结合表初始化和对象初始化 [英] Combining List initializer and object initializer

问题描述

时可以将一个列表初始化和对象初始化，同时结合？ 考虑下面的类定义：

Is is possible to combine a List initializer and object initializer at the same time? Given the following class definition:

class MyList : List<int>
{
    public string Text { get; set; }
}

// we can do this
var obj1 = new MyList() { Text="Hello" };

// we can also do that
var obj2 = new MyList() { 1, 2, 3 };

// but this one doesn't compile
//var obj3 = new MyList() { Text="Hello", 1, 2, 3 };

在设计这还是仅仅是一个错误或C＃编译器的丢失的功能？

Is this by design or is it just a bug or missing feature of the c# compiler?

推荐答案

没有，望着定义从C＃规范第7.6.10，一个对象或-集合初始化 EX pression是的或者的的对象初始化的或的一个集合初始化。

No, looking at the definitions from section 7.6.10 of the C# spec, an object-or-collection-initializer expression is either an object-initializer or a collection-initializer.

这是对象初始化由多个的成员初始化 S，每个的形式为初始化=初始值，而在集合初始化由多个的元素的初始 S，每一个都是一个非assigment-EX pression 。

An object-initializer is composed of multiple member-initializers, each of which is of the form initializer = initializer-value whereas a collection-initializer is composed of multiple element-initializers, each of which is a non-assigment-expression.

因此​​，看起来是由设计 - 可能为简单起见。我不能说我所见过的希望的做到这一点，说实话。 （我通常不会从导出列表＆LT; INT＆GT; 来开始 - 我撰写它吧。）我真的很讨厌看到：

So it looks like it's by design - possibly for the sake of simplicity. I can't say I've ever wanted to do this, to be honest. (I usually wouldn't derive from List<int> to start with - I'd compose it instead.) I would really hate to see:

var obj3 = new MyList { 1, 2, Text = "Hello", 3, 4 };

编辑：如果你的真的，真的的要实现这一点，你可以在课堂上把这样的：

If you really, really want to enable this, you could put this in the class:

class MyList : List<int>
{
    public string Text { get; set; }
    public MyList Values { get { return this; } }
}

在这一点，你可以写：

at which point you could write:

var obj3 = new MyList { Text = "Hello", Values = { 1, 2, 3, 4 } };

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