt.Triggered:Connect(function(player)
local name = sp.Name
local ss = game.ServerStorage
local item = ss.Hats:FindFirstChild(name)
local price = item.Price
game.ReplicatedStorage.ShopClickEvent:FireClient(player)
game.ReplicatedStorage.ShopInfoEvent:FireClient(player)
end)
And in the local script that listens for ShopInfoEvent
game.ReplicatedStorage.ShopInfoEvent.OnClientEvent:Connect(function(player, price, item)
script.Parent.Text = "Would you like to buy this ".. item.Name .." for ".. price.Value .."?"
end)
Please help, that would be greatly appreciated.
Your error is telling you that the object you are trying to add to a string is undefined.
This could be item.Name or price.Value is undefined and causing this string construction to fail.
Looking at how you are defining item and price shows that both of these values are undefined in your LocalScript's callback. When you call a RemoteEvent's FireClient function, the first argument tells the engine who to send the event to, and all the other arguments get passed in as the arguments of the callback. Currently, you aren't passing in any arguments at all.
So to fix your problem, you need to pass in the right arguments from the Script:
game.ReplicatedStorage.ShopInfoEvent:FireClient(player, price, item)
and parse them properly in your LocalScript :
game.ReplicatedStorage.ShopInfoEvent.OnClientEvent:Connect(function(price, item)
script.Parent.Text = "Would you like to buy this ".. item.Name .." for ".. tostring(price.Value) .."?"
end)
Players.ford200000.PlayerGui.BuyGui.Frame.TextInput.Text:2: attempt to
concatenate nil with string - Client -
tells you everything you need to know.
You're trying to concatenate nil with string. That means you're using the string concatenation operator .. with a nil operand in line 2
So let's look into line 2
script.Parent.Text = "Would you like to buy this ".. item.Name .." for ".. tostring(price.Value) .."?"
"Would you like to buy this ", " for " and "?" are obviously strings. That leaves us with item.Name and tostring(price.Value).
If price.Value were nil, tostring would turn it into "nil". So this cannot be the cause of this particular error message.
That leaves us with item.Name. If item were nil we would see an error for indexing a nil value instead. So that tells us that whatever item is, it is not what we expected to be. A table with an element for key "Name".
At this moment you know that something is wrong with the parameters of your function. So you (hopefully again) refer to the manual and compare that with the way you use those event functions.
I'm trying to get a bit tricky logging, but can't get why ... processing only 1st parameter in a function called
I have this function
local logger = function (name, ...)
-- Expected table processing here, but no.
print("[" .. name .. "] log called with " .. ...)
end
return setmetatable({}, {__index = function(self, name)
local log = function(...)
return logger(name, ...)
end
self[name] = log
return log
end})
And how it's called
local testf = require "test_log"["TestA"]
testf("TestB", "TestC")
testf("TestC", "TestB")
But getting back this result
[TestA] log called with TestB
[TestA] log called with TestC
The problem I can't get 2nd (and further) parameters from testf function and can't get why.
Thanks in advance!
Your code uses only first parameter
local s = ''
for i=1,select('#',...) do s = s .. select(i, ...) end
print("[" .. name .. "] log called with " .. s)
Also, you can use s = table.concat({...}), but it will produce different results in cases where vararg contains nil values
You can't concatenate ... because it's not a value. Instead, Lua just takes the first value of the list.
If you want to concatenate more than one value, use table.concat first:
local concatenated = table.concat({...})
You could also do something like this instead if you're feeling particularly smart today:
local logger = function (...)
print(string.format("[%s] log called with"..string.rep(" %s", select("#")), ...))
end
Currently, I'm working on a simple Lua Roblox script that is supposed to turn the parent part blue when "/blue" is entered in the chat by ANY player. When run, it returns the error "attempt to index global 'message' (a nil value)" in the output. Also, when I hover my cursor over "message" it says "unknown global 'message'". I am sure I'm doing something terribly wrong as I am new to the language. I have tried moving the script into Workspace and Chat (of course changing local part when I do) but those don't help. I'm confident it's a code issue specifically defining a global variable.
local part = script.Parent
local function scan()
if message:sub(1,5) == "/blue" then
part.BrickColor = BrickColor.Blue()
end
end
scan()
First, you didn't define "message" because "message" is supposed to be an argument of
player.Chatted()
So instead of just running scan(), make multiple functions, here is the revised code:
local part = script.Parent
game.Players.PlayerAdded:Connect(function(plr)
plr.Chatted:Connect(function(message)
message = string.lower(message)
if message == "/blue" then
part.BrickColor = BrickColor.new("Blue")
end
end)
end)
Let me know if you need me to elaborate, I understand that sometimes this stuff can be confusing.
