Using R, how to dput a list with an environment?-CodePudding

I am working on a function to basically grab arguments from inside a function. It works as expected, but when I try and transport the result, I have an envir in the list. It outputs fine via dput, but I CANNOT transport it.

> test(iris)
list(envir = <environment>, call = test(iris), fn.info = list(
    fn = "test", dot.keys = NULL, dot.vals = NULL, params = list(
        df = "iris"), map = list(df = "iris"), formals = list(
        df = "--EMPTY--")))

As you can see, the INTERNALS grab the fn function name, and function parameters. One element captured is the envir which is simple to reproduce as follows:

dput( (envir = environment()) );

The list at least TRAPPED the environment, but when I try and paste it back into a session, I get an error:

> x = list(envir = <environment>, call = test(iris), fn.info = list(
Error: unexpected '<' in "x = list(envir = <"
>     fn = "test", dot.keys = NULL, dot.vals = NULL, params = list(
Error: unexpected ',' in "    fn = "test","
>         df = "iris"), map = list(df = "iris"), formals = list(
Error: unexpected ')' in "        df = "iris")"
>         df = "--EMPTY--")))
Error: unexpected ')' in "        df = "--EMPTY--")"

Ideally, I would like to pair of functions that would cast it to/from envir as a string, so I can transport it.

Question: How to transport an environment via dput?

env.toString(envir) {}

env.fromString(envir) {}

The above represents my current roadmap, but I am open to suggestions. I have tried as.character , as.raw, as.hexmode... I believe deparse internally will work, but that will not enable me to recover the environment as an object without the propose env.fromString

CodePudding user response：

Perhaps you could use ls() to get the names of all objects in the environment, and then put their names and values in a list, then reconstruct an environment from that list with list2env()... Something like:

x <- new.env()
x$foo <- 1:3

xnames <- ls(envir = x)
xlist <- lapply(xnames, function(y) {
  z <- x[[y]]
  if (!inherits(z, 'environment'))
    return(z)
})
names(xlist) <- xnames

dput(list(my_env = xlist))
#> list(my_env = list(foo = 1:3))

a_list <- list(my_env = list(foo = 1:3))

x2 <- list2env(a_list$my_env)
print(x2$foo)
#> [1] 1 2 3

CodePudding user response：

If you just need to remove the items from a list that are an environment you can just iterate over the list remove the elements that inherit from 'environment'

x <- list(a = new.env(), b = "foo")
dput(x[-sapply(x, inherits, 'environment')])
#> list(b = "foo")