dbDriver("name")

Thanks for the suggestion, however, I remain a bit confused. The function
find_driver() seems like a direct replacement for dbConnect(), using a
string to identify the database driver. You would be supporting what is a
bad idea, and just changing the name of the function, which is a make work
project for everyone.

So unless we want to invent a completely new way of registering
drivers, it seems like patching dbDriver to use this strategy will be
effective. However, I think we should equally encourage people to use
the driver object directly, instead of the string. That doesn't help
you, but it does help people only concerned with connecting to one
database.

Here's a first stab at it. I think it should work for the majority of
existing packages, regardless of whether they're loaded or not:

setMethod("dbDriver", "character",
  definition = function(drvName, ...) {
    findDriver(drvName)(...)
  }
)

findDriver <- function(drvName) {
  # If it exists in the global environment, use that
  d <- get2(drvName, globalenv())
  if (!is.null(d)) return(d)

  # Otherwise, see if the appropriately named package is available
  if (has_namespace(drvName)) {
    d <- get2(drvName, asNamespace(drvName))
    if (!is.null(d)) return(d)
  }

  pkgName <- paste0("R", drvName)
  # First, see if package with name R + drvName is available
  if (has_namespace(pkgName)) {
    d <- get2(drvName, asNamespace(pkgName))
    if (!is.null(d)) return(d)
  }

  # Can't find it:
  stop("Couldn't find driver ", drvName, ". Looked in:\n",
    "* global namespace\n",
    "* in package called ", drvName, "\n",
    "* in package called ", pkgName,
    call. = FALSE)
}

get2 <- function(x, env) {
  if (!exists(x, envir = env)) return(NULL)
  get(x, envir = env)
}

has_namespace <- function(x) {
  suppressMessages(requireNamespace(x, quietly = TRUE))
}

Hadley

Chief Scientist, RStudio
http://had.co.nz/