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from functools import partial
from importlib import import_module
def import_string(dotted_path, dotted_attributes=None):
"""
Import a dotted module path and return the attribute/class designated by the
last name in the path. When a dotted attribute path is also provided, the
dotted attribute path would be applied to the attribute/class retrieved from
the first step, and return the corresponding value designated by the
attribute path. Raise ImportError if the import failed.
"""
try:
module_path, class_name = dotted_path.rsplit(".", 1)
except ValueError:
raise ImportError("%s doesn't look like a module path" % dotted_path)
module = import_module(module_path)
try:
result = getattr(module, class_name)
except AttributeError:
raise ImportError(
'Module "%s" does not define a "%s" attribute/class'
% (module_path, class_name)
)
if not dotted_attributes:
return result
attributes = dotted_attributes.split(".")
traveled_attributes = []
try:
for attribute in attributes:
traveled_attributes.append(attribute)
result = getattr(result, attribute)
return result
except AttributeError:
raise ImportError(
'Module "%s" does not define a "%s" attribute inside attribute/class "%s"'
% (module_path, ".".join(traveled_attributes), class_name)
)
def lazy_import(dotted_path, dotted_attributes=None):
return partial(import_string, dotted_path, dotted_attributes)
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