Lets imagine this:
tree = {}
tree.__newindex = tree
num = math.random(5,5)
tree.meta = {}
What I want to do here is replace the 'meta' in tree.meta with the var num without it creating a new object just simply called num. That way I can do something like tree.01415 for example. Maybe there is some syntax that I can put in there to designate meta as the variable num?
If I understand you correctly, I think this is what you want:
tree[num] = "whatever"
Then whatever will be added to table tree with the value of num as its key.
Related
So I am working on a script for GTA5 and I need to transfer data over to a js script. However so I don't need to send multiple arrays to js I require a table, the template for the table should appear as below.
The issue I'm having at the moment is in the second section where I receive all vehicles and loop through each to add it to said 'vehicleTable'. I haven't been able to find the "table.insert" method used in a multilayered table
So far I've tried the following
table.insert(vehicleTable,vehicleTable[class][i][vehicleName])
This seems to store an 'object'(table)? so it does not show up when called in the latter for loop
Next,
vehicleTable = vehicleTable + vehicleTable[class][i][vehicleName]
This seemed like it was going nowhere as I either got a error or nothing happened.
Next,
table.insert(vehicleTable,class)
table.insert(vehicleTable[class],i)
table.insert(vehicleTable[class][i],vehicleName)
This one failed on the second line, I'm unsure why however it didn't even reach the next problem I saw later which would be the fact that line 3 had no way to specify the "Name" field.
Lastly the current one,
local test = {[class] = {[i]={["Name"]=vehicleName}}}
table.insert(vehicleTable,test)
It works without errors but ultimately it doesn't file it in the table instead it seems to create its own branch so object within the object.
And after about 3 hours of zero progress on this topic I turn to the stack overflow for assistance.
local vehicleTable = {
["Sports"] = {
[1] = {["Name"] = "ASS", ["Hash"] = "Asshole2"},
[2] = {["Name"] = "ASS2", ["Hash"] = "Asshole1"}
},
["Muscle"] = {
[1] = {["Name"] = "Sedi", ["Hash"] = "Sedina5"}
},
["Compacts"] = {
[1] = {["Name"] = "MuscleCar", ["Hash"] = "MCar2"}
},
["Sedan"] = {
[1] = {["Name"] = "Blowthing", ["Hash"] = "Blowthing887"}
}
}
local vehicles = GetAllVehicleModels();
for i=1, #vehicles do
local class = vehicleClasses[GetVehicleClassFromName(vehicles[i])]
local vehicleName = GetLabelText(GetDisplayNameFromVehicleModel(vehicles[i]))
print(vehicles[i].. " " .. class .. " " .. vehicleName)
local test = {[class] = {[i]={["Name"]=vehicleName}}}
table.insert(vehicleTable,test)
end
for k in pairs(vehicleTable) do
print(k)
-- for v in pairs(vehicleTable[k]) do
-- print(v .. " " .. #vehicleTable[k])
-- end
end
If there is not way to add to a library / table how would I go about sorting all this without needing to send a million (hash, name, etc...) requests to js?
Any recommendations or support would be much appreciated.
Aside the fact that you do not provide the definition of multiple functions and tables used in your code that would be necessary to provide a complete answere without making assumptions there are many misconceptions regarding very basic topics in Lua.
The most prominent is that you don't know how to use table.insert and what it can do. It will insert (append by default) a numeric field to a table. Given that you have non-numeric keys in your vehicleTable this doesn't make too much sense.
You also don't know how to use the + operator and that it does not make any sense to add a table and a string.
Most of your code seems to be the result of guess work and trial and error.
Instead of referring to the Lua manual so you know how to use table.insert and how to index tables properly you spend 3 hours trying all kinds of variations of your incorrect code.
Assuming a vehicle model is a table like {["Name"] = "MyCar", ["Hash"] = "MyCarHash"} you can add it to a vehicle class like so:
table.insert(vehicleTable["Sedan"], {["Name"] = "MyCar", ["Hash"] = "MyCarHash"})
This makes sense because vehicleTable.Sedan has numeric indices. And after that line it would contain 2 cars.
Read the manual. Then revisit your code and fix your errors.
I am using LUA as embedded language on a µC project, so the ressources are limited. To save some cycles and memory I do always only indexed based table access (table[1]) instead og hash-based access (table.someMeaning = 1). This saves a lot of memory.
The clear drawback of this is approach are the magic numbers thrughtout the code.
A Cpp-like preprocessor would help here to replace the number with named-constants.
Is there a good way to achieve this?
A preprocessor in LUA itself, loading the script and editing the chunk and then loading it would be a variant, but I think this exhausts the ressources in the first place ...
So, I found a simple solution: write your own preprocessor in Lua!
It's probably the most easy thing to do.
First, define your symbols globally:
MySymbols = {
FIELD_1 = 1,
FIELD_2 = 2,
FIELD_3 = 3,
}
Then you write your preprocessing function, which basically just replace the strings from MySymbols by their value.
function Preprocess (FilenameIn, FilenameOut)
local FileIn = io.open(FilenameIn, "r")
local FileString = FileIn:read("*a")
for Name, Value in pairs(MySymbols) do
FileString = FileString:gsub(Name, Value)
end
FileIn:close()
local FileOut = io.open(FilenameOut, "w")
FileOut:write(FileString)
FileOut:close()
end
Then, if you try with this input file test.txt:
TEST FIELD_1
TEST FIELD_2
TEST FIELD_3
And call the following function:
Preprocess("test.txt", "test-out.lua")
You will get the fantastic output file:
TEST 1
TEST 2
TEST 3
I let you the joy to integrate it with your scripts/toolchain.