I have an small web server running on my ESP-12 with nodemcu firmware:
sv=net.createServer(net.TCP,10)
sv:listen(80,function(c)
c:on("receive", function(c, pl)
if(string.find(pl,"GET / ")) then
print("Asking for index")
c:send("Line 1")
c:send("Line 2")
c:send("Line 3")
c:close()
end
end)
c:on("sent",function(conn)
print("sended something...")
end)
end)
It seems my connection is getting closed after the first send, in my browser I only see the "line 1" text, line 2 a 3 does not appear, and in my serial console im just seeing the "sended something" text one time, even commenting the close statement and letting the connection to timeout does not change the behavior. What am I missing here?
I don't think that you can use send multiple times. Whenever I use one of my ESP8266 as a server I use a buffer variable :
sv=net.createServer(net.TCP,10)
-- 'c' -> connection, 'pl' -> payload
sv:listen(80,function(c)
c:on("receive", function(c, pl)
if(string.find(pl,"GET / ")) then
print("Asking for index")
local buffer = ""
buffer = buffer.."Line 1"
buffer = buffer.."Line 2"
buffer = buffer.."Line 3"
c:send(buffer)
c:close()
end
end)
c:on("sent",function(c)
print("sended something...")
end)
end)
EDIT: After reading the docs again, send can take another argument with a callback function, it can maybe be used to have multiple send command. Never tried it though :(.
EDIT 2: If you have a really long string to send, it's better to use table.concat
The net.socket:send() documentation provides a nice example which I repeat here.
srv = net.createServer(net.TCP)
function receiver(sck, data)
local response = {}
-- if you're sending back HTML over HTTP you'll want something like this instead
-- local response = {"HTTP/1.0 200 OK\r\nServer: NodeMCU on ESP8266\r\nContent-Type: text/html\r\n\r\n"}
response[#response + 1] = "lots of data"
response[#response + 1] = "even more data"
response[#response + 1] = "e.g. content read from a file"
-- sends and removes the first element from the 'response' table
local function send(localSocket)
if #response > 0 then
localSocket:send(table.remove(response, 1))
else
localSocket:close()
response = nil
end
end
-- triggers the send() function again once the first chunk of data was sent
sck:on("sent", send)
send(sck)
end
srv:listen(80, function(conn)
conn:on("receive", receiver)
end)
When call a lua function like
PrintMe(MyVariableName)
I would like to be able to actually print "MyVariableName" and not it's value(well, for demo purposes).
Obviously I could just pass the string but that requires extra quotes and I also would like to print it's value.
e.g.,
MyVariable = 4
PrintVariable(MyVariable)
Would print "MyVariable is 4" or whatever
I do not want to have to duplicate the name and variable like
PrintVariable(MyVariable, "MyVariable")
as this is unnecessary duplication.
Can lua handle it?
What I'm doing now is passing the variable name in quotes and using loadstring to get the value but I would like to just pass the variable directly without the extra unnecessary quotes(which I thought debug.getlocal did but it ends up returning the value instead of the name).
Here is mock example
function printme1(var, val)
print(var.." = "..val)
end
function printme2(v)
local r
loadstring("r = "..v)() -- equivalent to r = a but must be used since v is a string representing a and not the object a
print(v.." = "..tostring(r))
end
function printme3(v)
-- unknown
end
a = 3
printme1("a", a)
printme2("a")
printme3(a)
In this case all 3 should print the same thing. printme3 obviously is the most convenient.
You can't say PrintVariable(MyVariable), because Lua gives you no way of determining which variable (if any; a constant could have been used) was used to pass an argument to your function. However, you can say PrintVariable('MyVariable') then used the debug API to look for a local variable in the caller's scope which has that name:
function PrintVariable(name)
-- default to showing the global with that name, if any
local value = _G[name]
-- see if we can find a local in the caller's scope with that name
for i=1,math.huge do
local localname, localvalue = debug.getlocal(2,i,1)
if not localname then
break -- no more locals to check
elseif localname == name then
value = localvalue
end
end
if value then
print(string.format("%s = %s", name, tostring(value)))
else
print(string.format("No variable named '%s' found.", name))
end
end
Now you can say:
PrintVariable('MyVariable')
While in this case will print "MyVariable = 4".
