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C# 6.0 11个新特性
1. 静态using(static using)
静态using声明允许不使用类名直接调用静态方法。
The static using declaration allows invoking static methods without the class
name.
In C# 5
using System;Console.WriteLine("Hello, World!");
In C# 6
using static System.Console;WriteLine("Hello, World");
2. 表达式方法(Expression-Bodied Methods)
使用表达式方法,只有一条语句的方法可以使用lambda语法写。
With expression-bodied methods, a method that includes just one statement can
be written with the lambda syntax.
In C# 5
public bool IsSquare(Rectangle rect){ return rect.Height == rect.Width;}
In C# 6
public bool IsSquare(Rectangle rect) => rect.Height == rect.Width;
3. 表达式属性(Expression-Bodied Properties)
跟表达式方法类似,只有一个get访问器的单行属性可以使用lambda语法写。
Similar to expression-bodied methods, one-line properties with only a get accessor
can be written with the lambda syntax
In C# 5
public string FullName{ get { return FirstName +"" + LastName; }}
In C# 6
public string FullName => FirstName +"" + LastName;
4. 自动属性初始化器(Auto-Implemented Property Intializers)
自动属性可以使用属性初始化器初始化。
Auto-implemented properties can be initialized with a property initializer.
In C# 5
public class Person{ public Person() { Age = 24; } public int Age {get; set;}}
In C# 6
public class Person{ public int Age {get; set;} = 42;}
5. 只读自动属性(Read-Only Auto Properties)
C# 5需要完整的属性语法实现只读属性,C# 6可以使用自动属性实现。
To implement read-only properties, C# 5 requires the full property syntax. With
C# 6, you can do this using auto-implemented properties.
In C# 5
private readonly int _bookId;public BookId{ get { return _bookId; }}
In C# 6
public BookId {get;}
6. nameof操作符(nameof Operator)
字段、属性、方法和类型的name可以通过nameof访问。使用nameof,可以方便的重构name变化。
With the new nameof operator, names of fields, properties, methods, or types can
be accessed. With this, name changes are not missed with refactoring.
In C# 5
public void Method(object o){ if (o == null) throw new ArgumentNullException("o");
In C# 6
public void Method(object o){ if (o == null) throw new ArgumentNullException(nameof(o));
7. Null传递操作符(Null Propagation Operator)
Null传递操作符简化了空值检查。
The null propagation operator simplifies null checks.
In C# 5
int? age = p == null ? null : p.Age;
var handler = Event;if (handler != null){ handler(source, e);}
In C# 6
int? age = p?.Age;
handler?.Invoke(source, e);
8. 字符串插值(String Interpolation)
字符串差值移除了对string.Format的调用,使用表达式占位符取代数字格式占位符。
The string interpolation removes calls to string.Format. Instead of using
numbered format placeholders in the string, the placeholders can include
expressions.
In C# 5
public override ToString(){ return string.Format("{0}, {1}", Title, Publisher);}
In C# 6
public override ToString() => $"{Title} {Publisher}";
9. 字典初始化器(Dictionary Initializers)
字典可以使用类似集合的字典初始化器初始化。
Dictionaries can now be initialized with a dictionary initializer—similar to the
collection initializer.
In C# 5
var dict = new Dictionary<int, string>();dict.Add(3,"three");dict.Add(7,"seven");
In C# 6
var dict = new Dictionary<int, string>(){ [3] ="three", [7] ="seven"};
10. 异常过滤器(Exception Filters)
异常过滤器允许你在捕获异常前进行过滤。
Exception filters allow you to filter exceptions before catching them.
In C# 5
try{ //etc.} catch (MyException ex){ if (ex.ErrorCode != 405) throw; // etc.}
In C# 6
try{ //etc.} catch (MyException ex) when (ex.ErrorCode == 405){ // etc.}
11. 在Catch使用Await(Await in Catch)
await可以在catch块中直接使用,C# 5中需要变通使用。
await can now be used in the catch clause. C# 5 required a workaround.
In C# 5
bool hasError = false;string errorMessage = null;try{ //etc.} catch (MyException ex){ hasError = true; errorMessage = ex.Message;} if (hasError){ await new MessageDialog().ShowAsync(errorMessage);}
In C# 6
try{ //etc.} catch (MyException ex){ await new MessageDialog().ShowAsync(ex.Message);}
C# 6.0 11个新特性