Get or set function body — fn

fn_body() is a simple wrapper around base::body(). It always returns a \{ expression and throws an error when the input is a primitive function (whereas body() returns NULL). The setter version preserves attributes, unlike body<-.

Usage

fn_body(fn = caller_fn())

fn_body(fn) <- value

Arguments

fn: A function. It is looked up in the calling frame if not supplied.
value: New formals or formals names for fn.

Examples

# fn_body() is like body() but always returns a block:
fn <- function() do()
body(fn)
#> do()
fn_body(fn)
#> {
#>     do()
#> }

# It also throws an error when used on a primitive function:
try(fn_body(base::list))
#> Error in fn_body(base::list) : 
#>   `fn` must be an R function, not a primitive function.