backports/curl dependency may cause devtools::install_github("PolMine/cwbtools") to fail

[ablaette]

Just like many other packages, the function devtools::install_github() is recommended to install the development version of cwbtools. README.md recommends to use the following snippet:

devtools::install_github("PolMine/cwbtools", ref = "dev")

On Windows (not on macOS, Linux untested), this update mechanism may fail if a newer version of the packages curl or backports is available. The user is prompted whether the packages shall be updated, and if he/she agrees (the user behavior to be expected), binary packages are downloaded. But ultimately, there is an error telling that 'backports' or 'curl' cannot be deleted.

The reason seems to be as follows: The devtools package reimports the remotes package. The remotes package has curl as a dependency and attaches curl when it is attached, including loading the dll (dynamic library). However, the dll file is then write protected and cannot be overwritten / updated, causing the error.

The error can be cirumvented by not upgrading dependencies when being prompted to do so. An alternative might be to setting the argument upgrade as "never".

"Human" users may find this difficulty very hard to understand. Is there a recommended way to bring this issue to the attention of users?

[ablaette]

I posted this issue on the R-devel mailing list and received this very helpful hint from Gabor Csardi:

Hi, you can use the remotes package (that devtools itself uses under
the hood), and set the R_REMOTES_STANDALONE="true" environment
variable. Then remotes will not use any packages to perform the
downloads and the installations. See more here:
https://github.com/r-lib/remotes#standalone-mode

Gabor

---

Thus, this piece of code is included in the README file and explained somewhat:

Sys.setenv(R_REMOTES_STANDALONE = "true")
remotes::install_github("PolMine/cwbtools", ref = "dev", force = TRUE)