On Oct 14, 12:38 pm, mike b <michaeljber...@gmail.com> wrote:
> Hello everyone, thanks in advance for your . I'm new to C++
> templates and have run into some issues using member function
> templates. I have a shared library containing templates that I'm
> trying to use from an executable, compile using gcc 4.1.2. Everything
> works fine until I try specializing one of the static member function
> templates in a non-template class. I have a feeling I'm messing up
> something obvious so before I post a bunch of code does the following
> look correct? Thanks.
>
> --- Shared Library (Arrays.h) ---
>
> namespace example {
> class Arrays {
> public:
> template<class T> static int compareItems(T *a1, T *a2, int length);
> protected:
> Arrays() {};
>
> };
>
> template<class T> int Arrays::compareItems(T *a1, T *a2, int length) {
> printf("Calling generic function.\n");
> return 1;
>
> }
>
> template<> int Arrays::compareItems<char>(char *a1, char *a2, int
> length) {
> printf("Calling char specialization.\n");
> return 0;
>
> }
> }

Sincere thanks to everyone who responded, the problem has been
solved. The issue it seems is that I was defining my member
specializations in the header but only a declaration for the
specialization is allowed in the header, the actual implementation
must go in the implementation file, .cpp. So here is the change to
make the code work:

--- Arrays.h ---

namespace example {
class Arrays : public Object {
public:
template<class T> static int compareItems(const T a1[], const
T a2[], const int length);
};

// I was defining the function here but only the declaration goes here
template<> int Arrays::compareItems(const char a1[], const char a2[],
const int length);

template<class T> int compareItems(const T a1[], const T a2[], const
int length) {
// Generic implementation goes here.
}
}


--- Arrays.cpp ---

// This was in the header file before and was causing the problems,
moving it here solved it.
template<> int hydro::Arrays::compareItems(const char a1[], const char
a2[], const int length) {
return strncmp(a1, a2, length);
}

--- END ---

mike b wrote:
....
> Sincere thanks to everyone who responded, the problem has been
> solved. The issue it seems is that I was defining my member
> specializations in the header but only a declaration for the
> specialization is allowed in the header, the actual implementation
> must go in the implementation file, .cpp.

Sounds strange. What errors were you getting ?

On Oct 16, 3:45 pm, Gianni Mariani <gi4nos...@marian.ws> wrote:
> mike b wrote:
>
> ...
>
> > Sincere thanks to everyone who responded, the problem has been
> > solved. The issue it seems is that I was defining my member
> > specializations in the header but only a declaration for the
> > specialization is allowed in the header, the actual implementation
> > must go in the implementation file, .cpp.
>
> Sounds strange. What errors were you getting ?

I was getting errors about my specialization being defined multiple
times. This was with GCC 4.

mike b wrote:
> On Oct 16, 3:45 pm, Gianni Mariani <gi4nos...@marian.ws> wrote:
>> mike b wrote:
>>
>> ...
>>
>>> Sincere thanks to everyone who responded, the problem has been
>>> solved. The issue it seems is that I was defining my member
>>> specializations in the header but only a declaration for the
>>> specialization is allowed in the header, the actual implementation
>>> must go in the implementation file, .cpp.
>> Sounds strange. What errors were you getting ?
>
> I was getting errors about my specialization being defined multiple
> times. This was with GCC 4.


Declare the template as "inline" as see if you get the same errors.

On Oct 17, 1:17 am, Gianni Mariani <gi4nos...@marian.ws> wrote:
> mike b wrote:
> > On Oct 16, 3:45 pm, Gianni Mariani <gi4nos...@marian.ws> wrote:
> >> mike b wrote:
>
> >>> Sincere thanks to everyone who responded, the problem has been
> >>> solved. The issue it seems is that I was defining my member
> >>> specializations in the header but only a declaration for the
> >>> specialization is allowed in the header, the actual implementation
> >>> must go in the implementation file, .cpp.
> >> Sounds strange. What errors were you getting ?
>
> > I was getting errors about my specialization being defined multiple
> > times. This was with GCC 4.
>
> Declare the template as "inline" as see if you get the same errors.

An explicit function specialization follows the same rules as any
other C++ function: in order to be defined in a header file, the
specialization must be declared "inline."

Greg