Package Evaluation Policy Class — policy • val.meter

A descriptor of how package resources should be discovered, indicating which types of package resources should be considered and how they must be used to produce consistently sourced information.

Usage

policy(
  accepted_resources = list(
    source_archive_resource,
    source_code_resource,
    install_resource
  ),
  source_resources = list(
    repo_resource
  ),
  permissions = class_permissions(FALSE)
)

Arguments

accepted_resources: A list of resources types to permit. Ordered by priority, highest to lowest.
source_resources: A list of additional resource types, which may be used to discover a resource of an accepted type. For example, even if only source_archive_resource()s are accepted, a repo_resource() could be used as a means of acquiring the archive source, so long as it can be S7::convert()ed into a source_archive_resource().
permissions: Behavioral permissions provided for resource acquisition. For example, downloading and installing source code for more accurate metric evaluation requires the "network" and "write" permissions.

Details

The policy takes effect when packages are passed to pkg(), limiting how package resources can be discovered. A policy can be applied globally using provided options.

Examples

if (FALSE) { # \dontrun{
# discover locally installed file path, create `pkg` from `local_resource`
pkg(find.package("val.meter"))

# disable local resource discovery
options(val.meter.policy = policy(
  accepted_resources = list(source_archive_resource)
))

# expect error - unable to discover resource
tryCatch(
  pkg(find.package("val.meter")),
  error = function(error, ...) message(error$message)
)
} # }