evaluator: Class for safe evaluation
In GregorDeCillia/kasper: Another Safety Providing Evaluator in R

Description Usage Arguments Methods Fields Examples

This R6 Class can be used to evaluate R expressions or R strings in a safe environment.

evt <- evaluator$new(...)
evt$eval(str, new_device = FALSE, reset_env = TRUE)
evt$replay()
# -------------------------------------------------- #
evt$appendSymbol(x, package)
evt$plot
evt$getUserEnv()
# -------------------------------------------------- #
evt$hasPlot()
evt$hadError()
evt$hadWarning()

... Passed down to create_safe_environment
str A string or expression to evaluate
new_device Whether to open an new graphics device for plots. See evaluate::evaluate
reset_env Should the user environment be reset?
x A string representing a symbol. Can be a function name or an infix operator like %>%.
package The package where the symbol comes from.

new() initializes a new evaluator object.
eval() evaluates a string or expression in a safe environment.
replay() uses evaluate::replay() to show the result of the last evaluate() call.
appendSymbol() extends the safe environment by a function or operator.
getUserEnv() Returns a tabular representation of the environment created by the call to $eval()
hasPlot(), hadError() and hadWarning() are flags that can be used to check whether the expression in eval produced a plot, error or warning.

plot is an active binding that replays the last plot using grDevices::replayPlot(). In case of a gplot, a ggplot object is returned.

## create a new object
evt <- evaluator$new()

# evaluate a string and "replay" the result
evt$eval("2 + 2")
evt$replay()

# evaluate an expression. Useful if code spans several lines
evt$eval({
  x <- 2 + 1
  y <- x + 1
  cat(x, y, sep = " ")
})
evt$replay()