Template of ingredient class

I want create class with pattern of function. When I add definition of function to *.cpp file and call it in mainwindow.cpp, I have bugs:

Code:

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mainwindow.o:-1: error: In function `ZN10MainWindowC2EP7QWidget':
mainwindow.cpp:6: undefined reference to `readmemory::readmemory()'
mainwindow.o:-1: error: In function `ZN10MainWindowC1EP7QWidget':
mainwindow.cpp:6: undefined reference to `readmemory::readmemory()'
mainwindow.o:-1: error: In function `ZN10MainWindow11startSearchEv':
mainwindow.cpp:46: undefined reference to `void readmemory::test<int>(int)'
:-1: error: collect2: ld returned 1 exit status

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It's my exemplary code:
class.h

Code:

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class Pattern{ 
template<typename T> void function(T); 
};

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class.cpp

Code:

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template<typename T> 
void Pattern::function(T a) 
{ 
//code
}

---

mainwindow.h

Code:

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Pattern patternClass; 
int a; 
patternClass.function(a);

---

I tried use "export" like in Visual Studio and include class.cpp to class.h, but it doesn't work. Is it possible to use template like in my test code?

You declare a template... this makes the compiler happy.
But at link time, the calls can't be resolved as those functions have not been implemented (only called):
You have to tell the compiler that a specialization for int has to be compiled.

possible way to do it:
add

Code:

---

template<> void Pattern::function(int a) 
{ 
//code
}

---

to class.cpp

or just leave the implementation in class.hpp and save you the trouble.
(putting specializations into the .cpp will reduce code bloat, though.)

So, when i want use my function like:

Code:

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double a;
patternClass.function(a);

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Must I define new function with argument double? If it's true, I can glut function with the same result.