Add structref as a mutable struct that is pass-by-ref #5978
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sklam
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numba/core/structref.py
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| @lower_setattr_generic(struct_typeclass) | ||
| def struct_setattr_impl(context, builder, sig, args, attr): | ||
| [inst_type, val_type] = sig.args | ||
| [instance, val] = args | ||
| utils = _Utils(context, builder, inst_type) | ||
| dataval = utils.get_data_struct(instance) | ||
| # cast val to the correct type | ||
| field_type = inst_type.field_dict[attr] | ||
| casted = context.cast(builder, val, val_type, field_type) | ||
| # read old | ||
| old_value = getattr(dataval, attr) | ||
| # incref new value | ||
| context.nrt.incref(builder, val_type, casted) | ||
| # decref old value (must be last in case new value is old value) | ||
| context.nrt.decref(builder, val_type, old_value) | ||
| # write new | ||
| setattr(dataval, attr, casted) |
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I'm not sure that anything can be done about it right now, but implementing the setattr as direct lowering means that if the type of the attribute and the type of the value mismatch it'll end up as a lowering error via a (correctly raising) unimplement cast.
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I thought that would happen too. But, it turns out that the typer for setattr is forcing the RHS to match the attribute type.
numba/tests/test_struct_ref.py
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| class MyStruct(structref.StructRefProxy): | ||
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| def __new__(cls, values, counter): | ||
| # Define this method to customize the constructor. | ||
| # The default takes `*args`. Customizing allow the use of keyword-arg. | ||
| # The impl of the method calls `StructRefProxy.__new__` | ||
| return structref.StructRefProxy.__new__(cls, values, counter) | ||
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| # The below defines wrappers for attributes and methods manually | ||
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| @property | ||
| def values(self): | ||
| return get_values(self) | ||
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| @values.setter | ||
| def values(self, val): | ||
| return set_values(self, val) | ||
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| @property | ||
| def counter(self): | ||
| return get_counter(self) | ||
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| def testme(self, arg): | ||
| return self.values * arg + self.counter | ||
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| @structref.register | ||
| class MyStructType(types.StructRef): | ||
| """Test associated with this type represent the higher-level uses of | ||
| structef. | ||
| """ | ||
| pass | ||
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| # Call to define_proxy is needed to register the use of `MyStruct` as a | ||
| # PyObject proxy for creating a Numba-allocated structref. | ||
| # The `MyStruct` class and then be used in both jit-code and interpreted-code. | ||
| structref.define_proxy( | ||
| MyStruct, | ||
| MyStructType, | ||
| ['values', 'counter'], | ||
| ) |
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Is there benefit in making this into a factory? Also wonder if the getters and setters like those here https://github.com/numba/numba/pull/5978/files#diff-9b2fbc1beb945aef47f6c71220bcd54dR101-R113 could be autogenerated in such a case, perhaps into a base class from which the other's can inherit and later be proxied? Perhaps not for now :)!
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I was trying to autogenerate the getters/setters via a base class. Just too much work for now.
| # mutate | ||
| td['a'].values += 10 | ||
| self.assertEqual(td['a'].values, 12) # changed | ||
| self.assertEqual(td['a'].counter, 3.3) # unchanged |
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Perhaps also check a td['b'] = MyStruct(4, 5.6) works, as I think it should? Makes me wonder, should a MyStruct(int8(4), 5.6) be castable, I'd guess not at the typing layer?
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It's not casting the fields at the moment. That would be another potential enhancement
stuartarchibald
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Co-authored-by: stuartarchibald <stuartarchibald@users.noreply.github.com>
Co-authored-by: stuartarchibald <stuartarchibald@users.noreply.github.com>
numba/core/types/containers.py
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| msg = "expecting a str for field name" | ||
| raise ValueError(msg) | ||
| if not isinstance(typ, Type): | ||
| msg = f"expecting a Numba Type for field type" |
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| msg = f"expecting a Numba Type for field type" | |
| msg = "expecting a Numba Type for field type" |
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Thanks for the fixes, I think the only remaining this is the |
stuartarchibald
added
the
4 - Waiting on CI
stuartarchibald
added
5 - Ready to merge
# Conflicts: # numba/core/types/containers.py
Closes #5397
Add
structrefto support mutable structure that can be extended like typical custom types (i.e. with@overloadand friends). Also, support some nice default to minimizing work; i.e. default boxer/unboxer, default getter/setter, default constructor.TODOs: