class derived from template class

[Corey Wirun]

Hi All,

I've got a template class:

template < typename T >
class A: public B
{
public:
A();
virtual ~A();
virtual void PreSubclassWindow();
virtual void DefineColumns( int i ) = 0;
...
}

And I want to derive a class from 'A' called 'Derived':

class Derived: public A< DataClass >
{
Derived();
virtual ~Derived();
}

The problem is that when I link (VS.Net 2002, unmanaged), I get 'unsolved
symbols' for the constructor and all virtuals for the base class 'A', in the
derived class' object code.

e.g.
B.obj: unresolved external symbol "protected: virtual void __thiscall
A<class DataClass>:reSubclassWindow(void)"
(?PreSubclassWindow@?$A@VDataClass@@@@MAEXXZ)

Does anyone know why this occurs? Is there something extra I have to do
syntactically to get it to work?

Thanks all!
C.

 

[David Hilsee]

Hi All,

I've got a template class:

template < typename T >
class A: public B
{
public:
A();
virtual ~A();
virtual void PreSubclassWindow();
virtual void DefineColumns( int i ) = 0;
...
}

And I want to derive a class from 'A' called 'Derived':

class Derived: public A< DataClass >
{
Derived();
virtual ~Derived();
}

The problem is that when I link (VS.Net 2002, unmanaged), I get 'unsolved
symbols' for the constructor and all virtuals for the base class 'A', in the
derived class' object code.

e.g.
B.obj: unresolved external symbol "protected: virtual void __thiscall
A<class DataClass>:reSubclassWindow(void)"
(?PreSubclassWindow@?$A@VDataClass@@@@MAEXXZ)

Does anyone know why this occurs? Is there something extra I have to do
syntactically to get it to work?

Is all of the template code in the header? See the FAQ
(http://www.parashift.com/c++-faq-lite/) section 34 if you don't understand
why you have to do that.

 

[Andre Kostur]

Hi All,

I've got a template class:

template < typename T >
class A: public B
{
public:
A();
virtual ~A();
virtual void PreSubclassWindow();
virtual void DefineColumns( int i ) = 0;
...
}

And I want to derive a class from 'A' called 'Derived':

class Derived: public A< DataClass >
{
Derived();
virtual ~Derived();
}

The problem is that when I link (VS.Net 2002, unmanaged), I get
'unsolved symbols' for the constructor and all virtuals for the base
class 'A', in the derived class' object code.

e.g.
B.obj: unresolved external symbol "protected: virtual void __thiscall
A<class DataClass>:reSubclassWindow(void)"
(?PreSubclassWindow@?$A@VDataClass@@@@MAEXXZ)

Does anyone know why this occurs? Is there something extra I have to
do syntactically to get it to work?

Where's the body of PreSubclassWindow? It's a virtual, not a pure
virtual.... so it must have a body....

 

[Corey Wirun]

Woof! That was quick. Looks like exactly what I need. Thanks David!