Re: [Boost-users] [iostreams] how to say a filter is closable

From: frederic.bron_at_[hidden]
Date: 2008-01-09 02:37:29

ok, I have seen this now, thanks. However, I must create a derived class from dual_use_filter and those no-op operation are not virtual and it is good practice not to redefine non-virtual member
functions.
So what's happening whenever I use a pointer or reference to a base class? Maybe this never happens because chain.push takes a template parameter... am I right?

Regards,

F. Bron

boost-users-bounces_at_[hidden] a écrit sur 08/01/2008 22:12:21 :

> frederic.bron_at_[hidden] wrote:
> >
> >
> > I want to write a filter but this filter needs to do some things
> when the stream is ending.
> > Is it enough to do the following? I want the close function to be
> called at the end of the stream.
> > Do I need to category_flag to inherit from (closable_tag)?
> >
> > class my_filter : public io::dual_use_filter {
> >         public:
> >                 template<typename Source> int get(Source&) ;
> >                 template<typename Sink> bool put(Sink&, int) ;
> >                 template<typename Device> void close(Device&,
> std::ios_base::openmode) ;
> > } ;
>
> Hi Fred,
>
> Eric is correct: the convenience base class dual_use_filter has category
> convertible to closable_tag, and a no-op implementation of close.
>
> --
> Jonathan Turkanis
> CodeRage
> http://www.coderage.com
>
> _______________________________________________
> Boost-users mailing list
> Boost-users_at_[hidden]
> http://lists.boost.org/mailman/listinfo.cgi/boost-users

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