If you want to avoid attributing the number manually, you could just add a wonderful closure:
function MakeCounter ()
local Count = 0
return function ()
Count = Count + 1
return Count
end
end
NewField = MakeCounter()
MySymbols = {
FIELD_1 = NewField(),
FIELD_2 = NewField(),
FIELD_3 = NewField()
}
I am having a problem with variables inside tables. this is essential since I use tables as configuration for my program.
so I have tested the following code that works:
> x = "X"
> t = {["ref"]="table with value: "..x}
> print(t["ref"])
table with value: X
> x = "Y"
> t = {["ref"]="table with value: "..x}
> print(t["ref"])
table with value: Y
it however doesn't work without the second > t = ["ref"]="table with value: "..x
now I went to implement this into my main program witch consists of two files, one witch returns the configuration table. And one file with all the functions and stuff. it looks as following
FILE A (main.lua):
testString = "test1"
print(testString)
local CONFIG = require'config'
print(CONIFG[1].test)
testString = "test2"
print(testString)
local CONFIG = require'config'
print(CONIFG[1].test)
FILE B (config.lua):
local CONFIG = {
{["test"]=[[this is a test: ]]..testString}
}
return CONFIG
now when i run file A (a.k.a. main.lua) i get the following output:
test1
this is a test: test1
test2
this is a test: test1
i can't figure out what i am doing wrong here.. i thought it had something to do with that it was a single string so i made testString a table but that gave me the same result...
(that title really seems scary.. sorry)
require, by design, caches the return value. So if you call require with the same string, it will not execute the script again. It will simply return the previously returned value.
require is for loading modules. And modules should not change their return values based on other global state.
The function you're probably looking for is dofile. This will always load and execute the file (but it has none of the path searching properties of require). Alternatively, you can use loadfile to load the file as a function, then execute that function to regenerate the table whenever you want.
Also:
I am having a problem with variables inside tables.
There are no "variables inside tables". Or at least not the way you mean. Expecting a change to a variable to affect some other value is like expecting this:
a = 5
b = a + 5
a = 10
assert(b == 15, "This will never be true.")
When an expression (whether a + 5 or "table with value: " .. x) is evaluated, it results in a value. The resulting value is in no way dependent on any value or variable from the expression that generated it.
That's why you had to regenerate the value; because values don't change just because some variable changes.
I just studied Lua language. I am very confused about it.
I have two file
string.lua
STRINGS=
{
CHARACTER_NAMES =
{
web = "webby",
sac = "sacso",
}
}
STRINGS.BUNNYNAMES =
{
"Brassica",
"Bunium",
"Burdock",
"Carrot",
}
And I have generate.lua file for get value form table in string.lua.
Then print value.
But I don't know how to acess table form another file.
I want to use STRINGS and STRINGS.BUNNYNAMES too,
Please advise me.
string.lua defines one global variable named STRINGS which contains a table.
You need to execute string.lua before you can access STRINGS. Just do dofile("string.lua") for instance.
I asked earlier why my methods for a metatable weren't being located by Lua, and was told that by setting __index to my metatable, that it would resolve the issue, so I assumed that a method when called was searching by index in the metatable, but I've ran into an issue now that I need to use indexing brackets [ and ] on my metatable, so __indexis assigned to return an index from a table inside of it, how do I resolve the functionality needs of both using methods, and use of indexing brackets
I wrote a minimal example indicating the problem:
TestMetatable = {DataTable = {}}
TestMetatable.__index = TestMetatable
function TestMetatable.new()
local Tmp = {}
setmetatable(Tmp,TestMetatable)
Tmp.DataTable = {1}
return Tmp
end
function TestMetatable:TestMethod()
print("Ran Successfully")
end
function TestMetatable.__index(self,index)
return self.DataTable[index]
end
local Test = TestMetatable.new()
-- both functionalities are needed
print(Test[1])
Test:TestMethod()
You need to understand the difference between __index and __newindex, and their relationship with the current contents of the main table.
__newindex is only called/accessed when all the following are true:
When you are setting a value into the main table, via tbl[index] = expr (or equivalent syntax, like tbl.name = expr).
When the key you are trying to set into the main table does not already exist in the main table.
The second one trips people up often. And that's your problem here, because __index is only accessed when:
When the key being read from the main table does not already exist in the main table.
So if you want to filter every read from and write to a table, then that table must always be empty. Therefore, those reads and writes need to go into some other table you create for each new object. So your new function needs to create two tables: one that remains empty and one that has all the data in it.
Honestly, I wish Lua had a way to create just an empty piece of userdata that you could bind a user-defined metatable to, just to avoid these issues.
the way I resolved this problem, according to Nicol Bolas's solution, if it might give clarity to anyone else's confusion :-)
TestMetatable = {DataTable = {}, FunctionTable = {}}
function TestMetatable.new()
local Tmp = {}
setmetatable(Tmp,TestMetatable)
Tmp.DataTable = {1}
Tmp.FunctionTable = TestMetatable
return Tmp
end
function TestMetatable:TestMethod()
print("Ran Successfully")
end
function TestMetatable.__index(self,index)
if type(index) == "string" then
return self.FunctionTable[index]
else
return self.DataTable[index]
end
end
local Test = TestMetatable.new()
-- both functionalities are needed
print(Test[1])
Test:TestMethod()