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Re: [Boost-users] [multi_index] Sorting object based on some specified criteria!!
by Patel Priyank-PPATEL1 18 Apr '06

18 Apr '06

Hi Joaquin, Thanks for all your replies. Let me read carefully the link you sent out. I will write you back in case of any more questions. Thanks for this great library, it is really helpful. Thanks again, Priyank -----Original Message----- From: boost-users-bounces(a)lists.boost.org [mailto:boost-users-bounces@lists.boost.org] On Behalf Of Joaquín Mª López Muñoz Sent: Tuesday, April 18, 2006 2:21 AM To: boost-users(a)lists.boost.org Subject: Re: [Boost-users] [multi_index] Sorting object based on some specified criteria!! Patel Priyank-PPATEL1 ha escrito: > Hi Joaquin, > > First of all thanks for your time and response. I have it working as follows, but seems I have to recalculate iterators if in case I later on modify group associated with that access point. Is there any way that iterators will know automatically update when I update access point in future to some other group? > Let me know if you have come across that one. I am going to look in your code in detail and get back to you in case of any questions. Hello Priyank, there's an issue in your code: > // change paging group from access point 4 > a4->pg(2); This is incorrect and can lead to hard-to-detect failures later on during the execution of the program: basically, you're changing an element key "under the table", that is, without the multi-index container having a chance to notice, which directly breaks the internal invariants the container relies on. Under usual conditions it is difficult to change a key in such a way, because the elements of a multi-index container are treated as const, but here you can easily get by because it is pointers that you are storing. The proper way to modify an element is by using replace, modify of modify_key, as explained in http://boost.org/libs/multi_index/doc/tutorial.html#ord_updating In your case, instead of what you've got you could write the following: // get an iterator to a4. You could also have stored those iterators in the // first place when inserting the elements. Access_Points::iterator it=pool.find(4); // change paging group from access point 4 pool.modify(it,boost::bind(&Access_point::pg,_1,2)); By using modify(), the multi-index container is on control of the updating operation, and will rearrange a4 according to its new paging group. > // NEED TO RECALCULATE ITERATORS > boost::tuples::tie(pg0, pg1) = get<paging_group> > (pool).equal_range(1); As for your original question, yes, you've got to recalculate these iterators in the general case, as elements might have been moved around, inserted or deleted: for instance, if the element originally pointed to by pg0 had been deleted, pg0 would not even be valid after that. Joaquín M López Muñoz Telefónica, Investigación y Desarrollo _______________________________________________ Boost-users mailing list Boost-users(a)lists.boost.org http://lists.boost.org/mailman/listinfo.cgi/boost-users

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ptr_container: splice function in ptr_list
by Detlef Mages 18 Apr '06

18 Apr '06

Hi there, I am using a ptr_list as a (huge) container where I can store objects (different types of a single interface). I am using a ptr_list as I need to store iterators to elements that do not invalidate when reordering the structure. Though a standard function of the STL list is missing: "splice". I know, I can mimic "splice" by "transfer", though I think that this results in a runtime complexity of O(N) whereas "splice" would be O(1). Is there a way to add splice to ptr_list? Or will there be problems I haven't thought of? If you give me some hint I could take a shot on this functionality. Detlef

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Re: [Boost-users] [multi_index] Sorting object based on some specified criteria !!
by Patel Priyank-PPATEL1 18 Apr '06

