This functions uses
R_USER_CACHE_DIR if set. Otherwise, they follow
platform conventions. Typical user cache directories are:
Mac OS X:
C:\\Documents and Settings\\<username>\\Local Settings\\Application Data\\<AppAuthor>\\<AppName>\\Cache
user_cache_dir( appname = NULL, appauthor = appname, version = NULL, opinion = TRUE, expand = TRUE, os = NULL )
is the name of application. If NULL, just the system directory is returned.
(only required and used on Windows) is the name of the appauthor or distributing body for this application. Typically it is the owning company name. This falls back to appname.
is an optional version path element to append to the
path. You might want to use this if you want multiple versions
of your app to be able to run independently. If used, this
would typically be
If TRUE (the default) will expand the
Operating system whose conventions are used to construct the
requested directory. Possible values are "win", "mac", "unix". If
On Windows the only suggestion in the MSDN docs is that local settings go
CSIDL_LOCAL_APPDATA directory. This is identical to the
non-roaming app data dir (i.e.
user_data_dir()). But apps typically put
cache data somewhere under this directory so
Cache to the
CSIDL_LOCAL_APPDATA value, unless
opinion = FALSE.
tempdir() for a non-persistent temporary directory.
user_cache_dir("rappdirs")#>  "~/Library/Caches/rappdirs"