C#6中的新增功能 【Unity3D亲测】

随着Unity2017的普及，使用.NET 4X的开发者也越来越多了，下面笔者给大家介绍一下在C# 6中的新功能主要是怕自己忘记,2333，有些功能还是很实用的~

使用Unity版本2018.2.9f1

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有说错或者不准确的地方欢迎大家留言指正

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参考资料：

• C# 6 中的新增功能
• C# 可空类型（Nullable）
• ?. 和 ?[] NULL 条件运算符
• $ - 字符串内插

自动属性增强功能

    #region 常规
    public string FirstName0 { get; private set; }
    public string LastName0 { get; private set; }

    public readonly string FirstName1 = "菜鸟";
    public readonly string LastName1 = "海澜";
    #endregion

    #region 自动属性增强功能
    public string FirstName2 { get; }
    public string LastName2 { get; }

    public CSharpSix()
    {
        FirstName2 = "菜鸟";
        LastName2 = "海澜";
    }
    public CSharpSix(string firstName, string lastName)
    {
        if (string.IsNullOrWhiteSpace(lastName))
            throw new ArgumentException(message: "不能是空白", paramName: nameof(lastName));
        FirstName2 = firstName;
        LastName2 = lastName;
    }
    public void ChangeName(string newLastName)
    {
        //LastName2 = newLastName;//报错，因为属性只读
    }
    #endregion

---

自动属性初始值设定项

    #region 自动属性初始值设定项
    public string FirstName3 { get; } = "菜鸟";
    public string LastName3 { get; } = "海澜";
    #endregion

---

Expression-bodied 函数成员 这适用于方法和只读属性

    #region Expression-bodied 函数成员   这适用于方法和只读属性
    //还可以在只读属性中使用 expression-bodied 成员：
    public string FullName => $"{FirstName1} {LastName1}";
    //等同于     
    public readonly string FullName1 = "菜鸟海澜";

    //仅限一条可以表示为表达式的语句
    public override string ToString() => $"{FirstName1}, {LastName1}";
    public void LogMessage(string a, string b) => Debug.Log(a + b);
    #endregion

---

using static

增强功能可用于导入单个类的静态方法。 以前，using 语句将所有类型导入命名空间中
下面的示例中IsNullOrWhiteSpace可直接调用

    #region using static

    //using static 增强功能可用于导入单个类的静态方法。 以前，using 语句将所有类型导入命名空间中
    public void TestUsingStatic(string lastName)
    {

        //使用  using static
        if (IsNullOrWhiteSpace(lastName))
        {
            throw new ArgumentException(message: "Cannot be blank", paramName: nameof(lastName));
        }

        //原有方式
        if (string.IsNullOrWhiteSpace(lastName))
        {
            throw new ArgumentException(message: "Cannot be blank", paramName: nameof(lastName));
        }
    }

    #endregion

---

可空类型（Nullable）与 Null 条件运算符

示例1

    int? nullIntOne = 3;
    //等同于
    Nullable nullInt_One = new Nullable(3);

    double? num3 = new double?();
    bool? boolval = new bool?();

    int Number_Default; //默认值0
    public int? number_Null;//默认值null

如果number_Null 为null则打印666

       Debug.Log(cSharpSix.number_Null ?? 666);

如果打印则报错：NullReferenceException: Object reference not set to an instance of an object

        cSharpSix = null;
        //报错：NullReferenceException: Object reference not set to an instance of an object
        Debug.Log(cSharpSix.FirstName2);

使用Null 条件运算符不会报错，会打印Null
其中的 【?.】可以分别理解为【?】如果不为Null 【.】就执行

        //不会报错，打印Null   其中的 【?.】可以分别理解为【?】如果不为Null 【.】就执行
        Debug.Log(cSharpSix?.FirstName2);

在委托时的使用

    public Action actionOne;

    public void Test()
    {
        actionOne += CustomAction;

        actionOne?.Invoke();

        //等同于
        if (actionOne != null)
        {
            actionOne();
        }
    }

    public void CustomAction()
    {
        Debug.Log("123");
    }

当然也可以这么写，不过笔者认为这种写法还是少用为好，因为

• 可读性低，大量使用对其他阅读者将是灾难

        //灾难
        Debug.Log(cSharpSix?.FirstName2==null ? cSharpSix.number_Null?.ToString() : "三元运算菜鸟海澜");
        Debug.Log(cSharpSix?.number_Null?.ToString()??"defualt菜鸟海澜");

