将函数定义存储为字符对象

Question

Take the following example function

temp_fn <- function(){

    print("hello world")

}

I know that typing the function name without the parenthesis will return the function definition, that is:

> temp_fn
function(){

    print("hello world")

}

However, I can't figure out how to store what is printed out into a character object. For example

> store_temp_fn <- as.character(temp_fn)
Error in as.character(temp_fn) : 
  cannot coerce type 'closure' to vector of type 'character'

Answer 1

You can use capture.output() in combination with the function name like this:

temp_fn <- function(){

    print("hello world")

}

temp_fn_string <- cat(paste(capture.output(temp_fn), collapse = "\n"))

> temp_fn_string
function(){

    print("hello world")

}>

Answer 2

Here's another suggestion:

out <- as.character(getAnywhere(temp_fn)$objs)[[1]]
> out
#[1] "function () \n{\n    print(\"hello world\")\n}"
> cat(out)
#function () 
#{
#    print("hello world")
#}

Answer 3

deparse(yourFunction)

Or

paste(deparse(yourFunction), collapse="\n")

if you want it as one big string.

Or, if you want to save it to a file

dput(yourFunction, "yourfile.R")