wrap_kvs will wrap the instance but self of instance is not wrapped

[andeaseme]

This behavior is discovered while trying to display available options in a dropdown with streamlitfront without accessing the actual value until it is needed.

The get item of an instance is different from the get item from the self within the instance's method when wrapping a class with wrap_kvs. The self behaves as if the instance is not wrapped.

The test below has two classes:

1. DoubleWrapSquareStore reapplies wrap_kvs to self in the item_getter method call.
2. SingleWrapSquareStore does not reapply wrap_kvs and acts like it is not wrapped but you would expect the instance and self to have the same behavior.

Test:

import math
from dataclasses import dataclass
from typing import Any

from dol import wrap_kvs


@dataclass
class ItemGetter:
    """Wraps value in a callable to be retrieved later"""

    instance: Any
    key: Any

    def __call__(self):
        return self.instance[self.key]


wrap_kvs_as_square_data = wrap_kvs(data_of_obj=lambda x: x * x, obj_of_data=math.sqrt)


@wrap_kvs_as_square_data
class DoubleWrapSquareStore(dict):
    def item_getter(self, key) -> ItemGetter:
        """The instance self has wrap_kvs applied again to retain the data conversion"""
        return ItemGetter(instance=wrap_kvs_as_square_data(self), key=key)


@wrap_kvs_as_square_data
class SingleWrapSquareStore(dict):
    def item_getter(self, key) -> ItemGetter:
        """The instance self does not have wrap_kvs reapplied and does not act like the instance"""
        return ItemGetter(instance=self, key=key)


def test_square_store(ss):
    ss['2'] = 2
    ig_from_instance = ItemGetter(ss, '2')()
    ig_from_self = ss.item_getter('2')()

    print(
        f'\nTesting {type(ss).__name__}'
        'These values should be equal:',
        f"{ss['2']=}",
        f'{ig_from_instance=}',
        f'{ig_from_self=}',
        sep='\n',
    )

    assert (
        ss['2'] == ig_from_instance
    ), f'{type(ss).__name__}: ItemGetter value from instance does not match actual value'

    ig_2 = ss.item_getter('2')
    assert (
        ss['2'] == ig_from_self
    ), f'{type(ss).__name__}: ItemGetter value from self does not match actual value'

    assert (
        ig_from_instance == ig_from_self
    ), f'{type(ss).__name__}: ItemGetter value from instance does not match ItemGetter value from self'


test_square_store(DoubleWrapSquareStore())
test_square_store(SingleWrapSquareStore())

Result:

============================= test session starts ==============================
collecting ... 
Testing DoubleWrapSquareStoreThese values should be equal:
ss['2']=2.0
ig_from_instance=2.0
ig_from_self=2.0

Testing SingleWrapSquareStoreThese values should be equal:
ss['2']=2.0
ig_from_instance=2.0
ig_from_self=4

plunk/ap/pain/wrap_kvs_and_self.py:None (plunk/ap/pain/wrap_kvs_and_self.py)
wrap_kvs_and_self.py:64: in <module>
    test_square_store(SingleWrapSquareStore())
wrap_kvs_and_self.py:54: in test_square_store
    assert (
E   AssertionError: SingleWrapSquareStore: ItemGetter value from self does not match actual value
E   assert 2.0 == 4






collected 0 items / 1 error

=============================== 1 error in 0.13s ===============================

[thorwhalen]

Slightly editted:

import math
from dataclasses import dataclass
from typing import Any

from dol import wrap_kvs


@dataclass
class ItemGetter:
    """Wraps value in a callable to be retrieved later"""

    instance: Any
    key: Any

    def __call__(self):
        return self.instance[self.key]


wrap_kvs_as_square_data = wrap_kvs(data_of_obj=lambda x: x * x, obj_of_data=lambda x: math.sqrt(x))


@wrap_kvs_as_square_data
class DoubleWrapSquareStore(dict):
    def item_getter(self, key) -> ItemGetter:
        """The instance self has wrap_kvs applied again to retain the data conversion"""
        return ItemGetter(instance=wrap_kvs_as_square_data(self), key=key)


@wrap_kvs_as_square_data
class SingleWrapSquareStore(dict):
    def item_getter(self, key) -> ItemGetter:
        """The instance self does not have wrap_kvs reapplied and does not act like the instance"""
        return ItemGetter(instance=self, key=key)


def test_square_store(ss):
    ss['2'] = 2
    ig_from_instance = ItemGetter(ss, '2')()
    ig_from_self = ss.item_getter('2')()

    print(
        f'\nTesting {type(ss).__name__}'
        'These values should be equal:',
        f"{ss['2']=}",
        f'{ig_from_instance=}',
        f'{ig_from_self=}',
        sep='\n',
    )

    assert (
        ss['2'] == ig_from_instance
    ), f'{type(ss).__name__}: ItemGetter value {ig_from_instance=} from instance does not match actual value {ss["2"]=}'

    ig_2 = ss.item_getter('2')
    assert (
        ss['2'] == ig_from_self
    ), f'{type(ss).__name__}: ItemGetter value {ig_from_self=} from self does not match actual value {ss["2"]=}'

    assert (
        ig_from_instance == ig_from_self
    ), f'{type(ss).__name__}: ItemGetter value {ig_from_instance=} from instance does not match ItemGetter value from self {ig_from_self=}'


test_square_store(DoubleWrapSquareStore())
test_square_store(SingleWrapSquareStore())

Testing DoubleWrapSquareStoreThese values should be equal:
ss['2']=2.0
ig_from_instance=2.0
ig_from_self=2.0

Testing SingleWrapSquareStoreThese values should be equal:
ss['2']=2.0
ig_from_instance=2.0
ig_from_self=4
---------------------------------------------------------------------------
AssertionError                            Traceback (most recent call last)

...

     64 test_square_store(DoubleWrapSquareStore())
---> 65 test_square_store(SingleWrapSquareStore())

...

---> 56     ss['2'] == ig_from_self
     57 ), f'{type(ss).__name__}: ItemGetter value {ig_from_self=} from self does not match actual value {ss["2"]=}'

...

AssertionError: SingleWrapSquareStore: ItemGetter value ig_from_self=4 from self does not match actual value ss["2"]=2.0