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object_pool, O(N) destroy?
by kevin_godden＠agilent.com 29 Jan '02

29 Jan '02

Hi, I am considering using boost::object_pool for fast allocation and deallocation of likkle container/token objects. I need to make this as fast as possible, to this end I wonder why object_pool seems to use boost::pool::ordered_free() (O(N)) rather than the faster free() (O(1))? There must be a reason, but I can't seem to find it in the Lib's documentation. I would be interested in hearing if peoples experiences/comments on using object_pool. Thanks for reading! Kevin\

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RE: [Boost-Users] RE: object_pool, O(N) destroy?
by kevin_godden＠agilent.com 29 Jan '02

29 Jan '02

I agree, it does sound like a job for a Policy whatsit. If I get a chance I could try a few things and see if anything works out and let you know. Although, if time constraints work out the way I think they will, I might have to stick with a cut&paste solution! Kevin\ -----Original Message----- From: scleary(a)jerviswebb.com [mailto:scleary@jerviswebb.com] Sent: Tuesday, January 29, 2002 5:13 AM To: Boost-Users(a)yahoogroups.com Cc: shammah(a)voyager.net Subject: [Boost-Users] RE: object_pool, O(N) destroy? > -----Original Message----- > From: hicks [mailto:hicks@kgk.co.jp] > > It sounds like a case where a type trait, identifying the need for the > pool to responsible for deletion, > would be appropriate. Then objects which did not need to be destroyed > (e.g. ptrs, "plain" structs) > could be handled by optimized code. But that's more work than cut and > paste. Actually, the difference is in how the pool is used, not on the type of object being allocated. So it sounds more like a case for a policy-based design. Too bad, I just don't have time to do that right now... :( -Steve Info: <http://www.boost.org> Wiki: <http://www.crystalclearsoftware.com/cgi-bin/boost_wiki/wiki.pl> Unsubscribe: <mailto:boost-users-unsubscribe@yahoogroups.com> Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/

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RE: object_pool, O(N) destroy?
by scleary＠jerviswebb.com 29 Jan '02

29 Jan '02

> -----Original Message----- > From: hicks [mailto:hicks@kgk.co.jp] > > It sounds like a case where a type trait, identifying the need for the > pool to responsible for deletion, > would be appropriate. Then objects which did not need to be destroyed > (e.g. ptrs, "plain" structs) > could be handled by optimized code. But that's more work than cut and > paste. Actually, the difference is in how the pool is used, not on the type of object being allocated. So it sounds more like a case for a policy-based design. Too bad, I just don't have time to do that right now... :( -Steve

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Dependencies for tokenizer?
by Anthony Kolarik 29 Jan '02

29 Jan '02

In order to use the tokenizer classes I end up requiring 47 files, which seems a little steep for my purposes. All I really need is to tokenize strings based on a couple of single char delimiters. Kind of a C++ step above strtok() was what I had in mind. Any ideas about how to get this functionality w/o all the headers? Thanks, -- Tony K.

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RE: [Boost-Users] object_pool, O(N) destroy?
by kevin_godden＠agilent.com 29 Jan '02

29 Jan '02

Thanks for the Info Steve, In this case, I am less interested in the pool's destructor as I _should_ have a 1 to 1 on malloc()ing and destroying the individual objects (if all goes well...). The pool will only be destroyed once during the lifetime of the application so I could probably suffer a O(N^2) pool destructor. I will try what you recommend in your postscript. Thanks again.. Kevin\ -----Original Message----- From: scleary(a)jerviswebb.com [mailto:scleary@jerviswebb.com] Sent: Monday, January 28, 2002 2:10 PM To: Boost-Users(a)yahoogroups.com Cc: shammah(a)voyager.net Subject: RE: [Boost-Users] object_pool, O(N) destroy? > From: kevin_godden(a)agilent.com [mailto:kevin_godden@agilent.com] > > I am considering using boost::object_pool for fast allocation and > deallocation of likkle container/token objects. I need to make this as fast > as possible, to this end I wonder why object_pool seems to use > boost::pool::ordered_free() (O(N)) rather than the faster > free() (O(1))? > > There must be a reason, but I can't seem to find it in the Lib's > documentation. The object_pool keeps its free list ordered because of the requirements of its destructor. Its destructor steps through the free list, calling the destructor for any objects that weren't freed. The current algorithm is O(N) because the free list is ordered; if it wasn't ordered, it would be O(N^2). I'll document this in the code. -Steve P.S. An object_pool without the destructor behaviour may be what you want. Boost.Pool doesn't provide one, but you could just cut & paste the object_pool, remove the destructor, and change ordered_malloc/ordered_free to the regular malloc/free (you also won't need nextof). Just note that if you ever construct something from that pool and don't destruct it, you enter the fun realm of undefined behaviour... :) Info: <http://www.boost.org> Wiki: <http://www.crystalclearsoftware.com/cgi-bin/boost_wiki/wiki.pl> Unsubscribe: <mailto:boost-users-unsubscribe@yahoogroups.com> Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/

