Hi.
I'm trying to find a systematic way to prevent assignment to names of
existing functions. I've tried reassigning to the assignment operator,
with mixed results. The function definition for "<-" below works as
hoped for the demonstrated assignments to a and c. However, for the
assignment based on the test function, it appears that the formal
argument is not visible. Any suggestions?
Thanks,
Tim.
-------------------------------------------------------------
rm(list=ls())
"<-" <- function(x,value){
try(assign("y",x), silent=TRUE)
if (exists("y", mode="function"))
stop("assignment to an existing function")
else eval(substitute(.Primitive("<-")(x,
value)),sys.frame(sys.parent(2)))
}
MYLEN <- function(infile){
LEN <- nchar(infile)
return(LEN)
}
a <- 3
c <- 3
#Error in c <- 3 : assignment to an existing function
d <- MYLEN("word")
#Error in nchar(infile) : object "infile" not found
______________________________________________
R-devel@r-project.org mailing list
https://stat.ethz.ch/mailman/listinfo/r-devel
