Re: [boost] Interest in simple unformatted binary stream I/O?

Subject: Re: [boost] Interest in simple unformatted binary stream I/O?
From: Fernando Pelliccioni (fpelliccioni_at_[hidden])
Date: 2011-10-04 16:01:02

On Sun, Apr 24, 2011 at 9:12 AM, Beman Dawes <bdawes_at_[hidden]> wrote:

> There have been many requests on Boost and various C++ newsgroups for
> unformatted binary I/O. For example, in 2003 Neal Becker wrote:
>
>     I wonder if anyone has code for implementing unformatted I/O?
> What I have in mind is
>     for the simple case where the application that reads data knows
> the data types, so
>     this is not as complicated as the general marshalling situation.
>
> This proposal provides a very simple solution that works with standard
> library input and output streams. The one caveat is that the stream
> must be opened with filemode std::ios_base::binary to avoid certain
> data values being treated as line endings.
>
> int main()
> {
>  fstream f("binary_stream_example.dat",
>    std::ios_base::trunc | std::ios_base::in | std::ios_base::out |
> std::ios_base::binary);
>
>  int32_t x = 0x01020304;
>  int32_t y = 0;
>
>  f << bin(x);  // write 4 bytes
>  f.seekg(0);
>  f >> bin(y);   // read 4 bytes
>
>  BOOST_ASSERT(x == y);
>
>  return 0;
> }
>
> For docs, header, and example code, see
> http://mysite.verizon.net/beman/binary_stream/binary_stream.html
> http://mysite.verizon.net/beman/binary_stream/binary_stream.hpp
> http://mysite.verizon.net/beman/binary_stream/binary_stream_example.cpp
>
> Is there interest in this for Boost?
>
> It seems way too small and simple to be a whole library itself. Are
> there any ideas where it should live and what namespace it should be
> in?
>
> --Beman
>

Hi Beman,

I made a small modification to your example and it stopped working.
Do not compile. ADL issue. Because binary_data and const_binary_data are
defined within detail namespace.

Code:

#include <boost/io/detail/bin_manip.hpp>
#include <boost/integer.hpp>
#include <boost/assert.hpp>
#include <fstream>

int main()
{
  std::fstream f("binary_stream_example.dat", std::ios_base::trunc |
std::ios_base::in | std::ios_base::out | std::ios_base::binary);

  int32_t x = 0x01020304;
  int32_t y = 0;

  f << boost::bin(x);
  f.seekg(0);
  f >> boost::bin(y);
  BOOST_ASSERT(x == y);

  return 0;
}

MSVC-10 Error:

error C2679: binary '<<' : no operator found which takes a right-hand
operand of type 'boost::detail::binary_data<T>' (or there is no acceptable
conversion)
    with
    [
        T=int32_t
    ]

Regards,
Fernando.