August 2008 - Boost-users - lists.boost.org

Simply including boost/bind.hpp causes compilation error
by Ken Smith 28 Aug '08

28 Aug '08

Here is my environment. % g++ -v Using built-in specs. Target: i686-apple-darwin9 Configured with: /var/tmp/gcc/gcc-5483~1/src/configure --disable-checking -enable-werror --prefix=/usr --mandir=/share/man --enable-languages=c,objc,c++,obj-c++ --program-transform-name=/^[cg][^.-]*$/s/$/-4.0/ --with-gxx-include-dir=/include/c++/4.0.0 --with-slibdir=/usr/lib --build=i686-apple-darwin9 --with-arch=apple --with-tune=generic --host=i686-apple-darwin9 --target=i686-apple-darwin9 Thread model: posix gcc version 4.0.1 (Apple Inc. build 5483) Boost 1.35.0 (also produced same issue with Boost 1.34.1) Here is the code. 1 #include <boost/lambda/lambda.hpp> 2 #include <boost/lambda/construct.hpp> 3 #if defined(INCLUDE_BOOST_BIND) 4 # include <boost/bind.hpp> 5 #endif 6 #include <iostream> 7 #include <iterator> 8 #include <algorithm> 30 31 int main() 32 { 33 using namespace std; 34 using namespace boost::lambda; 35 36 typedef std::istream_iterator<int> in; 37 std::for_each(in(std::cin), in(), std::cout << (_1 * 3) << " " ); 76 } (The astute reader will note discontinuity in the line numbering. This is a playground for my exploration with boost. All elided lines are #if 0'ed. Here is the compile command line and the compilation error, both edited for clarity. g++ -c -g -Wall -fexceptions -DINCLUDE_BOOST_BIND -I/path/to/boost-1.35.0/include main.cpp -o main.o main.cpp: In function 'int main()': main.cpp:37: error: '_1' was not declared in this scope I have seen these related articles from the archives of this list but none of the suggestions eliminated the error. I added the inclusion of boost/lambda/construct.hpp per one of the suggestions there. Its inclusion or exclusion doesn't change the behavior. http://thread.gmane.org/gmane.comp.lib.boost.user/35128 http://thread.gmane.org/gmane.comp.lib.boost.user/16630 http://thread.gmane.org/gmane.comp.lib.boost.user/16887 As you may imagine, the elided (and commented out) lines contain actual uses of boost/bind.hpp but it is a mystery to me that simple inclusion of a header file would cause otherwise working code to stop compiling. This compile command (same as above but with -D removed): g++ -c -g -Wall -fexceptions -I/path/to/boost-1.35.0/include main.cpp -o main.o runs to completion and the subsequent link is successful. Any ideas? Thanks in advance, Ken

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[filesystem] Should fstream really 'force' in+out mode?
by Sachin Garg 27 Aug '08

27 Aug '08

I want to open a read only file in ios::in mode using fstream but its open forces in+out mode, causing my open to fail when it could have succeeded. In boost::filesystem::fstream::open, the file open mode is modified to mode | std::ios_base::in | std::ios_base::out Is this really necessary or can this be changed in future? Atleast with MSVC 9.0, std::fstream isn't forcing such behavior. SG

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[program_options] format_paragraph chops words
by Soren Soe 27 Aug '08

27 Aug '08

Hi, I have run into a problem with the program_options library chopping words when it formats help messages. I have created a small code fragment that will duplicate the problem: int main() { std::string p = "\n1234 6789 1234 6789 1234 6789 1234"; format_description(std::cout, p, 20, 44); return 0; } Results in this message: 1234 6789 1234 6789 123 4 6789 1234 In case formatting is not preserved, the 3'rd instance of '1234' is chopped into '123' with '4' on the next line. I think there might be a bug in format_paragraph in the block that is supposed to prevent word chopping. Specifically, this piece of code: // is last_space within the second half ot the // current line if ((unsigned)distance(last_space, line_end) < (line_length - indent) / 2) { line_end = last_space; } should probably not subtract 'indent' from 'line_length' since this was already done at the very beginning of the function. Thanks, Soren Soe. This email and any attachments are intended for the sole use of the named recipient(s) and contain(s) confidential information that may be proprietary, privileged or copyrighted under applicable law. If you are not the intended recipient, do not read, copy, or forward this email message or any attachments. Delete this email message and any attachments immediately.

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[range] STL algorithm wrappers accepting range?
by Nat Goodspeed 27 Aug '08

27 Aug '08

Apologies if I'm overlooking something obvious, or if this is a FAQ. Has anyone published a suite of wrappers for common STL algorithms that accept Boost.Range instances instead of iterator pairs? Or must we each write our own? Seems like redundant effort...

