<div class="termy">

```console
// Here we don't set the env var yet
$ python main.py

// As we didn't set the env var, we get the default value

Hello World from Python

// But if we create an environment variable first
$ export MY_NAME="Wade Wilson"

// And then call the program again
$ python main.py

// Now it can read the environment variable

Hello Wade Wilson from Python
```

它也被設計成可作為未來的參考，讓你隨時回來查看所需的內容。

## 運行程式碼

所有程式碼區塊都可以直接複製和使用（它們實際上是經過測試的 Python 檔案）。

要運行任何範例，請將程式碼複製到 `main.py` 檔案，並使用以下命令啟動 `fastapi dev`：

<div class="termy">

```console
$ <font color="#4E9A06">fastapi</font> dev <u style="text-decoration-style:single">main.py</u>
<font color="#3465A4">INFO    </font> Using path <font color="#3465A4">main.py</font>

    # o generateOutputDirectory: (NotRequired - Default Java:'../src/main/java' CSharp:'../source')
    #  The base output directory for generating.
    #  Basically you don't need to specify this if the project style is as follows:
    #
    #   *Java Project Style
    #     If this value is '../src/main/java' and your project is under the Maven,
    #     you don't need to set up this property!
    #

    #  Elements of this map are as below:
    #   o url: (NotRequired - Default same as main schema)
    #   o schema: (Required: if empty schema means valid schema, not required)
    #   o user: (NotRequired - Default same as main schema)
    #   o password: (NotRequired - Default same as main schema)
    #   o propertiesMap: (NotRequired - Default map:{})

    Set<DependencyScope> dependencyScopes();

    PathScope MAIN_COMPILE = pathScope(
            "main-compile",
            ProjectScope.MAIN,
            DependencyScope.COMPILE_ONLY,
            DependencyScope.COMPILE,
            DependencyScope.PROVIDED);

    PathScope MAIN_RUNTIME =
            pathScope("main-runtime", ProjectScope.MAIN, DependencyScope.COMPILE, DependencyScope.RUNTIME);

    PathScope TEST_COMPILE = pathScope(

// Package-wide variables from generator "generated".
option go_package = "k8s.io/api/authentication/v1alpha1";

// SelfSubjectReview contains the user information that the kube-apiserver has about the user making this request.
// When using impersonation, users will receive the user info of the user being impersonated.  If impersonation or

{!> ../../docs_src/settings/app02_an_py39/main.py!}
```

////

//// tab | Python 3.8+

```Python hl_lines="6  12-13"
{!> ../../docs_src/settings/app02_an/main.py!}
```

////

//// tab | Python 3.8+ 非注解版本

/// tip

如果可能，请尽量使用 `Annotated` 版本。

///

```Python hl_lines="5  11-12"
{!> ../../docs_src/settings/app02/main.py!}
```

////

/// tip

    public static final String RS_NONE = "none";
    public static final String RS_MAIN_COMPILE = "main-compile";
    public static final String RS_MAIN_COMPILE_PLUS_RUNTIME = "main-compilePlusRuntime";
    public static final String RS_MAIN_RUNTIME = "main-runtime";
    public static final String RS_MAIN_RUNTIME_PLUS_SYSTEM = "main-runtimePlusSystem";
    public static final String RS_TEST_COMPILE = "test-compile";

<div class="termy">

```console
$ <font color="#4E9A06">fastapi</font> dev <u style="text-decoration-style:single">main.py</u>
<font color="#3465A4">INFO    </font> Using path <font color="#3465A4">main.py</font>
<font color="#3465A4">INFO    </font> Resolved absolute path <font color="#75507B">/home/user/code/awesomeapp/</font><font color="#AD7FA8">main.py</font>

from fastapi.cli import main