什么时候有效使用匿名类型？ [英] When is efficient to use anonymous types?

问题描述

我的意思是var关键字。例如

  var  a =  10 ; 

或

  int  a =  10 ; 

。在我看来，程序是值得的，因为在使用var关键字的情况下，编译器应该为给定变量选择正确的类型。

解决方案

< blockquote> 这不是匿名类型;这只是从类型推断获得的类型。考虑

  var  stringBuilder =  new 系统.Text.StringBuilder（）; 
  string  whatIsIt = stringBuilder.GetType（）。FullName; 

最后一行将返回System.Text.StringBuilder，相当完全命名:-);并且第一行是严格等同到

 System.Text.StringBuilder（）; stringBuilder =  new  System.Text.StringBuilder（）; 

所以，这只是语法，语法糖（ http://en.wikipedia.org/wiki/Syntactic_sugar [ ^ ]）。



您可以尝试使用相同的数字和字符串，将看到具体的命名类型。



我猜你的表现很明显可以使用这个功能：当你知道编译器的猜测是显而易见的并且你得到了你所期望的。



匿名类型是完全不同的：https://msdn.microsoft.com/en-us/library/bb397696.aspx [ ^ ]。

-SA

I mean "var" keyword.For example

var a=10;

or

int a=10;

.In my opinion program will work worth,becouse in situation of using var keyword,compiler should choose right type for given variable.

解决方案

This is not an anonymous type; this is just a type obtained from type inference. Consider

var stringBuilder = new System.Text.StringBuilder();
string whatIsIt = stringBuilder.GetType().FullName;

The last line will return "System.Text.StringBuilder", quite fully named :-); and the first line is strictly equivalent to

System.Text.StringBuilder(); stringBuilder = new System.Text.StringBuilder();

So, this is nothing but syntax, syntactic sugar (http://en.wikipedia.org/wiki/Syntactic_sugar[^]).

You can try the same with the number and the string, will see a concrete named type.

I guess it's apparent when you can use this feature: when you know that "compiler's guess" is apparent and you get what you expected.

And anonymous type is something totally different: https://msdn.microsoft.com/en-us/library/bb397696.aspx[^].

—SA

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