R: Internal Generic Functions: Internal Generic Functions


Many R-internal functions are generic and allow methods to be written for.


The following primitive and internal functions are generic, i.e., you can write methods for them:

[, [[, $, [<-, [[<-, $<-,

length, length<-, dimnames, dimnames<-, dim, dim<-, names, names<-, levels<-,

c, unlist, cbind, rbind,

as.character, as.complex, as.double, as.integer, as.logical, as.raw, as.vector, is.array, is.matrix, is.na, is.nan, is.numeric, rep, seq.int (which dispatches methods for "seq") and xtfrm

In addition, is.name is a synonym for is.symbol and dispatches methods for the latter. Similarly, as.numeric is a synonym for as.double and dispatches methods for the latter, i.e., S3 methods are for as.double, whereas S4 methods are to be written for as.numeric.

Note that all of the group generic functions are also internal/primitive and allow methods to be written for them.

.S3PrimitiveGenerics is a character vector listing the primitives which are internal generic and not group generic. Currently as.vector, cbind, rbind and unlist are the internal non-primitive functions which are internally generic.

For efficiency, internal dispatch only occurs on objects, that is those for which is.object returns true.

See Also

methods for the methods which are available.

Questions? Problems? Suggestions? or email at ian@mutexlabs.com.

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