[R] an assert() function

[Greg Minshall]

hi.  i've looked for (and not found) an assert() function.  needing one,
i created the following (from stop()).  i'm posting it in case 1)
someone sees a problem with this; and 2) someone else has a need.

cheers, Greg
----
## an assert mechanism...
assert <- function (shouldbe, ...) {
  if (!shouldbe) {
    .Internal(stop(as.logical(TRUE),
                   .makeMessage("assertion failure: ", ..., domain = NULL)))
  }
}