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Is there any interest in tagged tuple?
by Pavel Chikulaev 27 Jun '05

27 Jun '05

Hi all, Is there any interest in tagged tuple as extension of tuples library or fusion library? The example: struct name_t {}; //tagged types struct year_t {}; void foo() { tagged_tuple<std::string, name_t, int, year_t> s; s.get<name_t>() = "Hello World"!; s.get<year_t>() = 2005; assert(s.get<0>() == s.get<name_t>()); assert(s.get<1>() == s.get<year_t>()); } It already works in VC7.1 and VC8.0 :) What do you think? -- Pavel Chikulaev

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Re: [boost] Is there any interest in tagged tuple?
by Roman Yakovenko 27 Jun '05

27 Jun '05

> From: Pavel Chikulaev [mailto:pavel.chikulaev@gmail.com] > > Hi all, > > Is there any interest in tagged tuple as extension of tuples > library or fusion > library? > The example: > > struct name_t {}; //tagged types > struct year_t {}; > > void foo() > { > tagged_tuple<std::string, name_t, int, year_t> s; > > s.get<name_t>() = "Hello World"!; > s.get<year_t>() = 2005; > assert(s.get<0>() == s.get<name_t>()); > assert(s.get<1>() == s.get<year_t>()); > } > > It already works in VC7.1 and VC8.0 :) > > What do you think? If you try to solve code readability then adding simple enum, even unnamed, solves the problem enum { name, year }; s.get<name>() If you try to solve an other problem, please describe the problem first. And second this has been already discussed on the list. One of the objections was the use case where you have same type occurs more then once in tuple. tagged_tuple<std::string, name_t, std::string, name_t > s; s.get<name_t>() - is this operation defined and what it's result > Pavel Chikulaev Roman

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Boost Chinese mirror dead?
by Beman Dawes 27 Jun '05

27 Jun '05

It looks to me as if the Boost Chinese mirror site is dead. If others can't reach it either, we should remove the link from the home page. --Beman

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Why shadowing?
by Haakon Humberset 27 Jun '05

27 Jun '05

Hi.. I've introduced boost as a utility libraries for the projects I work on. However, all of the people working on these projects compile code using the -Wshadow option. This generates lots of pages with warnings that clutter their compilation and makes it very hard for them to see what the real warnings and errors are in our code. I don't mind shadowing in the cpp compiled in boost, but shadowing in the header files are bad since these will show up for every piece of code we compile that uses boost. Consequently, I'm altering our boost library to remove the shadowing warnings we see.. This is a tad boring, but it works.. Only trouble is that when we at some point want a newer version of boost, we have to do it all over again. Any chance boost can be compiled with shadow warnings, making the boost developers not use shadowing? I don't see any reason to actually use shadowing. Having a local variable and a class member with the same name is just ground for confusion and subtle errors. From the code I've seen fixing names of local variables, I see that many variables have had an underscore added to the name to prevent shadowing already, why not use this consistently? Regards.. Haakon Humberset

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[Boost-bugs] [ boost-Bugs-1228242 ] Documentation not available on web site:
by SourceForge.net 27 Jun '05

27 Jun '05

Bugs item #1228242, was opened at 2005-06-27 13:17 Message generated for change (Tracker Item Submitted) made by Item Submitter You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=107586&aid=1228242&group_… Please note that this message will contain a full copy of the comment thread, including the initial issue submission, for this request, not just the latest update. Category: None Group: None Status: Open Resolution: None Priority: 5 Submitted By: Edward Grace (ejgrace) Assigned to: Nobody/Anonymous (nobody) Summary: Documentation not available on web site: Initial Comment: When browsing the documentation I get 404 not found errors for things relating to ublas, in particular http://www.boost.org/libs/numeric/ublas/doc/container_concept.htm ---------------------------------------------------------------------- You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=107586&aid=1228242&group_… ------------------------------------------------------- SF.Net email is sponsored by: Discover Easy Linux Migration Strategies from IBM. Find simple to follow Roadmaps, straightforward articles, informative Webcasts and more! Get everything you need to get up to speed, fast. http://ads.osdn.com/?ad_id=7477&alloc_id=16492&op=click _______________________________________________ Boost-bugs mailing list Boost-bugs(a)lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/boost-bugs

