C＃编译器如何检测COM类型？ [英] How does the C# compiler detect COM types?

问题描述

EDIT：我已将结果写成 blog post 。

---

编译器在某种程度上处理COM类型。例如，此语句看起来正常...

  Word.Application app = new Word.Application 
  

...直到你意识到 Application 是一个接口。调用接口上的构造函数？ Yoiks！这实际上转换为调用 Type.GetTypeFromCLSID（） 和另一个 Activator.CreateInstance 。

此外，在C＃4中， ref 参数的非引用参数，编译器只是添加一个局部变量作为引用传递，舍弃结果：

  // FileName参数是* really * a ref参数
 app.ActiveDocument.SaveAs（FileName：test.doc）; 
  

（是的，有一堆参数丢失。 / p>

我试图调查编译器的行为，我没有假的第一部分。我可以做第二部分没有问题：

 使用System; 
 using System.Runtime.InteropServices; 
 using System.Runtime.CompilerServices; 
 
 [ComImport，GuidAttribute（00012345-0000-0000-0000-000000000011）] 
 public interface Dummy 
 {
 void Foo（ref int x）; 
} 
 
 class Test 
 {
 static void Main（）
 {
 Dummy dummy = null; 
 dummy.Foo（10）; 
} 
} 
  

我希望能够写： / p>

  Dummy dummy = new Dummy（）; 
  

显然，它会在执行时间爆炸，但是没关系。

编译器为链接COM PIA添加的其他属性（ CompilerGenerated 和<$

解决方案

我不是我的专家，但我最近偶然发现了我想要的： CoClass 属性类。

  [System.Runtime .InteropServices.CoClass（typeof（Test））] 
 public interface Dummy {} 
  

coclass提供一个或多个
接口的具体
实现。在COM中，这种具体的
实现可以用支持COM
组件开发的任何
编程语言编写。 Delphi，
C ++，Visual Basic等。

查看我对类似问题的回答关于Microsoft Speech API ，其中你可以实例化接口 SpVoice （但实际上，你是实例化 SPVoiceClass ）。 p>

  [CoClass（typeof（SpVoiceClass））] 
 public interface SpVoice：ISpeechVoice，_ISpeechVoiceEvents_Event {} 
  




EDIT: I've written the results up as a blog post.

---

The C# compiler treats COM types somewhat magically. For instance, this statement looks normal...

Word.Application app = new Word.Application();

... until you realise that Application is an interface. Calling a constructor on an interface? Yoiks! This actually gets translated into a call to Type.GetTypeFromCLSID() and another to Activator.CreateInstance.

Additionally, in C# 4, you can use non-ref arguments for ref parameters, and the compiler just adds a local variable to pass by reference, discarding the results:

// FileName parameter is *really* a ref parameter
app.ActiveDocument.SaveAs(FileName: "test.doc");

(Yeah, there are a bunch of arguments missing. Aren't optional parameters nice? :)

I'm trying to investigate the compiler behaviour, and I'm failing to fake the first part. I can do the second part with no problem:

using System;
using System.Runtime.InteropServices;
using System.Runtime.CompilerServices;

[ComImport, GuidAttribute("00012345-0000-0000-0000-000000000011")]
public interface Dummy
{
    void Foo(ref int x);
}

class Test
{
    static void Main()
    {
        Dummy dummy = null;
        dummy.Foo(10);
    }
}

I'd like to be able to write:

Dummy dummy = new Dummy();

though. Obviously it'll go bang at execution time, but that's okay. I'm just experimenting.

The other attributes added by the compiler for linked COM PIAs (CompilerGenerated and TypeIdentifier) don't seem to do the trick... what's the magic sauce?

解决方案

By no means am I an expert in this, but I stumbled recently on what I think you want: the CoClass attribute class.

[System.Runtime.InteropServices.CoClass(typeof(Test))]
public interface Dummy { }

A coclass supplies concrete implementation(s) of one or more interfaces. In COM, such concrete implementations can be written in any programming language that supports COM component development, e.g. Delphi, C++, Visual Basic, etc.

See my answer to a similar question about the Microsoft Speech API, where you're able to "instantiate" the interface SpVoice (but really, you're instantiating SPVoiceClass).

[CoClass(typeof(SpVoiceClass))]
public interface SpVoice : ISpeechVoice, _ISpeechVoiceEvents_Event { }

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