How to include (source) R script in other scripts

Question

I\'ve created a utility R script, util.R, which I want to use from other scripts in my project. What is the proper way to ensure that the function this script defines are av

Answer 1

Here is a function I wrote. It wraps the base::source function to store a list of sourced files in a global environment list named sourced. It will only re-source a file if you provide a .force=TRUE argument to the call to source. Its argument signature is otherwise identical to the real source() so you don't need to rewrite your scripts to use this.

warning("overriding source with my own function FYI")
source <- function(path, .force=FALSE, ...) {
  library(tools)
  path <- tryCatch(normalizePath(path), error=function(e) path)
  m<-md5sum(path)

  go<-TRUE
  if (!is.vector(.GlobalEnv$sourced)) {
    .GlobalEnv$sourced <- list()
  }
  if(! is.null(.GlobalEnv$sourced[[path]])) {
    if(m == .GlobalEnv$sourced[[path]]) {
      message(sprintf("Not re-sourcing %s. Override with:\n  source('%s', .force=TRUE)", path, path))
      go<-FALSE
    }
    else {
      message(sprintf('re-sourcing %s as it has changed from: %s to: %s', path, .GlobalEnv$sourced[[path]], m))
      go<-TRUE
    }
  } 
  if(.force) {
    go<-TRUE
    message("  ...forcing.")
  }
  if(go) {
    message(sprintf("sourcing %s", path))
    .GlobalEnv$sourced[path] <- m
    base::source(path, ...)
  }
}

It's pretty chatty (lots of calls to message()) so you can take those lines out if you care. Any advice from veteran R users is appreciated; I'm pretty new to R.