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[英]std::ostream class member variable to be used as std::ofstream or std::ostringstream
[英]class does not export from dll when having std::map<int,std::ofstream> member
考慮導出類streamTest的dll。 以下代碼:
class streamTest
{
public:
TEST_API streamTest();
TEST_API ~streamTest();
private:
std::map<int,std::ofstream> streamMap;
};
編譯沒有錯誤,並且可以從鏈接到dll的應用程序正常運行,但是以下代碼:
class TEST_API streamTest
{
public:
streamTest();
streamTest();
private:
std::map<int,std::ofstream> streamMap;
};
給出警告然后出錯:
1>warning C4251: 'streamTest::streamMap' : class 'std::map<_Kty,_Ty>' needs to have dll-interface to be used by clients of class 'streamTest'
1> with
1> [
1> _Kty=int,
1> _Ty=std::ofstream
1> ]
1>c:\Program Files (x86)\Microsoft Visual Studio 10.0\VC\include\fstream(1116): error C2248: 'std::basic_ios<_Elem,_Traits>::basic_ios' : cannot access private member declared in class 'std::basic_ios<_Elem,_Traits>'
1> with
1> [
1> _Elem=char,
1> _Traits=std::char_traits<char>
1> ]
1> c:\Program Files (x86)\Microsoft Visual Studio 10.0\VC\include\ios(176) : see declaration of 'std::basic_ios<_Elem,_Traits>::basic_ios'
1> with
1> [
1> _Elem=char,
1> _Traits=std::char_traits<char>
1> ]
1> This diagnostic occurred in the compiler generated function 'std::basic_ofstream<_Elem,_Traits>::basic_ofstream(const std::basic_ofstream<_Elem,_Traits> &)'
1> with
1> [
1> _Elem=char,
1> _Traits=std::char_traits<char>
1> ]
為什么不編譯,如何為std :: map提供dll接口? 我已經在dll中將std :: ofstream以外的其他對象用於std :: map,之前沒有任何問題。 請讓我知道我在想什么...
PS TEST_API很簡單
#ifdef TEST_EXPORTS
#define TEST_API __declspec(dllexport)
#else
#define TEST_API __declspec(dllimport)
#endif
ofstream
是不可復制的。 導出該類將強制實例化map<int,std::ofstream>
所有方法-包括嘗試復制該值的方法。
您使用的是VC10,它不支持C ++ 11功能。 我不相信你可以存儲ofstream
在map
出現,出口或沒有出口。
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