template and dynamic polymorphism

[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.

[Jun]

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.

[Leandro Melo]

Re: template and dynamic polymorphism

On 11 ago, 17:09, Jun <junh...@gmail. comwrote:

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.
};

[Rolf Magnus]

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.

[Jun]

Re: template and dynamic polymorphism

On Aug 11, 10:14 pm, Rolf Magnus <ramag...@t-online.dewrote:

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.

[Noah Roberts]

Re: template and dynamic polymorphism

Jun wrote:

On Aug 11, 10:14 pm, Rolf Magnus <ramag...@t-online.dewrote:

>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
>>>traditiona l 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.