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1_26_0: regex/thread on W32 build via jam?
by Bruno.Voigt＠ic3s.de 28 Jan '02

28 Jan '02

Hi! For my statically linked application (w32/sol8/linux) I was up to now using only the boost regex library. I build the regex lib the oldstyle way going to the build path and calling nmake -f vc7.mak, etc. In the project settings I included the regex/build/vc7 path as an additional lib search path. The buld step works as expected this way. boost::thread does provide only the newstyle jam build way. So I downloaded the boost::winbuild stuff and tried to build the whole boost via jam -sBOOST_ROOT=. -sTOOLS=msvc. It shows some errors for some pytho stuff but builds the regex and thread lib part. So I get for example a path boost_1_26_0\libs\regex\build\bin\libboost_regex.lib\msvc\release\runtime-link-dynamic with a libboost_regex.lib But how do I have to change my project settings for a static executable? I just changed the the lib search path to this new monster path and it does not work The linker is missing the vc7-re300dm.lib then. And how to link the boost thread stuff? Is it supported for statically linked apps at all? Any suggestions on how to make use of the jam build stuff in the right way ae really appreciated. TIA, Bruno PS: will there be a working suncc-tools.jam file in the next release? -- Bruno.Voigt(a)ic3s.de # IC3S AG # Tel. +49.4106.655.105 # Fax. +49.4106.655.55 http://www.ic3s.de # Mobile +49.700.686.00.686 [Non-text portions of this message have been removed]

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RE: [Boost-Users] object_pool, O(N) destroy?
by scleary＠jerviswebb.com 28 Jan '02

28 Jan '02

> From: kevin_godden(a)agilent.com [mailto:kevin_godden@agilent.com] > > I am considering using boost::object_pool for fast allocation and > deallocation of likkle container/token objects. I need to make this as fast > as possible, to this end I wonder why object_pool seems to use > boost::pool::ordered_free() (O(N)) rather than the faster > free() (O(1))? > > There must be a reason, but I can't seem to find it in the Lib's > documentation. The object_pool keeps its free list ordered because of the requirements of its destructor. Its destructor steps through the free list, calling the destructor for any objects that weren't freed. The current algorithm is O(N) because the free list is ordered; if it wasn't ordered, it would be O(N^2). I'll document this in the code. -Steve P.S. An object_pool without the destructor behaviour may be what you want. Boost.Pool doesn't provide one, but you could just cut & paste the object_pool, remove the destructor, and change ordered_malloc/ordered_free to the regular malloc/free (you also won't need nextof). Just note that if you ever construct something from that pool and don't destruct it, you enter the fun realm of undefined behaviour... :)

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MacCVS Pro hints
by voidampersand 27 Jan '02

27 Jan '02

I'm trying to get with the program here, so I just got the boost sources from CVS, using MacCVS Pro. The main thing that tripped me up was the instructions on the SourceForge page have command lines that are word wrapped. Anyway, here are some MacCVS session settings that work for me: Remote Host Information Server Hostname: cvs.boost.sourceforge.net CVS Root: /cvsroot/boost CVS User Name: anonymous CVS Password: [+] Save Password Also, in "File Translation and Encoding" you will want to add these mappings before you check out: .hpp TEXT CWIE .cxx TEXT CWIE .jam TEXT CWIE .pdf TEXT CARO MacCVS Pro is available at <http://sourceforge.net/projects/maccvspro/>. Regards, Tom

