I'm trying to write a function 'exported' in R that will assign a value to a name in a desired environment (say .GlobalEnv). I'd like to use the following syntax.
# desired semantics: x <- 60
exported(x) <- 60
# ok if quotes prove necessary.
exported("x") <- 60
I've tried several variations. Most basically:
`export<-` <- function(x, obj) {
call <- as.list(match.call())
elem <- as.character(call[[2]])
assign(elem, obj, .GlobalEnv)
get(elem, .GlobalEnv)
}
exported(x) <- 50
The foregoing gives an error about the last argument being unused. The following complains that "object 'x' is not found."
setGeneric("exported<-", function(object, ...) {
standardGeneric("exported<-")
})
setReplaceMethod("exported", "ANY", function(object, func) {
call <- as.list(match.call())
name <- as.character(call$object)
assign(name, func, other.env)
assign(name, func, .GlobalEnv)
get(name, .GlobalEnv)
})
exported(x) <- 50
The above approach using a character vector in place of a name yields "target of assignment expands to non-language object."
Is this possible in R?
EDIT: I would actually like to do more work inside 'exported.' Code was omitted for brevity. I also realize I can use do something like:
exported(name, func) {
...
}
but am interested in seeing if my syntax is possible.
I can't understand why you wouldn't use assign
?
assign( "x" , 60 , env = .GlobalEnv )
x
[1] 60
The env
argument specifies the environment into which to assign the variable.
e <- new.env()
assign( "y" , 50 , env = e )
ls( env = e )
[1] "y"
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