Editing R (programming language) (section)

=== Object-oriented programming ===
The R language has native support for [[object-oriented programming]]. There are two native [[Application framework|frameworks]], the so-called S3 and S4 systems. The former, being more informal, supports single dispatch on the first argument and objects are assigned to a class by just setting a "class" attribute in each object. The latter is a [[CLOS|Common Lisp Object System (CLOS)-like system]] of formal classes (also derived from [[S (programming language)#S4|S]]) and generic methods that supports [[multiple dispatch]] and [[multiple inheritance]]<ref>{{cite web|url=https://stat.ethz.ch/R-manual/R-devel/library/base/html/UseMethod.html|title=Class Methods|access-date=2024-04-25}}</ref>

In the example, <code>summary</code> is a [[generic function]] that dispatches to different methods depending on whether its [[Argument of a function|argument]] is a numeric [[Vector (mathematics and physics)|vector]] or a "factor":
<syntaxhighlight lang="rout">
> data <- c("a", "b", "c", "a", NA)
> summary(data)
   Length     Class      Mode 
        5 character character 
> summary(as.factor(data))
   a    b    c NA's 
   2    1    1    1 
</syntaxhighlight>