Not, if you really want to do this without the quotes, you could check the caller's locals for variables that have a supplied value, but that's occasionally going to give you the wrong variable name if there is more than one variable in the caller's scope with a given value. With that said, here's how you'd do that:
function PrintVariable(value)
local name
-- see if we can find a local in the caller's scope with the given value
for i=1,math.huge do
local localname, localvalue = debug.getlocal(2,i,1)
if not localname then
break
elseif localvalue == value then
name = localname
end
end
-- if we couldn't find a local, check globals
if not name then
for globalname, globalvalue in pairs(_G) do
if globalvalue == value then
name = globalname
end
end
end
if name then
print(string.format("%s = %s", name, tostring(value)))
else
print(string.format("No variable found for the value '%s'.", tostring(value)))
end
end
Now you can say PrintVariable(MyVariable), but if there happened to be another variable in the caller's scope with the value 4, and it occurred before MyVariable, it's that variable name that will be printed.
you can do stuff like this with the debug library... something like this does what you seem to be looking for:
function a_func(arg1, asdf)
-- if this function doesn't use an argument... it shows up as (*temporary) in
-- calls to debug.getlocal() because they aren't used...
if arg1 == "10" then end
if asdf == 99 then end
-- does stuff with arg1 and asdf?
end
-- just a function to dump variables in a user-readable format
function myUnpack(tbl)
if type(tbl) ~= "table" then
return ""
end
local ret = ""
for k,v in pairs(tbl) do
if tostring(v) ~= "" then
ret = ret.. tostring(k).. "=".. tostring(v).. ", "
end
end
return string.gsub(ret, ", $", "")
end
function hook()
-- passing 2 to to debug.getinfo means 'give me info on the function that spawned
-- this call to this function'. level 1 is the C function that called the hook.
local info = debug.getinfo(2)
if info ~= nil and info.what == "Lua" then
local i, variables = 1, {""}
-- now run through all the local variables at this level of the lua stack
while true do
local name, value = debug.getlocal(2, i)
if name == nil then
break
end
-- this just skips unused variables
if name ~= "(*temporary)" then
variables[tostring(name)] = value
end
i = i + 1
end
-- this is what dumps info about a function thats been called
print((info.name or "unknown").. "(".. myUnpack(variables).. ")")
end
end
-- tell the debug library to call lua function 'hook 'every time a function call
-- is made...
debug.sethook(hook, "c")
-- call a function to try it out...
a_func("some string", 2012)
this results in the output:
a_func(asdf=2012, arg1=some string)
you can do fancier stuff to pretty this up, but this basically covers how to do what you're asking.
I have bad news, my friend. You can access function parameter names as they appear at the top of the function, but the data to access exactly what they were named in the calling function does not exist. See the following:
function PrintVariable(VariableToPrint)
--we can use debug.getinfo() to determine the name 'VariableToPrint'
--we cannot determine the name 'MyVariable' without some really convoluted stuff (see comment by VBRonPaulFan on his own answer)
print(VariableToPrint);
end
MyVariable = 4
PrintVariable(MyVariable)
To illustrate this, imagine if we had done:
x = 4
MyVariable = x
MyOtherVariable = x
x = nil
PrintVariable(MyVariable)
Now if you were Lua, what name would you attach in the metadata to the variable that ends up getting passed to the function? Yes, you could walk up the stack with debug.getint() looking for the variable that was passed in, but you may find several references.
Also consider:
PrintVariable("StringLiteral")
What would you call that variable? It has a value but no name.
You could just use this form:
local parms = { "MyVariable" }
local function PrintVariable(vars)
print(parms[1]..": "..vars[1])
end
local MyVariable = "bar"
PrintVariable{MyVariable}
Which gives:
MyVariable: bar
It isn't generic, but it is simple. You avoid the debug library and loadstring by doing it this way. If your editor is any good, you could write a macro to do it.
Another possible solution is add this facility your self.
The Lua C API and source is pretty simple and extendable.
I/we don't know the context of your project/work but if you ARE making/embedding your own Lua build you could extend the debug library with something to do this.
Lua passes it's values by reference, but unknown offhand if these contain a string name in them and if so if easily accessible.
In your example the value declaration is the same as:
_G["MyVariable"] = 4
Since it's global. If it were declared local then like others stated here you can enumerate those via debug.getlocal(). But again in the C context of the actual reference context it might not matter.
Implement a debug.getargumentinfo(...) that extends the argument table with name key, value pairs.
This is quite an old topic and I apologize for bringing it back to life.
In my experience with lua, the closest I know to what the OP asked for is something like this:
PrintVariable = {}
setmetatable(PrintVariable, {__index = function (self, k, v) return string.format('%s = %s', k, _G[k]) end})
VAR = 0
VAR2 = "Hello World"
print(PrintVariable.VAR, PrintVariable.VAR2)
-- Result: VAR = 0 VAR2 = Hello World
I do not give more explanation, because the code is quite readable, however:
What happens here is simple, you only set a metatable to the PrintVariable variable and add the __index metamethod that is called when the table is forced to search for a value in its index, thanks to this functionality you can achieve what you see in the example.
Reference: https://www.lua.org/manual/5.1/manual.html
I hope that future and new visitors will find this helpful.