### Dependências com `yield` e `except`, Detalhes Técnicos

Antes do FastAPI 0.110.0, se você utilizasse uma dependência com `yield`, e então capturasse uma dependência com `except` nessa dependência, caso a exceção não fosse relançada, ela era automaticamente lançada para qualquer manipulador de exceções ou o manipulador de erros interno do servidor.

-xl-5,.col-xl-6,.col-xl-7,.col-xl-8,.col-xl-9,.col-xl-auto{position:relative;width:100%;padding-right:15px;padding-left:15px}.col{-ms-flex-preferred-size:0;flex-basis:0;-ms-flex-positive:1;flex-grow:1;max-width:100%}.row-cols-1>*{-ms-flex:0 0 100%;flex:0 0 100%;max-width:100%}.row-cols-2>*{-ms-flex:0 0 50%;flex:0 0 50%;max-width:50%}.row-cols-3>*{-ms-flex:0 0 33.333333%;flex:0 0 33.333333%;max-width:33.333333%}.row-cols-4>*{-ms-flex:0 0 25%;flex:0 0 25%;max-width:25%}.row-cols-5>*{-ms-flex:0 0 20%;flex:0...

    /**
     * Pipe operations should behave like the <code>CallNamedPipe</code> Win32 Named Pipe function.
     */

    public static final int PIPE_TYPE_CALL   = 0x0100;

    /**
     * Pipe operations should behave like the <code>TransactNamedPipe</code> Win32 Named Pipe function.
     */

    public static final int PIPE_TYPE_TRANSACT = 0x0200;

                } else {
                    uni[ui] |= (ch & 0x3F) << 6;
                    ch = src[si++] & 0xFF;
                    uni[ui] |=  ch & 0x3F;
                    if ((ch & 0xC0) != 0x80 || uni[ui] < 0x800) {
                        throw new IOException( "Invalid UTF-8 sequence" );
                    }
                }
            } else {
                throw new IOException( "Unsupported UTF-8 sequence" );

/// warning | 注意

你大概率不需要了解这些技术细节，可以跳过这一章节继续阅读后续的内容。

如果你使用的FastAPI的版本早于0.106.0，并且在使用后台任务中使用了包含 `yield` 的依赖项中的资源，那么这些细节会对你有一些用处。

///

### 包含 `yield` 和 `except` 的依赖项的技术细节

在FastAPI 0.110.0版本之前，如果使用了一个包含 `yield` 的依赖项，你在依赖项中使用 `except` 捕获了一个异常，但是你没有再次抛出该异常，这个异常会被自动抛出/转发到异常处理器或者内部服务错误处理器。

### 后台任务和使用 `yield` 的依赖项的技术细节

在FastAPI 0.106.0版本之前，在 `yield` 后面抛出异常是不可行的，因为 `yield` 之后的退出代码是在响应被发送之后再执行，这个时候异常处理器已经执行过了。

	s_IFMT   = 0xf000
	s_IFSOCK = 0xc000
	s_IFLNK  = 0xa000
	s_IFREG  = 0x8000
	s_IFBLK  = 0x6000
	s_IFDIR  = 0x4000
	s_IFCHR  = 0x2000
	s_IFIFO  = 0x1000
	s_ISUID  = 0x800
	s_ISGID  = 0x400
	s_ISVTX  = 0x200

	msdosDir      = 0x10
	msdosReadOnly = 0x01
)

// Mode returns the permission and mode bits for the [FileHeader].
func (h *FileHeader) Mode() (mode fs.FileMode) {

	VMOVQ	$0x8040201008040202, $0x7040201008040201, V20         // VMOVQ	$-9205322385119247870, $8088500183983456769, V20

// mov(to/from sp)
	MOVD	$0x1002(RSP), R1              // MOVD	$4098(RSP), R1              // e107409121080091
	MOVD	$0x1708(RSP), RSP             // MOVD	$5896(RSP), RSP             // ff074091ff231c91

position: relative;\n  width: 100%;\n  padding-right: 15px;\n  padding-left: 15px;\n}\n\n.col {\n  -ms-flex-preferred-size: 0;\n  flex-basis: 0;\n  -ms-flex-positive: 1;\n  flex-grow: 1;\n  max-width: 100%;\n}\n\n.row-cols-1 > * {\n  -ms-flex: 0 0 100%;\n  flex: 0 0 100%;\n  max-width: 100%;\n}\n\n.row-cols-2 > * {\n  -ms-flex: 0 0 50%;\n  flex: 0 0 50%;\n  max-width: 50%;\n}\n\n.row-cols-3 > * {\n  -ms-flex: 0 0 33.333333%;\n  flex: 0 0 33.333333%;\n  max-width: 33.333333%;\n}\n\n.row-cols-4 > * {\n  -ms-flex:...

position: relative;\n  width: 100%;\n  padding-right: 15px;\n  padding-left: 15px;\n}\n\n.col {\n  -ms-flex-preferred-size: 0;\n  flex-basis: 0;\n  -ms-flex-positive: 1;\n  flex-grow: 1;\n  max-width: 100%;\n}\n\n.row-cols-1 > * {\n  -ms-flex: 0 0 100%;\n  flex: 0 0 100%;\n  max-width: 100%;\n}\n\n.row-cols-2 > * {\n  -ms-flex: 0 0 50%;\n  flex: 0 0 50%;\n  max-width: 50%;\n}\n\n.row-cols-3 > * {\n  -ms-flex: 0 0 33.333333%;\n  flex: 0 0 33.333333%;\n  max-width: 33.333333%;\n}\n\n.row-cols-4 > * {\n  -ms-flex:...

	STLXP (R6, R3), (R10), R2                  // 468d22c8
	STLXPW (R6, R11), (R22), R21               // c6ae3588
	//TODO STNPW 44(R1), R3, R10               // 2a8c0528
	//TODO STNP 0x108(R3), ZR, R7              // 67fc10a8
	LDP.P -384(R3), (R22, R26)                 // 7668e8a8
	LDP.W 280(R8), (R19, R11)                  // 13add1a9
	STP.P (R22, R27), 352(R0)                  // 166c96a8