- Boost-users - lists.boost.org

(no subject)
by Long P 07 Jul '10

07 Jul '10

Hi I have problem compiling the example for serialization (boost_asio/example/serialization/server.cpp…) using MS71, does anyone know how to fix this errors? (I don’t have any problem using MS80) Thanks Long Note: including file: C:\OpenSourceSoftware\InternetDownload\boost_1_41_0\boost/serialization/array.hpp Note: including file: C:\OpenSourceSoftware\InternetDownload\boost_1_41_0\boost/serialization/detail/get_data.hpp Note: including file: C:\Program Files\Microsoft Visual Studio .NET 2003\Vc7\include\valarray C:\Program Files\Microsoft Visual Studio .NET 2003\Vc7\include\valarray(314) : warning C4003: not enough actual parameters for macro 'min' C:\Program Files\Microsoft Visual Studio .NET 2003\Vc7\include\valarray(323) : warning C4003: not enough actual parameters for macro 'max' C:\Program Files\Microsoft Visual Studio .NET 2003\Vc7\include\valarray(314) : error C2059: syntax error : ')' C:\Program Files\Microsoft Visual Studio .NET 2003\Vc7\include\valarray(427) : see reference to class template instantiation 'std::valarray<_Ty>' being compiled C:\Program Files\Microsoft Visual Studio .NET 2003\Vc7\include\valarray(314) : error C2334: unexpected token(s) preceding ':'; skipping apparent function body C:\Program Files\Microsoft Visual Studio .NET 2003\Vc7\include\valarray(321) : error C2143: syntax error : missing ')' before '}' C:\Program Files\Microsoft Visual Studio .NET 2003\Vc7\include\valarray(321) : error C2143: syntax error : missing '}' before ')' C:\Program Files\Microsoft Visual Studio .NET 2003\Vc7\include\valarray(321) : error C2059: syntax error : ')' C:\Program Files\Microsoft Visual Studio .NET 2003\Vc7\include\valarray(321) : error C2143: syntax error : missing ';' before '}' C:\Program Files\Microsoft Visual Studio .NET 2003\Vc7\include\valarray(321) : error C2238: unexpected token(s) preceding ';' C:\Program Files\Microsoft Visual Studio .NET 2003\Vc7\include\valarray(323) : error C2146: syntax error : missing ';' before identifier '_Ty' C:\Program Files\Microsoft Visual Studio .NET 2003\Vc7\include\valarray(314) : error C2059: syntax error : ')' C:\Program Files\Microsoft Visual Studio .NET 2003\Vc7\include\valarray(1124) : see reference to class template instantiation 'std::valarray<_Ty>' being compiled with [ _Ty=size_t ] C:\Program Files\Microsoft Visual Studio .NET 2003\Vc7\include\valarray(314) : error C2334: unexpected token(s) preceding ':'; skipping apparent function body C:\Program Files\Microsoft Visual Studio .NET 2003\Vc7\include\valarray(321) : error C2143: syntax error : missing ')' before '}' C:\Program Files\Microsoft Visual Studio .NET 2003\Vc7\include\valarray(321) : error C2143: syntax error : missing '}' before ')' C:\Program Files\Microsoft Visual Studio .NET 2003\Vc7\include\valarray(321) : error C2059: syntax error : ')' C:\Program Files\Microsoft Visual Studio .NET 2003\Vc7\include\valarray(323) : error C2334: unexpected token(s) preceding ':'; skipping apparent function body C:\Program Files\Microsoft Visual Studio .NET 2003\Vc7\include\valarray(330) : error C2143: syntax error : missing ')' before '}' C:\Program Files\Microsoft Visual Studio .NET 2003\Vc7\include\valarray(330) : error C2143: syntax error : missing '}' before ')' C:\Program Files\Microsoft Visual Studio .NET 2003\Vc7\include\valarray(330) : error C2059: syntax error : ')' C:\Program Files\Microsoft Visual Studio .NET 2003\Vc7\include\valarray(330) : error C2143: syntax error : missing ';' before '}' C:\Program Files\Microsoft Visual Studio .NET 2003\Vc7\include\valarray(330) : error C2238: unexpected token(s) preceding ';' C:\Program Files\Microsoft Visual Studio .NET 2003\Vc7\include\valarray(332) : error C2146: syntax error : missing ';' before identifier 'valarray' C:\Program Files\Microsoft Visual Studio .NET 2003\Vc7\include\valarray(314) : error C2059: syntax error : ')' C:\Program Files\Microsoft Visual Studio .NET 2003\Vc7\include\valarray(1333) : see reference to class template instantiation 'std::valarray<_Ty>' being compiled with [ _Ty=std::_Bool ] C:\Program Files\Microsoft Visual Studio .NET 2003\Vc7\include\valarray(1335) : see reference to class template instantiation 'std::mask_array<_Ty>' being compiled C:\Program Files\Microsoft Visual Studio .NET 2003\Vc7\include\valarray(314) : error C2334: unexpected token(s) preceding ':'; skipping apparent function body C:\Program Files\Microsoft Visual Studio .NET 2003\Vc7\include\valarray(321) : error C2143: syntax error : missing ')' before '}' C:\Program Files\Microsoft Visual Studio .NET 2003\Vc7\include\valarray(321) : error C2143: syntax error : missing '}' before ')' C:\Program Files\Microsoft Visual Studio .NET 2003\Vc7\include\valarray(321) : error C2059: syntax error : ')' C:\Program Files\Microsoft Visual Studio .NET 2003\Vc7\include\valarray(321) : error C2143: syntax error : missing ';' before '}' C:\Program Files\Microsoft Visual Studio .NET 2003\Vc7\include\valarray(321) : error C2238: unexpected token(s) preceding ';' C:\Program Files\Microsoft Visual Studio .NET 2003\Vc7\include\valarray(323) : error C2146: syntax error : missing ';' before identifier '_Ty' _________________________________________________________________ Look 'em in the eye: FREE Messenger video chat http://go.microsoft.com/?linkid=9734386

