How do I reliably and efficiently hash a function?

In addition to what Charles wrote, you can also use 'local' if you don't
want a function that creates another function.

f <- local({info <- 10; function(x) x + info})
f(3)

[1] 13

best,
Mark


Op vr 11 dec. 2015 om 03:27 schreef Charles C. Berry <ccberry at ucsd.edu>:

On Thu, 10 Dec 2015, Konrad Rudolph wrote:

I?ve got the following scenario: I need to store information about an
R function, and retrieve it at a later point. In other programming
languages I?d implement this using a dictionary with the functions as
keys. In R, I?d usually use `attr(f, 'some-name')`. However, for my
purposes I do not want to use `attr` because the information that I
want to store is an implementation detail that should be hidden from
the user of the function (and, just as importantly, it shouldn?t
clutter the display when the function is printed on the console).

`comment` would be almost perfect since it?s hidden from the output
when printing a function ? unfortunately, the information I?m storing
is not a character string (it?s in fact an environment), so I cannot
use `comment`.

How can this be achieved?

See

https://cran.r-project.org/doc/manuals/r-release/R-intro.html#Scope

For example, these commands:

foo <- function() {info <- "abc";function(x) x+1}
func <- foo()
find("func")
func(1)
ls(envir=environment(func))
get("info",environment(func))
func

Yield these printed results:

: [1] ".GlobalEnv"
: [1] 2
: [1] "info"
: [1] "abc"
: function (x)
: x + 1
: <environment: 0x7fbd5c86bc60>

The environment of the function gets printed, but 'info' and other
objects that might exist in that environment do not get printed unless
you explicitly call for them.

HTH,

Chuck

p.s. 'environment(func)$info' also works.