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Install in Boost libs directories
by Vladimir Prus 27 Jun '05

27 Jun '05

I think I've implemented the logic needed for "bjam --v2 install" in libs/whatever/build to work. It respects the same --prefix, --libdir and --includedir options as top-level "bjam --v2 install" but only builds a single library. (But installs all headers, of course). Rene, now I have a question for you. In some libs, you've added this: install dist-lib : boost_filesystem : <install-type>LIB <location>../../../dist/lib ; Does the "install" functionality makes this unnecessary and I can safely remove it? (Replacing with boost-install boost_filesystem ; ) - Volodya -- Vladimir Prus http://vladimir_prus.blogspot.com Boost.Build V2: http://boost.org/boost-build2

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[serialization] a proposal for an alternative to the new const-saving rule
by Joaquín Mª López Muñoz 27 Jun '05

27 Jun '05

Hello, The new rule introduced in Boost.Serialization that forbids saving of non-const objects has proved a little controversial. My point of view is that the rule, albeit far from perfect, provides some level of safety against hard to track errors. Others' opinions differ. The current rule is a rough approximation to what IMHO would constitute the right enforcement: everytime a trackable object is saved, check wether an object with the same address has been previously saved and, if so, make sure that the object didn't change. The hardest part is checking for equality. My proposal is to follow a hash-based approach, which is effective both in terms of complexity and space (one word per tracked object.), and does not impose any special requirement on the serialized objects (for instance, an approach based on operator== would require that objects be equalitycomparable). How does one compute a hash value for an object being saved? It is easy to do recursively as follows (pseudocode): unsigned int* hash_addr=0; // a member of the current archive internal_save(object obj) { if(hash_addr!=0 || obj is trackable) { // a hash computation is in course or we need to initiate one unsigned int* old_hash_addr=hash_addr; unsigned int h=0; hash_addr=&h; user_defined_save(o); set_hash(o,h); hash_addr=old_hash_addr; if(hash_addr!=0){ // add h to the hash being computed boost::hash_combine(*hash_addr,h); } } else{ user_defined_save(o); } } user_defined_save(primitive_type x) // provided by Boost.Serialization { if(hash_addr!=0){ boost::hash_combine(*hash_addr,x); } // rest of serialization stuff, as always } This implementation does not impose any additional requirement on the objects being serialized and is totally transparent to the user (she doesn't have to do any hash-related work herself.) With the computed hash values, Boost.Serialization can emmit run-time errors if a trackable object is serialized twice and changed in between (currently, the errors are compile-time.) What do you think? Joaquín M López Muñoz Telefónica, Investigación y Desarrollo

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Re: [boost] [serialization] a proposal for an alternative to thenewconst-saving rule
by JOAQUIN LOPEZ MU?Z 27 Jun '05

27 Jun '05

----- Mensaje original ----- De: David Abrahams <dave(a)boost-consulting.com> Fecha: Sábado, Junio 25, 2005 1:39 am Asunto: Re: [boost] [serialization] a proposal for an alternative to thenewconst-saving rule > "JOAQUIN LOPEZ MU?Z" <joaquin(a)tid.es> writes: > > > > De: David Abrahams <dave(a)boost-consulting.com> > > >> But all of this misses the high-level problem: the author of > the code > >> doesn't know what he's doing. You simply can't serialize > objects from > >> distinct scopes with tracking into the same archive, because > there may > >> be aliasing. > > > > Totally agreed, this is what we are trying to detect > > in order to protect the author of the code. > > > >> And there's nothing we can reasonably do to detect that > >> problem when the aliased objects have the same type > > > > Nothing? I'm afraid I don't get you. A perfect > > aliasing detection mechanism is probably impossible > > to implement, but the hash test at least approximates it. > > This is better than providing no safety mechanism, > > as I understand you advocate. > > I'm not sure it is. There's an imposition on users: all the types > they want to serialize have to support hashing. No, no. Please check the piece of pseudocode on my first message: the hash code is automatically built by Boost.Serialization, without any intervention from the user, and certainly without any requirement that the type be hashable (in the sense of providing a hash_value overload or something like this.) Let me illustrate with an example: struct labelled_point { int x; int y; string label; template <class Archive> void serialize(Archive & ar, const unsigned int version) { ar & x; ar & y; ar & label; } }; struct labelled_segment { labelled_point p0,p1; template <class Archive> void serialize(Archive & ar, const unsigned int version) { ar & p0; ar & p1; } }; So, given an object seg of type labelled_line, the framework automatically constructs the following associated hash value: combine( combine( boost::hash<int>(seg.p0.x), boost::hash<int>(seg.p0.y), boost::hash<std::string>(seg.p0.label)), combine( boost::hash<int>(seg.p1.x), boost::hash<int>(seg.p1.y), boost::hash<std::string>(seg.p1.label))) (combine(...) is shorthand for the obvious combination formula of hash values using boost::hash_combine.) The process recursively goes down to primitive types, as specified in my proposed pseudocode, and only these have to be hashable, but fortunately they are. > > It is nice that the serialization library automatically takes care of > hashing aggregated types and leaving out the unserialized data... > > uh, wait: this will never work unless you plan only to do shallow > hashing. Otherwise you will get an exponential explosion for some > object graphs. Is that your intention? I'm not getting you. The hash value is calculated as part of the saving process itself, so it has the very same complexity. I've got the hunch you might be meaning something else, could you please elaborate? Joaquín M López Muñoz Telefónica, Investigación y Desarrollo

