Set CMDSTAN environment variable to gloabl .cmdstanr directory rather than version

[bwiernik]

Is your feature request related to a problem? Please describe.
I have cmdstan installed to a non-default directory (I'm on Windows and the default location is in a cloud storage folder). This means that I have to change my .Renviron every time I install a new version of cmdstan, rather than having the latest version automatically detected.

Describe the solution you'd like
I'd like to be able to set my CMDSTAN variable in .Renviron to be the .cmdstanr directory, rather than specific version directories. That way, the default when I call cmdstan could be to use the latest version in the directory.

To accomplish this, if the CMDSTAN path doesn't contain the CmdStan makefile, the logic from cmdstanr::cmdstan_default_path() would be run in the directory to find the latest version of cmdstan there.

[rok-cesnovar]

Thank you for the feature request Brenton. Seems like a valid use case and a simple fix. Hopefully, I will get to it this week.

[jgabry]

Yeah this sounds reasonable to me too.

[rok-cesnovar]

Should be addressed in #643 :

Run below to test:

remotes::install_github("stan-dev/cmdstanr@cmdstan-variable-refactor")
Sys.setenv("CMDSTAN" = "/top/level/folder/of/cmdstan/installs") # or set it in .Renviron

library(cmdstanr)

[bwiernik]

It seems to be working, but there is still a warning when the environment variable is set to a higher-level directory:

> Sys.setenv("CMDSTAN" = "~/cmdstanr")
> library(cmdstanr)
CmdStan path set to: /Users/brenton/cmdstanr/cmdstan-2.29.2
This is cmdstanr version 0.5.1
- CmdStanR documentation and vignettes: mc-stan.org/cmdstanr
- CmdStan path: /Users/brenton/cmdstanr/cmdstan-2.29.2
- CmdStan version: 2.29.2
Warning message:
Can't find CmdStan makefile to detect version number. Path may not point to valid installation.