Dynamic branching

Version 7.8.0

Bug fixes

• Prevent drake::drake_plan(x = target(...)) from throwing an error if drake is not loaded (#1039, @mstr3336).
• Move the transformations lifecycle badge to the proper location in the docstring (#1040, @jeroen).
• Prevent readd() / loadd() from turning an imported function into a target (#1067).
• Align in-memory disk.frame targets with their stored values (#1077, @brendanf).

New features

• Implement dynamic branching (#685).
• Add a new subtargets() function to get the cached names of the sub-targets of a dynamic target.
• Add new subtargets arguments to loadd() and readd() to retrieve specific sub-targets from a parent dynamic target.
• Add new get_trace() and read_trace() functions to help track which values of grouping variables go into the making of dynamic sub-targets.
• Add a new id_chr() function to get the name of the target while make() is running.
• Implement plot(plan) (#1036).
• vis_drake_graph(), drake_graph_info(), and render_drake_graph() now
  take arguments that allow behavior to be defined upon selection of nodes. (#1031, @mstr3336).
• Add a new max_expand argument to make() and drake_config() to scale down dynamic branching (#1050, @hansvancalster).

Enhancements

• Document transformation functions in a way that avoids having to create true functions (#979).
• Avoid always invalidating the memoized layout when we set the knitr hash.
• Change the names of environments in drake_config() objects.
• Assert that prework is a language object, list of language objects, or character vector (#1 at pat-s/multicore-debugging on GitHub, @pat-s).
• Use an environment instead of a list for config$layout. Supports internal modifications by reference. Required for #685.
• Clean up the code of the parallel backends.
• Make dynamic a formal argument of target().
• Always lock/unlock the environment target by target, allowing informative error messages to appear more readily (#1062, @PedramNavid)
• Automatically ignore storrs and decorated storrs (#1071).
• Speed up memory management by avoiding a call to setdiff() and avoiding names(config$envir_targets).