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[bind] Specifying bind types
by David A. Greene 31 Dec '05

31 Dec '05

I have a situation where I need to be able to specify the type of object that will be created by an invocation of bind(): template<typename F> class Callback { public: Callback(F func) ... } template<typename F, typename Arg> class OneMoreArgCallback : public Callback<SOME_BIND_TYPE> { public: OneMoreArgCallback(F func, Arg arg) : Callback(boost::bind(func, arg, _1)) {}; } What's the best way to do this? typeof? -Dave

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Re: [Boost-users] The boost Tokenizer package: split into a vectorof vectors of tokens
by Alex Vinokur 31 Dec '05

31 Dec '05

nitin motgi wrote: > > > > > if(It != string_find_iterator()) cout << "(" << i << ", " << j << ") : " > > << (*It) << endl; > > > Modify this line to (*It) ==> (*It++) > if(It != string_find_iterator()) cout << "(" << i << ", " << j << ") : " << > (*It++) << endl; > string s = "ab cd \n xy z\n123"; > And output would be > $ ./a.exe > (0, 0) : ab > (0, 1) : cd > (1, 0) : > (1, 1) : > (2, 0) : xy > (2, 1) : z [snip] How to interpret that output? * Why are there two spaces between 'cd' and 'xy'? * Why are there no spaces 'xy' and 'z'? * Why is '123' missing? -- Alex Vinokur email: alex DOT vinokur AT gmail DOT com http://mathforum.org/library/view/10978.html http://sourceforge.net/users/alexvn

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[multi_index] const_mem_fun with an inherited member function
by Matt Steele 31 Dec '05

31 Dec '05

I am trying to use Boost.Multi-index (version 1.33.0) to store a set of boost::tuples, and it appears that const_mem_fun has some difficulties when the desired member function is inherited from a base class. The following typedef typedef multi_index_container< tuple<int>, indexed_by< ordered_non_unique< const_mem_fun< tuple<int>, const int&, &tuple<int>::get<0> > > > > my_tuple_container_type; yields this error (edited for clarity) on my compiler (g++ 4.0.3): &TupleBaseClass<int>::get' is not a valid template argument for type 'const int& (tuple<int>::*)()const' because it is of type 'const int& (TupleBaseClass<int>::*)const' note: standard conversions are not allowed in this context Now the declaration of boost::tuple has something like this: template <class T> class tuple : public TupleBaseClass<T> { public: typedef typename TupleBaseClass<T> inherited; ... }; (Also, as far as I can tell, get<0>() is declared and implemented in TupleBaseClass, not tuple). The public typedef 'inherited' looked promising, so I modified my code as follows: typedef multi_index_container< tuple<int>, indexed_by< ordered_non_unique< const_mem_fun< tuple<int>::inherited, const int&, &tuple<int>::get<0> > > > > my_tuple_container_type; and that compiles. I have a few questions/comments about all this. First of all, is my compiler correct to generate the error for the first case? Secondly, is the above workaround satisfactory? My opinion is that it's a little ungainly; it appears to me that boost::tuple is a derived type for implementation reasons, and I'd rather not have to know about that fact. Thank you. Matt Steele

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Re: [Boost-users] multi_index new user question
by Todd Day 31 Dec '05

