Download a file into a local cache.

This function copies a remote file to a local cache once and makes sure it is reused.

Usage

cache_download(
  url,
  ...,
  .nocache = getOption("cache.disable", default = FALSE),
  .cache = getOption("cache.download.dir", default =
    rappdirs::user_cache_dir("ggrrr-download")),
  .stale = getOption("cache.stale", default = Inf),
  .extn = NULL
)

Arguments

url

the url to download

...

Named arguments passed on to utils::download.file

method

Method to be used for downloading files. Current download methods are "internal", "libcurl", "wget", "curl" and "wininet" (Windows only), and there is a value "auto": see ‘Details’ and ‘Note’.

The method can also be set through the option "download.file.method": see options().

quiet

If TRUE, suppress status messages (if any), and the progress bar.

mode

character. The mode with which to write the file. Useful values are "w", "wb" (binary), "a" (append) and "ab". Not used for methods "wget" and "curl". See also ‘Details’, notably about using "wb" for Windows.

cacheOK

logical. Is a server-side cached value acceptable?

extra

character vector of additional command-line arguments for the "wget" and "curl" methods.

headers

named character vector of additional HTTP headers to use in HTTP[S] requests. It is ignored for non-HTTP[S] URLs. The User-Agent header taken from the HTTPUserAgent option (see options) is automatically used as the first header.

...

allow additional arguments to be passed, unused.

.nocache

an option to defeat the cacheing which can be set globally as options("cache.disable"=TRUE)

.cache

the location of the cache as a directory. May get its value from getOption("cache.path") or the default value which is rappdirs::user_cache_dir(<package_name>)

.stale

the length of time in days before considering cached data as stale.

.extn

the file name extension

Value

the path to the downloaded file