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[lambda] Composing lambda expressions
by Robert Jones 17 Jul '08

17 Jul '08

Given a bit of code like this, struct S { bool pred( ) const; }; typdef vector<pair<string, S *> > V; V :: const_iterator i; i -> second -> pred( ); I'd like to rewrite the last line as a lambda expression. Looking at the documentation, I think this is done with bind( & S :: pred, bind( & V :: value_type :: second, _1 ) )( * i ); which works. But I'd rather be writing something like ( _1 -> second -> pred )( * i ); Am I right in thinking that Boost.Lambda just doesn't work like this, and the frst form is how it's done? Thanks, Rob.

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[fusion] constructing all elements of the fusion vector with the same argument
by Stjepan Rajko 17 Jul '08

17 Jul '08

Hello, I recently ran into a need to initialize a fusion vector with a single argument which is then used to construct all of the vector elements. For example, something that would allow: fusion::vector<int, float, double> ones(initialize_all_with(),1); // at_c<0>(ones) == 1 // at_c<1>(ones) == 1.0f // at_c<2>(ones) == 1.0; I hacked fusion::vector so that the above works. Is this addition of interest to anyone else? There is another (perhaps more elegant) solution in implementing a new fusion "array" Sequence (one where all element types are identical) which can construct all elements from a single constructor argument, and then using that sequence to do the above initialization. E.g., fusion::vector<int, float, double> ones(fusion::array<int, 3>(1)); ... or (another solution) a make_array function that returns a fusion::vector: fusion::vector<int, float, double> ones(fusion::make_array<3>(1)); It would be great if one of these solutions (or a different solution) were added to fusion. I can take a stab at putting something together, if any of them are acceptable. That is, unless this is already possible in some way that I can't see at the moment :-) Regards, Stjepan

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Possible MingW ASIO bug with Boost 1.35.0 g++ 4.2.1
by Jason Turner 17 Jul '08

17 Jul '08

Some ASIO test code is crashing in a way that I do not understand. GDB is unable to debug it (no stack available on crash) and the error is a rather obtuse "This application has requested the Runtime to terminate it in an unusual way. Please contact the application's support team for more information." Test code which crashes: #include <boost/asio/ip/address.hpp> #include <iostream> int main() { std::cout << boost::asio::ip::address::from_string("1.1.2.3") << std::endl; } By changing the asio file included, the code no longer crashes: #include <boost/asio.hpp> #include <iostream> int main() { std::cout << boost::asio::ip::address::from_string("1.1.2.3") << std::endl; } This is windowsxp professional, gcc version 4.2.1-dw2. I'm unable to test this on Linux at the moment, so I do not know if it affects other platforms. -Jason -- http://emptycrate.com Games, Programming, Travel & other stuff

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[iochain] mutable_buffer issues
by Robert Dailey 17 Jul '08

17 Jul '08

Assume the following code, which I wrote in an attempt to test very basic functionality of Boost.Iostream: namespace io = boost::io; void foo() { std::vector<boost::uint8_t> data; io::source<io::iobyte> src( io::chain( io::read_mem( data ) ) ); io::iobyte rcvbuffer; const io::mutable_buffer<io::iobyte> mutbuffer( &rcvbuffer, sizeof( rcvbuffer ) ); src.read( mutbuffer ); } The first issue I have is with mutable_buffer. Notice how it requires a template argument that *must* be the exact type passed into the io::source template parameter, in this case io::iobyte. Passing any other type in here results in lots of compiler errors on MSVC 9. Basically my biggest issue with this is that I can't pass an "int" into the mutable_buffer here if I want to read 4 bytes, because the type passed in must match io::iobyte. In my opinion, mutable_buffer should accept *any* type and just read in the number of bytes requested. Without this I fail to see the usefulness of mutable_buffer. The second issue has to do with the type of the first parameter in io::source::read(). Notice it takes a "const mutable_buffer&". Why is it taking a const mutable_buffer if the buffer is mutable? This seems conceptually wrong. I would expect it to take a "mutable_buffer&".