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[hash] hashing of smart pointer types - prevent conversion to bool?
by Alastair Rankine 07 Jul '10

07 Jul '10

Hi Boosters, I'm sure I'm not the first person to be caught out by this. If you try to use Boost.Functional/Hash on a smart pointer type such as boost::shared_ptr, the results may be, well, underwhelming: typedef boost::shared_ptr<int> IPtr; IPtr i1 = IPtr(new int(1234)); IPtr i2 = IPtr(new int(4321)); std::cout << std::hex << "hash(i1): " << boost::hash<IPtr>()(i1) << "\n" << "hash(i2): " << boost::hash<IPtr>()(i2) << "\n"; which produces: hash(i1): 1 hash(i2): 1 This is because the shared_ptr is being silently converted to a boolean type before being hashed. Now maybe this is all documented and so forth but I would argue that it's not really expected behaviour. Or to put it another way, it's very easy to go wrong and use smart pointers in a hashed container such as a boost::unordered_set. The performance of such a set obviously degrades considerably, when compared to a more intelligent hash function. Here's a simple snippet to show the problem: typedef boost::shared_ptr<int> IPtr; template <typename T> struct PtrHash : public std::unary_function<boost::shared_ptr<T>, std::size_t> { std::size_t operator() (boost::shared_ptr<T> const& ptr) const { return boost::hash<T*>()(ptr.get()); } }; template <typename Set> double TimeInserts(int i) { Set s; boost::timer t; while (i--) s.insert(IPtr(new int(i))); return t.elapsed(); } int main() { typedef boost::unordered_set<IPtr> IPtrSetDefaultHash; typedef boost::unordered_set<IPtr, PtrHash<int> > IPtrSetPtrHash; const int iterations = 10000; std::cout << std::dec << "IPtrSetDefaultHash: " << TimeInserts<IPtrSetDefaultHash>(iterations) << "s\n" << "IPtrSetPtrHash: " << TimeInserts<IPtrSetPtrHash>(iterations) << "s\n"; return 0; } Which outputs: IPtrSetDefaultHash: 2.14526s IPtrSetPtrHash: 0.006855s ... a noticable performance difference. OK so obviously it is reasonable to want to question the wisdom of using a smart pointer type in a hashed container like this. But I want to ignore that question for now, and instead ask whether it is possible to *prevent* the conversion of smart pointers to bool for the purposes of calculating hash values. The context for this question is a fairly large codebase with extensive use of hashed containers. Not everyone on the development team is aware of this particular limitation of smart pointers. So not only do I want to detect the use of "dangerous" hashing functions but also prevent them being used in the future. Instead I really want to either fix or prevent the conversion to bool for smart pointers when used in a hashing function (either through the boost:: or tr1:: namespace). One idea is to patch the boost headers to add a hash function for each of the smart pointer types (as per the example above) but there must be a better answer than this? Does this problem affect anyone else? How do people deal with this?