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Re: [Boost-Users] memcmp, strlen, strcmp not found in string.h?
by Steven Woolgar 27 Jan '02

27 Jan '02

> My question: Why aren't they in STLPort's string.h? > Is it a voluntary omission, and if so, why? > Should I talk to the guys who created Boost instead? > Should I be asking this on the developer's mailing list?? =) If I am not mistaken, the standard C functions would be in the the standard C include files, not the C++ files. So: strlen would be in <cstring> the string class would be in <string> Note that the new include style does not have the .h at the end. HTH Woolie

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Suggestion -- Boost Building
by Duane Murphy 26 Jan '02

26 Jan '02

It seems a lot of questions come up on the list about "building" the boost libraries. I wonder how many of these people realize that most of the functionality of the Boost "libraries" is completely encapsulated in the header files? There are significant portions like regex and the graph library (?) that do require compiling, but much of it does not. Is there anything that can be done to make it more clear that compiling is often not necessary? I'm just trying to relieve some stress from people who may very well not require compiling. And I have compassion for those that do and are having trouble. I'm not sure exactly what can be done, but it might be worth some thought. ...Duane

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Compiling with VC7
by Wismar, John 25 Jan '02

25 Jan '02

I wonder if someone can help me get up and running with Boost using VC7. I've tried to follow the Boost Build documentation, and am running into problems. A description of different things I've tried is below. Thanks in advance for any help anyone can provide! So far I've downloaded the Windows version of Boost.Build, and have run boost-build.exe (I couldn't tell if it did anything.) I added the boost-build directory to my PATH by hand, along with the VC7/bin directory. I also remember some discussion about how jam couldn't handle VC's default install dir (which is, for the purposes of this discussion, where mine is) because it has spaces in it, so I've used SUBST to define Z: as my VS.NET path. When I run jam from the boost_1_26_0 dir, using: jam -sBOOST_ROOT=. -sTOOLS="msvc" I get errors that look like: msvc-C++-action libs\regex\build\bin\libboost_regex.lib\msvc\debug\runtime-link- dynamic\c_regex_traits.obj c_regex_traits.cpp c1xx : fatal error C1108: unable to find DLL: 'mspdb70.dll' Z:\vc7\bin\cl /Zm400 -nologo -GX -c -I"libs\regex\build" -Fo"libs\reg ex\build\bin\libboost_regex.lib\MSVC\debug\c_regex_traits.obj" -Tp"libs\regex\b uild\../src\c_regex_traits.cpp" ...failed msvc-C++-action libs\regex\build\bin\libboost_regex.lib\MSVC\debug\c_regex_traits.obj ... msvc-C++-action libs\regex\build\bin\libboost_regex.lib\MSVC\debug\c_regex_traits_common.obj c_regex_traits_common.cpp c1xx : fatal error C1108: unable to find DLL: 'mspdb70.dll' So I added VC7's common7/IDE/ directory to my path, because that's where mspdb70.dll lives, but it didn't resolve the issue. Delving deeper into the docs, I found the suggestion that I do: set TOOLS=msvc jam instead of what the top level docs say, but then I get a message that I didn't set the toolset, and I should use: set VISUALC=<path> set JAM_TOOLSET=VISUALC jam When I do that, I get: Compiler is Microsoft Visual C++ warning: unknown rule project-root warning: unknown rule subinclude warning: unknown rule subinclude warning: unknown rule subinclude warning: unknown rule subinclude ...found 7 targets... Etc. -------------------------- John Wismar mailto:jwismar@alldata.com

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mem_fn and references?
by Duane Murphy 25 Jan '02

