Re: [Boost-users] [iostreams] Is it possible for a sink to get notified when the stream is closed?

Subject: Re: [Boost-users] [iostreams] Is it possible for a sink to get notified when the stream is closed?
From: Václav Haisman (v.haisman_at_[hidden])
Date: 2009-03-27 16:20:33

Bob van Manen wrote, On 27.3.2009 18:43:
> Hi All,
> 
> I am trying out the Boost iostreams library to build a sink, text sent
> to this sink is split up in to lines of text and each line is then being
> send over to our logging server (the function I'm calling to do this is
> static).   
> 
> So far I've built the write method as mentioned in the documentation for
> my sink, and push all the characters I receive in a buffer inside my
> sink class.  Then I look for the end of line characters and figure out
> the lines of text.  The problem I'm having is when there is no end of
> line character and the stream gets closed.
> 
> Is there a way to get notified when the stream gets closed?  Is there a
> better way to do this?
> 
> Here is the code I have:
> 
> class logging_sink
> {
> public:
>      typedef char char_type;
>      typedef boost::iostreams::sink_tag category;
Make this

struct category
  : boost::iostreams::sink_tag
  , boost::iostreams::closable_tag
{};

> 
>      std::streamsize write(const char* s, std::streamsize n)
>      {
>           buffer_.append(s, n);
>           // loop over buffer and find end of lines, send them to
> logging service
>      }
> 
>      void close()
>      {
>           // close is never called
>           if (!buffer_.empty())
>               log_message(buffer_);
>      }
> 
> private:
>      std::string buffer_;
> 
> };
> 
> class logging_stream   : public boost::iostreams::stream<logging_sink>
> {
> public:
>         logging_stream()
>               : boost::iostreams::stream<logging_sink>(logging_sink())
>         {}
> };
> 
> logging_stream s;
> s << "Hello World";
> s.close();

--
VH