Is it possible to get a function behind an active binding?

Question

In R, we can use makeActiveBinding to create an active binding by providing a function:

 e <- new.env() makeActiveBinding("var", function(x) if (missing(x)) cat("get\n") else cat("set\n"), e) 

Once the active binding is created, it seems there is no way to get the function behind it.

I wonder if it is possible to get a function behind an active binding, as shown below?

 > getActiveBindingFunction("var", e) function(x) if (missing(x)) cat("get\n") else cat("set\n"), e)