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C# in Depth Third Edition 学习笔记-- C#2的一些特性

2024-07-14 21:56:25   219人阅读

1. Partial class: 可以在多个源文件中写一个类。特别适合部分代码自动生成，部分代码手动添加的特性。

    编译器在编译前会把所有的源文件合并到意洽。但是一个方法不能在一个文件中开始，在另一个文件中结束。

       C#3中独有的pratial 方法：

// Generated.csusing System;partial class PartialMethodDemo{public PartialMethodDemo(){OnConstructorStart();Console.WriteLine("Generated constructor");OnConstructorEnd();}partial void OnConstructorStart();partial void OnConstructorEnd();}using System;partial class PartialMethodDemo{partial void OnConstructorEnd(){Console.WriteLine("Manual code");}}

2. 静态类型static classes

3. 独立的取值方法/赋值属性访问器separate getter/setter property access

     

string name;public string Name{get { return name; }private set{// Validation, logging etc herename = value;}}

4. 命名空间别名Namespace aliases

using System;using WinForms = System.Windows.Forms;using WebForms = System.Web.UI.WebControls;class Test{static void Main(){Console.WriteLine(typeof(WinForms.Button));Console.WriteLine(typeof(WebForms.Button));}}

　　C#2 告知编译器使用别名

using System;using WinForms = System.Windows.Forms;using WebForms = System.Web.UI.WebControls;class WinForms {}class Test{static void Main(){Console.WriteLine(typeof(WinForms::Button));Console.WriteLine(typeof(WebForms::Button));}}

　　全局命名空间别名

using System;class Configuration {}namespace Chapter7{class Configuration {}class Test{static void Main(){Console.WriteLine(typeof(Configuration));Console.WriteLine(typeof(global::Configuration));Console.WriteLine(typeof(global::Chapter7.Test));}}}

　　外部别名

// Compile with// csc Test.cs /r:FirstAlias=First.dll /r:SecondAlias=Second.dllextern alias FirstAlias;extern alias SecondAlias;using System;using FD = FirstAlias::Demo;class Test{static void Main(){Console.WriteLine(typeof(FD.Example));Console.WriteLine(typeof(SecondAlias::Demo.Example));}}

5. pragma directives

    禁用和恢复警告CS0169

    　

public class FieldUsedOnlyByReflection{int x;}If you try to compile listing 7.9, you’ll get a warning message like this:FieldUsedOnlyByReflection.cs(3,9): warning CS0169:The private field ‘FieldUsedOnlyByReflection.x‘ is never used

　　

public class FieldUsedOnlyByReflection{#pragma warning disable 0169int x;#pragma warning restore 0169}

　　Checksum pragmas

#pragma checksum "filename" "{guid}" "checksum bytes"

6. 非安全代码中的固定大小的缓冲区Fixed-size buffers in unsafe code

7. 把内部成员暴露给选定的程序集

   简单情况下的友元程序集

   

// Compiled to Source.dllusing System.Runtime.CompilerServices;[assembly:InternalsVisibleTo("FriendAssembly")]public class Source{internal static void InternalMethod() {}public static void PublicMethod() {}}// Compiled to FriendAssembly.dllpublic class Friend{static void Main(){Source.InternalMethod();Source.PublicMethod();}}// Compiled to EnemyAssembly.dllpublic class Enemy{static void Main(){// Source.InternalMethod();Source.PublicMethod();}}

　　

 


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