31 Dec '05

I've got the following in my project // dummies needed for tagging struct by_name {}; struct by_id {}; struct by_vreg {}; // breaking this up into two steps makes things easier on the compiler, and produces readable? error messages struct ParmListIndices : multi_index::indexed_by < multi_index::sequenced<>, multi_index::ordered_unique<multi_index::tag<by_name>, multi_index::const_mem_fun<ParmBase, string, &ParmBase::GetNameStripped> >, multi_index::ordered_non_unique<multi_index::tag<by_id>, multi_index::const_mem_fun<ParmBase, int, &ParmBase::GetID> >, multi_index::ordered_non_unique<multi_index::tag<by_vreg>, multi_index::const_mem_fun<ParmBase, int32, &ParmBase::GetVreg> > > {}; struct ParmList : multi_index::multi_index_container<ParmBase*, ParmListIndices> {}; typedef multi_index::nth_index<ParmList, 1>::type ParmList_by_name; typedef multi_index::nth_index<ParmList, 2>::type ParmList_by_id; typedef multi_index::nth_index<ParmList, 3>::type ParmList_by_vreg; typedef pair<ParmList::iterator, bool> ParmListResultPair; Note that I used structs to wrap a complicated multi_index instead of using typedefs. I learned this trick from a previous web discussion about multi_index. This relieves stress on the compiler (important for MSVC7.1 with maximum debugging turned on) and makes the error messages easier to read. I used typedef shortcuts for referring to the nth_index'es 'cause structs don't work there. This allowed me to write the following fairly simple looking code. Note the type of the variable "byName" and the iterator "f" below. ParmBase* ParmGroup::FindName(const string& name) { ParmList_by_name& byName = pParmList->get<by_name>(); ParmList_by_name::iterator f = byName.find(name); return (f != byName.end()) ? *f : NULL; } These sorts of tricks make the code a little bit more readable. You can do a similar thing for your iterator pair in your range variable. -todd- > -----Original Message----- > From: boost-users-bounces(a)lists.boost.org [mailto:boost-users- > bounces(a)lists.boost.org] On Behalf Of Evan Carew > Sent: Friday, December 30, 2005 1:03 PM > To: boost-users(a)lists.boost.org > Subject: [Boost-users] multi_index new user question > > -----BEGIN PGP SIGNED MESSAGE----- > Hash: SHA1 > > The following is todays log of my efforts to get multi_index to work: > > - ---First entry: > I'm using boost multi index for the first time. I've managed to populate > the container with my data & now I am trying to get the non-unique > ordered index to work. Does anyone have a source example (not from the > boost.multiindex tutorial please) used to get a list, set, whatever, of > tuples from such a search on such an index? > > Thanks, > Evan Carew > > P.S. > G++ V3.4.2 > Boost version 103300 > > - ---Second entry: > Hmm... Looks like their list server is down. I am unable to register. <sigh> > > - ---Third entry: > Well, lets try this example source code: > > > typedef multi_index::multi_index_container< > person, > multi_index::indexed_by< > multi_index::ordered_unique< > multi_index::tag<voterid>, > BOOST_MULTI_INDEX_MEMBER(person,unsigned long,voterid)>, > multi_index::ordered_non_unique< > > multi_index::tag<lastname>,BOOST_MULTI_INDEX_MEMBER(person,string,lastna me) > >, > multi_index::ordered_non_unique< > multi_index::tag<resstreetnum>, > BOOST_MULTI_INDEX_MEMBER(person,int,resstreetnum)> > > > people_set; > > ..... > > int main(){ > const people_set::nth_index<2>::type& resstreet_index=ps.get<2>(); > pair<people_set::iterator, people_set::iterator> range; > range = resstreet_index.equal_range((*domoItor).first); > } > > The above code doesn't compile. > > - ---Fourth entry: > By changing the pair instance to: > > pair<people_set::nth_index<2>::type::iterator, > people_set::nth_index<2>::type::iterator> range; > > I finally got it to compile. I managed this not by reading the tutorial > for the library (the information isn't there) but from reading the > rather prodigious code in multi_index. > > - ---Fifth entry: > Am I headed in the right direction, or is there specific interface that > defines the iterator types in a less painful/safe way? > > Evan Carew

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multi_index new user question
by Evan Carew 30 Dec '05