而且在文档中对应委托使用Null 条件运算符有这样的描述

这个缓存结果笔者有些不解，难道是让他具有原子性？有知道的大佬可以给我留言，不胜感谢~

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字符串内插

可读性提高

    public void LogMessage()
    {
        Debug.Log($"姓{FirstName3}名{LastName3}");

        Debug.LogFormat("姓：{0}名:{1}", FirstName3, LastName3);
    }

也可对字符串使用【:】设置格式
还有一些详细的设置，可参考：$ - 字符串内插

    public void LogDateTime()
    {
        Debug.Log($"现在的时间为{DateTime.Now}");

        Debug.Log($"现在的时间为{DateTime.Now:yyyy-MM-dd hh:mm:ss}");
    }

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异常筛选器

如果用于异常筛选器的表达式计算结果为 true，则 catch 子句将对异常执行正常处理。 如果表达式计算结果为 false，则将跳过 catch 子句，直接抛出异常。

老版本写法

    public void CatchException()
    {
        try
        {
            throw new Exception("海澜1");
        }
        catch (Exception ex)
        {
            if (ex.Message == "海澜0")
            {
                Debug.LogWarning("异常0");
            }
            if (ex.Message == "海澜1")
            {
                Debug.LogWarning("异常01");
            }
        }
    }

新版本写法

    public void CatchExceptionWhen()
    {
        try
        {
            throw new Exception("海澜1");
        }
        catch (Exception ex) when (ex.Message == "海澜0")
        {
            Debug.LogWarning("异常0");
        }
        catch (Exception ex) when(ex.Message == "海澜1")
        {
                Debug.LogWarning("异常1");          
        }
    }

优点：使用这个when可以更好的判断一个错误是继续处理还是重新抛出去。按照以前的做法，在catch块内如需再次抛出去，需要重新throw出去，这时的错误源是捕捉后在抛的，而不是原先的，有了when语法就可以直接定位到错误源。

使用异常筛选器的另一种推荐模式是将其用于日志记录例程。 这种用法还会利用当异常筛选器计算结果为 false 时，保留异常引发点的方式。
日志记录方法将是这样一种方法：其参数为无条件返回 false 的异常：

    public void CatchExceptionWhenWithLog()
    {
        try
        {
            throw new Exception("海澜1");
        }
        catch (Exception ex) when (LogException(ex.Message))
        {

        }
        catch (Exception ex) when (ex.Message == "海澜0")
        {
            Debug.LogWarning("异常0");
        }
        catch (Exception ex) when (ex.Message == "海澜1")
        {
            Debug.LogWarning("异常1");
        }
    }

    public bool LogException(string ex)
    {
        Debug.LogWarning($"记录异常信息{ex}");
        return false;
    }

---

nameof 表达式

    public void TestNameOf(string firstName)
    {
        Debug.Log($"输出{firstName}");

        Debug.Log($"输出{nameof(firstName)}");

        Debug.Log($"输出{nameof(CSharpSix.staticName)}");
    }

打印信息

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Catch 和 Finally 块中的 Await

在 catch 和 finally 子句中添加 await 支持的实现细节可确保该行为与同步代码的行为一致

    public async Task TestAwait()
    {
        try
        {
            throw new Exception("菜鸟海澜");
        }
        catch(Exception ex) when (ex.Message.Contains("海澜"))
        {
            await LogExceptionAsync();
        }
        finally
        {
            await CloseConnectionAsync();
        }
    }

    private Task CloseConnectionAsync()
    {
        Debug.Log("CloseConnectionAsync");
        Thread.Sleep(1000);
        return null;
    }

    private Task LogExceptionAsync()
    {
        Debug.Log("LogExceptionAsync");
        Thread.Sleep(1000);
        return null;
    }

---

索引初始值设定项

笔者现在用的这个版本会报错

    #region 索引初始值设定项
    private Dictionary webErrors = new Dictionary
    {
        [404] = "Page not Found",
        [302] = "Page moved, but left a forwarding address.",
        [500] = "The web server can't come out to play today."
    };
    #endregion

