急，高分求救，分不够加，加完为止，UP有分：关于强类型集合的问题！详细见内容！

[new_stranger]

//.h
#pragma once
#using <mscorlib.dll>
using namespace System;
using namespace System::Collections;

__gc class DictionaryInheritor : public DictionaryBase
{
public:

DictionaryInheritor(void);

~DictionaryInheritor(void);

__property Object * get_Item( Object * key ); //语句1
__property void set_Item( Object * key, Object * value ); //语句2

__property String * get_Item( String * key ); //语句3
__property void set_Item( String * key, String * value ); //语句4

};

//.cpp
#include "StdAfx.h"
#include "dictionaryinheritor.h"


DictionaryInheritor::DictionaryInheritor(void)
{

}


DictionaryInheritor::~DictionaryInheritor(void)
{

}

Object * DictionaryInheritor::get_Item(Object * key) //语句1
{
IDictionary * pDictionary = get_Dictionary();
return pDictionary->get_Item(key);
}

void DictionaryInheritor::set_Item(Object * key, Object * value) //语句2
{
IDictionary * pDictionary = get_Dictionary();
pDictionary->set_Item(key,value);
}


String * DictionaryInheritor::get_Item(String * key) //语句3
{
IDictionary * pDictionary = get_Dictionary();
return ( static_cast<String*>(pDictionary->get_Item(key)) );
}

void DictionaryInheritor::set_Item(String * key, String * value) //语句4
{
IDictionary * pDictionary = get_Dictionary();
pDictionary->set_Item( key, value );
}

/////////////////////
在.h和.cpp文件中
如果注释掉语句3和语句4，编译正常，运行正常，

如果注释掉语句1和语句2，这编译时的错误信息：
DictionaryInheritor.h(44): error C3815: “System::Collections::IDictionary::get_Item”方法的返回类型必须与“DictionaryInheritor::set_Item”最后一个参数的类型匹配
DictionaryInheritor.h(44): error C3815: “System::Collections::IDictionary::get_Item”方法的返回类型必须与“DictionaryInheritor::set_Item”最后一个参数的类型匹配

我的目的是实现强类型集合，在运行时不用对加入的对象进行类型转换了，
在MSDN里有一个类 DiscoveryExceptionDictionary 是这样实现的：
public: __property Exception* get_Item(String* url);
public: __property void set_Item(String* url, Exception*);

而我为什么不能改变Object 为String ?
听说.NET有很多BUG，这是我的程序有问题还是.NET的BUG?

???????????????????????????????WHY??????????????????????????????

[majh5235]

object转为string必须强制转化，而string转为object可隐式转化

[stavck]

2002的bug,装2003吧

[devzhao]

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