Dynamic variables in base R

Question

How to create please dependent variables in R ? For example

a <- 1
b <- a*2
a <- 2
b
# [1] 2

But I expect the result 4. How can R

Answer 1

Although what you want to do is not completely possible in R, with a simple modification of b into a function and thanks to lexical scoping, you actually can have a "dependent variable" (sort of).

Define a:

a <- 1

Define b like this:

b <- function() {
    a*2
}

Then, instead of using b to get the value of b, use b()

b() ##gives 2
a <- 4
b() ##gives 8