在对象初始化只读字段 [英] Readonly field in object initializer

问题描述

我不知道为什么它是不可能做到以下几点：

 结构TestStruct 
 {
公共只读对象TestField; 
} 
 
 TestStruct TS =新TestStruct {
 / * TestField =东西//不可能* / 
}; 
  

应该不是对象初始值可以设置字段
的值<？ / p>

解决方案

对象初始化内部使用的临时对象，然后分配每个值的属性。有一个只读字段将打破。

随着

  TestStruct TS =新TestStruct 
 { 
 TestField =东西; 
}; 
  

将转化为

  TestStruct TS; 
变种TMP =新TestStruct（）; 
 tmp.TestField =东西; //这是不可能的
 TS = tmp中; 
  

（这里是的从乔恩斯基特答案解释临时对象与对象initalizer但使用不同的场景的使用）

I wonder why it is not possible to do the following:

struct TestStruct
{
    public readonly object TestField;
}

TestStruct ts = new TestStruct {
    /* TestField = "something" // Impossible */
};

Shouldn't the object initializer be able to set the value of the fields ?

解决方案

Object Initializer internally uses a temporary object and then assign each value to the properties. Having a readonly field would break that.

Following

TestStruct ts = new TestStruct 
{
     TestField = "something";
};

Would translate into

TestStruct ts;
var tmp = new TestStruct();
tmp.TestField = "something"; //this is not possible
ts = tmp;

(Here is the answer from Jon Skeet explaining the usage of temporary object with object initalizer but with a different scenario)

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