Classes Corresponding to Basic Data Types

Description

Formal classes exist corresponding to the basic R data types, allowing these types to be used in method signatures, as slots in class definitions, and to be extended by new classes.

Usage

### The following are all basic vector classes.
### They can appear as class names in method signatures,
### in calls to as(), is(), and new().
"character"
"complex"
"double"
"expression"
"integer"
"list"
"logical"
"numeric"
"single"

### the class
"vector"
### is a virtual class, extended by all the above

### The following are additional basic classes
"NULL"     #  NULL objects
"function" #  function objects, including primitives
"externalptr" # raw external pointers for use in C code

"ANY"  # virtual classes used by the methods package itself
"VIRTUAL"
"missing"

Objects from the Classes

Objects can be created by calls of the form new(Class, ...), where Class is the quoted class name, and the remaining arguments if any are objects to be interpreted as vectors of this class. Multiple arguments will be concatenated.

The class "expression" is slightly odd, in that the ... arguments will not be evaluated; therefore, don't enclose them in a call to quote().

Extends

Class "vector", directly.

Methods

coerce

Methods are defined to coerce arbitrary objects to these classes, by calling the corresponding basic function, for example, as(x, "numeric") calls as.numeric(x).