When handling child files for lessons, it is important that changes in child files will cause the source file to change as well.
Arguments
- checksums
the hashes of the parent files
- files
the relative path of the parent files to the
root_path- children
a named list of character vectors specifying the child files for each parent file in order of appearance. These paths are relative to the folder of the parent file.
- root_path
the root path to the lesson.
- lsn
a pegboard::Lesson object
Value
get_child_files()a named list of charcter vectors specifying the child files within files in a lesson.hash_with_children()a character vector of hashes of the same length as the parent files.
Details
The
get_child_files()function finds the child files from a pegboard::Lesson object.Because we use a text database that relies on the hash of the file to determine if a file should be rebuilt,
hash_with_children()piggybacks on this paradigm by assigning a unique hash to a parent file with children that is the hash of the vector of hashes of the files. The hash of hashes is created withrlang::hash().
Examples
# This demonstration will show how a temporary database can be set up. It
# will only work with a sandpaper lesson
# setup -----------------------------------------------------------------
# The setup needs to include an R Markdown file with a child file.
tmp <- tempfile()
on.exit(fs::dir_delete(tmp), add = TRUE)
#> Error: [ENOENT] Failed to search directory '/tmp/RtmpUWqX2P/file18807b1194a0': no such file or directory
create_lesson(tmp, rmd = FALSE, open = FALSE)
#> → Creating Lesson in /tmp/RtmpUWqX2P/file18807b1194a0...
#> ℹ No schedule set, using Rmd files in episodes/ directory.
#> → Creating Lesson in /tmp/RtmpUWqX2P/file18807b1194a0...
#> → To remove this message, define your schedule in config.yaml or use `set_episodes()` to generate it.
#> → Creating Lesson in /tmp/RtmpUWqX2P/file18807b1194a0...
#> ────────────────────────────────────────────────────────────────────────
#> → Creating Lesson in /tmp/RtmpUWqX2P/file18807b1194a0...
#> ℹ To save this configuration, use
#>
#> set_episodes(path = path, order = ep, write = TRUE)
#> → Creating Lesson in /tmp/RtmpUWqX2P/file18807b1194a0...
#> ✔ First episode created in /tmp/RtmpUWqX2P/file18807b1194a0/episodes/introduction.md
#> → Creating Lesson in /tmp/RtmpUWqX2P/file18807b1194a0...
#> ℹ Workflows up-to-date!
#> → Creating Lesson in /tmp/RtmpUWqX2P/file18807b1194a0...
#> ✔ Lesson successfully created in /tmp/RtmpUWqX2P/file18807b1194a0
#> → Creating Lesson in /tmp/RtmpUWqX2P/file18807b1194a0...
#> /tmp/RtmpUWqX2P/file18807b1194a0
# get namespace to use internal functions
sp <- asNamespace("sandpaper")
db <- fs::path(tmp, "site/built/md5sum.txt")
resources <- fs::path(tmp, c("episodes/introduction.md", "index.md"))
# create child file
writeLines("Hello from another file!\n",
fs::path(tmp, "episodes", "files", "hi.md"))
# use child file
cat("\n\n```{r child='files/hi.md'}\n```\n",
file = resources[[1]], append = TRUE)
# convert to Rmd
fs::file_move(resources[[1]], fs::path_ext_set(resources[[1]], "Rmd"))
resources[[1]] <- fs::path_ext_set(resources[[1]], "Rmd")
set_episodes(tmp, fs::path_file(resources[[1]]), write = TRUE)
# get_child_files ------------------------------------------------------
# we can get the child files by scanning the Lesson object
lsn <- sp$this_lesson(tmp)
class(lsn)
#> [1] "Lesson" "R6"
children <- sp$get_child_files(lsn)
print(children)
#> $introduction.Rmd
#> [1] "files/hi.md"
#>
# hash_with_children ---------------------------------------------------
# get hash of parent
phash <- tools::md5sum(resources[[1]])
rel_parent <- fs::path_rel(resources[[1]], start = tmp)
sp$hash_with_children(phash, rel_parent, children, tmp)
#> episodes/introduction.Rmd
#> "f0803606fb41fb5ba9d03df618d492ae"
# demonstrate how this works ----------------
# the combined hashes have their names removed and then `rlang::hash()`
# creates the hash of the unnamed hashes.
chash <- tools::md5sum(fs::path(tmp, "episodes", children[[1]]))
hashes <- unname(c(phash, chash))
print(hashes)
#> [1] "4c6b9769ec953e27d83c6c707d549b82"
#> [2] "a649c757324fc9c289e38f3d77c206d5"
rlang::hash(hashes)
#> [1] "f0803606fb41fb5ba9d03df618d492ae"