## Change Summary

This means `pydantic/__init__.py` is now lazy about all imports using `__getattr__`.

Import performance changes:
### Before

```
code/pydantic 0 ➤ pdm run python -m timeit -n 1 -r 1 "import pydantic"
1 loop, best of 1: 29.7 msec per loop
```

```
code/pydantic 0 ➤ pdm run python -m timeit -n 1 -r 1 "from pydantic import BaseModel"
1 loop, best of 1: 30.4 msec per loop
```

### After

```
code/pydantic 0 ➤ pdm run python -m timeit -n 1 -r 1 "import pydantic"
1 loop, best of 1: 4.8 msec per loop
```

```
(env3112) code/pydantic 0 ➤ pdm run python -m timeit -n 1 -r 1 "from pydantic import BaseModel"           
1 loop, best of 1: 18.7 msec per loop
```

Tuna output:

<img width="1421" alt="image" src="https://github.com/pydantic/pydantic/assets/4039449/0a57434e-fdda-4709-8793-d96c0a0ee762">

## Related issue number

As promised in https://github.com/pydantic/pydantic/pull/7423#issuecomment-1733361629.

## Checklist

* [x] The pull request title is a good summary of the changes - it will be used in the changelog
* [ ] Unit tests for the changes exist
* [x] Tests pass on CI
* [ ] Documentation reflects the changes where applicable
* [x] My PR is ready to review, **please add a comment including the phrase "please review" to assign reviewers**


Selected Reviewer: @sydney-runkle
Use `__getattr__` for all package imports, improve import time. ## Change Summary

This means `pydantic/__init__.py` is now lazy about all imports using `__getattr__`.

Import performance changes:
### Before

```
code/pydantic 0 ➤ pdm run python -m timeit -n 1 -r 1 "import pydantic"
1 loop, best of 1: 29.7 msec per loop
```

```
code/pydantic 0 ➤ pdm run python -m timeit -n 1 -r 1 "from pydantic import BaseModel"
1 loop, best of 1: 30.4 msec per loop
```

### After

```
code/pydantic 0 ➤ pdm run python -m timeit -n 1 -r 1 "import pydantic"
1 loop, best of 1: 4.8 msec per loop
```

```
(env3112) code/pydantic 0 ➤ pdm run python -m timeit -n 1 -r 1 "from pydantic import BaseModel"           
1 loop, best of 1: 18.7 msec per loop
```

Tuna output:

<img width="1421" alt="image" src="https://github.com/pydantic/pydantic/assets/4039449/0a57434e-fdda-4709-8793-d96c0a0ee762">

## Related issue number

As promised in https://github.com/pydantic/pydantic/pull/7423#issuecomment-1733361629.

## Checklist

* [x] The pull request title is a good summary of the changes - it will be used in the changelog
* [ ] Unit tests for the changes exist
* [x] Tests pass on CI
* [ ] Documentation reflects the changes where applicable
* [x] My PR is ready to review, **please add a comment including the phrase "please review" to assign reviewers**


Selected Reviewer: @sydney-runkle
import abc
import sys

import pytest

from pydantic import BaseModel


def test_model_subclassing_abstract_base_classes():
    class Model(BaseModel, abc.ABC):
        some_field: str


@pytest.mark.skipif(sys.version_info < (3, 12), reason='error value different on older versions')
def test_model_subclassing_abstract_base_classes_without_implementation_raises_exception():
    class Model(BaseModel, abc.ABC):
        some_field: str

        @abc.abstractmethod
        def my_abstract_method(self):
            pass

        @classmethod
        @abc.abstractmethod
        def my_abstract_classmethod(cls):
            pass

        @staticmethod
        @abc.abstractmethod
        def my_abstract_staticmethod():
            pass

        @property
        @abc.abstractmethod
        def my_abstract_property(self):
            pass

        @my_abstract_property.setter
        @abc.abstractmethod
        def my_abstract_property(self, val):
            pass

    with pytest.raises(TypeError) as excinfo:
        Model(some_field='some_value')
    assert str(excinfo.value) == (
        "Can't instantiate abstract class Model without an implementation for abstract methods "
        "'my_abstract_classmethod', 'my_abstract_method', 'my_abstract_property', 'my_abstract_staticmethod'"
    )

import abc
import sys

import pytest

from pydantic import BaseModel


def test_model_subclassing_abstract_base_classes():
    class Model(BaseModel, abc.ABC):
        some_field: str


@pytest.mark.skipif(sys.version_info < (3, 12), reason='error value different on older versions')
def test_model_subclassing_abstract_base_classes_without_implementation_raises_exception():
    class Model(BaseModel, abc.ABC):
        some_field: str

        @abc.abstractmethod
        def my_abstract_method(self):
            pass

        @classmethod
        @abc.abstractmethod
        def my_abstract_classmethod(cls):
            pass

        @staticmethod
        @abc.abstractmethod
        def my_abstract_staticmethod():
            pass

        @property
        @abc.abstractmethod
        def my_abstract_property(self):
            pass

        @my_abstract_property.setter
        @abc.abstractmethod
        def my_abstract_property(self, val):
            pass

    with pytest.raises(TypeError) as excinfo:
        Model(some_field='some_value')
    assert str(excinfo.value) == (
        "Can't instantiate abstract class Model without an implementation for abstract methods "
        "'my_abstract_classmethod', 'my_abstract_method', 'my_abstract_property', 'my_abstract_staticmethod'"
    )
