Modifying an object referenced by "get()" in R - r

Question

Apologies if this has been asked before. It's at the limit of my understanding of R, so I'm not even sure of the correct language in which to couch the query (hence, my inability to identify duplicate questions).
In my environment, I have an unknown number of objects (dataframes), each of which has an unknown number of columns that have meaningful names but with nonsense endings, which make it hard to reference them. The meaningful parts of the column names are usually followed by a double period and some further text. I want to automate finding and removing the meaningless suffixes. All the objects I want to modify have ".dat" in their names. Here's my attempt at an example:
# create some objects in my environment
a <- "a string, not of interest to me"
b.dat <- data.frame(col1 = 1:2, col2..gibberish = 3:4)
c.dat <- data.frame(col1..some.text = 5:6, col2 = 7:8)
# find the dataframes that I want to manipulate
dfs <- ls(pattern = ".dat")
# loop through the objects in question, finding and changing the problematic column names
colrename <- lapply(dfs, function(df){
# get the relevant dataframe
dat <- get(df)
# find its column names
nms <- names(dat)
# find the column names with the problematic ".." suffixes
problem.cols <- grep("\\.\\.",nms)
# pull out the meaningful first parts of each problematic name
parts <- strsplit(nms[problem.cols],"\\.\\.")
parts <- sapply(parts, function(x) x[1])
# and, the bit that doesn't work: change the problematic column names to their shorter alternatives
names(get(df))[problem.cols] <<- parts
return(0)
})
If I run this line by line, it does everything I want, up to and including names(get(df))[problem.cols], which it knows are the names of the columns in the dataframe I'm trying to alter. However, it won't assign the altered names to that, yielding the error message: Error in get(*tmp*) : invalid first argument.
I'm open to alternative approaches to achieve my desired end-point. However, I'm also intrigued by why this doesn't work and how, more generally, it's possible to alter an object referenced using "get()". Thanks in advance for any advice - and apologies if this is so naive it's been a waste of your time just reading it.
FWIW, I can see the similarity to this question but I can't adapt the answer to my needs.

Answer 1

Actually, I eventually made the link to using the "assign" function. This seems to work (so I've posted it here, in case it helps anyone else) - but I'd still be interested in alternative solutions:
# loop through the objects in question, finding and changing the problematic column names
colrename <- lapply(dfs, function(df){
# get the relevant dataframe
dat <- get(df)
# find its column names
nms <- names(dat)
# find the column names with the problematic ".." suffixes
problem.cols <- grep("\\.\\.",nms)
# pull out the meaningful first parts of each problematic name
parts <- strsplit(nms[problem.cols],"\\.\\.")
parts <- sapply(parts, function(x) x[1])
# change the problematic column names to their shorter alternatives
nms[problem.cols] <- parts
names(dat) <- nms
assign(df, dat, envir = .GlobalEnv)
return(0)
})