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[math][constants] Documentation?
by Michael Marcin 17 Jul '08

17 Jul '08

I found the math constants library in the 1.35.0 release and it looks like it will be useful to me. I can't find it documented anywhere however. It is not in a detail folder so I assume it is a public library. I've found documentation for a Math Constants library on yahoo groups from what looks like the initial review of this library. http://lists.boost.org/Archives/boost/2003/06/48724.php Is this the same library? Where did the documentation go? Thanks, Michael Marcin

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[iochain] Suggestion for chain
by Robert Dailey 17 Jul '08

17 Jul '08

Hi, Currently I'm doing this: namespace io = boost::io; std::vector<boost::uint8_t> data; io::source<io::iobyte> src( io::chain( io::read_mem( data ) ) ); Notice how I have to specify io::chain() explicitly. Would it be possible for it to be implicitly constructable from a stub? This would allow me to clean up the code a bit to this: namespace io = boost::io; std::vector<boost::uint8_t> data; io::source<io::iobyte> src( io::read_mem( data ) ); Doing this results in compiler errors right now. Finding the solution to the problem (as obvious as it seems) took a long time for me.

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[asio] SSL documentation
by Michael Marcin 17 Jul '08

17 Jul '08

The ASIO documentation leaves a lot to be desired when it comes to its SSL support. All the SSL related classes have 1 line of meaningless documentation in the reference section. There is 1 SSL related example with no comments in it. There is no mention of SSL in the Tutorial or Design sections. Has anyone written some documentation, a blog, or even a newsgroup post about the SSL portion of ASIO? Thanks, Michael Marcin

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[iochain] Overloaded >> and << operators?
by Robert Dailey 17 Jul '08

17 Jul '08

Hi, Reading through the documentation for the Boost.Iochain library, I do not see that any default >> and << operators have been provided. I would expect to be able to use these to stream data out of a stream and into a stream, respectively. An example of the >> operator would be below: template< typename t_type > source& operator>> ( source& stream, t_type& data ) { stream.read( data ); return stream; }

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[1.36.0] Beta plans
by Beman Dawes 17 Jul '08

17 Jul '08

According to the schedule, a 1.36.0 beta release is due today. I'm going to delay the beta because there are still too many release regression test failures. See http://beta.boost.org/development/tests/release/developer/summary.html. Developers with release test failures need to redouble efforts to clear those failures. I'll start pester individuals where there doesn't seem to be any movement. The good news is that the number of failures is dropping fairly quickly as backed up merges for several important libraries takes effect, so I don't expect the delay to last more than a few days. Thanks, --Beman

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Boost with Intel/VS
by Adam Black 17 Jul '08

17 Jul '08

Am trying to use boost::circular_buffer. I am using the Intel Compiler v10.1 and am building via VS 2008. Read as the Intel Compiler is bolted up to VS. I am getting the following error: ..\boost_1_35_0\boost/mpl/aux_/integral_wrapper.hpp(80): error: expected an operator 1> operator AUX_WRAPPER_VALUE_TYPE() const { return static_cast<AUX_WRAPPER_VALUE_TYPE>(this->value); } 1> ^ 1> 1>..\boost_1_35_0\boost/mpl/aux_/integral_wrapper.hpp(80): error: identifier "L" is undefined 1> operator AUX_WRAPPER_VALUE_TYPE() const { return static_cast<AUX_WRAPPER_VALUE_TYPE>(this->value); } This is my first foray into boost. I have tried using the Windows install of boost as well as manually changing BOOST_COMPILER_CONFIG "boost/config/compiler/intel.hpp" in boost/config/user.hpp From what I've gleaned thus far that should have solved my issue. But it hasn't. I'm at a loss and as time is short I am going to throw this out there for any tips or suggestions. Thank you.

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