xfun: pkg_attach – R documentation

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pkg_attach

Attach or load packages, and automatically install missing packages if requested

Description

pkg_attach() is a vectorized version of library() over the package argument to attach multiple packages in a single function call. pkg_load() is a vectorized version of requireNamespace() to load packages (without attaching them). The functions pkg_attach2() and pkg_load2() are wrappers of pkg_attach(install = TRUE) and pkg_load(install = TRUE), respectively. loadable() is an abbreviation of requireNamespace(quietly = TRUE). pkg_available() tests if a package with a minimal version is available.

Usage

pkg_attach(
  ...,
  install = FALSE,
  message = getOption("xfun.pkg_attach.message", TRUE)
)

pkg_load(..., error = TRUE, install = FALSE)

loadable(pkg, strict = TRUE, new_session = FALSE)

pkg_available(pkg, version = NULL)

pkg_attach2(...)

pkg_load2(...)

Arguments

`...`	Package names (character vectors, and must always be quoted).
`install`	Whether to automatically install packages that are not available using `install.packages()`. Besides `TRUE` and `FALSE`, the value of this argument can also be a function to install packages (`install = TRUE` is equivalent to `install = install.packages`), or a character string `"pak"` (equivalent to `install = pak::pkg_install`, which requires the pak package). You are recommended to set a CRAN mirror in the global option `repos` via `options()` if you want to automatically install packages.
`message`	Whether to show the package startup messages (if any startup messages are provided in a package).
`error`	Whether to signal an error when certain packages cannot be loaded.
`pkg`	A single package name.
`strict`	If `TRUE`, use `requireNamespace()` to test if a package is loadable; otherwise only check if the package is in `.packages(TRUE)` (this does not really load the package, so it is less rigorous but on the other hand, it can keep the current R session clean).
`new_session`	Whether to test if a package is loadable in a new R session. Note that `new_session = TRUE` implies `strict = TRUE`.
`version`	A minimal version number. If `NULL`, only test if a package is available and do not check its version.

Details

These are convenience functions that aim to solve these common problems: (1) We often need to attach or load multiple packages, and it is tedious to type several library() calls; (2) We are likely to want to install the packages when attaching/loading them but they have not been installed.

Value

pkg_attach() returns NULL invisibly. pkg_load() returns a logical vector, indicating whether the packages can be loaded.

Examples

library(xfun)
pkg_attach("stats", "graphics")
# pkg_attach2('servr') # automatically install servr if it is not installed

(pkg_load("stats", "graphics"))

xfun

Miscellaneous Functions to Support Packages Maintained by 'Yihui Xie'

v0.22

MIT + file LICENSE

Authors

Yihui Xie [aut, cre, cph] (<https://orcid.org/0000-0003-0645-5666>), Wush Wu [ctb], Daijiang Li [ctb], Xianying Tan [ctb], Salim Brüggemann [ctb] (<https://orcid.org/0000-0002-5329-5987>), Christophe Dervieux [ctb]

Initial release