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import importlib |
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def relative_import(parent_name, rel_modules=(), rel_classes=()): |
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""" |
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Helper function to import submodules lazily in Python 3.7+ |
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Parameters |
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---------- |
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rel_modules: list of str |
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list of submodules to import, of the form .submodule |
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rel_classes: list of str |
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list of submodule classes/variables to import, of the form ._submodule.Foo |
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Returns |
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------- |
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tuple |
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Tuple that should be assigned to __all__, __getattr__ in the caller |
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""" |
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module_names = {rel_module.split(".")[-1]: rel_module for rel_module in rel_modules} |
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class_names = {rel_path.split(".")[-1]: rel_path for rel_path in rel_classes} |
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def __getattr__(import_name): |
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if import_name in module_names: |
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rel_import = module_names[import_name] |
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return importlib.import_module(rel_import, parent_name) |
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if import_name in class_names: |
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rel_path_parts = class_names[import_name].split(".") |
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rel_module = ".".join(rel_path_parts[:-1]) |
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class_name = import_name |
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class_module = importlib.import_module(rel_module, parent_name) |
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return getattr(class_module, class_name) |
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raise AttributeError( |
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"module {__name__!r} has no attribute {name!r}".format( |
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name=import_name, __name__=parent_name |
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) |
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) |
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__all__ = list(module_names) + list(class_names) |
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def __dir__(): |
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return __all__ |
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return __all__, __getattr__, __dir__ |
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