我可以设置一个结构的值通过反射无拳？ [英] Can I set a value on a struct through reflection without boxing?

问题描述

其实，我应该问：我怎么能做到这一点的和的仍然符合CLS？因为我能想到这样做是如下，但使用的唯一方法要么 __ makeref ， FieldInfo.SetValueDirect 或只是 System.TypedReference 一般CLS的失效符合。

Actually, I should've asked: how can I do this and remain CLS Compliant? Because the only way I can think of doing this is as follows, but using either __makeref, FieldInfo.SetValueDirect or just System.TypedReference in general invalidates CLS Compliance.

// code illustrating the issue:
TestFields fields = new TestFields { MaxValue = 1234 };  // test struct with one field

FieldInfo info = fields.GetType().GetField("MaxValue");  // get the FieldInfo

// actual magic, no boxing, not CLS compliant:
TypedReference reference = __makeref(fields);
info.SetValueDirect(reference, 4096);

的兼容对应 SetValueDirect 是的SetValue ，但它需要一个对象作为目标，因此，我的结构将被装箱，让我在副本而不是原始变量设置的值。

The compliant counterpart of SetValueDirect is SetValue, but it takes an object as the target, hence my struct will be boxed, making me setting a value on a copy, not the original variable.

为的SetValue A一般对应不会因为据我所知存在。有没有通过反射设置的（参考一）结构该领域的任何其他方式？

A generic counterpart for SetValue doesn't exist as far as I know. Is there any other way of setting the field of a (reference to a) struct through reflection?

推荐答案

请符合CLS包装在SetValueDirect：

Make cls-compliant wrapper on SetValueDirect:

  var item = new MyStruct { X = 10 };

  item.GetType().GetField("X").SetValueForValueType(ref item, 4);


[CLSCompliant(true)]
static class Hlp
{
  public static void SetValueForValueType<T>(this FieldInfo field, ref T item, object value) where T : struct
  {
    field.SetValueDirect(__makeref(item), value);
  }
}

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