def create_variant (self, value, scope, datatype=None):
"""Creates a `Variant` of this topic name with the specified
string `value` and `scope`.
If `datatype` is None, the newly created `Variant` will have
the datatype xsd:string.
The newly created `Variant` will contain all themes from the
parent name and the themes specified in `scope`.
:param value: the string value or locator which represents an IRI
:type value: string or `Locator`
:param scope: list of themes
:type scope: list of `Topic`s
:rtype: `Variant`
"""
if value is None:
raise ModelConstraintException(self, 'The value may not be None')
if not scope:
raise ModelConstraintException(self, 'The scope may not be None')
if type(scope) not in (type([]), type(())):
scope = [scope]
if scope == list(self.get_scope()):
raise ModelConstraintException(
self, 'The variant would be in the same scope as the parent')
if datatype is None:
if isinstance(value, Locator):
datatype = Locator(XSD_ANY_URI)
elif isinstance(value, str):
datatype = Locator(XSD_STRING)
if isinstance(value, Locator):
value = value.to_external_form()
variant = Variant(name=self, datatype=datatype.to_external_form(),
value=value, topic_map=self.topic_map)
variant.save()
for theme in scope:
variant.scope.add(theme)
return variant