25 Jan '02

I am trying to make a member function call to all objects returned by an iterator. mem_fn is giving me an error when trying to call get_pointer() for a reference object. There is no overload for get_pointer of a reference object. Is there some reason or should I be doing this differently. The long description is that I am iterating over a container of objects. I would like to make a member function call on each of these objects. Then I get an error that there is no matching function for get_pointer( obj ). I have solved this by providing my own get_pointer() overload specifically for obj to prevent any bad things from happening until I can found out what the real problem is. Here is some pseudo code to get things in the right orientation. class obj { public: void method(); }; class obj_iterator { public: obj& iterator::operator*() const { return obj_; } }; class obj_container { public: obj_iterator begin(); obj_iterator end(); } { ... obj_container c; foreach( c.begin(), c.end(), mem_fn( method ) ); } Thanks, ...Duane

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Solaris/sparcWorks 5.0
by sebmarc 24 Jan '02

24 Jan '02

Does anybody know how to compile boost with Solaris 7 and sparcWorks 5.0. Looking at http://www.boost.org/tools/build/index.html, there is no place for this compiler. Any help appreciated. Thanks, Seb.

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RE: [Boost-Users] Subject: Poll results for Boost-Users
by Tom Matelich 24 Jan '02

24 Jan '02

I asked the original question that sparked this, and its because (at the root) I want to know whether feature requests need to be mirrored on the main boost list. So if I can be sure that the author of the library is at least listening to my boost-users message, I don't have to CC him/her or spam both lists. That is why I wanted access to the members, and as a support mechanism, why I thought it was important for boost-users. I realize membership != reading the messages, so perhaps my point is moot. > -----Original Message----- > From: Jim.Hyslop [mailto:jim.hyslop@leitch.com] > Sent: Wednesday, January 23, 2002 7:20 AM > To: 'Boost-Users(a)yahoogroups.com' > Subject: RE: [Boost-Users] Subject: Poll results for Boost-Users > > > Chris Little [SMTP:clittle@renlearn.ca] wrote: > > When the question first came up of allowing members to view > the membership > > list, one of the moderators started a poll (around the beginning of > > January). > That'd be me. > > > Unfortunately polling in this group is limited to moderators. > > The moderators then decided to discuss the issue amongst > themselves and > they > > haven't reported back. > > Hoo, boy, I seem to have dropped the ball on several counts here. > > First, my apologies for not cancelling the poll after > discovering polling > was limited to moderators. > > Second, my apologies for not reporting back to the group on > the results of > our discussion (I'm taking responsibility for this, since I'm > the one who > opened the can of worms in the first place). > > We identified a potential problem with spam email harvesting. > Granted, in > the public pages emails are hidden, so that only the first > letter of the > domain appears (my address, for example, would appear as > "jim.hyslop@l..." > One of the moderators pointed out: > > > About half of the email addresses on > > the first page start with either an a, h, or y. > > ... the problem is that when harvesting email addresses you > > don't need 100% accuracy. Just assume that a's are aol, all b's are > > bigfoot, all e's are earthlink, all h's are hotmail.com, > and all y's > > are yahoo.com. These letters are going to be [greater than] > half the list > and you > > will be correct [greater than] half the time. > > We could not come up with any compelling arguments in favour > of opening the > list. I believe the best summary was: > > > I'm not sure what the benefits of public membership would be. > > Arguments such as "I need to know if X is a member of > > the group" seem empty - this is a *mailing list* after all. > > To access individuals, you should get hold of them in > > other ways. If they are active members of the list, you'll > > still know they're members. > > No moderators actually spoke out in favour of opening the > list up, so the > status quo remains. > > We moderators are, of course, open to suggestions, and if a reasonably > strong argument comes up, then we will re-examine the issue. > If anyone feels > strongly about it, you can either post your rationale here or > email the > moderators at boost-users-owner(a)yahoogroups.com (the > 'boost-users-owner' > name is a bit misleading - email goes to all moderators, not > just to the > owner). > > Similarly, on the topic of polls themselves, the general > consensus was that > if or when we identify a good reason to run a poll, then we > will open up the > feature. Until then, there's no reason to change the status quo. > > -- > Jim > > > ------------------------ Yahoo! Groups Sponsor > ---------------------~--> > Tiny Wireless Camera under $80! > Order Now! FREE VCR Commander! > Click Here - Only 1 Day Left! > http://us.click.yahoo.com/nuyOHD/7.PDAA/yigFAA/EbFolB/TM > -------------------------------------------------------------- > -------~-> > > Info: <http://www.boost.org> > Wiki: <http://www.crystalclearsoftware.com/cgi-bin/boost_wiki/wiki.pl> > Unsubscribe: <mailto:boost-users-unsubscribe@yahoogroups.com> > > > Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/

