R: Attach or load packages, and automatically install missing...

pkg_attach {xfun} | R Documentation

## 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)`.

### Usage

    pkg_attach(..., install = FALSE)

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

    loadable(pkg, strict = TRUE)

    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()`. You are recommended to set a CRAN mirror in the global option `repos` via `options()` if you want to automatically install packages.
`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).

### 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"))

[Package xfun version 0.1 Index]