> system.time(x <- rnorm(10))
   user  system elapsed
      0       0       0
> system.time(x = rnorm(10))
Error in system.time(x = rnorm(10)) : unused argument(s) (x = rnorm(10))

`=` <- function(...) stop("Assignment by = disabled, use <- instead")
# seems to work
a = 1
Error in a = 1 : Assignment by = disabled, use <- instead
# appears not to break named arguments
sum(1:2,na.rm=TRUE)
[1] 3

temp <- tempfile()
write("foo = function(...) {
          good <- 0
          bad = 1
          sum(..., na.rm = TRUE)
       }", file = temp)

library(lint)
lint(file = temp, style = list(styles.assignment.noeq))
# Lint checking: C:UsersflodelAppDataLocalTempRtmpwF3pZ6file19ac3b66b81
# Lint: Equal sign assignemnts: found on lines 1, 3

`=` <- function(...){
        .what <- as.list(match.call())
        .call <-  sprintf('%s <- %s', deparse(.what[[2]]),  deparse(.what[[3]]))
        mess <- 'Use <- instead of = for assigment '
        if(getOption('warn_assign', default = T)) {
        stop (mess) } else {
        warning(mess)
        eval(parse(text =.call), envir = parent.frame())
          }
        }

# with no option set
z = 1
## Error in z = 1 : Use <- instead of = for assigment
options(warn_assign = T)
z = 1
## Error in z = 1 : Use <- instead of = for assigment
 options(warn_assign = F)
 z = 1
## Warning message:
##  In z = 1 : Use <- instead of = for assigment