tar_renv: Set up package dependencies for compatibility with `renv`

Description

Write package dependencies to a script file (by default, named _packages.R in the root project directory). Each package is written to a separate line as a standard library() call (e.g. library(package)) so renv can identify them automatically. This is only necessary if the user invokes tar_option_set() or tar_target() to declare packages rather than the usual library() or namespaced call (i.e. package::function()). See Details for more information.

Usage

tar_renv(
  packages = targets::tar_option_get("packages"),
  path = "_packages.R",
  ask = NULL
)

Arguments

packages

Character vector of packages to load right before the target builds. Use tar_option_set() to set packages globally for all subsequent targets you define.

path

Character of length 1, path to the script file to populate with library() calls.

ask

Logical, whether to ask before writing if _packages.R already exists. If NULL, defaults to Sys.getenv("TAR_ASK"). (Set to "true" or "false" with Sys.setenv()). If ask and the TAR_ASK environment variable are both indeterminate, defaults to interactive().

Value

Nothing, invisibly.

Details

This function gets called for its side-effect, which writes package dependencies provided to the packages argument to a script. If you do not explicitly set the packages argument, tar_renv() will only detect the packages that tar_option_get("packages") returns at that point in the code. The generated file should not be edited by hand and will be overwritten each time tar_renv() runs non-interactively.

With the script written by tar_renv(), renv is able to crawl the file to identify package dependencies (with renv::dependencies()). Calling renv::init() after tar_renv() has ran will set up a project-local R library. This allows your targets pipeline to have its own self-contained R library separate from your standard R library. See https://rstudio.github.io/renv/index.html for more information.

Examples

Run this code

# NOT RUN {
tar_dir({
  tar_option_set(packages = c("tibble", "qs"))
  tar_renv()
  readLines("_packages.R")
})
# }