isS4 | R Documentation |
Tests whether the object is an instance of an S4 class.
isS4(object) asS4(object, flag = TRUE, complete = TRUE) asS3(object, flag = TRUE, complete = TRUE)
object |
Any R object. |
flag |
Optional, logical: indicate direction of conversion. |
complete |
Optional, logical: whether conversion to S3 is completed. Not usually needed, but see the details section. |
Note that 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.
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
.
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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