Explore arrange implementation

[hadley]

Interesting because you embed quosures in an expression

arrange2 <- function(.df, ..., .na.last = TRUE) {
  # Capture all dots
  args <- enquos(...)
  
  # Uses `!!!` to splice in the individual arguments
  # Use `!!` to inline `.na.last` to avoid it being matched in the data mask
  order_call <- expr(order(!!!args, na.last = !!.na.last))
  
  # Evaluate the call to order using data mask
  ord <- eval_tidy(order_call, .df)
  stopifnot(length(ord) == nrow(.df))
  
  .df[ord, , drop = FALSE]
}

df <- data.frame(x = c(2, 3, 1), y = runif(3))

arrange2(df, x)
arrange2(df, -y)

[hadley]

Compare and contrast with

arrange3 <- function(.data, ..., .na.last = TRUE) {
  args <- enquos(...)
  
  ords <- purrr::map(args, eval_tidy, data = .data)
  ord <- exec(order, !!!ords, na.last = .na.last)
  
  .data[ord, , drop = FALSE]
}