specialization

[Amadeus W. M.]

I have a class

template <class Vector_t>
class A;

where Vector_t is some sort of vector. I want to provide different
specializations for real and for complex vectors. I need the following:

// Real vectors:
A< valarray<double > >; // templated
A< MyRealVector >; // non-tempalted

// Complex vectors:
A< vector< complex<double> >; // templated
A< MyComplexVector >; // non-templated.

Is this possible? How would I do that? Bad design? What's the right way?
Thanks!

[Victor Bazarov]

Re: specialization

Amadeus W. M. wrote:[color=blue]
> I have a class
>
> template <class Vector_t>
> class A;
>
> where Vector_t is some sort of vector. I want to provide different
> specializations for real and for complex vectors. I need the following:
>
> // Real vectors:
> A< valarray<double > >; // templated[/color]

What do you mean by the word 'templated' in the comment?
[color=blue]
> A< MyRealVector >; // non-tempalted
>
> // Complex vectors:
> A< vector< complex<double> >; // templated
> A< MyComplexVector >; // non-templated.
>
> Is this possible? How would I do that? Bad design? What's the right way?[/color]

Have you tried? What's the result? If you haven't, what's stopping you?
What book are you reading that doesn't tell how to specialise a template?

template<> class A<MyRealVector > { /* specialisation */ };

or

typedef A<MyRealVector > MyRealA;

They give you different results, of course. The former would require you
to actually specify the inner workings (which are supposedly different
from the original template), the latter _uses_ the inner workings of the
original template.

V
--
Please remove capital As from my address when replying by mail

[Amadeus W. M.]

Re: specialization

On Fri, 24 Feb 2006 12:31:02 -0500, Victor Bazarov wrote:
[color=blue]
> Amadeus W. M. wrote:[color=green]
>> I have a class
>>
>> template <class Vector_t>
>> class A;
>>
>> where Vector_t is some sort of vector. I want to provide different
>> specializations for real and for complex vectors. I need the following:
>>
>> // Real vectors:
>> A< valarray<double > >; // templated[/color]
>
> What do you mean by the word 'templated' in the comment?
>[color=green]
>> A< MyRealVector >; // non-tempalted
>>
>> // Complex vectors:
>> A< vector< complex<double> >; // templated
>> A< MyComplexVector >; // non-templated.[/color][/color]

Sorry, I didn't explain very well.
I mean that the template argument of A is itself a template.

So I have the most general

template <class Vector_t>
class A
{
};

I don't want to specialize it to a particular vector type, such as
valarray<double > or MyNonTemplatedV ector. The specializations differ in
the SCALAR type of the vector, but should be irrespective of the actual
container. So what I'd like would be rather

template <class Scalar_t, template<class> class Vector_t>
class A
{
// work on Vector_t<Scalar _t>;
};

Then this should somehow be specialized (1) to Scalar_t = float/double and
(2) to Scalar_t = complex<double> , for instance, but still have the
container Vector_t as a parameter.

I'm reading Stroustrup's book. Can this be done?

Even if it CAN be done, with a template Vector_t I won't be able to have a

A<MyNonTemplate dVector>;


Maybe I should just do

template <class Vector_t>
class RealA
{

};

template <class Vector_t>
class ComplexA
{

};

Then Vector_t is the most general, and I have two implementations - one
for real, one for complex. It won't be transparent to the user though.

[Greg]

Re: specialization


Amadeus W. M. wrote:[color=blue]
> On Fri, 24 Feb 2006 12:31:02 -0500, Victor Bazarov wrote:
>[color=green]
> > Amadeus W. M. wrote:[color=darkred]
> >> I have a class
> >>
> >> template <class Vector_t>
> >> class A;
> >>
> >> where Vector_t is some sort of vector. I want to provide different
> >> specializations for real and for complex vectors. I need the following:
> >>
> >> // Real vectors:
> >> A< valarray<double > >; // templated[/color]
> >
> > What do you mean by the word 'templated' in the comment?
> >[color=darkred]
> >> A< MyRealVector >; // non-tempalted
> >>
> >> // Complex vectors:
> >> A< vector< complex<double> >; // templated
> >> A< MyComplexVector >; // non-templated.[/color][/color]
>
> Sorry, I didn't explain very well.
> I mean that the template argument of A is itself a template.
>
> So I have the most general
>
> template <class Vector_t>
> class A
> {
> };
>
> I don't want to specialize it to a particular vector type, such as
> valarray<double > or MyNonTemplatedV ector. The specializations differ in
> the SCALAR type of the vector, but should be irrespective of the actual
> container. So what I'd like would be rather
>
> template <class Scalar_t, template<class> class Vector_t>
> class A
> {
> // work on Vector_t<Scalar _t>;
> };
>
> Then this should somehow be specialized (1) to Scalar_t = float/double and
> (2) to Scalar_t = complex<double> , for instance, but still have the
> container Vector_t as a parameter.
>
> I'm reading Stroustrup's book. Can this be done?
>[/color]

Yes:

template <class Scalar_t, template<class> class Vector_t>
class A
{
// work on Vector_t<Scalar _t>;

};

template < template<class> class Vector_t>
class A<double, Vector_t>
{

};
[color=blue]
> Even if it CAN be done, with a template Vector_t I won't be able to have a
>
> A<MyNonTemplate dVector>;
>[/color]

You can if you declare another "A" class template, in addition to the
first.

Greg