why would you need srcpkgs?

loading

devtools is designed to manage a single source package. Let’s use it to load our lotr source package:

load_all('lotr')

## ℹ Loading lotr

## Error in `load_depends()`:
## ! The package "hobbits" is required.

–> devtools can NOT load lotr since it can not possibly find the hobbits package, which is a dependency.

Let’s help him:

load_all('hobbits')

## ℹ Loading hobbits

## Error in `load_depends()`:
## ! The package "bilbo" is required.

–> same problem

Here is how we must load the packages, following the dependencies order. Note that we also need to roxygenize them (using document())

document('frodo')
load_all('frodo')
document('bilbo')
load_all('frodo')
document('hobbits')
load_all('hobbits')

document('legolas')
load_all('legolas')
document('galadriel')
load_all('galadriel')
document('elves')
load_all('elves')

document('gimli')
load_all('gimli')
document('aragorn')
load_all('aragorn')
document('gandalf')
load_all('gandalf')

and finally we can load it

document('lotr')

## ℹ Updating lotr documentation
## ℹ Loading lotr

load_all('lotr')

## ℹ Loading lotr

# use it
str(lotr())

## List of 5
##  $ hobbits:List of 1
##   ..$ frodo:List of 4
##   .. ..$ first  : chr "Frodo"
##   .. ..$ last   : chr "Baggins"
##   .. ..$ weapons: chr [1:2] "sting" "barrow-blade"
##   .. ..$ race   : chr "hobbit"
##  $ elves  :List of 2
##   ..$ galadriel:List of 4
##   .. ..$ first  : chr "Galadriel"
##   .. ..$ last   : chr NA
##   .. ..$ weapons: chr "nenya"
##   .. ..$ race   : chr "elf"
##   ..$ legolas  :List of 4
##   .. ..$ first  : chr "Legolas"
##   .. ..$ last   : chr "Greenleaf"
##   .. ..$ weapons: chr "nebownya"
##   .. ..$ race   : chr "elf"
##  $ dwarves:List of 1
##   ..$ gimli:List of 4
##   .. ..$ first  : chr "Gimli"
##   .. ..$ last   : chr "Durin"
##   .. ..$ weapons: chr "axe"
##   .. ..$ race   : chr "dwarf"
##  $ humans :List of 1
##   ..$ aragorn:List of 4
##   .. ..$ first  : chr "Aragorn"
##   .. ..$ last   : chr "Strider"
##   .. ..$ weapons: chr "anduril"
##   .. ..$ race   : chr "human"
##  $ ainur  :List of 1
##   ..$ gandalf:List of 4
##   .. ..$ first  : chr "Gandalf"
##   .. ..$ last   : chr "Mithrandir"
##   .. ..$ weapons: chr "glamdring"
##   .. ..$ race   : chr "ainur"

editing and reloading

Let’s modify one of the direct dependency of lotr, e.g. the hobbits package. Currently:

names(lotr()$hobbits)

## [1] "frodo"

lines <- readLines('hobbits/R/main.R')
cat(lines, sep = '\n')

## #' list the available hobbits
## #' @return hobbit names as character
## #' @export
## hobbits <- function() {
##   res <- list()
##   # N.B: easier to edit programmatically in the vignette this way
##   res$frodo <- frodo::frodo() # in imports
## 
##   res
## }

Edit hobbits/R/main.R and comment out bilbo, which comes from the bilbo package in Depends.

edited_lines <- grep('bilbo', lines, invert = TRUE, value = TRUE)
writeLines(edited_lines, 'hobbits/R/main.R')

Let’s try to apply our changes:

load_all('lotr')

## ℹ Loading lotr

names(lotr()$hobbits)

## [1] "frodo"

–> load_all() can not properly reload our package, since it does not know that a dependency has been modified.

