Add optional uniqueness checks for Binder
#235
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injector/__init__.py
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| """A dictionary that raises an exception when trying to add duplicate bindings.""" | ||
| def __setitem__(self, key: type, value: Binding) -> None: | ||
| if key in self.data: | ||
| raise NonUniqueBinding(key.__name__) |
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I would like to see a more human readable error message here. Our other error messages help the more novice users understad what is wrong.
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I completely agree! I will add a message that explains "Binding for 'X' already exists". Do you think that is detailed enough, or would you like to seeing some mention of the unique flag?
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I think the first message would be good enough, but that it would be even better to also mention the flag.
injector_test.py
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| def test_binder_with_uniqueness_checking_raises_error(): | ||
| def configure(binder): | ||
| binder.bind(int, to=123) | ||
| binder.bind(int, to=456) | ||
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| with pytest.raises(NonUniqueBinding): | ||
| _ = Injector([configure], unique=True) |
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Good!
I would like to see how the unique flag interacts with parent/child injectors though, both to verify the functionality and as a form of documentation of the expected behavior. I would expect child injectors to be allowed to override binds in parent injectors (and I see no reason to why this should not work). What do you think of adding another test for that?
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No problem! It looks like there are a couple of tests keying on similar concepts - I will borrow from them.
| def configure(binder): | ||
| binder.bind(str, to='asd') | ||
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| parent = Injector(configure) | ||
| child = parent.create_child_injector() | ||
| child = parent.create_child_injector(unique=unique) |
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Wouldn't it be even more interesting to add the unique flag to the parent injector as well, to see that they interact as expected, since it's an even stricter case? I think that it should be allowed and work with the current implementation.
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Yup, I agree. Also: I'm wondering if child injectors shouldn't inherit the unique value of the parent injector by default.
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That crossed my mind as well, and yes, I think that would be reasonable.
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| def test_injector_with_uniqueness_checking_raises_error(): | ||
| def configure(binder): | ||
| binder.bind(int, to=123) | ||
| binder.bind(int, to=456) | ||
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| with pytest.raises(NonUniqueBinding, match="Binding for 'int' already exists"): | ||
| _ = Injector([configure], unique=True) |
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Do we want a test for the opposite case, where overriding works without unique=True?
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@craig8 apologies, I completely forgot about this PR. I will try and push the requested changes this weekend.
This PR attempts to address issue #234 by introducing a unique key dictionary in the
Binderwhenunique=True.