Conversion functions temperature

[Huh]

It would be nice to be able to flip between Fahrenheit and Celsius

[foresthayes]

I have been experimenting with S3 methods and am hoping for some feedback or suggestions on how we generally want to structure functions that use multiple classes.

In this instance I think it makes most sense to have two separate functions one for each conversion (rather than a single function that takes the temperature unit as an input).

Suggestions on the function below?

cllr_cels_to_fahr <- function(x, col = NULL) {
  c2f <- function(x) {x * (9 / 5) + 32}

  f <- function(x) UseMethod("f")

  f.numeric <- function(x) {
    assertthat::assert_that(is.numeric(x))
    c2f(x)
  }

  f.data.frame <- function(x) {
    if (is.null(col)) {
      warning("Temperature column not specified. Conversion not performed!")
      return(invisible(x))
    }
    assertthat::assert_that(is.numeric(pull(x, col)))
    mutate_at(x, col, c2f)
  }
  f(x)
}  

[kissmygritts]

@foresthayes, what if you write one function that deals with converting both, then partially apply that function to create the cels_to_fahr and fahr_to_cels?

cllr_conv_temp <- function(x, to) {
    ...
}

# then
cllr_cels_to_fahr <- function(x) {
    cllr_conv_temp(x, fahr)
}

# and 
cllr_fahr_to_cels <- function(x) {
    cllr_conv_temp(x, cels)
}

I'm still trying to figure my way around this library to help contribute. Maybe you've already done this.