This is a tutorial about setfenv() and getfenv(). Since it's in the advanced section, you should understand functions, tables, variables, etc. Knowing what pointer variables are is good too, but since we don't have those in Lua, I'll cover those too.

Now, you may be wondering, "What do setfenv and getfenv mean? What the heck is a fenv?" Well, "fenv" is short for "function environment". Without overcomplicating things, the function environment is all the variables that you have access to in a certain spot.

variables and the function environment

The function environment is like a table, and when you set a variable, you're setting a new index (the variable) to a new value (the value it is being assigned to).

Code:

Pie = "Pie"

In the above example, you are setting a new index of Pie in the function environment, and giving it the value of "Pie".

setfenv()

setfenv is a function that you use to change the function environment to a new function environment. The first argument is where to change the function environment. You can give it an actual function to change the environment of, or you can tell it how many stack levels to go down. Zero would be telling it to manipulate the function environment that the setfenv() is inside, one would tell it to change the function environment of where the current function was called from, etc.

The second argument is a table that will become the new function environment. The indices you set are variables that can be accessed in the function, and the values are the values those variables are assigned to.

Code:

setfenv(1, {Stuff = "Hello, World!"})
print(Stuff)

Now, if you were to test the above code, it would give you output something like this:

Script:2:Attempt to call global 'print' (a nil value)

You may be wondering why that is. print is a global function, right? Well, when you use setfenv(), you completely reset the function environment. Global variables need to be re-defined.

Code:

setfenv(1, {Stuff = "Hello, World!", print = print})
print(Stuff) -->Hello, World!

getfenv()

getfenv is another function, but before I explain too much about it, I'm going to explain a little bit about pointer variables.

Pointer variables are variables that, instead of just having the same value as another variable, actually use the same data as another variable. For example:

Code:

a = 5
b = a
a = 6
print(a,b) -->6 5

See how b didn't changed? It's because b simply got a clone of the data that a contained, instead of actually having the same data. Pointer variables use the same exact data. Let's say that I could create a pointer variable by adding an asterisk after a variable. Here's how it would work:

Code:

Var1 = 5
Var2* = Var1 -- this is now a pointer variable :O
Var1 = 6
print(Var1, Var2) -->6 (numbers/letters)

But why did it print like that? That's where the data is stored. The pointer variable doesn't refer to the data itself, it refers to the spot where the data is. We will use the ampersand (&) to refer to the data itself.

Code:

Var1 = 5
Var2* = Var1
Var1 = 6
print(Var1, &Var2) -->6 6

See? And since pointers point the the space where the data is stored, they can change the data too by changing what is in that spot:

Code:

Var1 = 5
Var2* = Var1
Var2 = 6
print(Var1) -->6

See how when we edited Var2, Var1 changed too? That's the usefulness of a pointer variable. Sadly, we can't use any type of pointer variable in Lua, or RBX.Lua.

Now back to getfenv.

The reason I had to explain pointers to you is because getfenv returns something that acts like a pointer variable. When you use getfenv(), it returns a table of the function environment. It only takes one argument, and it acts just like a pointer variable, because when you manipulate it, you manipulate the function environment that it refers to.

Note: When using getfenv(), leaving the parenthesis empty is the same as putting a zero in them. It takes the function environment of the current function.

Code:

pie = getfenv()
pie.Caik = "Hello!"
print(Caik) -->Hello!

See? We added an index to the function environment that we were currently in, and then we were able to use it. A shorter way to do this is:

Code:

getfenv().Caik = "Hi!" -- no just shortening the word doesn't make it a shorter script
print(Caik) -->Hi!

And another example of each:

Code:

function Pie()
print(lolwut)
end

function Caik()
print(lolwut)
end

getfenv(Pie).lolwut = "Hola"
setfenv(Caik, {print = print, lolwut = "Bonjour"})
Pie() -->Hola
Caik() -->Bonjour

See? Simple as that.

FEEDBACK PL0X?

Nice!

Great

he makes things look easy. lol

Great tutorial. But would this work?

Script 1:
getfenv().hi = "lol"
Script 2:
print(hi)
>lol

that might work... might

this is my question

Code:

setmetatable(tab = {}, {__metatable = "access denied"})
print(getfenv(getmetatable(tab).__metatable = nil))

--> no complaints?

would that work?

it might.

wait no i meant this

Code:

print(getfenv(setmetatable(tab = {}, {__metatable = "access denied"}).__metatable = nil))

it won't work, you can't use more than one '=' in one line except for '=='.
the parameter for getfenv has to be a number, blank or function. not a table.

first of all, you can use more than one line in tables

Code:

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

and second of all, setmetatable() is a function

Oh ya forgot about that. Try testing your script in the output.

thats my problem. wheres the output?

view>output in roblox studio

k thx

Heres an observation i made earlier about this for people who are knew to this ... To always remember what Setfenv() and Getfenv() are you remember it like this.

Set in Setfenv() is Set, f in Setfenv() is function, env in Setfenv() is Environment, and put it all together and it means Setfenv() Set's the function's environment,

Get in Getfenv() is Get, f in Getfenv is function, env in Getfenv() is environment, put it all together, and it means Getfenv() Get's a function's environment.

Nice little observation i made earlier today lol, but this is a good way to remember what Setfenv() and Getfenv() does.

would this be a _G fixer:

script1:

getfenv(print).bai = "lol"

script2:
print(bai)

Great job NotAPotato!

Quote :

Heres an observation i made earlier about this for people who are knew to this ... To always remember what Setfenv() and Getfenv() are you remember it like this.

Set in Setfenv() is Set, f in Setfenv() is function, env in Setfenv() is Environment, and put it all together and it means Setfenv() Set's the function's environment,

Get in Getfenv() is Get, f in Getfenv is function, env in Getfenv() is environment, put it all together, and it means Getfenv() Get's a function's environment.

Nice little observation i made earlier today lol, but this is a good way to remember what Setfenv() and Getfenv() does.

Not a bad way of looking at it ninga!

erm. thats why the creator of the lua gave this function its name

setfenv: set function environment
getfenv: get function environment

I knew that Supernapalm. That still doesn't effect my actual statement, "way of looking at it".

actaully, its pretty much the only way of looking at it, cuz the lua creator said so

Yes, that way of looking at it is still interesting.

lol it's the way I looped at it before i saw this tutorial. I think it's the only way of seeing it. :P