File-backed read-only Daf class.

Concrete DafReadOnly subclass instantiated by files_daf() when opened with mode "r". All mutating format_* generics reject calls on this class with a clear "store opened read-only" error.

Usage

FilesDafReadOnly(
  name = character(0),
  internal = new.env(parent = emptyenv()),
  cache = new.env(parent = emptyenv()),
  axis_version_counter = new.env(parent = emptyenv()),
  vector_version_counter = new.env(parent = emptyenv()),
  matrix_version_counter = new.env(parent = emptyenv())
)

Arguments

name

Human-readable identifier for the Daf store.

internal

Internal per-store environment used by format backends to stash backend-specific state; reserved for package use.

cache

Three-tier cache environment (mapped / memory / query). See new_cache_env().

axis_version_counter

Environment tracking per-axis mutation counters; invalidates cached reads when an axis is modified.

vector_version_counter

Environment tracking per-vector mutation counters.

matrix_version_counter

Environment tracking per-matrix mutation counters.

Examples

if (FALSE) { # \dontrun{
d <- files_daf("/path/to/existing/store", mode = "r")
inherits(d, "dafr::FilesDafReadOnly")
} # }