Package uniset provides an easily accessible,
user-friendly text file as settings-file for your R-package.
Description
Package uniset enables any package (the ‘target
package’) to provide its users an easily accessible, user-friendly and
human readable text file where key=value pairs (used by functions
defined in the target package) can be saved.
This settings file lives in a location defined by the user of the target package, and its user-defined values remain unchanged even when the author of the target package is introducing or deleting keys, or when the target package is updated or re-installed.
In order to enable the target package to make use of the
functionality offered by package uniset, three files have
to be exported by uniset and be placed into the target
package.
Advantage
The most imminent advantage of the uniset settings-file
system over using any static file for permanently storing settings for
any package is the fact that the key=value pairs in the ‘settings.R’
file get updated (added / deleted) dynamically.
So the developer of a package can delete keys or introduce new ones, and
the new key=value pairs will be automatically added to or deleted from
the local ‘settings.R’ file.
Values changed by the user of the
target package will be preserved.
So the author of the target package can add or delete keys from the
‘settings.R’ file without worrying that this will cause any effort or
troubles for the user of the target package.
Two ways to generate the required files
A) Export and Move Files
Use
uniset_getFiles(), then move the ‘xxx_settings.R’ file (‘xxx’ for the name of the target package) into the ‘inst’ folder (create one if not already done) of the target package.Move the files ‘uniset_globals.R’ and ‘uniset_functions.R’ to the ‘R’ folder of the target package.
B) Write files directly to target package
Alternatively, use uniset_copyFilesToPackage() to copy
the required files directly into the target package.
In both cases the name of a setup-function has to be provided, that
is the name of a function defined in the target package
that contains the uniset function
uniset_setup().
Accessing values from within target package
Every variable defined in the ‘settings.R’ file is accessible in the code of the target package.
The target package has to list uniset as an import, and
then the functions uniset_updateSettings(),
uniset_autoUpS() or uniset_getstn() called
from a function defined in the target package can be
used to manually or automatically update the settings, i.e. to read in
the key=value pairs stored in the ‘settings.R’ file.
See next page for a practical example.
Some more explanations
You can define functions in the target package (what
in this example will be the package ‘dogPack’) that can call the
following functions from uniset:
uniset_setup(where="somePath", get("uniset_handover"))uniset_test(get("uniset_handover"))uniset_updateSettings(get("uniset_handover"), "nameOfSetupFunction")uniset_autoUpS(get("uniset_handover"), "nameOfSetupFunction")uniset_getstn(get("uniset_handover"))
uniset_handover is a global variable defined in
the target package (the package ‘dogPack’ in our example). It
contains the name of a function exported by the target package that
hands over required values to package uniset.
uniset_test() is a testing function to see if the
handover of environments etc. is working properly.
nameOfSetupFunctionis the name of the function
defined in the target package that is
containing the uniset setup-function
uniset_setup().
The function uniset_setup() is:
Creating the required environment variable in the .Renviron file, and
copying the ‘dogPack_settings.R’ file to a destination specified by the user of ‘dogPack’.
It is this file (’dogPack_settings.R) that is meant to be seen, read and modified by the user of packagedogPack.
The functions uniset_updateSettings() and
uniset_autoUpS() are updating (adding / deleting) the
key=value pairs in the local, user-level ‘dogPack_settings.R’ file
according to a possibly new template in the dogPack
installation folder.
Thus, whenever the developer of package dogPack is
introducing new or deleting obsolete key=value pairs, they will be
automatically added to or deleted from the user´s file.
Any values that the user modified will be preserved.
Thus, a new update or installation of package
dogPack will not force the user of package
dogPack to completely re-customize the ‘dogPack_settings.R’
file.
Only Sourcing vs. Compare Keys
The difference between uniset_getstn() on the one hand
and uniset_autoUpS() and
uniset_updateSettings() on the other hand is that the first
one is merely sourcing the values from the ‘settings.R’
file, while the other ones are first
comparing the keys in the user defined
settings.R file with those in the root of the target packge. If the keys
differ, the user-defined settings.R file is modified accordingly. Only
then, after the comparison of the keys, is the user
defined settings.R file sourced.
Go on and see what uniset can do in a practical
example.