def type_check(self, type_):
if not isinstance_generic(type_, self.type_):
bound = concretize_typevars(get_generic_args(self.type_)[0])
raise self.exc_cls(
self.type_,
type_,
TypeError("{} is not a subclass of {}".format(type_, bound)),
)
return type_
def instance_from(
__classpath__=None,
__args__=None,
__kwargs__=None,
__constructor__=None,
target_type=None,
):
"""
Instantiate general values from configuration files. E.g. with the json-compatible configuration
conf = {"__classpath__":"sklearn.cluster.KMeans", "__kwargs__": {"n_clusters": 10, "n_init": 10}},
instance_from(**conf) returns an sklearn.cluster.KMeans clustering model.
:param __classpath__: str, optional path to the class to be instantiated. If no __constructor__ is passed, this
will be called directly, otherwise it will be used for a final instance check.
:param __args__: optional positional args to be passed to the class constructor (or function if classpath refers to
a general callable)
:param __kwargs__: optional keyword args to be passed to the class constructor (or function if classpath refers to a
general callable)
:param __constructor__: optional path to a callable to call to construct the desired instance
:param target_type: optional type to check the classpath against before attempting to inflate an instance
:return: an instance of the class (or the results of calling the function) identified by classpath
"""
logger.debug(
"Attempting to instantiate {} instance with{} args {} and kwargs {}".
format(
__classpath__,
" constructor {},".format(__constructor__)
if __constructor__ is not None else "",
__args__,
__kwargs__,
))
if __classpath__ is not None:
cls = import_type(__classpath__)
if not isinstance(cls, TYPE_TYPES):
raise TypeError(
"classpath {} does not specify a class or type; got {}".format(
__classpath__, cls))
# don't waste time on the construction if the specified type is incorrect
if target_type is not None:
target_type_ = concretize_typevars(target_type)
if not issubclass_generic(cls, target_type_):
raise TypeError(
"classpath {} does not specify a generic subclass of the target type {}"
.format(__classpath__, target_type))
# only check the instance if the constructor is other than the class itself
instance_check = __constructor__ is not None
else:
instance_check = False
cls = None
if __constructor__ is not None:
constructor = import_object(__constructor__)
if not callable(constructor):
raise TypeError(
"constructor {} does not specify a callable; got {}".format(
__constructor__, constructor))
elif cls is None:
raise ValueError("Must pass either __classpath__ or __constructor__")
else:
constructor = cls
wrapper = typed_config_callable(constructor)
if __kwargs__ is None and __args__ is None:
obj = wrapper()
elif __kwargs__ is None:
obj = wrapper(*__args__)
elif __args__ is None:
obj = wrapper(**__kwargs__)
else:
obj = wrapper(*__args__, **__kwargs__)
if instance_check and not isinstance_generic(obj, cls):
raise TypeError(
"Inflation using constructor {} resulted in a {} instance; expected {}"
.format(constructor, type(obj), cls))
logger.info("Instantiated {} instance successfully{}".format(
__classpath__,
" with constructor {}".format(__constructor__)
if __constructor__ is not None else "",
))
return obj
def __init__(self, type_, *args):
super().__init__(type_, *args)
self.type_ = concretize_typevars(eval_type_tree(type_))
def concretize_annotation(ann, globals_):
return concretize_typevars(eval_forward_refs(ann, globals_))
def __init__(self, type_, value, exc=None):
super().__init__(type_, value)
self.type_ = concretize_typevars(eval_type_tree(type_))
self.value = value
self.exc = exc