template and dynamic polymorphism
 

struct Abstract{

virtual void run() const = 0;

};

template <typename T>
struct S : F{
void run(){}
};


I just want to use as :

Abstract* a = new S<policy_1>(); // doesn't work


I just wanna to know how i could mix the templates with the
traditional abstract class design, thank you in advance.

Re: template and dynamic polymorphism
 

Sorry, the code is :


> struct Abstract{
>
> * * virtual void run() const = 0;
>
> };
>
> template <typename T>
> struct S : Abstract{
> * * void *run(){}
>
> };
>
> I just want to use as :
>
> Abstract* a = new S<policy_1>(); // doesn't work
>
> I just wanna to know how i could mix the templates with the
> traditional abstract class design, thank you in advance.

Re: template and dynamic polymorphism
 

On Aug 11, 9:46*pm, "Alf P. Steinbach" <al...@start.no> wrote:
> * Jun:
>
>
>
> > struct Abstract{
>
> > * * virtual void run() const = 0;
>
> > };
>
> > template <typename T>
> > struct S : F{
> > * * void *run(){}
> > };
>
> > I just want to use as :
>
> > Abstract* a = new S<policy_1>(); // doesn't work
>
> > I just wanna to know how i could mix the templates with the
> > traditional abstract class design, thank you in advance.
>
> How about deriving S from Abstract.
>
> Cheers, & hth.,
>
> - Alf
>
> --
> A: Because it messes up the order in which people normally read text.
> Q: Why is it such a bad thing?
> A: Top-posting.
> Q: What is the most annoying thing on usenet and in e-mail?

Sorry, my code is actually :

struct S : Abstract // and still doesn't work

Re: template and dynamic polymorphism
 

On 11 ago, 17:09, Jun <junh...@gmail.com> wrote:
> Sorry, the code is :
>
> > struct Abstract{
>
> > * * virtual void run() const = 0;
>
> > };
>
> > template <typename T>
> > struct S : Abstract{
> > * * void *run(){}
>
> > };
>
> > I just want to use as :
>
> > Abstract* a = new S<policy_1>(); // doesn't work
>
> > I just wanna to know how i could mix the templates with the
> > traditional abstract class design, thank you in advance.
>
>

You get the error because you're hidding run() from class abstract (in
S you're not making the function const). Try this:
template <typename T>
struct S : Abstract
{
void run()const {} //Notice the const at the end.
};

Re: template and dynamic polymorphism
 

Alf P. Steinbach wrote:

> * Jun:
>> struct Abstract{
>>
>> virtual void run() const = 0;
>>
>> };
>>
>> template <typename T>
>> struct S : F{
>> void run(){}
>> };
>>
>>
>> I just want to use as :
>>
>> Abstract* a = new S<policy_1>(); // doesn't work
>>
>>
>> I just wanna to know how i could mix the templates with the
>> traditional abstract class design, thank you in advance.
>
> How about deriving S from Abstract.

Another thing that comes to mind would be to make run() in S const, like in
Abstract, as well as telling, what "doesn't work" exactly means in this
case.

Re: template and dynamic polymorphism
 

On Aug 11, 10:14*pm, Rolf Magnus <ramag...@t-online.de> wrote:
> Alf P. Steinbach wrote:
> > * Jun:
> >> struct Abstract{
>
> >> * * virtual void run() const = 0;
>
> >> };
>
> >> template <typename T>
> >> struct S : F{
> >> * * void *run(){}
> >> };
>
> >> I just want to use as :
>
> >> Abstract* a = new S<policy_1>(); // doesn't work
>
> >> I just wanna to know how i could mix the templates with the
> >> traditional abstract class design, thank you in advance.
>
> > How about deriving S from Abstract.
>
> Another thing that comes to mind would be to make run() in S const, like in
> Abstract, as well as telling, what "doesn't work" exactly means in this
> case.

Thanks a lot, after changing the run as const in S, it works fine.

Re: template and dynamic polymorphism
 

Jun wrote:
> On Aug 11, 10:14 pm, Rolf Magnus <ramag...@t-online.de> wrote:
>> Alf P. Steinbach wrote:
>>> * Jun:
>>>> struct Abstract{
>>>> virtual void run() const = 0;
>>>> };
>>>> template <typename T>
>>>> struct S : F{
>>>> void run(){}
>>>> };
>>>> I just want to use as :
>>>> Abstract* a = new S<policy_1>(); // doesn't work
>>>> I just wanna to know how i could mix the templates with the
>>>> traditional abstract class design, thank you in advance.
>>> How about deriving S from Abstract.
>> Another thing that comes to mind would be to make run() in S const, like in
>> Abstract, as well as telling, what "doesn't work" exactly means in this
>> case.
>
> Thanks a lot, after changing the run as const in S, it works fine.
>

This will repeatedly mess with you. Make it the first thing you check.