30 Dec '05

-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 The following is todays log of my efforts to get multi_index to work: - ---First entry: I'm using boost multi index for the first time. I've managed to populate the container with my data & now I am trying to get the non-unique ordered index to work. Does anyone have a source example (not from the boost.multiindex tutorial please) used to get a list, set, whatever, of tuples from such a search on such an index? Thanks, Evan Carew P.S. G++ V3.4.2 Boost version 103300 - ---Second entry: Hmm... Looks like their list server is down. I am unable to register. <sigh> - ---Third entry: Well, lets try this example source code: typedef multi_index::multi_index_container< person, multi_index::indexed_by< multi_index::ordered_unique< multi_index::tag<voterid>, BOOST_MULTI_INDEX_MEMBER(person,unsigned long,voterid)>, multi_index::ordered_non_unique< multi_index::tag<lastname>,BOOST_MULTI_INDEX_MEMBER(person,string,lastname)>, multi_index::ordered_non_unique< multi_index::tag<resstreetnum>, BOOST_MULTI_INDEX_MEMBER(person,int,resstreetnum)> > > people_set; ..... int main(){ const people_set::nth_index<2>::type& resstreet_index=ps.get<2>(); pair<people_set::iterator, people_set::iterator> range; range = resstreet_index.equal_range((*domoItor).first); } The above code doesn't compile. - ---Fourth entry: By changing the pair instance to: pair<people_set::nth_index<2>::type::iterator, people_set::nth_index<2>::type::iterator> range; I finally got it to compile. I managed this not by reading the tutorial for the library (the information isn't there) but from reading the rather prodigious code in multi_index. - ---Fifth entry: Am I headed in the right direction, or is there specific interface that defines the iterator types in a less painful/safe way? Evan Carew -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.0.6 (GNU/Linux) Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org iD8DBQFDtaBppxCQXwV2bJARAtYyAJ4lZRAoEbT1m0jsllTGAfmUZEpqSwCguhZO V18uawK1QSD2iJF00hPm4qA= =qn+Q -----END PGP SIGNATURE-----

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Re: [Boost-users] The boost Tokenizer package: split into a vectorof vectors of tokens
by Alex Vinokur 30 Dec '05

30 Dec '05

Pavol Droba wrote: > On Sat, Dec 24, 2005 at 09:06:51AM +0200, Alex Vinokur wrote: > > > > "Pavol Droba" <droba(a)topmail.sk> wrote in message news:20051223180408.GP15407@lenin.felcer.sk... > > > Hi, > > > > > > You might be able to do it using the string_algo find_iterator. > > > > > > #include <boost/algorithm/string.hpp> > > > > > > using namespace std; > > > using namespace boost; > > > > > > ... > > > > > [snip] > > typedef split_iterator<string::iterator> string_find_iterator; > > ------------------------------------------------------------------------------ > > > string_find_iterator It=make_find_iterator(str1, token_finder(is_space())); > > > > That line produces the following error message: > > > > error: conversion from `boost::algorithm::find_iterator<__gnu_cxx::__normal_iterator<char*, std::basic_string<char, > > std::char_traits<char>, std::allocator<char> > > >' to non-scalar type > > `boost::algorithm::split_iterator<__gnu_cxx::__normal_iterator<char*, std::basic_string<char, std::char_traits<char>, > > std::allocator<char> > > >' requested > > > > Sorry, I have fixed one error, but the other line was tied to it. > the second line should be > string_find_iterator It=make_split_iterator(str1, token_finder(is_space())); > > Regards, > Pavol Thanks. Here is what I compiled: -------- #include<iostream> #include<boost/tokenizer.hpp> #include<boost/algorithm/string.hpp> #include<string> using namespace std; using namespace boost; void test() { string s = "ab cd \n xy z\n123"; typedef split_iterator<string::iterator> string_find_iterator; string_find_iterator It = make_split_iterator(s, token_finder(is_space())); const int maxi = 3; const int maxj = 2; for(int i=0; i < maxi; i++) { for(int j=0; j < maxj; j++) { if(It != string_find_iterator()) cout << "(" << i << ", " << j << ") : " << (*It) << endl; else break; } } } int main () { test(); return 0; } -------- And here is what I have got after running: --- (0, 0) : ab (0, 1) : ab (1, 0) : ab (1, 1) : ab (2, 0) : ab (2, 1) : ab --- Alex Vinokur email: alex DOT vinokur AT gmail DOT com http://mathforum.org/library/view/10978.html http://sourceforge.net/users/alexvn

