Binding External Variables in R

Question

Suppose I have the following function:

g = function(x) x+h

Now, if I have an object with a name in my environment h, I would not have a problem:

h = 4
g(2)

## should be 6

Now I have another function:

f = function() {
    h = 3
    g(2)
}

I would expect:

rm(h)
f()

## should be 5, isn't it?

Instead, I get an error message

## Error in g(2) : object 'h' not found

I would expect it to gbe evaluated in the environment f, so that hin fwill be attached to h in g, as it was when I performed gwithin .GlobalEnv. This does not happen (obviously). any explanation why? how to overcome this so that the function inside the function (for example g) is evaluated using the environment?

Answer 1

() .

, . g R:

g = function(x) x+h

g . , g :

f = function() {
    h = 3
    g(2)
}

f. g, , , . h, f.

, g h, f, g f:

f = function() {
    h = 3
    g = function(x) x+h
    g(2)
}

g f ( , g g, R).

g :

f = function() {
    h = 3
    environment(g) <- environment()
    g(2)
}