Creates a new Parsable subclass (of the given parsable_type) from
the given xml.
An object of the given parsable_type is created, and its pre_parse_xml, parse_xml and
post_parse_xml class functions called on the XML tree obtained from xml. pre_parse_xml and
post_parse_xml are called once each on the root node of the tree, while parse_xml is called for each of the child
nodes of the root node.
If length is -1, xml will be assumed to be null-terminated.
If an error occurs during parsing, a suitable error from ParserError will be returned.
| parsable_type |
the type of the class represented by the XML |
| xml |
the XML for just the parsable object, with full namespace declarations |
| length |
the length of |
|
a new Parsable, or |