What/Where are the attributes of a function object?

Question

By playing around with a function in R, I found out there are more aspects to it than meets the eye.

Consider ths simple function assignment, typed directly in the c

Answer 1

I jst figured out an attribute that compiled functions (package compiler) have that is not available with attributes or str. It's the bytecode.

Example:

require(compiler)

f <- function(x){ y <- 0; for(i in 1:length(x)) y <- y + x[i]; y }

g <- cmpfun(f)

The result is:

> print(f, useSource=FALSE)
function (x) 
{
    y <- 0
    for (i in 1:length(x)) y <- y + x[i]
    y
}

> print(g, useSource=FALSE)
function (x) 
{
    y <- 0
    for (i in 1:length(x)) y <- y + x[i]
    y
}

However, this doesn't show with normal commands:

> identical(f, g)
[1] TRUE
> identical(f, g, ignore.bytecode=FALSE)
[1] FALSE
> identical(body(f), body(g), ignore.bytecode=FALSE)
[1] TRUE
> identical(attributes(f), attributes(g), ignore.bytecode=FALSE)
[1] TRUE

It seems to be accessible only via .Internal(bodyCode(...)):

> .Internal(bodyCode(f))
{
    y <- 0
    for (i in 1:length(x)) y <- y + x[i]
    y
}

> .Internal(bodyCode(g))