18 Apr '06

Hi Joaquin, First of all thanks for your time and response. I have it working as follows, but seems I have to recalculate iterators if in case I later on modify group associated with that access point. Is there any way that iterators will know automatically update when I update access point in future to some other group? Let me know if you have come across that one. I am going to look in your code in detail and get back to you in case of any questions. Thanks Priyank // class Access point test class Access_Point { public: Access_Point(int id, int paging_group):id_(id), pg_(paging_group) { } bool by_id(int _id) const { return (_id == id_); } int paging_group(int _pg) const { return (_pg == pg_); } int id() const { return id_; } int pg() const { return pg_; } int pg(int _pg) { pg_ = _pg; } friend ostream& operator << (ostream& _os, const Access_Point& _ap); private: int id_; int pg_; }; ostream& operator << (ostream& _os, const Access_Point& _ap) { _os << "Id: " << _ap.id_ << "Pg: " << _ap.pg_ << endl; return _os; } // tag ids struct hashed_objs { }; struct paging_group { }; // Create multi index container typedef multi_index_container< Access_Point*, indexed_by< hashed_unique< tag<hashed_objs>, const_mem_fun<Access_Point, int, &Access_Point::id> >, ordered_non_unique < tag<paging_group>, const_mem_fun<Access_Point, int, &Access_Point::pg> > > > Access_Points; int ACE_MAIN (int, ACE_TCHAR *[]) { // ACCESS POINT CHECK Access_Points pool; Access_Point * a1 = new Access_Point(1, 1); Access_Point * a2 = new Access_Point(2, 1); Access_Point * a3 = new Access_Point(3, 2); Access_Point * a4 = new Access_Point(4, 1); // insert all the access points pool.insert(a1); pool.insert(a2); pool.insert(a3); // get iterator index_iterator<Access_Points, paging_group>::type pg0, pg1; boost::tuples::tie(pg0, pg1) = get<paging_group> (pool).equal_range(1); pool.insert(a4); // print all that is there while (pg0 != pg1) { cout << *(*pg0) << endl; pg0++; } // change paging group from access point 4 a4->pg(2); // NEED TO RECALCULATE ITERATORS boost::tuples::tie(pg0, pg1) = get<paging_group> (pool).equal_range(1); while (pg0 != pg1) { cout << *(*pg0) << endl; pg0++; } // return success return 0; } -----Original Message----- From: boost-users-bounces(a)lists.boost.org [mailto:boost-users-bounces@lists.boost.org] On Behalf Of Joaquin M Lopez Munoz Sent: Monday, April 17, 2006 2:26 PM To: boost-users(a)lists.boost.org Subject: Re: [Boost-users][multi_index] Sorting object based on some specified criteria !! Patel Priyank-PPATEL1 <priyankpatel <at> motorola.com> writes: > > > Hi > all, > > > I have following > kind of class and having some identifier and group id associated with > particular procedure. I want to know if I have to get the procedures > relating particular > > group for ex. > (groupId == 1). How do I do using multiindex container? Can somebody > please give me some hint or code if they have done something similar > to what I want to do? > Hello Priyank, I'm not sure I've understood what you're after, but let me try anyway: As you'll search for group, you'll need an additional index (the one you've set up is based on process ID). The following has not been compiled, beware typos: struct id {}; struct group {}; typedef multi_index_container< Procedure*, indexed_by< hashed_unique< tag<id>, const_mem_fun<Procedure, int, &Procedure::get_id> > >, hashed_non_unique< tag<group>, const_mem_fun<Procedure, int, &Procedure::get_group> > > > > Procedure_Hashed_Pool; typedef Procedure_Hashed_Pool:: index<id>::type Procedure_By_Id; typedef Procedure_Hashed_Pool:: index<group>::type Procedure_By_Group; (I've decided to make the new index hashed non-unique, you could also have it ordered non-unique if you need the elements to be sorted by group ID --hashing only guarantees fast retrieval.) And now you can simply use equal_range() on this index to do what you want: int gr=...; const Procedure_By_Group& procedure_bg= procedure_pool.get<group>(); std::pair< Procedure_By_Group::iterator, Procedure_By_Group::iterator > p=procedure_bg.equal_range(gr); p will hold the range of elements with group ID == gr. Is this what you were after? Joaquín M López Muñoz Telefónica, Investigación y Desarrollo _______________________________________________ Boost-users mailing list Boost-users(a)lists.boost.org http://lists.boost.org/mailman/listinfo.cgi/boost-users

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Re: [Boost-users] [format] 64bit integer
by Wu Yinghui, Freddie 18 Apr '06

18 Apr '06

> Christian Henning wrote : > >> boost::format will not swallow "%I64d". Instead, it throws a >> boost::io::bad_format_string exception. How can I use 64 bit integers? > > C++ doesn't have a 64 bit integer type. I mean no offense. But I'm a bit sick seeing this answer. Yes, we all know that C++/98 doesn't have 64-bit integral types. But it is a matter of fact that many of us have to deal with 64-bit integral types on a daily basis. I think we can only push boost to its full potential if it supports 64-bit integral types natively. Just my 5 cents... Cheers, Freddie -- Wu Yinghui, Freddie Research & Development Software Engineer Volume Interactions Pte Ltd 1 Kim Seng Promenade, #12-01 Great World City East Tower Singapore 237994 Tel: +65 62226962 (Ext 216) Fax: +65 62226215 Email: yhwu(a)volumeinteractions.com URL: http://www.volumeinteractions.com Important: This message is intended for the recipient(s) addressed above. It contains privileged and confidential information. If you are not the intended recipient, please notify the sender immediately by replying to this message and then delete it from your system. You must not read, copy, use, or disseminate this communication in any form. Thank you.

