template inheritance

[zl2k]

hi, all
Suppose I have a template class A

template<class Tclass A{...}

Then I have another class B which inherits class A. Should I say

class B: public A{...}

or class B: template<class TA{...}

or template<class Tclass B : public A {...}

or something else? I assume that class A is also a template. But can
class A be a non template class? If yes, how can A handle the different
type of T? Thanks ahead.

zl2k

[Frederick Gotham]

template<class T>
class Derived : public Base<T{

};

--

Frederick Gotham

[Thomas J. Gritzan]

zl2k schrieb:

hi, all
Suppose I have a template class A

template<class Tclass A{...}

Then I have another class B which inherits class A. Should I say

class B: public A{...}

or class B: template<class TA{...}

or template<class Tclass B : public A {...}

Depends.

If you want class B to be a template like class A, then:

template <class T>
class B : public A<T>
{
// ...
};

If you want that class B inherits from a specific class A, say with
template parameter int:

class B : public A<int>
{
// ...
};

--
Thomas

[Michiel.Salters]

zl2k wrote:

hi, all
Suppose I have a template class A

template<class Tclass A{...}

No, that's a class template. A is not a class. A<intand A<charare
classes.

Then I have another class B which inherits class A. Should I say

Same problem, you can have a class B<intwhich inherits from A<int>
but
remember that A is not a class.

class B: public A{...}

or class B: template<class TA{...}

or template<class Tclass B : public A {...}

or something else? I assume that class A is also a template. But can
class A be a non template class? If yes, how can A handle the different
type of T? Thanks ahead.

template B<Tcan inherit from any class. When you instantiate it, you
have
a type for parameter T. Thus, you can also instantiate template A<Tas
a
base class, or A<std::pair<T,T, or std::ostream. The base class
doesn't
have to be a template instantiation. In fact, it often isn't. The base
class has
no more need to "handle" T as any member of B has. Only your design
will
tell you whether the base class needs to know about T, and how. (E.g.
it
might be a non-template class with a templated contructor)

Regards,
Michiel Salters

[zl2k]

Mi*************@tomtom.com wrote:

zl2k wrote:

hi, all
Suppose I have a template class A

template<class Tclass A{...}

No, that's a class template. A is not a class. A<intand A<charare
classes.

Then I have another class B which inherits class A. Should I say

Same problem, you can have a class B<intwhich inherits from A<int>
but
remember that A is not a class.

class B: public A{...}

or class B: template<class TA{...}

or template<class Tclass B : public A {...}

or something else? I assume that class A is also a template. But can
class A be a non template class? If yes, how can A handle the different
type of T? Thanks ahead.

template B<Tcan inherit from any class. When you instantiate it, you
have
a type for parameter T. Thus, you can also instantiate template A<Tas
a
base class, or A<std::pair<T,T, or std::ostream. The base class
doesn't
have to be a template instantiation. In fact, it often isn't. The base
class has
no more need to "handle" T as any member of B has. Only your design
will
tell you whether the base class needs to know about T, and how. (E.g.
it
might be a non-template class with a templated contructor)

Regards,
Michiel Salters

Thanks for all the comments, very helpful. Have a good day.
zl2k