C++類模板明確實例化工作在macos上，不能在Ubuntu上工作

Question

我正在寫一些代碼，我想發佈爲.h文件和靜態庫。代碼是使用C++模板編寫的，在.cpp文件中定義時使用.h文件中的類聲明。我使用了「顯式實例化」技巧，可以將代碼編譯到靜態庫中。明確的實例化被添加到.cpp文件的末尾。我寫了一些代碼來測試這個庫。它在macos和windows上工作正常，但在ubuntu上它返回「未定義參考」鏈接錯誤。看起來「顯式實例化」技巧在Ubuntu上不起作用。有人知道爲什麼嗎？

ubuntu的g ++版本是4.5.3。

編輯

這是模板類的.h文件：

#ifndef PHYSIKA_CORE_MATRICES_MATRIX_2X2_H_ 
#define PHYSIKA_CORE_MATRICES_MATRIX_2X2_H_ 

#include "Physika_Core/Utilities/global_config.h" 
#include "Physika_Core/Matrices/matrix_base.h" 

namespace Physika{ 

template <typename Scalar> 
class Matrix2x2: public MatrixBase<Scalar,2,2> 
{ 
public: 
Matrix2x2(); 
Matrix2x2(Scalar x00, Scalar x01, Scalar x10, Scalar x11); 
~Matrix2x2(); 
inline int rows() const{return 2;} 
inline int cols() const{return 2;} 
Scalar& operator() (int i, int j); 
const Scalar& operator() (int i, int j) const; 
Matrix2x2<Scalar> operator+ (const Matrix2x2<Scalar> &) const; 
//other operation declarations 
//omitted here 
}; 

//overriding << for Matrix2x2 
template <typename Scalar> 
std::ostream& operator<< (std::ostream &s, const Matrix2x2<Scalar> &mat) 
{ 
    s<<mat(0,0)<<", "<<mat(0,1)<<std::endl; 
    s<<mat(1,0)<<", "<<mat(1,1)<<std::endl; 
    return s; 
} 

} //end of namespace Physika 

#endif //PHYSIKA_CORE_MATRICES_MATRIX_2X2_H_ 

模板類的.cpp文件都按：

#include "Physika_Core/Matrices/matrix_2x2.h" 

namespace Physika{ 

template <typename Scalar> 
Matrix2x2<Scalar>::Matrix2x2() 
{ 
} 

template <typename Scalar> 
Matrix2x2<Scalar>::Matrix2x2(Scalar x00, Scalar x01, Scalar x10, Scalar x11) 
{ 
#ifdef PHYSIKA_USE_EIGEN_MATRIX 
    eigen_matrix_2x2_(0,0) = x00; 
    eigen_matrix_2x2_(0,1) = x01; 
    eigen_matrix_2x2_(1,0) = x10; 
    eigen_matrix_2x2_(1,1) = x11; 
#endif 
} 

//other operation definitions 
//omitted here 

//explicit instantiation of template so that it could be compiled into a lib 
template class Matrix2x2<float>; 
template class Matrix2x2<double>; 

} //end of namespace Physika 

測試代碼是一樣：

#include <iostream> 
#include "Physika_Core/Matrices/matrix_2x2.h" 
using namespace std; 
using Physika::Matrix2x2; 

int main() 
{ 
    cout<<"Matrix2x2 Test"<<endl; 
    Matrix2x2<double> mat_double(2.0,1.0,1.0,2.0); 
    cout<<"A 2x2 matrix of double numbers:"<<endl; 
    cout<<mat_double; 
    return 0; 
} 

錯誤信息是：

g++ -Wall -Wno-write-strings -O2 -I ../../Public_Library/include -L ../../Public_Library/lib -l matrices matrix2x2_test.cpp -o matrix2x2_test 
/tmp/ccUrtwwf.o: In function `main': 
matrix2x2_test.cpp:(.text+0x91): undefined reference to `Physika::Matrix2x2<double>::Matrix2x2(double, double, double, double)' 
matrix2x2_test.cpp:(.text+0x1b9): undefined reference to `Physika::Matrix2x2<double>::Matrix2x2(double, double, double, double)' 
//more moitted here 
collect2: ld returned 1 exit status 
make: *** [matrix2x2_test] Error 1 

Answer 1

我用替換編譯命令

g++ -Wall -Wno-write-strings -O2 -I ../../Public_Library/include -L ../../Public_Library/lib -l matrices matrix2x2_test.cpp -o matrix2x2_test 

解決了這個問題：

g++ matrix2x2_test.cpp -o matrix2x2_test -Wall -Wno-write-strings -O2 -I ../../Public_Library/include -L ../../Public_Library/lib -l matrices 

它是如此怪異，我所做的是正義之舉「 matrix2x2_test.cpp -o matrix2x2_test「。無論如何，問題解決了。