targets (version 0.4.1)

tar_workspace: Load a saved workspace and seed for debugging.

Description

Load the packages, workspace, and random number generator seed of target attempted with a workspace file.

Usage

tar_workspace(name, envir = parent.frame(), packages = TRUE, source = TRUE)

Arguments

name

Symbol, name of the target whose workspace to read.

envir

Environment in which to put the objects.

packages

Logical, whether to load the required packages of the target.

source

Logical, whether to run _targets.R to load user-defined global object dependencies into envir. If TRUE, then envir should either be the global environment or inherit from the global environment.

Value

This function returns NULL, but it does load the target's required packages, as well as multiple objects into the environment (envir argument) in order to replicate the workspace where the error happened. These objects include the global objects at the time tar_make() was called and the dependency targets. The random number generator seed for the target is also assigned with set.seed()

Details

If you set error = "workspace" in tar_option_set() or tar_target(), then if that target throws an error in tar_make(), it will save its workspace to an RDS file in _targets/workspaces/. Workspaces also get saved for targets supplied to the workspace argument of tar_option_set(), even individual branches. The workspace is a compact reference that allows tar_workspace() to load the target's dependencies and random number generator seed as long as the data objects are still in the data store (usually files in _targets/objects/). When you are done debugging, you can remove the workspace files using tar_destroy(destroy = "workspaces").

See Also

Other debug: tar_traceback(), tar_workspaces()

Examples

# NOT RUN {
if (identical(Sys.getenv("TAR_LONG_EXAMPLES"), "true")) {
tar_dir({ # tar_dir() runs code from a temporary directory.
tmp <- sample(1)
tar_script({
  tar_option_set(error = "workspace")
  list(
    tar_target(x, "loaded"),
    tar_target(y, stop(x))
  )
}, ask = FALSE)
# The following code throws an error for demonstration purposes.
try(tar_make())
exists("x") # Should be FALSE.
tail(.Random.seed) # for comparison to the RNG state after tar_workspace(y)
tar_workspace(y)
exists("x") # Should be TRUE.
print(x) # "loaded"
# Should be different: tar_workspace() runs set.seed(tar_meta(y, seed)$seed)
tail(.Random.seed)
})
}
# }