hadley/devtools — pull request #526 by wch (2014-07-17 03:21:48+00:00)
Title: Add print.sessionInfo function

This overrides the `utils:::print.sessionInfo` function so that it prints out a package's `GithubSHA1` value, if present. Output looks like this:

```
> library(devtools)
> library(ggvis)
> sessionInfo()
R version 3.1.1 (2014-07-10)
Platform: x86_64-apple-darwin13.1.0 (64-bit)

locale:
[1] en_US.UTF-8/en_US.UTF-8/en_US.UTF-8/C/en_US.UTF-8/en_US.UTF-8

attached base packages:
[1] stats graphics grDevices utils datasets methods base

other attached packages:
[1] ggvis_0.3.0.99(70aef48) devtools_1.5.0.99

loaded via a namespace (and not attached):
[1] assertthat_0.1 bitops_1.0-6 caTools_1.17
[4] digest_0.6.4 dplyr_0.2 evaluate_0.5.5
[7] htmltools_0.2.4 httpuv_1.3.0 httr_0.3
[10] magrittr_1.0.1 memoise_0.2.1 parallel_3.1.1
[13] Rcpp_0.11.2 RCurl_1.95-4.1 RJSONIO_1.2-0.2
[16] shiny_0.10.0.9002(89dc132) stringr_0.6.2 tools_3.1.1
[19] whisker_0.3-2 xtable_1.7-3
```

It could also be invoked without loading devtools, with `devtools:::print.sessionInfo(sessionInfo())`.

@hadley what do you think about this approach, of overriding the method?