<div class="termy">

```console
$ which python

/home/user/code/awesome-project/.venv/bin/python
```

</div>

If it shows the `python` binary at `.venv/bin/python`, inside of your project (in this case `awesome-project`), then it worked. 🎉

////

//// tab | Windows PowerShell

<div class="termy">

```console
$ Get-Command python

Hello Wade Wilson
```

</div>

////

## Pythonで環境変数を読み取る

環境変数をPythonの**外側**、ターミナル（や他の方法）で作成し、**Python内で読み取る**こともできます。

例えば、以下のような`main.py`ファイルを用意します:

```Python hl_lines="3"
import os

name = os.getenv("MY_NAME", "World")
print(f"Hello {name} from Python")
```

/// tip

So, if we create a Pydantic object `user_in` like:

```Python
user_in = UserIn(username="john", password="secret", email="******@****.***")
```

and then we call:

```Python
user_dict = user_in.model_dump()
```

we now have a `dict` with the data in the variable `user_dict` (it's a `dict` instead of a Pydantic model object).

And if we call:

```Python
print(user_dict)
```

## Managing hermetic Python

To make sure that TensorFlow's build is reproducible, behaves uniformly across
supported platforms (Linux, Windows, MacOS) and is properly isolated from
specifics of a local system, we rely on hermetic Python (see
[rules_python](https://github.com/bazelbuild/rules_python)) for all build
and test commands executed via Bazel. This means that your system Python
installation will be ignored during the build and Python interpreter itself

/// info

To receive uploaded files, first install <a href="https://github.com/Kludex/python-multipart" class="external-link" target="_blank">`python-multipart`</a>.

Make sure you create a [virtual environment](../virtual-environments.md){.internal-link target=_blank}, activate it, and then install it, for example:

```console
$ pip install python-multipart
```

This is because uploaded files are sent as "form data".

///

Para receber arquivos enviados, primeiro instale o <a href="https://github.com/Kludex/python-multipart" class="external-link" target="_blank">`python-multipart`</a>.

Garanta que você criou um [ambiente virtual](../virtual-environments.md){.internal-link target=_blank}, o ativou e então o instalou, por exemplo:

```console
$ pip install python-multipart
```

# pylint: disable=g-bad-import-order,protected-access,g-import-not-at-top
from tensorflow.python import pywrap_tensorflow  # pylint: disable=unused-import
from tensorflow.python.tools import module_util as _module_util
from tensorflow.python.platform import tf_logging as _logging
from tensorflow.python.util.lazy_loader import LazyLoader as _LazyLoader
from tensorflow.python.util.lazy_loader import KerasLazyLoader as _KerasLazyLoader

# API IMPORTS PLACEHOLDER

Así que, si creamos un objeto Pydantic `user_in` como:

```Python
user_in = UserIn(username="john", password="secret", email="******@****.***")
```

y luego llamamos a:

```Python
user_dict = user_in.dict()
```

ahora tenemos un `dict` con los datos en la variable `user_dict` (es un `dict` en lugar de un objeto modelo Pydantic).

Y si llamamos a:

```Python
print(user_dict)
```

Вы делаете это с помощью стандартных современных типов Python.

Вам не нужно изучать новый синтаксис, методы или классы конкретной библиотеки и т.п.

Только стандартный **Python**.

Например, для `int`:

```Python
item_id: int
```

или для более сложной модели `Item`:

```Python
item: Item
```

...и с этим единственным объявлением вы получаете:

    ...
```

但就在 Python 比较完 `johndoe` 的第一个字母 `j` 与 `stanleyjobson` 的 `s` 时，Python 就已经知道这两个字符串不相同了，它会这么想，**没必要浪费更多时间执行剩余字母的对比计算了**。应用立刻就会返回**错误的用户或密码**。

但接下来，攻击者继续尝试 `stanleyjobsox` 和 密码 `love123`。

应用代码会执行类似下面的操作：

```Python
if "stanleyjobsox" == "stanleyjobson" and "love123" == "swordfish":
    ...
```

此时，Python 要对比 `stanleyjobsox` 与 `stanleyjobson` 中的 `stanleyjobso`，才能知道这两个字符串不一样。因此会多花费几微秒来返回**错误的用户或密码**。