6 replies to this topic

[HurricaneCoder]

I want to know what does setFenv, getFenv, loadString does. I have read the lua wiki but it does not help me one bit.

[H4X0RZ]

setfenv:

Spoiler

It allows you to set a function environment.
That means that all global variables defined in the function are saved in your environment. The standard environment is _G.
Example code:

local env = {}
local function cake()
    myCake = "yummy"
end
setfenv(env, cake)
cake()
print(env.myCake) --returns "yummy"

Summary:
An environment is a table which contains the variables of a function.
The standard environment is _G.
You set a environment with setfenv(table, functionWithoutBrackets).

[HurricaneCoder]

Freack100, on 27 June 2013 - 04:06 PM, said:

setfenv:

Spoiler

It allows you to set a function environment.
That means that all global variables defined in the function are saved in your environment. The standard environment is _G.
Example code:

local env = {}
local function cake()
	myCake = "yummy"
end
setfenv(env, cake)
cake()
print(env.myCake) --returns "yummy"

Summary:
An environment is a table which contains the variables of a function.
The standard environment is _G.
You set a environment with setfenv(table, functionWithoutBrackets).

Thx that helps me a lot but can you explain to me what is getFenv as well?

[GopherAtl]

getfenv gets a function's environment. I'd've thought that was obvious from the explanation of setfenv...

[H4X0RZ]

Yea, I'm not sure if my explaination of getfenv is right but here is it:

Spoiler

getfenv returns the current function environment.
You can use it in many things, for exampl, you want a table which has access to the current environment, and It own variables:

local allVars = {}
setmetatable(allVars, {__index = getfenv())

now the table allVars has access to all variables in the current environment.

EDIT:
Damn ninjas

[GopherAtl]

:ninja:

To explain a bit more, getfenv() with no arguments gets the current function environment, i.e., what your current function or program is running in. getfenv(myfunc) returns the function environment of the specified function. And getfenv(#), where # is an integer, can be used to get the function environment of parent scopes. The applications of the last are a bit obscure, most frequently you'll want either getfenv() to get the current environment, or getfenv(myfunc) to get the environment of a specific function.

[Imgoodisher]

loadstring takes a string and tries to load it as lua code. If it works with no errors, it returns a function that does the code you gave it, otherwise it returns nil and an error message
For example,

func = loadstring("print('Hello World!')")
func()

will print 'Hello World!'

loadstring("print('Hello World!'")

would return nil and "lua: 1: [string "string"]: 1: ')' expected" because it's missing the ending )