CODEWITHSUNDEEP
rdeprecatedr-package
landau
landau

Reputation: 5841

How long should I keep a deprecated function?

For R packages, is there a guideline for how long I should keep around an obsolete function once I deprecate it? What about demoting to defunct? De-thoughts?

Upvotes: 3

Views: 425

Answers (1)

teunbrand
teunbrand

Reputation: 37923

I admit that this question is mostly opinion based, but here are some thoughts.

Hadley Wickham ran a poll on twitter asking a very similar question, and the majority of people voted that he should wait 4-5 years before removing a deprecated function. Granted, it was the shortest available option in the poll, but the next most popular answer was 10+ years.

Now, it of course depends on how you are deprecating it. The documentation of the {lifecycle} packages gathers some thoughts around function deprecation and is worth a read. The {lifecycle} article suggests first to issue a warning when a function is used in the global environment and testthat functions (i.e. not when other developers use your soft-deprecated function in their packages). Next to issue hard warnings every time and lastly to have the function return an error every time.

Things change a little when you have released very similar functionality under a different function name, which is called 'superseding' a function. I think this fine for any update. My advice would be to using something along the following lines:

# Your function that supercedes the older one
plus <- function(x, y) x + y

# Your deprecated function
add <- function(x, y) {
  warning("`add()` is deprecated. Using `plus()` instead.")
  plus(x, y)
}

Another thing you could do is to scour the internet (or GitHub) for a verbatim search library(your_package) or your_package::my_to_be_deprecated_function to see if and how other people are using it in code that they share (and whether that code is just an one-off analysis script or intended to be re-used by others). If you find someone has a use-case that cannot be easily superseded with another function, you might think about keeping it around for longer or soft-deprecating it instead of hard-deprecating it.

If you find out people barely use your function, your package isn't on a centralised repository (CRAN / Bioconductor) or you haven't advertised your function anywhere, I personally think you're allowed to take more liberties than if you're the developer behind the base::data.frame() function.

Upvotes: 5

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