Question

my compiler is torturing me with this instantiation error which I completely don’t understand.

i have template class listItem:

template <class T>
class tListItem{
    public:
        tListItem(T t){tData=t; next=0;}
        tListItem *next;
        T data(){return tData;}
    private:
        T tData;
};

if i try to initialize an object of it with non-primitive data type like e.g:

sPacket zomg("whaever",1);
tListItem<sPacket> z(zomg);

my compiler always throws this error.. the error isnť thrown with primitive types.

output from compiler is:

../linkedList/tListItem.h: In constructor ‘tListItem<T>::tListItem(T) [with T = sPacket]’:
recvBufTest.cpp:15:   instantiated from here

../linkedList/tListItem.h:4: error: no matching function for call to ‘sPacket::sPacket()’

../packetz/sPacket.h:2: note: candidates are: sPacket::sPacket(const char*, int)

../packetz/sPacket.h:1: note:                 sPacket::sPacket(const sPacket&)

i wouldn’t bother you but i don’t want to spend 2 hours with something stupid….. so thx for all your replies

Answer 1

As it stands, your code needs a default constructor for the type T. Change your template constructor to:

 tListItem(T t)  : tData(t), next(0) {}

The difference being that your version default constructs an instance of type T and then assigns to it. My version uses an initialisation list to copy construct the instance, so no default constructor is required.