////

## 在 Python 中读取环境变量

你也可以在 Python **之外**的终端中创建环境变量（或使用任何其他方法），然后在 Python 中**读取**它们。

例如，你可以创建一个名为 `main.py` 的文件，其中包含以下内容：

```Python hl_lines="3"
import os

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

/// tip

第二个参数是 <a href="https://docs.python.org/zh-cn/3.8/library/os.html#os.getenv" class="external-link" target="_blank">`os.getenv()`</a> 的默认返回值。

	token, err := MockOpenIDTestUserInteraction(ctx, testAppParams, "******@****.***", "dillon")
	if err != nil {
		c.Fatalf("mock user err: %v", err)
	}
	// fmt.Printf("TOKEN: %s\n", token)

	webID := cr.STSWebIdentity{
		Client:      s.TestSuiteCommon.client,
		STSEndpoint: s.endPoint,
		GetWebIDTokenExpiry: func() (*cr.WebIdentityToken, error) {

             * for whatever reason. I copy over the uid here so it appears correct
             * in logging output. Logging of andx segments of messages inadvertantly
             * print header information because of the way toString always makes a
             * super.toString() call(see toString() at the end of all smbs classes).
             */

            this.andx.uid = this.uid;

is specified via the `role_policy` configuration parameter or the `MINIO_IDENTITY_OPENID_ROLE_POLICY` environment variable. The value is a comma-separated list of IAM access policy names already defined in the server. In this situation, the server prints a role ARN at startup that must be specified as a `RoleArn` API request parameter in the STS AssumeRoleWithWebIdentity API call. When using Role Policies, multiple OpenID providers and/or client applications (with unique client IDs) may be configured...

```Python
with open("./somefile.txt") as f:
    contents = f.read()
    print(contents)
```

その後の`open("./somefile.txt")`は「コンテキストマネージャ」と呼ばれるオブジェクトを作成します。

`with`ブロックが終了すると、例外があったとしてもファイルを確かに閉じます。

`yield`を依存関係を作成すると、**FastAPI** は内部的にそれをコンテキストマネージャに変換し、他の関連ツールと組み合わせます。

        final MyBean src = new MyBean();
        src.aaa = "2008/01/17";
        final MyBean2 dest = new MyBean2();
        BeanUtil.copyBeanToBean(src, dest, converter(new DateConverter("yyyy/MM/dd")));
        System.out.println(dest.aaa);
        assertThat(dest.aaa, is(notNullValue()));
    }

    /**
     * @throws Exception
     */
    @Test
    public void testCopy_beanToMap() throws Exception {

		return err
	}
	return nil
}

func TestPropagateUnscoped(t *testing.T) {
	_DB, err := OpenTestConnection(&gorm.Config{
		PropagateUnscoped: true,
	})
	if err != nil {
		log.Printf("failed to connect database, got error %v", err)
		os.Exit(1)
	}

	_DB.Migrator().DropTable(&Product6{}, &ProductItem2{})
	_DB.AutoMigrate(&Product6{}, &ProductItem2{})

	p := Product6{

}

type printSQLLogger struct {
	logger.Interface
}

func (l *printSQLLogger) Trace(ctx context.Context, begin time.Time, fc func() (sql string, rowsAffected int64), err error) {
	sql, _ := fc()
	fmt.Println(sql + ";")
	l.Interface.Trace(ctx, begin, fc, err)
}

// GormDataTypeInterface gorm data type interface
type GormDataTypeInterface interface {
	GormDBDataType(*gorm.DB, *schema.Field) string
}

		size:          actualSize,
		offset:        0,
		reader:        nil,
	}
}

// Seek call to implement io.Seeker
func (rsc *ObjectReadSeekCloser) Seek(offset int64, whence int) (int64, error) {
	// fmt.Printf("actual: %v offset: %v (%v) whence: %v\n", rsc.size, offset, rsc.offset, whence)
	switch whence {
	case io.SeekStart:
		rsc.offset = offset
	case io.SeekCurrent:
		rsc.offset += offset
	case io.SeekEnd:

```Python
with open("./somefile.txt") as f:
    contents = f.read()
    print(contents)
```

Por baixo dos panos, o código `open("./somefile.txt")` cria um objeto que é chamado de "Gerenciador de Contexto".