isS4(object)asS4(object, flag = TRUE, complete = TRUE)
asS3(object, flag = TRUE, complete = TRUE)
isS4 always returns TRUE or FALSE according to
whether the internal flag marking an S4 object has been turned on for
this object. asS4 and asS3 will turn this flag on or off,
and asS3 will set the class from the objects .S3Class
slot if one exists. Note that asS3 will not turn
the object into an S3 object
unless there is a valid conversion; that is, an object of type other
than "S4" for which the S4 object is an extension, unless
argument complete is FALSE.isS4 does not rely on the methods
package, so in particular it can be used to detect the need to
require that package. asS3 uses the value of
complete to control whether an attempt is made to transform
object into a valid object of the implied S3 class. If
complete is TRUE,
then an object from an S4 class extending an S3 class will be
transformed into an S3 object with the corresponding S3 class (see
S3Part). This includes classes extending the
pseudo-classes array and matrix: such objects will have
their class attribute set to NULL. isS4 is primitive.is.object for a more general test; Introduction
for general information on S4; Classes_Details for more on S4
class definitions.
isS4(pi) # FALSE
isS4(getClass("MethodDefinition")) # TRUE
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