ExtensionType class

ExtensionType class

Methods

TheExtensionType class inherits fromDataType, but also definesextra methods specific to extension types:

• $storage_type(): Returns the underlyingDataType used to storevalues.

• $storage_id(): Returns theType identifier corresponding to the$storage_type().

• $extension_name(): Returns the extension name.

• $extension_metadata(): Returns the serialized version of the extensionmetadata as araw() vector.

• $extension_metadata_utf8(): Returns the serialized version of theextension metadata as a UTF-8 encoded string.

• $WrapArray(array): Wraps a storageArray into anExtensionArraywith this extension type.

In addition, subclasses may override the following methods to customizethe behaviour of extension classes.

• $deserialize_instance(): This method is called when a new ExtensionTypeis initialized and is responsible for parsing and validatingthe serialized extension_metadata (araw() vector)such that its contents can be inspected by fields and/or methodsof the R6 ExtensionType subclass. Implementations must also check thestorage_type to make sure it is compatible with the extension type.

• $as_vector(extension_array): Convert anArray orChunkedArray to an Rvector. This method is called byas.vector() onExtensionArrayobjects, when aRecordBatch containing anExtensionArray isconverted to adata.frame(), or when aChunkedArray (e.g., a columnin aTable) is converted to an R vector. The default method returns theconverted storage array.

• $ToString() Return a string representation that will be printedto the console when this type or an Array of this type is printed.