但是放在方法中不会，估计官方会在后续版本中修复

    public void aaa()
    {
        Dictionary webErrors = new Dictionary
        {
            [404] = "Page not Found",
            [302] = "Page moved, but left a forwarding address.",
            [500] = "The web server can't come out to play today."
        };
    }

---

改进了重载解析

现在可以正确的区分 Task.Run(Action) 和 Task.Run(Func())。

    #region 改进了重载解析
    public static Task DoThings()
    {
        return Task.FromResult(666);
    }
    #endregion

        Task result = CSharpSix.DoThings();
        Debug.Log($"结果为{result.Result}");

---

集合初始值设定项中的扩展 Add 方法

这个感兴趣的同学可以自行查看，不过笔者没发现他的特别便利之处

下面是笔者测试时所有的示例代码

using System.Collections;
using System.Collections.Generic;
using UnityEngine;
using System;
using System.Threading.Tasks;

public class TestCSharpSix : MonoBehaviour
{


    void Start()
    {
        var cSharpSix = new CSharpSix();

        Debug.Log(cSharpSix.number_Null ?? 666);

        cSharpSix = null;
        //报错：NullReferenceException: Object reference not set to an instance of an object
        //Debug.Log(cSharpSix.FirstName2);
        //不会报错，打印Null   其中的 【?.】可以分别理解为【?】如果不为Null 【.】就执行
        Debug.Log(cSharpSix?.FirstName2);
        Debug.Log(cSharpSix?.FirstName2 ?? "自定义菜鸟海澜");
        Debug.Log(cSharpSix?.FirstName2 ?? "自定义菜鸟海澜");
        cSharpSix = new CSharpSix();
        //灾难
        Debug.Log(cSharpSix?.FirstName2 == null ? cSharpSix.number_Null?.ToString() : "三元运算菜鸟海澜");
        Debug.Log(cSharpSix?.number_Null?.ToString() ?? "defualt菜鸟海澜");

        cSharpSix.LogMessage();
        cSharpSix.CatchException();
        cSharpSix.CatchExceptionWhen();
        cSharpSix.CatchExceptionWhenWithLog();

        cSharpSix.TestNameOf("菜鸟海澜");

        Task.Run(() => { cSharpSix.TestAwait(); });

        Task result = CSharpSix.DoThings();
        Debug.Log($"结果为{result.Result}");

    }
}

using System;
using System.Collections;
using System.Collections.Generic;
using UnityEngine;
using static System.String;
using static System.Linq.Enumerable;
using System.Threading.Tasks;
using System.Threading;

public class CSharpSix
{
    #region 常规
    public string FirstName0 { get; private set; }
    public string LastName0 { get; private set; }

    public readonly string FirstName1 = "菜鸟";
    public readonly string LastName1 = "海澜";
    #endregion

    #region 自动属性增强功能
    public string FirstName2 { get; }
    public string LastName2 { get; }

    public CSharpSix()
    {
        FirstName2 = "菜鸟";
        LastName2 = "海澜";
    }
    public CSharpSix(string firstName, string lastName)
    {
        if (string.IsNullOrWhiteSpace(lastName))
            throw new ArgumentException(message: "不能是空白", paramName: nameof(lastName));
        FirstName2 = firstName;
        LastName2 = lastName;
    }
    public void ChangeName(string newLastName)
    {
        //LastName2 = newLastName;//报错，因为属性只读
    }
    #endregion

    #region 自动属性初始值设定项
    public string FirstName3 { get; } = "菜鸟";
    public string LastName3 { get; } = "海澜";
    #endregion

    #region Expression-bodied 函数成员   这适用于方法和只读属性
    //还可以在只读属性中使用 expression-bodied 成员：
    public string FullName => $"{FirstName1} {LastName1}";
    //等同于     
    public readonly string FullName1 = "菜鸟海澜";

    //仅限一条可以表示为表达式的语句
    public override string ToString() => $"{FirstName1}, {LastName1}";
    public void LogMessage(string a, string b) => Debug.Log(a + b);
    #endregion

    #region using static

    //using static 增强功能可用于导入单个类的静态方法。 以前，using 语句将所有类型导入命名空间中
    public void TestUsingStatic(string lastName)
    {

        //使用  using static
        if (IsNullOrWhiteSpace(lastName))
        {
            throw new ArgumentException(message: "Cannot be blank", paramName: nameof(lastName));
        }

