| | |
| | """ Utilities for developers only. |
| | These are not visible to users (not automatically imported). And should not |
| | appeared in docs.""" |
| | |
| |
|
| |
|
| | def create_dummy_class(klass, dependency, message=""): |
| | """ |
| | When a dependency of a class is not available, create a dummy class which throws ImportError |
| | when used. |
| | |
| | Args: |
| | klass (str): name of the class. |
| | dependency (str): name of the dependency. |
| | message: extra message to print |
| | Returns: |
| | class: a class object |
| | """ |
| | err = "Cannot import '{}', therefore '{}' is not available.".format(dependency, klass) |
| | if message: |
| | err = err + " " + message |
| |
|
| | class _DummyMetaClass(type): |
| | |
| | def __getattr__(_, __): |
| | raise ImportError(err) |
| |
|
| | class _Dummy(object, metaclass=_DummyMetaClass): |
| | |
| | def __init__(self, *args, **kwargs): |
| | raise ImportError(err) |
| |
|
| | return _Dummy |
| |
|
| |
|
| | def create_dummy_func(func, dependency, message=""): |
| | """ |
| | When a dependency of a function is not available, create a dummy function which throws |
| | ImportError when used. |
| | |
| | Args: |
| | func (str): name of the function. |
| | dependency (str or list[str]): name(s) of the dependency. |
| | message: extra message to print |
| | Returns: |
| | function: a function object |
| | """ |
| | err = "Cannot import '{}', therefore '{}' is not available.".format(dependency, func) |
| | if message: |
| | err = err + " " + message |
| |
|
| | if isinstance(dependency, (list, tuple)): |
| | dependency = ",".join(dependency) |
| |
|
| | def _dummy(*args, **kwargs): |
| | raise ImportError(err) |
| |
|
| | return _dummy |
| |
|