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[iostreams] array_sink full exception
by Robert Ramey 30 Dec '05

30 Dec '05

I'm looking at array_sink stream buffer as a possible speed enhancement to binary_oarchive in some cases. My quesion is" What happens when the capacity of the array used for the buffer is exceeded? Is an exception thrown or what? I've looked through the documentation and don't find exceptions mentioned. Robert Ramey

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Re: [Boost-users] [Multi-index] Sorted range selection
by JOAQUIN LOPEZ MU?Z 29 Dec '05

29 Dec '05

Hello Tamas, ----- Mensaje original ----- De: Tamas Szepes <tamas.szepes(a)ieee.org> Fecha: Miércoles, Diciembre 28, 2005 9:11 pm Asunto: [Boost-users] [Multi-index] Sorted range selection > Hi All, > > I'm learning to use the multi-index library by rewriting an > existing STL > based code. > I'm storing rectangles (X, Y, Width, Height, ...) in a set ordered > by a > composite key on X, Y. > > What is the best way to select rectangles where X has a certain > value and > sort the result by Width? Can I use a sorted indice on Width, or I > must sort > the range? I also thought to create a composite key on X and > Width, but > sorting order is run time determined and I have a dosen other > properties. Your analysis is correct. I'm afraid you have to externally sort the interval returned by range(), pseudocode follows: std::vector<boost::reference_wrapper<const Rectangle> > rng; std::pair< YourCompositeKeyIndex::iterator, YourCompositeKeyIndex::iterator> p= yourcompositekeyindex.range(...); while(p.first!=p.second)rng.push_back(boost::cref(*p.first++)); std::sort(rng.begin(),rng.end(),WidthCompare()); Having a composite key on (X,Width) is also an option, but as you say the number of combinations might be too large, and manipulating those indices with run-time decisions is not trivial. So, my suggestion is to follow the scheme proposed on the pseudocode above. > I'm realy looking for the possibility to mimic SQL's ORDER BY clause. Well, Boost.MultiIndex does not aim to provide complete functionality for relational stuff, as stated explicitly in the rationale at http://boost.org/libs/multi_index/doc/tutorial.html. The idea is to keep Boost.MultiIndex application-agnostic and more focused on the STL conceptual framework. As I see it, this kind of funcionality could be better served by a relational-specific lib built on top of Boost.MultiIndex. There are currently two libs approaching this goal, Arkadiy Vertleyb's RTL and Calum Grant's RML (look for those on recent discussions on the Boost list.) Unfortunately, neither of these libs actually uses internally Boost.MultiIndex, but this is another story :) > > Thanks for any help in advance, I'm sorry I can't be more helpful. Thanks for using Boost.MultiIndex and please come back if you have further problems or want to comment on proposals for enhancements of the library. Joaquín M López Muñoz Telefónica, Investigación y Desarrollo

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BGL question: non local exit by throwing an exception
by Andreas Fabri 29 Dec '05

29 Dec '05

Hi, I am wondering, if it is good style to throw an exception in the middle of a BGL algorithm, for example during BFS when I have found what I want. Or are there nicer ways to achive the same goal? Thanks in advance, andreas

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[BGL] Mixing bundled properties and property lists
by Nicola Vitacolonna 29 Dec '05

29 Dec '05

Hi, consider the following (excerpt from a) class wrapper around an adjacency_list: using namespace boost; template <typename VertexProperty = no_property> class MyGraphWrapper { private: typedef adjacency_list<vecS, listS, bidirectionalS, property<vertex_index_t, int, VertexProperty> > GraphImpl; // ... }; I want to store some property (in this case, a vertex index) inside the graph implementation, but at the same time I want to allow the client to specify further properties via the template parameter. May the client use the bundled property mechanism, e.g. struct Label { std::string lab; }; MyGraphWrapper<Label> g; My test compiled and it seems to run fine. Is it really possible/safe to mix bundle properties with property lists in this way? Or, is there a way to avoid property lists? Nicola

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