drake_meta: Compute the metadata of a target or import.

Description

The metadata helps determine if the target is up to date or outdated. The metadata of imports is used to compute the metadata of targets.

Usage

drake_meta(target, config)

Arguments

target

Character scalar, name of the target to get metadata.

config

Master internal configuration list produced by drake_config().

Value

A list of metadata on a target. Does not include the file modification time if the target is a file. That piece is provided later in make() by drake:::finish_meta.

Details

Target metadata is computed with drake_meta() and then drake:::finish_meta(). This metadata corresponds to the state of the target immediately after it was built or imported in the last make() that did not skip it. The exception to this is the $missing element of the metadata, which indicates if the target/import was missing just before it was built.

Examples

Run this code

# NOT RUN {
test_with_dir("Quarantine side effects.", {
# This example is not really a user-side demonstration.
# It just walks through a dive into the internals.
# Populate your workspace and write 'report.Rmd'.
load_basic_example() # Get the code with drake_example("basic").
# Create the master internal configuration list.
config <- drake_config(my_plan)
# Optionally, compute metadata on 'small',
# including a hash/fingerprint
# of the dependencies. If meta is not supplied,
# drake_build() computes it automatically.
meta <- drake_meta(target = "small", config = config)
# Should not yet include 'small'.
cached()
# Build 'small'.
# Equivalent to just drake_build(target = "small", config = config).
drake_build(target = "small", config = config, meta = meta)
# Should now include 'small'
cached()
readd(small)
})
# }