Question

I am developing a package in R. Let’s call it mypkg.

Because some functions behave differently when they are run from a package (I am not sure why–but this is not the question), I am editing functions in the package, then rebuilding the package from the command line. For some reason a given R instance retains older versions of the functions even though the source has been changed and the package rebuilt and re-installed. I need to start a new instance to see the changes.

Here is the typical workflow.

1. Make changes to myfunction() in mypkg.R
2. In R: detach(package:mypkg); remove.packages("mypkg")
3. Command line: R CMD INSTALL --build c:\mypkg
4. Notifies me that it has been installed to the default library
5. In R: library(mypkg)
6. In R: myfunction() runs the previous version before changes.

[The next three steps I want to avoid]

1. Start a new R instance
2. In R: library(mypkg)
3. myfunction() works as expected

Run under R.2.14.1.

I am looking for suggestions of how to improve this workflow to avoid starting a new R instance.

Answer 1

You need to try to unload the package as well as detach it. ?detach has:

If a package has a namespace, detaching it does not by default
unload the namespace (and may not even with ‘unload=TRUE’), and
detaching will not in general unload any dynamically loaded
compiled code (DLLs). Further, registered S3 methods from the
namespace will not be removed. If you use ‘library’ on a package
whose namespace is loaded, it attaches the exports of the already
loaded namespace. So detaching and re-attaching a package may not
refresh some or all components of the package, and is inadvisable.

Note the last sentence in particular.

Try:

detach(package:mypkg, unload = TRUE)

Note that the “If a package has a namespace” now means all packages as this was changed in R 2.14.0 (IIRC the version number)

If the code you are changing is R code, consider using assignInNamespace() to assign an object/function in your global workspace (i.e. the newer version of function in mypkg) to the namespace of mypkg. For example we have function foo() in mypkg and locally we have newfoo() which is the newer version of foo():

assignInNamespace("foo", newfoo, "mypkg")

If the changes relate to C code, or the above don’t work, then perhaps you should follow the advice of R Core and spawn a new R instance instead of trying to detach your package.

See also the devtools package of Hadley Wickham and Emacs+ESS might make the development process easier (spawning new R instances etc) if you speak Emacs.