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[BGL]:adjacency_list swap
by Louis Lavery 17 Apr '06

17 Apr '06

Hello, Does adjacency_list::swap swap the bundled vertex properties? Also, does it invalidate vertex_descriptors? Thanks, Louis.

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[multi_index] Sorting object based on some specified criteria !!
by Patel Priyank-PPATEL1 17 Apr '06

17 Apr '06

Hi all, I have following kind of class and having some identifier and group id associated with particular procedure. I want to know if I have to get the procedures relating particular group for ex. (groupId == 1). How do I do using multiindex container? Can somebody please give me some hint or code if they have done something similar to what I want to do? Thanks a lot, Priyank // class procedure test class Procedure { public: Procedure(int _id, int _group ) : id_(_id), group_(_group) { } int get_id() const { return id_; } int get_group() const { return group_; } friend ostream& operator << (ostream& _os, const Procedure& _proc); private: int id_; int group_; }; ostream& operator << (ostream& _os, const Procedure& _proc) { _os << "PROCEDURE : " << _proc.id_ << endl; return _os; } // Defines multiindex container that is hashed based on id struct id { }; typedef multi_index_container< Procedure*, indexed_by< hashed_unique< tag<id>, const_mem_fun<Procedure, int, &Procedure::get_id> > > > Procedure_Hashed_Pool; typedef Procedure_Hashed_Pool::index<id>::type Procedure_By_Id;

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lambdaL
by chun ping wang 17 Apr '06

17 Apr '06

the thing is i have list<list<string> > examples. template <typename T, template <typename ELEM,typename = std::allocator<ELEM> > class CONT > void testFunc(const CONT<CONT<T> >& container) { std::find_if(container.begin(), container.end(), ( bind(&CONT<T>::back(), _1) == var(targetValue) ) ); } std::vector<std::vector<std::string> > examples; testFunc<std::string, std::vector>(examples); since list don't have indexing i want to see if the last item in the container is. . However i get this error... cannot call member function `typename _Alloc::reference std::vector<_Tp, _Alloc>::back() [with _Tp = std::string, _Alloc = std::allocator<std::string>]' without object

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Re: [Boost-users] question on using any.
by Alan M. Carroll 17 Apr '06

17 Apr '06

I would look at Boost.Variant and see if that would work for you. Any is designed primarily for libraries that need to carry data for clients and give it back later without having to know anything about the type. At 08:36 PM 4/16/2006, you wrote: > Any ideas on how to store the type of an object stored in an any instance for later use in comparisons (like <, >, ==, etc)? I don't want to store an instance of the class unless necessary. I thought about storing a pointer to the type, but could that be used with any_cast?

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stl questions: how can I compare 2 stl list?
by yinglcs2＠yahoo.com 17 Apr '06

17 Apr '06

is there a better way to compare 2 stl list? I write a function like this below, but I wonder if there is a better way to achieve that with boost(e.g. less code)? bool isSame(const list<int>& srcList, const list<int>& destList ) { if (srcList.size() != destList.size()) { return false; } int size = srcList.size(); for (int i = 0; i < size; i++) { if (srcList[i] != destList[i]) { return false; } } return true; } Thank you. __________________________________________________ Do You Yahoo!? Tired of spam? Yahoo! Mail has the best spam protection around http://mail.yahoo.com

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question on using any.
by Joe McCay 17 Apr '06

17 Apr '06

Any ideas on how to store the type of an object stored in an any instance for later use in comparisons (like <, >, ==, etc)? I don't want to store an instance of the class unless necessary. I thought about storing a pointer to the type, but could that be used with any_cast? like: template<class type> class typestuffPOD { typedef type value_type; type *datatype_; } This requires knowing the type when you want to use the any_cast. Sincerely, Joe McCay

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