max_expand and text_drake_graph()

Version 7.3.0

Bug fixes

• Accommodate rlang's new interpolation operator {{, which was causing make() to fail when drake_plan() commands are enclosed in curly braces (#864).
• Move "config$lock_envir <- FALSE" from loop_build() to backend_loop(). This makes sure config$envir is correctly locked in make(parallelism = "clustermq").
• Convert factors to characters in the optional .data argument of map() and cross() in the DSL.
• In the DSL of drake_plan(), repair cross(.data = !!args), where args is an optional data frame of grouping variables.
• Handle trailing slashes in file_in()/file_out() directories for Windows (#855).
• Make .id_chr work with combine() in the DSL (#867).
• Do not try make_spinner() unless the version of cli is at least 1.1.0.

New features

• Add functions text_drake_graph() (and r_text_drake_graph() and render_text_drake_graph()). Uses text art to print a dependency graph to the terminal window. Handy for when users SSH into remote machines without X Window support.
• Add a new max_expand argument to drake_plan(), an optional upper bound on the lengths of grouping variables for map() and cross() in the DSL. Comes in handy when you have a massive number of targets and you want to test on a miniature version of your workflow before you scale up to production.

Enhancements

• Delay the initialization of clustermq workers for as long as possible. Before launching them, build/check targets locally until we reach an outdated target with hpc equal to FALSE. In other words, if no targets actually require clustermq workers, no workers get created.
• In make(parallelism = "future"), reset the config$sleep() backoff interval whenever a new target gets checked.
• Add a "done" message to the console log file when the workflow has completed.
• Replace CodeDepends with a base R solution in code_to_plan(). Fixes a CRAN note.
• The DSL (transformations in drake_plan()) is no longer experimental.
• The callr API (r_make() and friends) is no longer experimental.
• Deprecate the wildcard/text-based functions for creating plans: evaluate_plan(), expand_plan(), map_plan(), gather_plan(), gather_by(), reduce_plan(), reduce_by().
• Change some deprecated functions to defunct: deps(), max_useful_jobs(), and migrate_drake_project().