Can't restore project if some packages available only as a "source" and some only as a "binary"

Hi Guys,
I'm still working on migration of our current project to packrat package manager. On Linux and MacOSx everything works fine, but I've been stuck on Windows.

Let A be a dependency available only and only in "binary" form for Windows (eg. RCurl - it is almost impossible to get complete toolchain to compile RCurl for std R developer/researcher on Windows machine)

Let B be a dependency available only and only in "source" form for Windows (eg. our private packages)

A and B are both compilable on Linux and MacOS.

Now assume that you are on Windows. If you set options(pkgType = "source") then packrat::restore() fails on A (can't compile). And if you set options(pkgType = "win.binary") then packrat::restore() fails on B (binary not found).

This is potential issue for many other developers and I think it should be handled somehow.

It is possible to set standard R option ( options(pkgType="...") ) to define the way how packages should be installed (and packrat now respects it) but I suggest to add another packrat-related option (eg. packrat::set_opts(pkgType.fallback=c("source", "binary", ... )) defining fallback pkgTypes used in case the default one does not work. So the workflow should be as following

• try to download using default option set in options(pkgType..)
• try first fallback option if not used already (so if default option is "source" and first fallback option is also "source", skip it and confinue with second fallback option if defined) and if available for current platform (eg. don't try to use mac.binary on windows workstations)
• try second fallback option ....
• if the package still can't be installed, fail

Start by reading the packrat::restore() package-installation flow and how it respects options(pkgType). Compare that behavior with the proposed packrat::set_opts(pkgType.fallback=...) workflow; done means Windows restoration can try compatible source and binary package types in order and still fail clearly when none work.