How to memoise a function in a package

[MalteThodberg]

I'm making a package with RStudio+roxygen2, and I would like to memoise a function that reads from a zipped file or URL and returns a value.

What I've tried so far (inspired from other CRAN packages):

1. add memoise under Imports.
   usethis::use_package("memoise")

2 )Define a function like this:

#' Title
#'
#' @param object value
#'
#' @return value
#' @export
hello <- memoise::memoise(function(object) {
  object + 1
})

3. Check and Build the package with Rstudio

4. Check if function is memoised
   > memoise::is.memoised(hello)
   [1] TRUE

5. Run an example
   > hello(2)
   [1] 3

6. Check if result is cached:
   > memoise::has_cache(hello)(2)
   [1] FALSE

So is.memoise reports the function as memoised, but it doesn't seem to cache the result.

What's the correct way of memoising a function in package in this way?

[jimhester]

I am pretty sure this works at least for the CRAN version of memoise, perhaps there is a bug in the devel version that is preventing it however.

[JosiahParry]

I too am running into this issue. Is there a vignette on using memoise with a package's function?

Edit: I believe this might be because the function that I was calling had additional function calls inside of it that themselves were not memoised. I memoised additional functions that were being called and that has seemingly resolved the issue.