Retrieves and evaluates remote R sources including those served over secure http (https) connections. Requires RCurl package.

remoteSource.R

##' Retrieves and evaluates a remote R source file.
##'
##' @param file defines a URL as the remote source file path
##' @param local indicates if the remote source should be evaluated in
##' the environment which calls remoteSource. If FALSE (default),
##' evaluated in the global environment.
##' @param verbose indicates if verbose output should be printed.
##' @param echo indicates if the source should be echoed before
##' evaluation.
##' @return result of evaluating the remote source.
remoteSource <- function(file, local=FALSE, verbose=FALSE, echo=FALSE) {
  ## Define verbose output method:
  .ccat = function (...) {
    if (verbose) {
      cat(...)
    }
  }

  ## We need the RCurl for remote source served over https:
  require(RCurl)

  ## Attempt to get the remote source:
  .ccat("Attempting to retrieve the remote source...\n")
  csource <- getURL(file)
  .ccat("Remote source retrieved...\n")

  ## Prepare arguments:
  .ccat("Parsing the source...\n")
  args = list(expr=parse(text=csource))
  if (local) {
    args = append(args, envir=.GlobalEnv)
  }

  ## Done, evaluate the source:
  .ccat("Evaluating the source...\n")
  if (echo) {
    cat(sprintf("%s\n", csource))
  }
  return(do.call(eval, args))
}