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Re: [BGL] BFS and copy problem (was Re: [boost] Compilation)
by Jeremy Siek 24 Jan '02

24 Jan '02

Again, Luca, we can't help you unless you post the code (the complete C++ file). I can't just guess what is going wrong. You're probably forgetting to do something, and there's no way I can tell what that is based on what you've written below. On Thu, 24 Jan 2002, lucatoldo wrote: luca.t> I think there is something I do not know, rather important, about the luca.t> process of adding edges to the graph object. Infact, even in the luca.t> simple example/bfs.cpp if I swap the start with the ends, I get luca.t> different results. Namely: luca.t> luca.t> If I change the code from this luca.t> luca.t> boost::add_edge(0,2,G); luca.t> boost::add_edge(1,1,G); luca.t> boost::add_edge(3,1,G); luca.t> ... luca.t> boost::add_edge(4,1,G); luca.t> luca.t> to luca.t> luca.t> boost::add_edge(2,0,G); luca.t> boost::add_edge(1,1,G); luca.t> boost::add_edge(1,3,G); luca.t> ... luca.t> boost::add_edge(1,4,G); luca.t> luca.t> then I get luca.t> luca.t> the graph OK but the distances and the parent vectors are screwed: luca.t> luca.t> I get luca.t> luca.t> distances: 0 2 2 2 1 luca.t> instead of luca.t> distances: 0 2 1 2 2 luca.t> luca.t> and luca.t> luca.t> parent[0] = 0 luca.t> parent[1] = 4 luca.t> parent[2] = 4 luca.t> parent[3] = 4 luca.t> parent[4] = 0 luca.t> luca.t> instead of luca.t> luca.t> parent[0] = 0 luca.t> parent[1] = 2 luca.t> parent[2] = 0 luca.t> parent[3] = 2 luca.t> parent[4] = 2 luca.t> luca.t> I feel I am missing some basic knowledge on how to appropriately use luca.t> this powerful and amazingly fast system. I would love to learn the luca.t> missing bit. luca.t> luca.t> Looking forward your advice and sorry again for the dumminess of this luca.t> question. luca.t> luca.t> luca.t> Info: http://www.boost.org Send unsubscribe requests to: <mailto:boost-unsubscribe@yahoogroups.com> luca.t> luca.t> Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/ luca.t> luca.t> ---------------------------------------------------------------------- Jeremy Siek http://php.indiana.edu/~jsiek/ Ph.D. Student, Indiana Univ. B'ton email: jsiek(a)osl.iu.edu C++ Booster (http://www.boost.org) office phone: (812) 855-3608 ----------------------------------------------------------------------

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RE: [Boost-Users] Subject: Poll results for Boost-Users
by Jim.Hyslop 24 Jan '02

24 Jan '02

Tom Matelich [SMTP:tmatelich@zetec.com] wrote: > I asked the original question that sparked this, and its because (at the > root) I want to know whether feature requests need to be mirrored on the > main boost list. So if I can be sure that the author of the library is at > least listening to my boost-users message, I don't have to CC him/her or > spam both lists. The moderators have agreed that one of our duties will be to ensure appropriate cross-pollination of messages. In other words, if a discussion here in Boost-Users raises an issue that is appropriate to the main Boost list (such as a feature request or a bug report), we will ensure it gets forwarded to that forum. Similarly, if someone posts a message to Boost that is more appropriate to this list, we will encourage the original poster to switch to this forum. -- Jim

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Adding edges to a graph. Problems.
by lucatoldo 24 Jan '02

