[boost] comment about more_io

From: John Torjo (john_at_[hidden])
Date: 2003-04-24 01:29:09

Hi,

I've just looked at the more_io library
(http://groups.yahoo.com/group/boost/files/ -> more_io.zip)

I would have a comment:

The I/O streambuf wrapping seems unnecessary complex.
It can be easily emulated like this:
(the key function is basic_ios::init(&buf) )
(no unnecessary boost::io::...wrapping... classes)

// the following compiles and runs as expected
#include <iostream>

struct nul_streambuf : public std::streambuf
{
    nul_streambuf() { this->setp( NULL, NULL); }
    virtual int sync() { return 0; }
    virtual int overflow(int nChar) { return 0; }
    virtual std::streamsize xsputn(const char *S, std::streamsize N)
 return N; }
};

template< class StreamBuf>
struct ostream_base : public std::ostream
{
    typedef std::ostream base_class;
    ostream_base()
        : base_class( NULL)
    {
        this->init( &m_buf);
    }
private:
    StreamBuf m_buf;
};

class nul_ostream : public ostream_base< nul_streambuf>
{};

int main(int argc, char* argv[])
{
    nul_ostream out;
    out << "test" << std::endl;
}

Of course, the ostream_base can be templated (by char_type, traits_type).

Best,
John

--
John Torjo
-- "Practical C++" column writer for builder.com.com
Freelancer, C++ consultant
mailto:john_at_[hidden]