ATL COM - 如何重用接口方法的代码

问题描述

我有几个介面，例如IA，IB，IC等，它们具有共同的性质，例如。现场。我想知道如何重用这些接口的代码（请保存我对COM聚合的答案）。

当前实现如下：

class CA
// ATL specific ...
{
STDMETHODIMP get_Site（...）{.. 。}
STDMETHODIMP put_Site（...）{...}
}

类BA
// ATL特定...
{
STDMETHODIMP get_Site（...）{...}
STDMETHODIMP put_Site（...）{...}
}

class CC
// ATL specific ...
{
STDMETHODIMP get_Site（...）{...}
STDMETHODIMP put_Site（...）{...}
}


我想实现（但不能），如下。

 模板< typename T> 
 class SharedProperties 
 {
 STDMETHODIMP get_Site（...）{...} 
 STDMETHODIMP put_Site（...）{...} 
} 
 
 class CA：
 // ATL specific ... 
 SharedProperties< CA> 
 {
 //属性是继承的，可以从IC 
}访问
 
 class BA 
 // ATL specific ... 
 SharedProperties< ; CB> 
 {
 //属性是继承的，可以从IB 
访问} 
 
 class CC 
 // ATL specific ... 
 SharedProperties< ; CC> 
 {
 //属性是继承的，可从IA 
访问} 
  

我在阅读后遇到了这个想法（），但网站没有一个工作示例，无论我尝试多少，我不能得到它的工作。我仍然得到不能实例化抽象类，因为纯虚函数get_Site和put_Site没有实现（按照第二个片段）。

EDIT
请注意，我使用的是VS2010。以下示例实现：

  class ATL_NO_VTABLE CArticle：
 public CComObjectRootEx< CComSingleThreadModel> ;, 
 public CComCoClass< CArticle ，& CLSID_Article>，
 public IDispatchImpl< IArticle，& IID_IArticle，& LIBID_GeodeEdiLib，/ * wMajor = * / 1，/ * wMinor = * / 0> 
 {
 public：
 CArticle（）
 {
} 
  

解决方案

编译器不知道方法 get_Site 和 put_Site 从接口实现方法。您需要从相应的接口继承SharedProperties类模板。这是使 SharedProperties 一个模板的论据。

  
 {
 STDMETHOD（get_Site）（）= 0; 
 STDMETHOD（put_Site）（）= 0 
}; 
 
 template< typename T> 
 class Sharedproperties：T 
 {
 public：
 STDMETHODIMP get_Site（）{return E_NOTIMPL; }; 
 STDMETHODIMP put_Site（）{return E_NOTIMPL; }; 
}; 
 
 class CAX：public IA 
 {
 STDMETHOD（other）（）{return S_OK; } 
} 
 
 class CA：public Sharedproperties< CAX> 
 {
 public：
 CA（）{} 
}; 
  

请注意，类CA不是直接继承自接口IA。

编辑： VS2008类向导为简单的ATL类对象生成这个继承：

  class ATL_NO_VTABLE CMyObject：
 public CComObjectRootEx< CComMultiThreadModel> ;, 
 public CComCoClass< CMyObject，& CLSID_MyObject> ;, 
 IMyObject 
  

其中 IMyObject 是在IDL定义的接口中。所以在ATL上下文中，你只需要替换IMyObject继承：

  class ATL_NO_VTABLE CMyObject：
 public CComObjectRootEx< CComMultiThreadModel> ，
 public CComCoClass< CMyObject，& CLSID_MyObject>，
 public Sharedproperties< MyIntermediateClass> 
  

I have several interfaces, e.g. IA, IB, IC, and so on, that share common properties, e.g. Site. I would like to know how to reuse code for these interfaces (please save me the answer on COM aggregation).

Current implementation is as follows:

class CA
// ATL specific...
{
    STDMETHODIMP get_Site(...) {...}
    STDMETHODIMP put_Site(...) {...}
}

class BA
// ATL specific...
{
    STDMETHODIMP get_Site(...) {...}
    STDMETHODIMP put_Site(...) {...}
}

class CC
// ATL specific...
{
    STDMETHODIMP get_Site(...) {...}
    STDMETHODIMP put_Site(...) {...}
}

What I want to achieve (but cannot) is as follows.

template<typename T>
class SharedProperties
{
    STDMETHODIMP get_Site(...) {...}
    STDMETHODIMP put_Site(...) {...}
}

class CA :
// ATL specific...
SharedProperties<CA>
{
    // properties are inherited and are accessible from IC
}

class BA
// ATL specific...
SharedProperties<CB>
{
    // properties are inherited and are accessible from IB
}

class CC
// ATL specific...
SharedProperties<CC>
{
// properties are inherited and are accessible from IA
}

I came across this idea after reading up (http://vcfaq.mvps.org/com/7.htm) but the site does not have a working example and no matter how much I tried I could not get it to work. I keep getting "Cannot instantiate abstract class" because the pure virtual functions get_Site and put_Site are not implemented (as per the second snippet).

EDITDo note that I am using VS2010. Sample implementation below:

class ATL_NO_VTABLE CArticle :
    public CComObjectRootEx<CComSingleThreadModel>,
    public CComCoClass<CArticle, &CLSID_Article>,
    public IDispatchImpl<IArticle, &IID_IArticle, &LIBID_GeodeEdiLib, /*wMajor =*/ 1, /*wMinor =*/ 0>
{
public:
    CArticle()
    {
    }

解决方案

The compiler does not know that the methods get_Site and put_Siteimplement the methods from the interface. You need to inherit the SharedProperties class template from the corresponding interface. That's the argument to make SharedProperties a template at all.

interface IA
{
    STDMETHOD(get_Site)() = 0;
    STDMETHOD(put_Site)() = 0;
};

template<typename T>
class Sharedproperties : T
{
public:
    STDMETHODIMP get_Site() { return E_NOTIMPL; };
    STDMETHODIMP put_Site() { return E_NOTIMPL; };
};

class CAX : public IA
{
    STDMETHOD(other)() { return S_OK; }
}

class CA: public Sharedproperties<CAX>
{
public:
    CA() {}
};

Please note that the class CA is not directly inherited from the interface IA.

Edit: The VS2008 class wizard generates this inheritance for a simple ATL class object:

class ATL_NO_VTABLE CMyObject :
    public CComObjectRootEx<CComMultiThreadModel>,
    public CComCoClass<CMyObject, &CLSID_MyObject>,
    IMyObject

where IMyObject is the in the IDL defined interface. So in ATL context you just need to replace the IMyObject inheritance:

class ATL_NO_VTABLE CMyObject :
    public CComObjectRootEx<CComMultiThreadModel>,
    public CComCoClass<CMyObject, &CLSID_MyObject>,
    public Sharedproperties<MyIntermediateClass>

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