因為這些程式碼分別在應用開始接收請求**之前**與**完成**處理請求之後執行，所以涵蓋了整個應用的**生命週期**（「lifespan」這個詞稍後會很重要 😉）。

這對於為整個應用設定需要**共用**於多個請求的**資源**，以及在之後進行**清理**，非常有用。比如資料庫連線池、或載入一個共用的機器學習模型。

## 使用情境 { #use-case }

先從一個**使用情境**開始，然後看看如何用這個機制解決。

想像你有一些要用來處理請求的**機器學習模型**。🤖

同一組模型會在多個請求間共用，所以不是每個請求或每個使用者各有一個模型。

再想像一下，載入模型**需要一段時間**，因為它必須從**磁碟**讀取大量資料。所以你不想在每個請求都做一次。

/*
 * Copyright (C) 2007 The Guava Authors
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,

Variáveis de ambiente podem ser úteis para lidar com **configurações** do aplicativo, como parte da **instalação** do Python, etc.

## Criar e Usar Variáveis de Ambiente { #create-and-use-env-vars }

Você pode **criar** e usar variáveis de ambiente no **shell (terminal)**, sem precisar do Python:

//// tab | Linux, macOS, Windows Bash

<div class="termy">

```console

Каждый раз, когда вы передаете точно такое же содержимое (точно такой же пароль), вы получаете точно такую же тарабарщину.

Но преобразовать тарабарщину обратно в пароль невозможно.

### Для чего нужно хеширование паролей { #why-use-password-hashing }

Если ваша база данных будет украдена, то вор не получит пароли пользователей в открытом виде, а только их хэши.

Als Nächstes werden die Daten konvertiert und validiert. Wenn Sie also dieses `settings`-Objekt verwenden, verfügen Sie über Daten mit den von Ihnen deklarierten Typen (z. B. ist `items_per_user` ein `int`).

### `settings` verwenden { #use-the-settings }

Dann können Sie das neue `settings`-Objekt in Ihrer Anwendung verwenden:

{* ../../docs_src/settings/tutorial001_py310.py hl[18:20] *}

### Den Server ausführen { #run-the-server }

/*
 * Copyright 2012-2025 CodeLibs Project and the Others.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,

Il convertira ensuite et validera les données. Ainsi, lorsque vous utilisez cet objet `settings`, vous aurez des données des types que vous avez déclarés (par exemple, `items_per_user` sera un `int`).

### Utiliser `settings` { #use-the-settings }

Vous pouvez ensuite utiliser le nouvel objet `settings` dans votre application :

{* ../../docs_src/settings/tutorial001_py310.py hl[18:20] *}

### Exécuter le serveur { #run-the-server }

Chat'i sadece genel sohbetler için kullanın.

///

### Sorular için chat'i kullanmayın { #dont-use-the-chat-for-questions }

Chat sistemleri daha "serbest sohbet"e izin verdiği için, çok genel ve yanıtlaması daha zor sorular sormak kolaylaşır; bu nedenle cevap alamayabilirsiniz.

Las variables de entorno pueden ser útiles para manejar **configuraciones** de aplicaciones, como parte de la **instalación** de Python, etc.

## Crear y Usar Variables de Entorno { #create-and-use-env-vars }

Puedes **crear** y usar variables de entorno en la **shell (terminal)**, sin necesidad de Python:

//// tab | Linux, macOS, Windows Bash

<div class="termy">

```console

/*
 * Copyright 2012-2025 CodeLibs Project and the Others.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,