Assigning list attributes in an environment

Question

The title is the self-contained question. An example clarifies it: Consider

x=list(a=1, b="name")
f <- function(){
    assign('y[["d"]]', FALSE, parent.frame() )
}
g <- function(y) {f(); print(y)}

g(x)

$a
[1] 1

$b
[1] "name"

whereas I would like to get

g(x)

$a
[1] 1

$b
[1] "name"

$d
[1] FALSE

A few remarks. I knew what is wrong in my original example, but am using it to make clear my objective. I want to avoid <<-, and want x to be changed in the parent frame.

I think my understanding of environments is primitive, and any references are appreciated.

Answer 1

The first argument to assign must be a variable name, not the character representation of an expression. Try replacing f with:

f <- function() with(parent.frame(), y$d <- FALSE)

Note that a, b and d are list components, not list attributes. If we wanted to add an attribute "d" to y in f's parent frame we would do this:

f <- function() with(parent.frame(), attr(y, "d") <- FALSE)

Also, note that depending on what you want to do it may (or may not) be better to have x be an environment or a proto object (from the proto package).