Make an Active Binding

Source: R/py-classes.R

Make an Active Binding

sym %<-active% value

Arguments

sym

symbol to bind
value

A function to call when the value of sym is accessed.

Value

value, invisibly

Details

Active bindings defined in a %py_class% are converted to @property decorated methods.

See also

makeActiveBinding()

Examples

x %<-active% function(value) {
  message("Evaluating function of active binding")
  if(missing(value))
    runif(1)
  else
   message("Received: ", value)
}
x

#> Evaluating function of active binding
#> [1] 0.08075014
x

#> Evaluating function of active binding
#> [1] 0.834333
x <- "foo"

#> Evaluating function of active binding
#> Received: foo
x <- "foo"

#> Evaluating function of active binding
#> Received: foo
x

#> Evaluating function of active binding
#> [1] 0.6007609
rm(x) # cleanup