Evaluation basics
We use eval() to evaluate, run, or execute expressions. It requires two arguments:
expr: the object to evaluate, either an expression or a symbol.env: the environment in which to evaluate the expression or where to look for the values.
Defaults to current env.
sumexpr <- expr(x + y)
x <- 10
y <- 40
eval(sumexpr)
#> [1] 50
eval(sumexpr, envir = env(x = 1000, y = 10))
#> [1] 1010