do_call: Prune and call a function with a set arguments

In HenrikBengtsson/environments: Working with Environments and Closures in R

Prune and call a function with a set arguments

Description

Prune and call a function with a set arguments

Usage

do_call(fcn, args = list(), envir = parent.frame(), prune = FALSE)

Arguments

fcn	A function.
args	A list of arguments passed to the function fcn.
envir	An environment within which to evaluate the call.
prune	If TRUE, the environment stack of fcn is pruned.

Value

Return the value of function call.

See Also

base::do.call()

Examples

## ------------------------------------------------------------------------
## Example how to avoid huge local objects being part of a local function,
## which might be costly if the function is serialized, e.g. exported
## to a parallel workers
## ------------------------------------------------------------------------

## Report on the 'fcn' size before and after pruning
trace(
  do_call,
  at = 3L, tracer = quote(fcn_size <- size_of(fcn)),
  exit = quote({
    if (prune) {
      message(sprintf("Size of '%s': %s bytes (%s bytes when pruned)",
                      fcn_name, fcn_size, size_of(fcn)))
    } else {
      message(sprintf("Size of '%s': %s bytes",
                      fcn_name, fcn_size))
    }
  }),
  print = FALSE
)

my_fcn <- function(g = NULL, prune = FALSE) {
  cargo <- rnorm(1e6)
  
  n <- 2

  if (is.null(g)) {
    g <- local({
      pi <- 3.14
      function() n * pi
    })
  }

  do_call(g, prune = prune)
}


## Non-pruned function local to a function carries also large 'cargo' object
my_fcn()

## Pruned function local to a function without large 'cargo' object
my_fcn(prune = TRUE)


## WARNING: Large objects inside local environments of
##          the function will not the pruned!
g <- local({
  cargo <- rnorm(1e6)
  n <- 2
  local({
    pi <- 3.14
    function() n * pi
  })
})

my_fcn(g)
my_fcn(g, prune = TRUE)

untrace(do_call)

HenrikBengtsson/environments documentation built on Jan. 15, 2025, 12:58 a.m.