How do getfenv and setfenv functions work? And what is their usages?
What am i trying to do
Know the usage of getfenv and setfenv and know if it works for a sandbox
My problem
Don't exactly know how to use them
My attempts to resolve the problem
When i was testing getfenv i noticed that it is a table so i used this
table.foreach(getfenv(),print)
Nothing was printed out, and still didnt know how to figure out its usage
What is my question
How does getfenv and setfenv work? Is it good for making script sandboxes? What are their usage?
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1 answer
Just a side note: table.foreach is deprecated, use a generic for loop instead.
setfenv
setfenv(f, env) sets a function's environment. When it receives a function as the first argument, it will set f's environment to env . The env table is a dictionary of what will be the variables for the functions environment.
Here is an example:
local function fn()
print("Fn")
end
setfenv(fn, { })
fn()
You will get an exception like attempt to call a nil value, because the environment is empty.
Now let's add print variable in the environment of fn.
setfenv(fn, { print = print })
fn() --> Fn
When called with 1, it will set the environment of the current environment.
setfenv(1, { })
print("XD")
The same attempt to call a nil value exception.
You could use 2, which is another environment, however I am unsure of what it exactly is. I think there are numbers you could use too.
getfenv
getfenv(fn) is practically the opposite. It gets an environment. Knowing how setfenv works now, I think I don't need to explain further. The numbers thing is still the same.
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