Add slice type to reverse typemap

[zhenruiliao]

SliceType was missing from _reverse_typemap, which led to KeyError: 'SliceType' when _load_type is called. I add SliceType to _reverse_typemap explicitly

[mmckerns]

@zhenruiliao: slice is already in the reverse_typemap. Can you shed some light on why this change is necessary?

[zhenruiliao]

we are getting KeyError: 'SliceType' when _load_type when unpickling objects with slices as data in our production code, which this change solved. The classes that have this problem are relatively complex but I will try to reproduce with a minimal example

[mmckerns]

Can you also check if this is true:

>>> import dill
>>> 'slice' in dill._dill._reverse_typemap.keys()
True
>>> slice in dill.Pickler.dispatch.keys()
True
>>>

[mmckerns]

If you look at what's in the reverse typemap, the keys are generally the names that are used in builtins and then from types. So, slice is preferred over SliceType. Also, if SliceType is needed, then BoolType and so on should also be needed as keys.

>>> import dill
>>> dill._dill._reverse_typemap.keys()
dict_keys(['bool', 'memoryview', 'bytearray', 'bytes', 'classmethod', 'complex', 'dict', 'enumerate', 'filter', 'float', 'frozenset', 'property', 'int', 'list', 'map', 'object', 'range', 'reversed', 'set', 'slice', 'staticmethod', 'str', 'super', 'tuple', 'type', 'zip', 'BaseException', 'Exception', 'TypeError', 'StopAsyncIteration', 'StopIteration', 'GeneratorExit', 'SystemExit', 'KeyboardInterrupt', 'ImportError', 'ModuleNotFoundError', 'OSError', 'EnvironmentError', 'IOError', 'EOFError', 'RuntimeError', 'RecursionError', 'NotImplementedError', 'NameError', 'UnboundLocalError', 'AttributeError', 'SyntaxError', 'IndentationError', 'TabError', 'LookupError', 'IndexError', 'KeyError', 'ValueError', 'UnicodeError', 'UnicodeEncodeError', 'UnicodeDecodeError', 'UnicodeTranslateError', 'AssertionError', 'ArithmeticError', 'FloatingPointError', 'OverflowError', 'ZeroDivisionError', 'SystemError', 'ReferenceError', 'MemoryError', 'BufferError', 'Warning', 'UserWarning', 'DeprecationWarning', 'PendingDeprecationWarning', 'SyntaxWarning', 'RuntimeWarning', 'FutureWarning', 'ImportWarning', 'UnicodeWarning', 'BytesWarning', 'ResourceWarning', 'ConnectionError', 'BlockingIOError', 'BrokenPipeError', 'ChildProcessError', 'ConnectionAbortedError', 'ConnectionRefusedError', 'ConnectionResetError', 'FileExistsError', 'FileNotFoundError', 'IsADirectoryError', 'NotADirectoryError', 'InterruptedError', 'PermissionError', 'ProcessLookupError', 'TimeoutError', 'FunctionType', 'LambdaType', 'CodeType', 'MappingProxyType', 'GeneratorType', 'CoroutineType', 'AsyncGeneratorType', 'MethodType', 'BuiltinFunctionType', 'BuiltinMethodType', 'WrapperDescriptorType', 'MethodWrapperType', 'MethodDescriptorType', 'ClassMethodDescriptorType', 'ModuleType', 'TracebackType', 'FrameType', 'GetSetDescriptorType', 'MemberDescriptorType', 'CellType', 'PartialType', 'SuperType', 'ItemGetterType', 'AttrGetterType', 'FileType', 'BufferedRandomType', 'BufferedReaderType', 'BufferedWriterType', 'TextWrapperType', 'PyBufferedRandomType', 'PyBufferedReaderType', 'PyBufferedWriterType', 'PyTextWrapperType', 'DictKeysType', 'DictValuesType', 'DictItemsType', 'OdictKeysType', 'OdictValuesType', 'OdictItemsType', 'ExitType', 'SymtableStentryType', 'PyCapsuleType'])

Related to some of the conversation in #472.

I'm going to close this. However, if you can provide a case that demonstrates how SliceType etc is needed, then we should reopen it.