        //原有方式
        if (string.IsNullOrWhiteSpace(lastName))
        {
            throw new ArgumentException(message: "Cannot be blank", paramName: nameof(lastName));
        }
    }

    #endregion

    #region 可空类型

    int? nullIntOne = 3;
    //等同于
    Nullable nullInt_One = new Nullable(3);

    double? num3 = new double?();
    bool? boolval = new bool?();

    int Number_Default; //默认值0
    public int? number_Null;//默认值null

    public Action actionOne;

    public void Test()
    {
        actionOne += CustomAction;

        actionOne?.Invoke();

        //等同于
        if (actionOne != null)
        {
            actionOne();
        }
        Debug.Log("注册成功");
    }

    public void CustomAction()
    {
        Debug.Log("123");
    }

    #endregion

    #region 字符串内插

    public void LogMessage()
    {
        Debug.Log($"姓{FirstName3}名{LastName3}");

        Debug.LogFormat("姓：{0}名:{1}", FirstName3, LastName3);
    }

    public void LogDateTime()
    {
        Debug.Log($"现在的时间为{DateTime.Now}");

        Debug.Log($"现在的时间为{DateTime.Now:yyyy-MM-dd hh:mm:ss}");
    }

    #endregion

    #region 异常筛选器

    public void CatchException()
    {
        try
        {
            throw new Exception("海澜1");
        }
        catch (Exception ex)
        {
            if (ex.Message == "海澜0")
            {
                Debug.LogWarning("异常0");
            }
            if (ex.Message == "海澜1")
            {
                Debug.LogWarning("异常01");
            }
        }
    }
    public void CatchExceptionWhen()
    {
        try
        {
            throw new Exception("海澜1");
        }
        catch (Exception ex) when (ex.Message == "海澜0")
        {
            Debug.LogWarning("异常0");
        }
        catch (Exception ex) when (ex.Message == "海澜1")
        {
            Debug.LogWarning("异常1");
        }
    }
    public void CatchExceptionWhenWithLog()
    {
        try
        {
            throw new Exception("海澜1");
        }
        catch (Exception ex) when (LogException(ex.Message))
        {

        }
        catch (Exception ex) when (ex.Message == "海澜0")
        {
            Debug.LogWarning("异常0");
        }
        catch (Exception ex) when (ex.Message == "海澜1")
        {
            Debug.LogWarning("异常1");
        }
    }

    public bool LogException(string ex)
    {
        Debug.LogWarning($"记录异常信息{ex}");
        return false;
    }

    #endregion

    #region nameof 表达式

    public static string staticName = "静态菜鸟海澜";
    public void TestNameOf(string firstName)
    {
        Debug.Log($"输出{firstName}");

        Debug.Log($"输出{nameof(firstName)}");

        Debug.Log($"输出{nameof(CSharpSix.staticName)}");
    }
    #endregion

    #region Catch 和 Finally 块中的 Await
    public async Task TestAwait()
    {
        try
        {
            Thread.Sleep(1000);
            throw new Exception("菜鸟海澜");
        }
        catch (Exception ex) when (ex.Message.Contains("海澜"))
        {
            await LogExceptionAsync();
        }
        finally
        {
            await CloseConnectionAsync();
        }
    }

    private Task CloseConnectionAsync()
    {
        Debug.Log("CloseConnectionAsync");
        Thread.Sleep(1000);
        return null;
    }

    private Task LogExceptionAsync()
    {
        Debug.Log("LogExceptionAsync");
        Thread.Sleep(1000);
        return null;
    }

    #endregion

    #region 索引初始值设定项

    private List messages = new List
{
    "Page not Found",
    "Page moved, but left a forwarding address.",
    "The web server can't come out to play today."
};

    public void aaa()
    {
        Dictionary webErrors = new Dictionary
        {
            [404] = "Page not Found",
            [302] = "Page moved, but left a forwarding address.",
            [500] = "The web server can't come out to play today."
        };
    }

    //Dictionary webErrors11 = new Dictionary
    //{
    //    [404] = "Page not Found",
    //    [302] = "Page moved, but left a forwarding address.",
    //    [500] = "The web server can't come out to play today."
    //};
    #endregion

    #region 改进了重载解析
    public static Task DoThings()
    {
        return Task.FromResult(666);
    }
    #endregion