LNK2019 on some class functions, but not on others (template class in dll)

Question

Ok, without including the whole codebase...

#ifdef KIT_EXPORTS
    #define KIT_API __declspec(dllexport)
    #define EXP_TEMPLATE
#else
    #define KIT_API __declspec(dllimport)
    #define EXP_TEMPLATE extern
#endif


#ifndef KIT_LINKED_LIST_H
#define KIT_LINKED_LIST_H

#includes ...

namespace Kit
{
template <class tmplt>
class KIT_API KitLinkedList
{
private:
    ...

public:
    KitLinkedList()
    {
        ...
    }

    KitLinkedList(tmplt obj)
    {
        ...
    }

    KitLinkedList(const KitLinkedList& other)
    {
        ...
    }

    ~KitLinkedList()
    {
        ...
    }

    void PushBack(tmplt obj)
    {
        KitLinkedListNode<tmplt>* addedNode = new KitLinkedListNode<tmplt>(obj);
        tail->nextNode = addedNode;
        tail = addedNode;
        count++;
    }

    uint64_t Count()
    {
        return count;
    }

    KitLinkedListIterator<tmplt> GetIterator()
    {
        return KitLinkedListIterator<tmplt>(root->nextNode);
    }

... some other happy functions live here

};
}

My non-dll code:

KitLinkedList<KitString> savedGameList = saveSet.ListSavedGames();
savedGameList.PushBack(KitString("blah"));

if (savedGameList.Count() > 0)
{
}

I have a linked list template class declared and defined entirely in a .h file, inside a dll.
I successfully use the template class outside of the dll, compiling, linking, and running
Using some functions in the class cause a linker error.

savedGameList.Count() causes LNK2019, but the pushback() and getiterator() don't.

If your class temlate is defimed entirely in the header, it has nothing to do with your DLL. The non-DLL code pulls all of it from the header. Remove KIT_API from the definition of KitLinkedList. — n. m. could be an AI, Apr 05 '17 at 06:15
You have the exact error message from your compiler, but choose to withhold it and just tell rhe world that the compiler doesn't like your code. What do you expect the world to do now? — n. m. could be an AI, Apr 05 '17 at 06:52
I wanted to see how good the world was. It seems the world's answer was sufficient. I expect the world to post "Remove KIT_API from the definition of KitLinkedList." as an answer instead of a comment so I can mark it as the correct answer, then go and have itself a nice cup of tea. — NapkinTrout, Apr 05 '17 at 14:33
Yes, removing KIT_API from the class definition compiles and links successfully, thank you. — NapkinTrout, Apr 05 '17 at 16:21

score 1 · Accepted Answer · answered Apr 06 '17 at 03:54

1

The correct answer is that the template class isn't dependent on the dll, since everything it needs is in the header. So KIT_API should be removed.

answered Apr 06 '17 at 03:54

NapkinTrout

269
1
9

score 0 · Answer 2 · answered Apr 05 '17 at 06:24

0

Ok, this got me building, but I don't know why it works:

Declare the function as:

template <class tmplt>
uint64_t Count()
{
    return count;
}

And call it thus:

if (savedGameList.Count<KitString>() > 0)

Apparently the compiler doesn't see the function because it doesn't carry the templated type (even though it is within the scope of the class declaration)

answered Apr 05 '17 at 06:24

NapkinTrout

269
1
9

This is woodoo-oriented programming. Your change makes zero sense and there is no reason whatsoever why it would be needed. Try to revert it and make a full rebuild. – n. m. could be an AI Apr 05 '17 at 06:55

LNK2019 on some class functions, but not on others (template class in dll)

2 Answers2