Details
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Bug
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Status: Open
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P3
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Resolution: Unresolved
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None
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None
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None
Description
Typehints may be given as string literals: https://www.python.org/dev/peps/pep-0484/#forward-references
These are currently not evaluated and result in errors.
Example 1:
def test_typed_callable_string_hints(self):
def do_fn(element: 'int') -> 'typehints.List[str]':
return [[str(element)] * 2]
result = [1, 2] | beam.ParDo(do_fn)
self.assertEqual([['1', '1'], ['2', '2']], sorted(result))
This results in:
> return issubclass(sub, base) E TypeError: issubclass() arg 2 must be a class or tuple of classes typehints.py:1168: TypeError
Example 2:
def test_typed_dofn_string_hints(self):
class MyDoFn(beam.DoFn):
def process(self, element: 'int') -> 'typehints.List[str]':
return [[str(element)] * 2]
result = [1, 2] | beam.ParDo(MyDoFn())
self.assertEqual([['1', '1'], ['2', '2']], sorted(result))
This results in:
> raise ValueError('%s is not iterable' % type_hint)
E ValueError: typehints.List[str] is not iterable
typehints.py:1194: ValueError
where the non-iterable entity the error refers to is a string literal ("typehints.List[str]").
