auto-property initializer

auto-property initializer是C# 6.0引入的一个特性，它允许我们在自动属性中为属性提供一个初始值。在之前的版本中，我们必须在构造函数中手动为属性赋值，而现在我们可以直接在属性声明中为其提供一个初始值。

使用auto-property initializer可以简化代码，并且使得属性的初始化更加直观和简洁。例如，我们可以这样声明一个带有初始值的自动属性：

public string Name { get; set; } = "John";

在这个例子中，Name属性的初始值被设置为"John"。当我们创建该类的实例时，Name属性将自动被初始化为"John"，而无需在构造函数中手动赋值。

需要注意的是，auto-property initializer只能用于自动属性，而不能用于显式实现的接口属性或只读属性。另外，如果我们在构造函数中手动为属性赋值，那么手动赋值将会覆盖auto-property initializer提供的初始值。

希望以上解答对您有帮助！如果您还有其他问题，请随时提问。

相关问题

Traceback (most recent call last): File "kivy\_event.pyx", line 235, in kivy._event.EventDispatcher.__init__ TypeError: object.__init__() takes exactly one argument (the instance to initialize) The above exception was the direct cause of the following exception: Traceback (most recent call last): File "D:\python\main.py", line 113, in <module> MyApp().run() File "D:\python\Lib\site-packages\kivy\app.py", line 955, in run self._run_prepare() File "D:\python\Lib\site-packages\kivy\app.py", line 925, in _run_prepare root = self.build() File "D:\python\main.py", line 107, in build return MyGridLayout() File "D:\python\main.py", line 72, in __init__ self.add_widget(TextInput(multiline=False, my_id='text_input')) File "D:\python\Lib\site-packages\kivy\uix\textinput.py", line 557, in __init__ super().__init__(**kwargs) File "D:\python\Lib\site-packages\kivy\uix\behaviors\focus.py", line 393, in __init__ super(FocusBehavior, self).__init__(**kwargs) File "D:\python\Lib\site-packages\kivy\uix\widget.py", line 357, in __init__ super(Widget, self).__init__(**kwargs) File "kivy\_event.pyx", line 238, in kivy._event.EventDispatcher.__init__ TypeError: Properties ['my_id'] passed to __init__ may not be existing property names. Valid properties are ['_cursor_blink', '_cursor_visual_height', '_cursor_visual_pos', '_editable', '_hint_text', '_hint_text_lines', '_ime_composition', '_ime_cursor', '_keyboard', '_lines', 'allow_copy', 'auto_indent', 'background_active', 'background_color', 'background_disabled_normal', 'background_normal', 'base_direction', 'border', 'center', 'center_x', 'center_y', 'children', 'cls', 'cursor', 'cursor_blink', 'cursor_col', 'cursor_color', 'cursor_pos', 'cursor_row', 'cursor_width', 'disabled', 'disabled_foreground_color', 'do_wrap', 'focus', 'focus_next', 'focus_previous', 'focused', 'font_context', 'font_family', 'font_name', 'font_size', 'foreground_color', 'halign', 'handle_image_left', 'handle_image_middle', 'handle_image_right', 'height', 'hint_text', 'hint_text_color', 'ids', 'input_filter', 'input_type', 'is_focusable', 'keyboard', 'keyboard_mode', 'keyboard_suggestions', 'line_height', 'line_spacing', 'lines_to_scroll', 'minimum_height', 'motion_filter', 'multiline', 'opacity', 'padding', 'padding_x', 'padding_y', 'parent', 'password', 'password_mask', 'pos', 'pos_hint', 'readonly', 'replace_crlf', 'right', 'scroll_distance', 'scroll_from_swipe', 'scroll_timeout', 'scroll_x', 'scroll_y', 'selection_color', 'selection_from', 'selection_text', 'selection_to', 'size', 'size_hint', 'size_hint_max', 'size_hint_max_x', 'size_hint_max_y', 'size_hint_min', 'size_hint_min_x', 'size_hint_min_y', 'size_hint_x', 'size_hint_y', 'tab_width', 'text', 'text_language', 'text_validate_unfocus', 'top', 'unfocus_on_touch', 'use_bubble', 'use_handles', 'width', 'write_tab', 'x', 'y']

这个错误是因为你在创建 TextInput 时传入了一个名为 'my_id' 的参数，但是 TextInput 中没有 'my_id' 这个属性。Kivy 中的 Widget 只接受预定义的属性作为参数，你可以在 TextInput 中使用其他预定义的属性代替 'my_id'。如果你需要为 TextInput 添加自定义属性，可以通过继承 TextInput 并添加自定义属性的方式实现。

lan8720 linux驱动

LAN8720是一款常用的以太网PHY芯片，它可以通过RMII或MII接口与Linux系统连接。下面是一个可能的LAN8720 Linux驱动程序的示例代码：

#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/i2c.h>
#include <linux/netdevice.h>
#include <linux/ethtool.h>
#include <linux/of.h>
#include <linux/of_device.h>

/* LAN8720 PHY registers */
#define LAN8720_REG_BCR     0x00    /* Basic Control Register */
#define LAN8720_REG_BSR     0x01    /* Basic Status Register */
#define LAN8720_REG_PHYID1  0x02    /* PHY Identifier 1 */
#define LAN8720_REG_PHYID2  0x03    /* PHY Identifier 2 */
#define LAN8720_REG_ANAR    0x04    /* Auto-Negotiation Advertisement Register */
#define LAN8720_REG_ANLPAR  0x05    /* Auto-Negotiation Link Partner Ability Register */
#define LAN8720_REG_ANER    0x06    /* Auto-Negotiation Expansion Register */
#define LAN8720_REG_DSCR    0x10    /* PCS/TX Descriptor Register */
#define LAN8720_REG_DSCSR   0x11    /* PCS/TX Descriptor and Status Register */
#define LAN8720_REG_PHYCR   0x19    /* PHY Control Register */

