MethodsList-class {methods} | R Documentation

## Class MethodsList, Defunct Representation of Methods

### Description

This class of objects was used in the original implementation of the package to control method dispatch. Its use is now defunct, but object appear as the default method slot in generic functions. This and any other remaining uses will be removed in the future.

For the modern alternative, see listOfMethods.

The details in this documentation are retained to allow analysis of old-style objects.

### Details

Suppose a function `f` has formal arguments `x` and `y`. The methods list object for that function has the object `as.name("x")` as its `argument` slot. An element of the methods named `"track"` is selected if the actual argument corresponding to `x` is an object of class `"track"`. If there is such an element, it can generally be either a function or another methods list object.

In the first case, the function defines the method to use for any call in which `x` is of class `"track"`. In the second case, the new methods list object defines the available methods depending on the remaining formal arguments, in this example, `y`.

Each method corresponds conceptually to a signature; that is a named list of classes, with names corresponding to some or all of the formal arguments. In the previous example, if selecting class `"track"` for `x`, finding that the selection was another methods list and then selecting class `"numeric"` for `y` would produce a method associated with the signature `x = "track", y = "numeric"`.

### Slots

`argument`:

  Object of class `"name"`. The name of the argument being used for dispatch at this level.

`methods`:

  A named list of the methods (and method lists) defined explicitly for this argument. The names are the names of classes, and the corresponding element defines the method or methods to be used if the corresponding argument has that class. See the details below.

`allMethods`:

  A named list, contains all the directly defined methods from the `methods` slot, plus any inherited methods. Ignored when methods tables are used for dispatch (see Methods_Details).

### Extends

Class `"OptionalMethods"`, directly.

[Package methods version 3.5.1 Index]