[SOLVED] link error w/ generic class

[g0dwyn]

Hey everyone,

Are there any known precautions I should take when building code with a generic class? I've made sure to fully define my classes in the source file, i.e:

template<typename T> void C1<T>::foo(){...}

The reason I ask is that I'm getting undefined reference errors at link time, such as:

error: undefined reference to C1<int>::foo()

My header file is included, and the namespaces match up. Any other things I should be watching out for?

[helios]

The declaration looks okay. Is the definition of foo() compiled with the rest of the code?

[g0dwyn]

Actually, that is the definition, I just truncated out the code. The declaration is in the header, where it's declared as:

template<typename T> class C1
{
...
void foo();
};

Would it help if I posted the header and source on the net? Be advised that it's about 150 lines in total, and there's a couple of other classes in there too...

[helios]

It might be better to upload it to http://pastebin.com/

[g0dwyn]

http://pastebin.com/d7d5572b8

Header from line 1-64; source begins at line 65

[helios]

Uh... How am I supposed to know what class is C1 and what function is foo()?

[g0dwyn]

...through magic telepathic abilities, of course...

My apologies. The class is question is ObjectManager, and unfortunately all of its methods are problematic. Each one gives me an undefined reference error.

[helios]

Actually, now that I look closer, ObjectManager is the only class there. :-P

Are you sure you're compiling the cpp along with the rest of the project? I don't see any discrepancies between the declaration and definition signatures.

You can use this example to see how template methods should be declared and defined:

template <typename T>
struct A{
	A(T &a);
	A(T a);
	T &get();
private:
	T d;
};

template <typename T>
A<T>::A(T &a){
	this->d=a;
}

template <typename T>
A<T>::A(T a){
	this->d=a;
}

template <typename T>
T &A<T>::get(){
	return this->d;
}

int main(){
	A<int> a(12);
	return 0;
}

[g0dwyn]

I'm dead certain. It's in the compile log and everything. I guess I'll just keep this topic open and see if we can't get some more input.

[kbw]

Typically, template functions are defined inline, in the header file. Are yours defined in a seperate CPP file?

Line 64 seems to imply end of header file/start of cpp file. Is this the case?

[helios]

Man, I always forget that!
Whose idea was to put something so counter-intuitive in the standard?

[g0dwyn]

ahh, for real? Yeah, they're defined in a header/source pair. Jeez, that is weird. I'll give it a shot and put them in the header. Thanks a lot for the tip!