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[unique_ptr] Questions
by dariomt＠gmail.com 07 Jul '10

07 Jul '10

Hi list, I found a C++03 emulation of unique_ptr here http://home.roadrunner.com/~hinnant/unique_ptr.hpp Is there any reason this is not part of Boost? Are there any known issues with this code? Thanks!

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boost serialisation number of global symbols per serializable type
by Avi Bahra 07 Jul '10

07 Jul '10

How can I work out the number of global symbols introduced per serializable type ? Is this fixed or does it vary according to type of serialisation , i.e by ptr, versus by value ? On linux I tried: nm test | grep GLOBAL | grep RepeatDay | wc Which revealed about 26, however this does not seem right ? Is there any way to reduce this overhead? Any help appreciated. Best regards, Ta, Avi

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Re: [Boost-users] Is there any existing/similar C++ lib for Java FileChannel
by Tan, Tom (Shanghai) 07 Jul '10

07 Jul '10

I did not look too much into details, but it seems to be related to memory-mapped files. Boost.iostream does support memory mapped files: http://www.boost.org/doc/libs/1_43_0/libs/iostreams/doc/classes/mapped_f ile.html >Date: Tue, 6 Jul 2010 07:25:12 +0800 >From: Bo Xie <xiebopublic(a)gmail.com> >To: boost-users(a)lists.boost.org > >Hello, > >Java FileChannel ( >http://java.sun.com/j2se/1.4.2/docs/api/java/nio/channels/FileChannel.h tml) >supports to lock a region of the file [e.g.lock(long position, long size, boolean shared)]. Is there any existing/similar C++ lib for it (so than I need not to reinvent the wheel)? > >Best Regards, >Bo Xie

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Compiler error when using property map get()
by Trevor Harmon 06 Jul '10

06 Jul '10

Hi, The get() function for property maps has me puzzled. Calling it in one context gives a compiler error, while in another context it does not. A trivial example is below. Note that the code in foo() and main() are identical. Any guesses as to why the foo() version gives a compiler error while the main() version does not? FWIW, the error is: subgraph.cpp: In member function ‘virtual void MyGraph::foo()’: subgraph.cpp:15: error: conversion from ‘boost::subgraph_global_property_map<Subgraph*, boost::adj_list_edge_property_map<boost::bidirectional_tag, size_t, size_t&, size_t, boost::property<boost::edge_index_t, size_t, boost::no_property>, boost::edge_index_t>, boost::edge_index_t>’ to non-scalar type ‘boost::adj_list_edge_property_map<boost::bidirectional_tag, size_t, size_t&, size_t, boost::property<boost::edge_index_t, size_t, boost::no_property>, boost::edge_index_t>’ requested Thanks, Trevor #include <boost/graph/adjacency_list.hpp> #include <boost/graph/subgraph.hpp> using namespace boost; typedef subgraph<adjacency_list<vecS, vecS, bidirectionalS, int, property<edge_index_t, std::size_t> > > Subgraph; typedef property_map<Subgraph, edge_index_t>::type EdgeIndexMap; class MyGraph : public Subgraph { virtual void foo(); }; void MyGraph::foo() { Subgraph g; EdgeIndexMap edgeMap = get(edge_index, g); } int main(int, char**) { Subgraph g; EdgeIndexMap edgeMap = get(edge_index, g); return 0; }

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Error in [Range] document
by John Dlugosz 06 Jul '10

06 Jul '10

In <http://www.boost.org/doc/libs/1_43_0/libs/range/doc/html/range/reference/ad…>, the example: std::vector<int> vec; boost::replace_copy_if( rng, std::back_inserter(vec), pred ); should have a with_what argument after pred. To match the following example, it should be called new_value. --John (stupid footer; sorry) TradeStation Group, Inc. is a publicly-traded holding company (NASDAQ GS: TRAD) of three operating subsidiaries, TradeStation Securities, Inc. (Member NYSE, FINRA, SIPC and NFA), TradeStation Technologies, Inc., a trading software and subscription company, and TradeStation Europe Limited, a United Kingdom, FSA-authorized introducing brokerage firm. None of these companies provides trading or investment advice, recommendations or endorsements of any kind. The information transmitted is intended only for the person or entity to which it is addressed and may contain confidential and/or privileged material. Any review, retransmission, dissemination or other use of, or taking of any action in reliance upon, this information by persons or entities other than the intended recipient is prohibited. If you received this in error, please contact the sender and delete the material from any computer.

