在反思的对象struct的接入领域 [英] Access fields of a Struct in an Object with Reflection

问题描述

我想使用反射（最终在编译时未知）对象包括结构。我得尽可能 TypedReference.MakeTypedReference ，但我已经碰了壁。

I'm trying to use reflection (ultimately on unknown at compile time) object which include struct. I've got as far as TypedReference.MakeTypedReference but I've hit a wall.

下面是我和类结构

public class MyObject
{
    public int Id;
    public Money Amount; 
}

public struct Money
{
    public int Vaule;
    public string Code;
}

这是我想设置代码，金额的在为MyObject使用反射。正如我上面提到的，我找不知道这些类型在编译时（这将是太容易了！）

And here is how I am trying to set "Code" of "Amount" in MyObject using reflection. As I mention above, I'm looking for a solution which does not know about these types at compile time (that would be too easy!)

下面的解决方案是我的代码到目前为止，（我用[0]，[1]，使代码更简单）

Here's the code I have so far (I've used [0], [1] to make the code simpler)

var obj = new MyObject() { Id = 1 };
obj.Amount.Vaule = 10;
obj.Amount.Code = "ABC";

FieldInfo[] objFields = obj.GetType().GetFields();
FieldInfo[] moneyFields = objFields[1].GetValue(obj).GetType().GetFields();

List<FieldInfo> fields = new List<FieldInfo>() { objFields[1] };
fields.AddRange( moneyFields );

TypedReference typeRef = TypedReference.MakeTypedReference( 
                           objFields[1].GetValue( obj ), fields.ToArray() );

moneyFields[1].SetValueDirect( typeRef, "XXX" );

的

TypedReference.MakeTypedReference与炸毁; 字段信息不匹配目标类型。同样，如果我只是通过 objFields [1] 。而如果通过只是 moneyFields 我得到TypedReferences不能被重新定义为基元。

The TypedReference.MakeTypedReference blows up with; "FieldInfo does not match the target Type." Likewise if I just pass objFields[1]. And if pass just moneyFields I get "TypedReferences cannot be redefined as primitives."

为什么？比方说，我创建的随机测试夹具和要填充类字段随机数据：）

Why? Let's say I'm creating Random test fixtures and want to populate class fields with random data :)

推荐答案

坦率地说，有没有需要任何的 TypedReference 在这里 - 只是一个盒装的结构应很好地工作：

Frankly, there's no need whatsoever for TypedReference here - just a boxed struct should work fine:

    var amountField = obj.GetType().GetField("Amount");
    object money = amountField.GetValue(obj);
    var codeField = money.GetType().GetField("Code");
    codeField.SetValue(money, "XXX");
    amountField.SetValue(obj, money);

不过！我会告诉你的几件事情：

However! I will advise you of a few things:

• 公共领域，而不是性能通常不是个好主意;这往往会咬你以后


• 可变（可以创建之后不得更改，即结构）结构是的几乎没有的一个好主意，会咬人，甚至更多的时候，咬较硬


• 结合可变结构和公共领域的化合物，但使它很有问题在后来修改

• public fields instead of properties are not usually a good idea; that will often bite you later
• mutable structs (i.e. structs that can be changed after creation) are almost never a good idea, and will bite even more often, and bite harder
• combining mutable structs and public fields compounds it, but making it very problematic to change later

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