#define LAN8720_PHY_RESET_DELAY_MS      100

struct lan8720_priv {
    struct device *dev;
    struct net_device *netdev;
    void __iomem *regs;
};

static int lan8720_mdio_read(struct mii_bus *bus, int phy_addr, int reg_addr)
{
    struct lan8720_priv *priv = bus->priv;
    void __iomem *regs = priv->regs;
    int val;

    writel(0x80000000 | (phy_addr << 23) | (reg_addr << 18), regs + LAN8720_REG_DSCR);
    while (!(readl(regs + LAN8720_REG_DSCSR) & 0x80000000));
    val = readl(regs + LAN8720_REG_DSCR) & 0xffff;
    return val;
}

static int lan8720_mdio_write(struct mii_bus *bus, int phy_addr, int reg_addr, u16 val)
{
    struct lan8720_priv *priv = bus->priv;
    void __iomem *regs = priv->regs;

    writel(0xc0000000 | (phy_addr << 23) | (reg_addr << 18) | val, regs + LAN8720_REG_DSCR);
    while (!(readl(regs + LAN8720_REG_DSCSR) & 0x80000000));
    return 0;
}

static int lan8720_phy_reset(struct lan8720_priv *priv)
{
    u16 val;

    /* Reset PHY */
    lan8720_mdio_write(priv->netdev->mdio_bus, priv->netdev->phydev->addr, LAN8720_REG_BCR, 0x8000);
    msleep(LAN8720_PHY_RESET_DELAY_MS);

    /* Wait for PHY to come out of reset */
    val = lan8720_mdio_read(priv->netdev->mdio_bus, priv->netdev->phydev->addr, LAN8720_REG_BCR);
    if (val & 0x8000)
        return -EBUSY;

    return 0;
}

static int lan8720_phy_init(struct lan8720_priv *priv)
{
    u16 val;

    /* Reset PHY */
    if (lan8720_phy_reset(priv))
        return -EBUSY;

    /* Enable auto-negotiation */
    lan8720_mdio_write(priv->netdev->mdio_bus, priv->netdev->phydev->addr, LAN8720_REG_BCR, 0x1000);

    /* Wait for auto-negotiation to complete */
    do {
        val = lan8720_mdio_read(priv->netdev->mdio_bus, priv->netdev->phydev->addr, LAN8720_REG_BSR);
    } while (!(val & 0x0020));

    /* Enable RX/TX */
    lan8720_mdio_write(priv->netdev->mdio_bus, priv->netdev->phydev->addr, LAN8720_REG_BCR, 0x2000);

    return 0;
}

static int lan8720_probe(struct platform_device *pdev)
{
    struct lan8720_priv *priv;
    struct net_device *netdev;
    struct device_node *np = pdev->dev.of_node;
    struct resource *res;
    int ret;

    /* Allocate private data */
    priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL);
    if (!priv)
        return -ENOMEM;

    /* Allocate netdev */
    netdev = alloc_etherdev(sizeof(*priv));
    if (!netdev)
        return -ENOMEM;

    /* Set netdev MAC address */
    of_property_read_u8_array(np, "local-mac-address", netdev->dev_addr, ETH_ALEN);

    /* Initialize netdev */
    netdev->netdev_ops = &lan8720_netdev_ops;
    netdev->ethtool_ops = &lan8720_ethtool_ops;
    netdev->needs_free_netdev = true;
    netif_napi_add(netdev, &priv->napi, lan8720_rx_napi, NAPI_POLL_WEIGHT);

    /* Allocate MDIO bus */
    netdev->phydev = mdiobus_alloc();
    if (!netdev->phydev) {
        free_netdev(netdev);
        return -ENOMEM;
    }

    /* Set MDIO bus parameters */
    netdev->phydev->bus = priv->netdev->mdio_bus;
    netdev->phydev->mdio_read = lan8720_mdio_read;
    netdev->phydev->mdio_write = lan8720_mdio_write;
    netdev->phydev->priv = priv;

    /* Initialize PHY */
    ret = lan8720_phy_init(priv);
    if (ret) {
        mdiobus_free(netdev->phydev->bus);
        free_netdev(netdev);
        return ret;
    }

    /* Set netdev device and add it to network interface */
    priv->dev = &pdev->dev;
    priv->netdev = netdev;
    platform_set_drvdata(pdev, priv);
    ret = register_netdev(netdev);
    if (ret) {
        mdiobus_free(netdev->phydev->bus);
        free_netdev(netdev);
        return ret;
    }

    return 0;
}

static int lan8720_remove(struct platform_device *pdev)
{
    struct lan8720_priv *priv = platform_get_drvdata(pdev);

    unregister_netdev(priv->netdev);
    mdiobus_free(priv->netdev->phydev->bus);
    free_netdev(priv->netdev);

    return 0;
}

static const struct of_device_id lan8720_of_match[] = {
    { .compatible = "smsc,lan8720" },
    { },
};
MODULE_DEVICE_TABLE(of, lan8720_of_match);

static struct platform_driver lan8720_driver = {
    .probe = lan8720_probe,
    .remove = lan8720_remove,
    .driver = {
        .name = "lan8720",
        .of_match_table = lan8720_of_match,
    },
};

module_platform_driver(lan8720_driver);

MODULE_AUTHOR("Your Name Here");
MODULE_DESCRIPTION("LAN8720 driver");
MODULE_LICENSE("GPL");

需要注意的是，以上示例代码只是一个框架，实际的驱动程序需要根据硬件的具体特性进行实现。另外，该驱动程序还包含了一个NAPI驱动程序，以便在高速网络环境下进行数据接收。