Using fields from object in for-loop | twitteR - r

Question

I am kind of a newbie to R. I am trying to build a function to retrieve and output all the dimensions. I am using the twitteR package which has an object 'user'. I use the getUser() which outputs a 'user' class type of object. As a part of the twitteR packages documentation, this object is not subsettable but does have fields such as names, screenNames, description, etc., e.g.:
> g <- getUser("CNN")
> g$name
[1] "CNN"
> g$screenName
[1] "CNN"
> g$description
[1] "Bringing you breaking news and the most talked about stories. Join the conversation and let’s connect!"
> g$statusesCount
[1] 35605
> g$followersCount
[1] 10542191
This is my function that I am trying to create and am struggling with:
userInfo <- function(user) {
userDims<- c("name", "screenName", "id", "lastStatus", "description", "statusesCount", "followersCount", "favoritesCount", "friendsCount")
for(i in seq_along(userDims)){
userObj <- getUser(user)
userObj$userDims[i]
}
}
My question is: How do I concatenate userObj$ with each entry in userDim without getting this error:
Error in envRefInferField(x, what, getClass(class(x)), selfEnv) :
‘userDims’ is not a valid field or method name for reference class “user”**