Convert an R container name to character

Question

How to convert a container name to a character since I got a error using the following code:

tenv = new.env()
evalq({    }, tenv)

y = function(myEnv) {
  print(as.character(myEnv))
}

y(tenv)

Error in as.character(myEnv) :
cannot coerce type 'environment' to vector of type 'character' 

Answer 1

If you just want to grab the name of the object passed to the myEnv argument, then one common idiom is deparse(substitute( )) . The function can be written as:

y <- function(myEnv) {
  deparse(substitute(myEnv))
}

which in use gives

> tenv = new.env()
> evalq({    }, tenv)
> y(tenv)
[1] "tenv"

[Note I don't explicitly print the result of deparse(substitute( )) , I just return it and leave the printing up to the R environment]

Another way to do this is to grab the matched function call with match.call() and then extract from the resulting language object the bit you want. For example:

yy <- function(myEnv) {
  .call <- match.call()
  .call[[2]]
}

which in use gives

> yy(tenv)
tenv
> yy(myEnv = tenv)
tenv

Answer 2

You cannot convert a "container" (environment) to a character string because an environment does not posses such a property. If you want the name of the variable where the environment is stored and was passed as argument to function y , then use the solution proposed by @Gavin above.

OTOH, if you want to dump the environment contents, then use this:

y = function(myEnv) {
  print(as.list(myEnv))
}

BTW, I must point out that I don't understand why do you run evalq({ }, tenv) . It doesn't change the environment. Try the following (after running your commands):

> uenv <- new.env()
> identical(as.list(uenv),as.list(tenv))