To apply the changes:

load_all('hobbits')

## ℹ Loading hobbits

names(lotr()$hobbits)

## [1] "frodo"

–> now it works. Note that this is because load_all() is now able to force the unload of a package even though it is needed by another package:

unloadNamespace('hobbits')

## Error: package 'hobbits' is required by 'lotr' so will not be detached

But:

devtools::unload('hobbits')

Note that now lotr is broken:

lotr()

## Error in hobbits(): could not find function "hobbits"

Let’s fix it

load_all('hobbits')

## ℹ Loading hobbits

names(lotr())

## [1] "hobbits" "elves"   "dwarves" "humans"  "ainur"

unloading

the srcpkgs::pkg_unload() takes into account the dependencies between the source packages.

plan <- pkg_unload('bilbo')

## executing unload on lotr

## executing unload on hobbits

## executing unload on bilbo

print(plan)

##   package action
## 1    lotr unload
## 2 hobbits unload
## 3   bilbo unload

unload all our packages to start from a clean state. We will also

for (pkg in get_srcpkgs()) pkg_unload(pkg)

## executing unload on aragorn

## executing unload on elves

## executing unload on frodo

## executing unload on galadriel

## executing unload on gandalf

## executing unload on gimli

## executing unload on legolas

loading

srcpkgs::pkg_load() takes care of everything: it roxygenizes the packages if needed, and load them in the appropriate order:

plan <- pkg_load('lotr')

## executing load on aragorn

## ℹ Loading aragorn
## executing load on bilbo
## 
## ℹ Loading bilbo
## executing load on frodo
## 
## ℹ Loading frodo
## executing load on galadriel
## 
## ℹ Loading galadriel
## executing load on gandalf
## 
## ℹ Loading gandalf
## executing load on gimli
## 
## ℹ Loading gimli
## executing load on legolas
## 
## ℹ Loading legolas
## executing load on elves
## 
## ℹ Loading elves
## executing load on hobbits
## 
## ℹ Loading hobbits
## executing load on lotr
## 
## ℹ Loading lotr

print(plan)

##      package action params
## 1    aragorn   load   NULL
## 2      bilbo   load   TRUE
## 3      frodo   load   NULL
## 4  galadriel   load   NULL
## 5    gandalf   load   NULL
## 6      gimli   load   NULL
## 7    legolas   load   NULL
## 8      elves   load   NULL
## 9    hobbits   load   TRUE
## 10      lotr   load   TRUE

print(names(lotr()))

## [1] "hobbits" "elves"   "dwarves" "humans"  "ainur"

editing and reloading

Let’s edit the frodo package, and change the weapon from sting to sword:

lotr()$hobbits$frodo

## $first
## [1] "Frodo"
## 
## $last
## [1] "Baggins"
## 
## $weapons
## [1] "sting"        "barrow-blade"
## 
## $race
## [1] "hobbit"

lines <- readLines('frodo/R/main.R')
cat(lines, sep = '\n')

## #' provides frodo
## #' @return as a list
## #' @export
## frodo <- function() {
##   list(
##     first = 'Frodo',
##     last = 'Baggins',
##     weapons = c('sting', 'barrow-blade'),
##     race = 'hobbit'
##   )
## }

edited_lines <- sub('sting', 'sword', lines)
writeLines(edited_lines, 'frodo/R/main.R')

Now let’s ask srcpkgs to make sure the lotr package is up-to-date:

plan <- pkg_load('lotr')

## package '/tmp/RtmpFmkvCZ/file307653aaabc0/srcpkgs_lotr_demo/frodo' has changed: 'R/main.R' was "modified"

## executing unload on lotr

## executing unload on hobbits

## executing unload on frodo

## executing load on frodo

## ℹ Updating frodo documentation
## ℹ Loading frodo
## ℹ Loading frodo
## executing load on hobbits
## 
## ℹ Loading hobbits
## executing load on lotr
## 
## ℹ Loading lotr

print(plan)

##   package action params
## 1    lotr unload   NULL
## 2 hobbits unload   NULL
## 3   frodo unload   NULL
## 4   frodo   load   TRUE
## 5 hobbits   load   TRUE
## 6    lotr   load   TRUE

–> It figured out that frodo was modified, and needed to be reloaded, and for that all its dependents needed to be also properly unloaded and re-loaded.

lotr()$hobbits$frodo$weapons

## [1] "sword"        "barrow-blade"