Doomulation
?????????????????????????
I'm wondering, is it possible to mix these somehow? Mixing virtual functions in a template class. Trying to override MFC's WindowProc in a class using templates.
Virtual functions and templates
- Thread starter Doomulation
- Start date
smcd
Active member
Code:
#include<iostream>
#include<string>
template<class t>
class Foo
{
public:
virtual void spitstuff(t val)
{
std::cout<<"Foo spitstuff(val) = "<<val<<std::endl;
}
};
template<class t>
class Bar : public Foo<t>
{
public:
void spitstuff(t val)
{
std::cout<<"Bar spitstuff(val) = "<<val<<std::endl;
}
};
int main()
{
Foo<int> foo;
Bar<std::string> bar;
foo.spitstuff(5);
bar.spitstuff("test");
return 0;
}
OP
Doomulation
?????????????????????????
- Thread Starter
- #3
I see. Then it's a problem with the templates.
Whenever I override the WindowProc in the template class, I get an unresolved symbol linking error (yes, I'm defining the function correctly in the source file! ... If I don't, I get a compile error). Sigh... stupid templates.
Maybe I'll post the code later if someone wants to see what the heck is going on...
EDIT: I think I just solved that one... seems definitions need to be in the same file as the delcarations (ie, the header). Why? I don't know. But who cares?! It works! It works!
Whenever I override the WindowProc in the template class, I get an unresolved symbol linking error (yes, I'm defining the function correctly in the source file! ... If I don't, I get a compile error). Sigh... stupid templates.
Maybe I'll post the code later if someone wants to see what the heck is going on...
EDIT: I think I just solved that one... seems definitions need to be in the same file as the delcarations (ie, the header). Why? I don't know. But who cares?! It works! It works!
Last edited:
zenogais
New member
I believe the C++ standard dictates that the complete sources for a template class must be in the header file, though this is soon going to change. Of course there are ways around this, i.e. this classic:
Where CTemplateClass.inl has your template sources. This technique isn't perfect, but it should work for you in most cases, and it should help make your headers smaller and neater.
Code:
#ifndef TEMPLATE_CLASS_HPP
#define TEMPLATE_CLASS_HPP
template<typename T, class R = CDefaultClass>
class CTemplateClass
{
public:
//...
private:
//...
};
typedef CTemplateClass<ulong> CDefaultTemplateClass;
typedef CTemplateClass<ulong, CSpecialized> CSpecializedTemplateClass;
#include "CTemplateClass.inl"
#endif // ~TEMPLATE_CLASS_HPPWhere CTemplateClass.inl has your template sources. This technique isn't perfect, but it should work for you in most cases, and it should help make your headers smaller and neater.
Last edited: