use the LOTR dummy collection of source packages

To illustrate the use of the srcpkgs, we need some source packages. An easy way to experiment with srcpkgs is with the https://github.com/kforner/srcpkgs_lotr_demo repository:

install the srcpkgs package (cf https://kforner.github.io/srcpkgs/#installation)
check out the https://github.com/kforner/srcpkgs_lotr_demo repository:

git clone https://github.com/kforner/srcpkgs_lotr_demo.git
cd srcpkgs_lotr_demo

then start a R session in that folder (type R):

# load srcpkgs
>library(srcpkgs)

get_srcpkgs()

The get_srcpkgs() fetches the list of source packages that are currently managed by srcpkgs. You should see all packages from the srcpkgs_lotr_demo repository.

# let's see what source packages are discovered:
> get_srcpkgs()
            package version                                                path                     imports depends suggests
aragorn     aragorn     0.1   /workspaces/srcpkgs_pkg/srcpkgs_lotr_demo/aragorn                                             
bilbo         bilbo     0.1     /workspaces/srcpkgs_pkg/srcpkgs_lotr_demo/bilbo                                             
elrond       elrond     0.1    /workspaces/srcpkgs_pkg/srcpkgs_lotr_demo/elrond                                             
elves         elves     0.1     /workspaces/srcpkgs_pkg/srcpkgs_lotr_demo/elves         galadriel,\nlegolas                 
frodo         frodo     0.1     /workspaces/srcpkgs_pkg/srcpkgs_lotr_demo/frodo                                             
galadriel galadriel     0.1 /workspaces/srcpkgs_pkg/srcpkgs_lotr_demo/galadriel                                             
gandalf     gandalf     0.1   /workspaces/srcpkgs_pkg/srcpkgs_lotr_demo/gandalf                                             
gimli         gimli     0.1     /workspaces/srcpkgs_pkg/srcpkgs_lotr_demo/gimli                                             
hobbits     hobbits     0.1   /workspaces/srcpkgs_pkg/srcpkgs_lotr_demo/hobbits                       frodo   bilbo         
legolas     legolas     0.1   /workspaces/srcpkgs_pkg/srcpkgs_lotr_demo/legolas                                             
lotr           lotr     0.1      /workspaces/srcpkgs_pkg/srcpkgs_lotr_demo/lotr elves,gimli,aragorn,gandalf hobbits

This function returns a srcpkgs object, that is a named list of srcpkg objects. You can print that object, or transform it in a data frame using as.data.frame().

pkgs <- get_srcpkgs()
print(pkgs)

df <- as.data.frame(pkgs)

loading and reloading packages

hacked R loaders

Since by default, the R loaders should be automatically hacked by srcpkgs (cf hack_r_loaders()), you may simply load and/or ttach these packages using library(), loadNamespace(), getNamespace, :: and so on:

library(elves)
loadNamespace('bilbo')
frodo::frodo()

The rationale for hacking the R loaders is not just for convenience. It’s also for writing R code that will still work once the source packages are installed.

using pkg_load()

The pkg_load() is the workhorse function to load packages. A major difference with devtools::load_all() defaults is that it does not source the test helpers, nor does it export all objects (cf export_all). The rationale is to stick as much as possible to the standard R loaders behaviour.

You may use a package name, path, package or srcpkgs object to designate the package to load:

pkg_load('lotr')
pkg_load('/workspaces/srcpkgs_pkg/srcpkgs_lotr_demo/lotr')
pkg_load(pkgs$lotr)

updating

When you execute pkg_load() on a package already loaded, it will check for changes not only in that package but also in all its dependencies (among the source packages), and will do what’s needed to roxygenize, unload, reload until your package is up-to-date inside your R session.

reset and settings

At srcpkgs startup time, i.e. when the library(srcpkgs) statement is executed, the R loaders are automatically hacked (cf hack_r_loaders()) UNLESS the hack is inhibited using the option srcpkgs.inhibit_r_loaders_hack or the environment variable SRCPKGS.INHIBIT_R_LOADERS_HACK.

Then the fist time get_srcpkgs() will be executed (for example indirectly by calling pkg_load()), srcpkgs will figure out the project root, and from this root will search for source packages, using a heuristic. Since that can take a bit of I/O time, the project root and the paths of found source packages are cached.

You may check those using the settings() function, and can change them using the reset() function.