ExtensionType class inherits from
DataType, but also defines
extra methods specific to extension types:
$storage_type(): Returns the underlying DataType used to store
$storage_id(): Returns the Type identifier corresponding to the
$extension_name(): Returns the extension name.
$extension_metadata(): Returns the serialized version of the extension
metadata as a
$extension_metadata_utf8(): Returns the serialized version of the
extension metadata as a UTF-8 encoded string.
In addition, subclasses may override the following methos to customize the behaviour of extension classes.
$deserialize_instance(): This method is called when a new ExtensionType
is initialized and is responsible for parsing and validating
the serialized extension_metadata (a
such that its contents can be inspected by fields and/or methods
of the R6 ExtensionType subclass. Implementations must also check the
storage_type to make sure it is compatible with the extension type.
$as_vector(extension_array): Convert an Array or ChunkedArray to an R
vector. This method is called by
as.vector() on ExtensionArray
objects, when a RecordBatch containing an ExtensionArray is
converted to a
data.frame(), or when a ChunkedArray (e.g., a column
in a Table) is converted to an R vector. The default method returns the
converted storage array.
$ToString() Return a string representation that will be printed
to the console when this type or an Array of this type is printed.