将反射与 COM 互操作一起使用

Using Reflection with COM Interop(将反射与 COM 互操作一起使用)

问题描述

在互操作调用之后，我得到了一个 COM 对象.我知道这个对象将是三个可能的 COM 类(Class1、Class2、Class3)之一，但不知道运行时是哪一个.

After an interop call, I get back a COM object. I know this object will be one of three possible COM classes (Class1, Class2, Class3), but do not know which one in runtime.

对该对象的反射 (interopObject.GetType()) 返回 System.__ComObject 的基本 RCW 包装器.

The reflection upon that object (interopObject.GetType()) returns the base RCW wrapper of System.__ComObject.

我需要在对象上设置一些属性 - Text1、Text2、... Text30(实际名称，顺便说一句:))，它们存在于所有三个类中.

What I need is to set some properties on the object - Text1, Text2, ... Text30 (actual names, btw :)), which exist in all three classes.

所以，问题是，我能否以某种方式获取对象的运行时类型(这将解决我的问题，但可能是不可能的，因为 .net 运行时可能没有该信息)，或者我可以设置一个属性盲目的COM对象

So, the question is, can I somehow get the runtime type of the object (this would solve my problem, but might be impossible, as the .net runtime might not have that info), or can I set a property of a COM object blindly

这是我当前的代码，但失败了:

this is my current code, which fails:

for ( int i = 1; i <= 30; i++ )
{
  ProprertyInfo pi =interopObject.GetType().GetProperty("Text" +i.ToString()) 
  // this returns null for pi
  pi.GetSetMethod().Invoke(interopObject, new object[] { someValue });
}

<小时>

感谢 Marc，这三个都进入了我的永久噱头收藏:

---

Thanks to Marc, these three go in my permanent gimmicks collection:

private static object LateGetValue(object obj, string propertyName)
{
  return RuntimeHelpers.GetObjectValue(NewLateBinding.LateGet(obj, null,
            propertyName, new object[0], null, null, null));
}

private static void LateSetValue(object obj, string propertyName, object value)
{
  NewLateBinding.LateSet(obj, null, propertyName, new []{value}, null, null);
}

private static void LateCallMethod(object obj, string methodName)
{
  NewLateBinding.LateCall(obj, null, methodName, new object[0], null,
            null, null, true);
}

推荐答案

在 C# 4.0 中，dynamic 非常适合这种类型的鸭子类型.

In C# 4.0, dynamic would be ideal for this type of duck-typing.

在那之前，我想知道 VB.Net 是否会更好，使用 Option Strict Off 以允许对 object 进行后期绑定.

Until then, I wonder if VB.Net would be better, with Option Strict Off to allow late binding against object.

最坏的情况:用VB.Net写，然后用reflector为你写C#；-p

Worst case: write it in VB.Net, then use reflector to write the C# for you ;-p

这是一个示例，需要引用 Microsoft.VisualBasic.dll，但在 C# 中很好:

Here's an example, that requires a reference to Microsoft.VisualBasic.dll, but is fine in C#:

public static object GetValue(object obj, string propertyName)
{
    return RuntimeHelpers.GetObjectValue(NewLateBinding.LateGet(obj, null,
         propertyName, new object[0], null, null, null));
}

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