| MethodsList-class {methods} | R Documentation |
This class of objects was used in the original implementation of the package to control method dispatch. Its use is now deprecated, 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.
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".
Class "OptionalMethods", directly.