neon_dir: Default directory for persistent NEON file store
Description
Use neon_dir() to view or access the currently active local store.
By default, neon_download() downloads files into the neon_dir(),
which uses an appropriate application directory for your operating system,
see tools::R_user_dir(). This location can be overridden by setting
the environmental variable NEONSTORE_HOME. neonstore functions
(e.g. neon_index(), and neon_read()) look for files in
the neon_dir() directory by default. (All functions can also take
a one-off argument to dir in the function call in place of the calling
neon_dir() to access the default.
# NOT RUN {neon_dir()
## Override with an environmental variable:Sys.setenv(NEONSTORE_HOME = tempdir())
neon_dir()
## UnsetSys.unsetenv("NEONSTORE_HOME")
# }