一个简单而简洁definiton和匿名类型说明在C＃中？ [英] A simple and succinct definiton and explanation of anonymous types in C#?

问题描述

我不知道什么是匿名类型是在C＃也不是如何使用的。 ？可以somone给我这一个很好的说明，它的使用

I have no clue what an "anonymous type" is in C# nor how it is used. Can somone give me a good description of it and it's use?

[注：我真的知道它是什么，以及如何使用它，但想到我会问那些不这样做]

[Note: i really know what it is and how to use it but thought i'd ask for those that don't]

推荐答案

这是匿名类型是由编译器生成的类型，由于这样的表达式：

An anonymous type is a type generated by the compiler due to an expression such as:

new { Property1 = x.Value1, Property2 = y.Value2, z.Value3 }

（最后一个是像 =值3 z.Value3 ）。

匿名类型的名称是难以启齿 - 即你不能在普通的C＃指定它 - 但它是一个完全正常的类型至于CLR而言。正如你不能写名字，如果你想创建一个匿名类型的变量（或使用匿名类型作为类型参数泛型类型），您需要使用的隐式类型的局部变量与 VAR 关键字：

The name of the anonymous type is "unspeakable" - i.e. you can't specify it in normal C# - but it's a perfectly normal type as far as the CLR is concerned. As you can't write the name, if you want to create a variable of an anonymous type (or a generic type using an anonymous type as the type argument), you need to use an implicitly typed local variable with the var keyword:

var person = new { Name = "Bill", Address = "..." };

C＃匿名类型是不可变的（即属性是只读） - 生成的类型有单构造函数取值为所有属性作为参数。该物业类型从数值推断出来的。

C# anonymous types are immutable (i.e. the properties are read-only) - the generated type has a single constructor which takes values for all the properties as parameters. The property types are inferred from the values.

匿名类型覆盖的GetHashCode ，等于和的ToString 在相当明显的方式 - 默认的相等比较每个属性类型用于哈希和平等

Anonymous types override GetHashCode, Equals and ToString in reasonably obvious ways - the default equality comparer for each property type is used for hashing and equality.

它们通常在LINQ使用，你会使用选择值1作为Property1，值2作为Property2，值3在SQL以同样的方式。

They are typically used in LINQ in the same way that you'd use "SELECT Value1 As Property1, Value2 As Property2, Value3" in SQL.

它使用了相同的顺序将指向同一类型相同的属性名称和类型，所以你可以写的每一个匿名类型初始化表达式：

Every anonymous type initializer expression which uses the same property names and types in the same order will refer to the same type, so you can write:

var x = new { Name = "Fred", Age = 10 };
x = new { Name = "Bill", Age = 15 };

这也是值得了解VB匿名类型稍有不同：在默认情况下，他们是可变的。您可以使用钥匙关键字使每单个属性不变。我个人比较喜欢C＃的方式，但我可以看到易变性是在某些情况下非常有用。

It's also worth knowing that VB anonymous types are slightly different: by default, they're mutable. You can make each individual property immutable using the "Key" keyword. Personally I prefer the C# way, but I can see mutability being useful in some situations.

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