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[Interprocess] Shared Mutex - Permission Denied
by Matt Cupp 06 Jul '10

06 Jul '10

From: http://groups.google.com/group/boost-list/browse_thread/thread/fc728b9d416c… > Interprocess has this embarrasing permission limitations, but I still > don't know how to fix it. Does the permissions limitation apply to Linux (CentOS) and shared mutexes or segments created by other users or root? I have a mutex in the /dev/shm folder created by another user with these permissions (from ls -l): -rwxr-xr-x 1 webers users 160 Jul 1 15:24 Lookup_Mutex My user account is a member of the users group, but since it defaults to just read only access I can't actually use the mutex as a mutex. Is there any way to get around it? Thanks, Matt

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[Assign] reservation and insert efficiency
by John Dlugosz 06 Jul '10

06 Jul '10

Does the initialization form I showed earlier, e.g. std::vector<record_type> newvec= list_of().range(RecVec.begin(),db).range(newdata).range(de,RecVec.end()); know to get the total length first, or will it keep re-allocating storage with each underlying insertion? That is, do I get a performance benifit from manually doing: std::vector<record_type> newvec; newvec.reserve (... add up the sizes of my three ranges ...) newvec += range(RecVec.begin(),db).range(newdata).range(de,RecVec.end()); Hmm, I'm sure the last line would be somewhat different. Anyway, do I need to reserve first, or will it be reasonably smart about that? --John (awkward footer alert!) TradeStation Group, Inc. is a publicly-traded holding company (NASDAQ GS: TRAD) of three operating subsidiaries, TradeStation Securities, Inc. (Member NYSE, FINRA, SIPC and NFA), TradeStation Technologies, Inc., a trading software and subscription company, and TradeStation Europe Limited, a United Kingdom, FSA-authorized introducing brokerage firm. None of these companies provides trading or investment advice, recommendations or endorsements of any kind. The information transmitted is intended only for the person or entity to which it is addressed and may contain confidential and/or privileged material. Any review, retransmission, dissemination or other use of, or taking of any action in reliance upon, this information by persons or entities other than the intended recipient is prohibited. If you received this in error, please contact the sender and delete the material from any computer.

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[Assign]
by John Dlugosz 06 Jul '10

06 Jul '10

This is my first time reaching for the Assign library, but I'm insprired by what I've seen discussed here in the list. I'm creating a vector from three ranges. So something like: std::vector<record_type> newvec= list_of().range(a,b).range(c,d).range(e,f); would be right? The tutorial doesn't show anything where the stuff begins with a range, only stuff in the list_of(). But I'm thinking I have to start with list_of, even if it's empty, to kick it off, right? I'm hoping that correctly kicks it off but doesn't add default elements! Next question: the range c,d is going to be a whole vector. That is, the V.begin(), V.end() pair from another object. Can I just name V alone? Would that be done in a range(V) wrapper, or by itself, or some other function name? --John TradeStation Group, Inc. is a publicly-traded holding company (NASDAQ GS: TRAD) of three operating subsidiaries, TradeStation Securities, Inc. (Member NYSE, FINRA, SIPC and NFA), TradeStation Technologies, Inc., a trading software and subscription company, and TradeStation Europe Limited, a United Kingdom, FSA-authorized introducing brokerage firm. None of these companies provides trading or investment advice, recommendations or endorsements of any kind. The information transmitted is intended only for the person or entity to which it is addressed and may contain confidential and/or privileged material. Any review, retransmission, dissemination or other use of, or taking of any action in reliance upon, this information by persons or entities other than the intended recipient is prohibited. If you received this in error, please contact the sender and delete the material from any computer.

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