Enable install_github to specify a subdir of github repo to use as package root

[lianos]

Currently, install_github assumes the that the repository named in the params served as the root of the R package.

Adding support for a packge that looks like so would be helpful:

+ my-uber-project
`- C/
|   + C src files that are the core of my library
`- Python/
|  +- Python language bindings
`- R/
   +- DESCRIPTION
   +- NAMESPACE
   +- R/
   +- src/
    ...

Imagine that the R subfolder of my-uber-project repository is CRAN-stallable binding/part/whatever of my-uber-project.

You can imagine calling install_github something like:

install_github('my-uber-package', 'lianos', subdir=c('R''))

Where subdir might support a character vector, eg. c('path', 'to', 'subfolder', 'with', 'R-pkg').

[lianos]

I'll take a shot at forking + provide pull request if others also find this useful -- just wanted to get some feedback on a good way to name/specify the subdir param I'm proposing.

[hadley]

I'd recommend working with install_url - then all other install methods will follow natural. I think subdir is probably an ok param name.

[BrianDiggs]

To give another example where this could be useful: R-Forge subversion repositories also have this structure: the package are not at the root of the repository, but under a pkg directory off the root.

[hadley]

I wonder if we also need an install_rforge function.

[jlehtoma]

@lianos we would definitely find this feature really useful! We're exactly in the situation @BrianDiggs described: maintaining the dev-version in GitHub and pushing the releases to R-Forge for Win and Mac builds. Let me know if there's anything I can do to help.

[hadley]

Anyone have any repos I can test this on?

[jlehtoma]

Thanks for looking into this. Here's one repo you can test with:

https://github.com/louhos/soRvi-dev/

Few notes:

• Branch rforge-dir-structure is what is on R-forge, so ideally this would work

install_github(repo='soRvi-dev', username='louhos', branch='rforge-dir-structure', subdir='pkg')

• master is essentially the content of pkg dir in R-Forge; this currently works with install_github
• Our package currently has (too!) many dependencies, which may cause some trouble