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[Boost-bugs] [ boost-Support Requests-1228143 ] Grep() hangs for a particular string
by SourceForge.net 27 Jun '05

27 Jun '05

Support Requests item #1228143, was opened at 2005-06-27 10:26 Message generated for change (Tracker Item Submitted) made by Item Submitter You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=207586&aid=1228143&group_… Please note that this message will contain a full copy of the comment thread, including the initial issue submission, for this request, not just the latest update. Category: None Group: None Status: Open Resolution: None Priority: 5 Submitted By: NPrasad (prasadrn) Assigned to: Nobody/Anonymous (nobody) Summary: Grep() hangs for a particular string Initial Comment: We have the following code. std::vector<std::string> v; boost::RegEx expr(strSearchValue, TRUE); expr.Grep(v, strObjectValue); Statement expr.Grep(v, strObjectValue); hangs when expr is "(?=stl)" and strObjectValue is Example (M- STL) Could somebody tell me why are we hanging doing Grep ()? ---------------------------------------------------------------------- You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=207586&aid=1228143&group_… ------------------------------------------------------- SF.Net email is sponsored by: Discover Easy Linux Migration Strategies from IBM. Find simple to follow Roadmaps, straightforward articles, informative Webcasts and more! Get everything you need to get up to speed, fast. http://ads.osdn.com/?ad_id=7477&alloc_id=16492&op=click _______________________________________________ Boost-bugs mailing list Boost-bugs(a)lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/boost-bugs

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[Boost-bugs] [ boost-Support Requests-1228130 ] Grep() hangs for a particular string
by SourceForge.net 27 Jun '05

27 Jun '05

Support Requests item #1228130, was opened at 2005-06-27 10:04 Message generated for change (Tracker Item Submitted) made by Item Submitter You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=207586&aid=1228130&group_… Please note that this message will contain a full copy of the comment thread, including the initial issue submission, for this request, not just the latest update. Category: None Group: None Status: Open Resolution: None Priority: 5 Submitted By: NPrasad (prasadrn) Assigned to: Nobody/Anonymous (nobody) Summary: Grep() hangs for a particular string Initial Comment: We have the following code. std::vector<std::string> v; boost::RegEx expr(strSearchValue, TRUE); expr.Grep(v, strObjectValue); Statement expr.Grep(v, strObjectValue); hangs when expr is "(?=stl)" and strObjectValue is Example (M- STL) Could somebody tell me why are we hanging doing Grep ()? ---------------------------------------------------------------------- You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=207586&aid=1228130&group_… ------------------------------------------------------- SF.Net email is sponsored by: Discover Easy Linux Migration Strategies from IBM. Find simple to follow Roadmaps, straightforward articles, informative Webcasts and more! Get everything you need to get up to speed, fast. http://ads.osdn.com/?ad_id=7477&alloc_id=16492&op=click _______________________________________________ Boost-bugs mailing list Boost-bugs(a)lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/boost-bugs

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