Best way to learn advanced Lua? [closed]

Roblox wiki, Youtube videos like Friaza Peaspod and many more. Even try understanding free model scripts.

If you are looking for some good places to learn environments and metatable manipulation, these are some good links

Environments http://lua-users.org/wiki/EnvironmentsTutorial

Metatable Manipulation http://lua-users.org/wiki/MetamethodsTutorial

PS: This site is also good for learning any level of Lua (Beginners - Professional)

• http://www.lua.org/manual/5.1/ - The official documentation for Lua 5.1, the version Roblox runs.
• http://lua-users.org/wiki/LuaDirectory - Lua-users.org has a lot of information and code snippets that can be both useful and informative.
• https://scriptinghelpers.org/blog/metatables-a-table-within-a-table-maybe-not - a blog post on metatables.

I might tack on a few more resources if I recall them.

On metatables and the environment. First, we'll start with metatables.

A metatable is a table, just like any other, except that it can be assigned to another table to give the table more functionality. Metatables can be given specific keys called metamethods to control what happens when you, say, try to get something from the table that isn't there. That can be achieved with the __index metamethod. The __index method can be a table/userdata, or it can be a function.

Example 1: __index as a table

t = {a = 1, b = 2, c = 3}

mt = {
    __index = {d = 4}
}

setmetatable(t, mt)

print(t.a, t.b, t.c, t.d) --"d" isn't in the table, but it's in the __index, so we can still print it.

Example 2: __index as a userdata

t = {a = 1, b = 2, c = 3}
part = Instance.new("Part")
mt = {__index = part}
setmetatable(t, mt)
print(t.BrickColor) --There's no BrickColor in t, but there's a BrickColor in part.

Example 3: __index as a function with the table and key as arguments

t = {a = 1, b = 2, c = 3}
mt = {
    __index = function(self, key)
        return "Key: "..key.." was not found."
    end
}
setmetatable(t, mt)
print(t.d)

There's also __newindex, a function that controls what happens when you try to set a new key in the table.

t = {a = 1, b = 2, c = 3}

mt = {
    __newindex = function(self, key, value)
        --[[Since doing "self[key] = value" would trigger __newindex again
            and create an infinite loop, we have the rawget/rawset functions to
            prevent the above from happening.
        --]]
        rawset(self, key, value)
        print(key.. " was appended with a value of "..value)
    end
}

setmetatable(t, mt)

t.a = 5
t.b = 4
t.c = 3
t.d = 2
t.e = 1

The environment is a table of every global variable that the current stack level, or a given function, has access to. When you create a (non-localized) variable, it gets stored in the environment. You can access the script's environment with getfenv.

a = 1
print(a)
print(getfenv().a)

getfenv().b = 2
print(getfenv().b)
print(b)

We can alter the environment with setfenv.

setfenv(1, {a = 1, b = 2, c = 3})
print(a)

Notice how we can't print anything, because print was in our old environment, and now we have a new environment. How do we fix that? We use __index.

env = getfenv()
mt = {__index = env}
setfenv(1, setmetatable({a = 1, b = 2, c = 3}, mt))
print(a) --Now it works, since we brought the old environment with us in the __index.

And that's the basics of it. From there, you just build on it with your creativity.