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Wrap a function to capture side-effects

Source: R/adverb-quietly.R
quietly.Rd

Create a modified version of .f that captures side-effects along with the return value of the function and returns a list containing the result, output, messages and warnings.

Usage

quietly(.f)

Arguments

.f

A function to modify, specified in one of the following ways:

  • A named function, e.g. mean.

  • An anonymous function, e.g. \(x) x + 1 or function(x) x + 1.

  • A formula, e.g. ~ .x + 1. Only recommended if you require backward compatibility with older versions of R.

Value

A function that takes the same arguments as .f, but returns a different value, as described above.

Adverbs

This function is called an adverb because it modifies the effect of a function (a verb). If you'd like to include a function created an adverb in a package, be sure to read faq-adverbs-export.

See also

Other adverbs: auto_browse(), compose(), insistently(), negate(), partial(), possibly(), safely(), slowly()

Examples

f <- function() {
  print("Hi!")
  message("Hello")
  warning("How are ya?")
  "Gidday"
}
f()
#> [1] "Hi!"
#> Hello
#> Warning: How are ya?
#> [1] "Gidday"

f_quiet <- quietly(f)
str(f_quiet())
#> List of 4
#>  $ result  : chr "Gidday"
#>  $ output  : chr "[1] \"Hi!\""
#>  $ warnings: chr "How are ya?"
#>  $ messages: chr "Hello\n"