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# generics
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`generics` is designed to help package authors reduce dependencies by
providing a set of generic methods that can be imported. For example, if
a package author wanted to include a `tidy` method for their object,
they would have to import the `broom` package to do so. This would work
but would potentially increase the number of package dependencies
required to install and/or test the package.
## Installation
To install `generics` from CRAN, use:
``` r
install.packages("generics")
```
To install the development version, use:
``` r
# install.packages("pak")
pak::pak("r-lib/generics")
```
## Usage
`generics` is a simple, lightweight package that contains S3 generics to
be used by other packages. Some examples are:
``` r
library(generics)
#>
#> Attaching package: 'generics'
#> The following objects are masked from 'package:base':
#>
#> as.difftime, as.factor, as.ordered, intersect, is.element, setdiff,
#> setequal, union
fit
#> function(object, ...) {
#> UseMethod("fit")
#> }
#> <bytecode: 0x107df2b38>
#> <environment: namespace:generics>
tidy
#> function(x, ...) {
#> UseMethod("tidy")
#> }
#> <bytecode: 0x107e583a8>
#> <environment: namespace:generics>
```
To use `generics` with your package, we recommend that you import and
re-export the generic(s) of interest. For example, if you want to
provide a method for the S3 `explain()` method, you’d using the
following `roxygen2` code:
``` r
#' @importFrom generics explain
#' @export
generics::explain
```
As an example, the [recipes](https://github.com/tidymodels/recipes)
package defines a number of `tidy()` S3 methods by importing this
package (whereas it previously depended on `broom`).
## Documentation
When searching for help on a method that is exported from `generics` by
one or more packages, using `?method` will show entries for all exported
methods. If the version from `generics` is selected, the Methods section
dynamically lists all specific methods exported by any loaded packages.
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