Same as cached_lookup, but returns the full result

Callers that need to tell a confirmed "absent" apart from an inconclusive "failed" lookup (see resolve_external_field) need the status, not just the value cached_lookup returns.

Usage

cached_lookup_result(key, dirs, lookup)

Arguments

key

List of values identifying the lookup

dirs

Cache subdirectory below the R.cache root

lookup

Function of no arguments returning a list with elements `status` ("found", "absent" or "failed") and `value`

Value

A list with `status` ("found", "absent" or "failed") and `value`