def ensure(self, *predicates):
for pred in predicates:
ensure(self._test_predicate(pred),
lambda: self._format_error(pred),
self.exception_type,
stack_level=self.stack_level)
return self.value
def or_else(self, func):
if self:
return self
else:
res = func()
ensure(isinstance(res, Opt),
lambda: 'or_else: result Opt expected',
stack_level=2)
return res
def map(self, func):
func = to_unary(func)
if self:
res = func(self._value)
ensure(not isinstance(res, Opt),
lambda: 'map: result Opt not expected',
stack_level=2)
return Opt(res)
else:
return Opt.none()
def get_or_raise(self, exception):
ensure(self, exception, error_type=OptError)
return self._value
def some(value):
ensure(value is not None,
lambda: OptError('value expected, got None'),
stack_level=2)
return Opt(value)
def and_(self, other):
ensure(isinstance(other, Opt), lambda: 'Opt expected', stack_level=2)
return self if not self else other