Cache class for object, file or directory caching

A class to handle caching of objects, files, or directories. It generates a signature from the provided object and creates cached versions based on that signature.

Public fields

cache_dir

Directory where cached files are stored

source

path to the original file/directory/prefix

Methods

Public methods

• Cache$new()

• Cache$clear()

• Cache$clear_all()

• Cache$restore()

• Cache$is_cached()

• Cache$get_path()

• Cache$save()

• Cache$clone()

---

Method new()

Initialize a new Cache object

Usage

Cache$new(
  sig_object,
  prefix,
  cache_dir,
  save_sig = FALSE,
  kind = c("object", "file", "dir", "prefix"),
  path = NULL
)

Arguments

sig_object

Object used to generate the cache signature

prefix

Prefix for the cache filename

cache_dir

Directory where cached files are stored

save_sig

Whether to save the signature to a file

kind

Type of cache: "object", "file", "dir" or "prefix"

• object: cache an R object

• file: cache a file

• dir: cache a directory

• prefix: cache files/directories with the same prefix

path

Path to the file or directory to cache This is required when kind is "file", "dir", or "prefix"

Details

The sig_object is used to generate a unique signature for the cache. The signature is based on an expanded utils::str() representation of the object, which helps in determining if the cached version is still valid. The prefix is used to create a unique identifier for the cached files. The cache_dir is the directory where the cached files will be stored. If save_sig is TRUE, the signature will be saved to a file in the cache directory. The kind parameter determines how the cache will be handled:

• "object": The cache will store an R object.

• "file": The cache will store a file.

• "dir": The cache will store a directory.

• "prefix": The cache will store files/directories with the same prefix. The path parameter is required when kind is "file", "dir", or "prefix". It specifies the path to the file or directory to cache. If cache_dir is NULL or an empty string, caching will not be performed. If cache_dir is FALSE, caching will not be performed.

Returns

A new Cache object

Examples

\dontrun{
# Create a Cache object for an R object
cache <- Cache$new(sig_object = mtcars, prefix = "mtcars_cache",
                   cache_dir = tempdir(), save_sig = TRUE, kind = "object")
# Save the object to cache
cache$save(mtcars)
# Restore the cached object
cached_mtcars <- cache$restore()
# Check if the object is cached
cache$is_cached()  # Should return TRUE
# Clear the cache
cache$clear()
# Clear all cached objects in the cache directory
cache$clear_all()
}

---

Method clear()

Clear the current cached object/file/directory

Usage

Cache$clear()

---

Method clear_all()

Clear all cached objects in the cache directory Be careful with this operation as it will remove all cached files in the cache directory

Usage

Cache$clear_all()

---

Method restore()

Retrieve the cached object/file/directory When NULL is returned, it means the cache does not exist

Usage

Cache$restore()

Returns

The cached object if kind is "object", otherwise NULL

---

Method is_cached()

Check if we have a cached object/file/directory

Usage

Cache$is_cached()

Returns

TRUE if the cached object/file/directory exists, FALSE otherwise

---

Method get_path()

Get the path to the cached object/file/directory

Usage

Cache$get_path()

Returns

The path to the cached object/file/directory

---

Method save()

Save an object/file/directory/prefix to cache

Usage

Cache$save(data = NULL)

Arguments

data

The object to cache, or NULL for non-"object" kinds

---

Method clone()

The objects of this class are cloneable with this method.

Usage

Cache$clone(deep = FALSE)

Arguments

deep

Whether to make a deep clone.

Examples

## ------------------------------------------------
## Method `Cache$new`
## ------------------------------------------------

if (FALSE) { # \dontrun{
# Create a Cache object for an R object
cache <- Cache$new(sig_object = mtcars, prefix = "mtcars_cache",
                   cache_dir = tempdir(), save_sig = TRUE, kind = "object")
# Save the object to cache
cache$save(mtcars)
# Restore the cached object
cached_mtcars <- cache$restore()
# Check if the object is cached
cache$is_cached()  # Should return TRUE
# Clear the cache
cache$clear()
# Clear all cached objects in the cache directory
cache$clear_all()
} # }