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[graph] [serialization] loading adjacency_list
by Mojmir Svoboda 27 Aug '08

27 Aug '08

hello, i have 1.36.0 now and i have troubles serializing adjacency list. graph itself saves okay in whatever oarchive and looks okay, but when loading graph, his properties are not set.. in fact defaults are used instead what serialization is trying to load. is there something that changed from 1.35.0 and 1.36.0 in this area? my (uneducated!) guess is that the serialization loads data into temporary that is discarded afterwards. i traced it to file adj_list_serialize.hpp around line 90: now i want the line ar >> serialization::make_nvp("vertex_property", get(vertex_all_t(), graph, v)); to be transformed into form: something & vp = get(vertex_all_t(), graph, v); ar >> serialization::make_nvp("vertex_property", vp); at least for debugging purposes.. i'm wondering that this "something" could be.. i tried property_map<...>::type etc, but failed ultimately. the same apply to edge: what is the return type of get(edge_all... when my graph is defined by: typedef boost::adjacency_list< boost::vecS, boost::vecS, boost::undirectedS, VertexProp, boost::property<boost::edge_index_t, uint16_t, EdgeProp> > T_Graph; many thanks, mojmir // please excuse incomplete information, i'm under pressure :/

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base64_from_binary Q
by Terdale, Shantibhushan 27 Aug '08

27 Aug '08

I am using this sample to prove myself that base64_from_binary and binary_from_base64 can be used in my app. But I am having little problem and not able to understand whats missing Here is the sample #include "boost/archive/iterators/base64_from_binary.hpp" #include "boost/archive/iterators/binary_from_base64.hpp" #include "boost/archive/iterators/transform_width.hpp" #include <string> #include <iostream> using namespace std; using namespace boost::archive::iterators; typedef base64_from_binary< transform_width<std::string::iterator, 6, sizeof(char) * 8> > base64_t; typedef transform_width< binary_from_base64<std::string::iterator>, sizeof(char) * 8, 6 > binary_t; int main() { string str = "Hello, world!"; cout << str << endl; string enc(base64_t(str.begin()), base64_t(str.end())); // Problem here. It works when I specify "str.end()-1" instead of "str.end()" but I loose last character after decoding. cout << enc << endl; string dec(binary_t(enc.begin()), binary_t(enc.end())); cout << dec << endl; return 0; } Will appreciate any help. I tried std::copy as well and have same problem.

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question about time_facet and date/time formatting
by Axel 27 Aug '08

27 Aug '08

Hello Following the documentation, the time_facet::put function take 3 common parameters : "an iterator pointing to the next item in the stream, an ios_base object, and the fill character.".But this is not clear for me, i m totally new to facets. I m using it like that and it works well : stringstream log_stream ; ptime time = second_clock::local_time() ; time_facet facet("%Y-%m-%d %H:%M:%S") ; facet.put(log_stream, log_stream, ' ' , time) ; cout << log_stream.str() ; But I don't understand WHY it works and I wonder some things : What does mean the "iterator to the next item" from the documentation since I consider the target as an input stream ? Why use the same object for the "ios_base object" parameter ? This means I could use a different stream, but what could be the utility of such an usage of put() ? Finally, what is the use of the "fill character" ? Thanks in advance.

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a little Graph guidance (looking for hints)
by Carsten Hoyer 27 Aug '08

27 Aug '08

Hi Just turned to Boost - What a fantastic library :) I have a question about the construction of a Graph. I can't figure out how to use boost to represent a graph where each Vertex has several outs. F.ex Vertex 1 has out 1, 2 and 3. Vertex A has in a, b and c. I can then make edges going from 1-a, 1-b, 2-b etc. Like F.ex http://messe.harmony-central.com/Musikmesse05/Content/Native_Instruments/PR… Reaktor Any hints? Thank you Carsten -- View this message in context: http://www.nabble.com/a-little-Graph-guidance-%28looking-for-hints%29-tp190… Sent from the Boost - Users mailing list archive at Nabble.com.

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MAC Address
by Jean-Sebastien Stoezel 27 Aug '08

27 Aug '08

Hello, How to get the MAC address of an ethernet interface, using the boost C++ library? Thanks, Jean

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serialization of large complex structure
by Diane 27 Aug '08

27 Aug '08

I have a large, complex struct that is made up of many levels of structs, getting eventually to int, char*, enum, etc. There are also pointers to structs and arrays of pointers. There are no STL types within these structures. I am trying to wrap my head around how I can use boost.serialization for this, without modifying the structures themselves (I can't make changes to the definitions). Does anyone know the best way to do this? I saw several mentions of wrapper classes for serializing a float and figure I could use that approach, but I think I would have to make a mirror structure that's made up of my struct wrappers and copy the data over from the real struct into these classes. Or I guess I could use pointers, but I would still have to create this second monster. Is that really the best possibility? Any help is appreciated! Thanks, Diane

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