24 Jan '02

I think there is something I do not know, rather important, about the process of adding edges to the graph object. Infact, even in the simple libs/graph/example/bfs.cpp if I swap the start with the ends, I get different results. Namely: If I change the code from this boost::add_edge(0,2,G); boost::add_edge(1,1,G); boost::add_edge(3,1,G); ... boost::add_edge(4,1,G); to boost::add_edge(2,0,G); boost::add_edge(1,1,G); boost::add_edge(1,3,G); ... boost::add_edge(1,4,G); then I get the graph OK but the distances and the parent vectors are screwed: I get distances: 0 2 2 2 1 instead of distances: 0 2 1 2 2 and parent[0] = 0 parent[1] = 4 parent[2] = 4 parent[3] = 4 parent[4] = 0 instead of parent[0] = 0 parent[1] = 2 parent[2] = 0 parent[3] = 2 parent[4] = 2 I feel I am missing some basic knowledge on how to appropriately use this powerful and amazingly fast system. I would love to learn the missing bit. Looking forward your advice and sorry again for the dumminess of this question.

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A tip from the Dr.
by jackthompson99 23 Jan '02

23 Jan '02

Hey guys, I sent an e-mail to Dr. Stroustrup a couple nights ago, and he replied, "Have a look at boost.org. They exist specifically to provide better libraries in the context of the C++ standard library and to act as a test bed for new library ideas". So, here I am. I've installed and built my boost libraries, and I'm trying to figure out how to dig in. Anyway, here's what I was telling the Dr. I've been using C for about a decade, and C++ for about 7 yrs. I'm a huge fan of your invention, and I honestly feel like your name should eventually be as well known as Tesla and Edison. And the Standard Template Library is an incredibly well engineered system. I have a way to use it that is generic enough that it may be a candidate to be another standard. I know that's a lot to say. I'd like to explain it briefly, but first I should explain why I find it useful. Since I started working with assembler, I've always felt like the language I was using was missing something. I've used an assortment of languages, and it seems like they are all missing the same thing. The main part isn't really missing from C++, it's just not commonly understood. The concept of virtual construction is the core of the issue. Now I know that this problem is solved, but it really could stand for just one more thing to wrap it up into something usable for any ordinary C++ developer. Using a virtual constructor by way of a template, a developer can easily create any kind of object based on any type of identifier, but what good is that when the developer has exhausted all of his efforts on just building a simple system to dynamically create objects. The developer needs a way to organize these objects, without building another data warehouse. And I have never heard of a complicated database that shouldn't be fully hierarchical. So, the system should be one hundred percent re-entrant. Well, I have such a beast. I'm not done with it yet. I'm just now finishing up a project for Textron, where some of this concept was cultivated into my skill set. I am having a rough time explaining the system to my boss, and I'm in a real bind, but that's another story. The main thing that I've learned from this job is that the world needs to come together on one simple international standard for dealing with data and persistent C++ objects. I've used my ClassFactory / DataStore system as a foundation for another library that I call the WinFactory. This system simply uses the ClassFactory / DataStore as a database manager. The objects held in the database are simply graphical user interface components. This worked out really well, `till by boss took it apart. But I have a version of it that I'm re-writing at home that is much better. The database can be held either in a simple text format, resembling hypertext, or a binary file. The system relies heavily on the memory manager, so fast memory allocation is required. I have also populated an MFC user interface with data held in these objects. The system seems to be able to flex with just about anything, and I feel like it could at least contribute to discussions about new standards that are based on your standards. By the way, I need to find a team that I can work with who has good work ethics and integrity. Suggestions would be much appreciated. ..... So, I've looked at the library list in Boost, and haven't recognized anything like what I've built. I would love to explain this system. But, again, this one belongs to Textron, and all of the documentation too. I need to find some time to build this system for Boost.org. The main concept behind the system is a warehouse environment. The warehouse hase isles of goods. Each isle is any length, and each isle contains exactly one type of product. And every product contains a single pointer which is initally NULL. This makes it so that when you pull the product off the shelf and open it, you will see whatever the product is ( characters, integers, strings, etc. ), and you will find one more thing. It's called the nest. Now, until you try to use the nest, it's empty (NULL). But when you need it, it is created. What is this nest you ask? It's another warehouse. Just like the one that it is contained within. So, the entier concept is one hundred percent re-entrant. This makes it easy to build hierarchical infrastructures. The objects can be virtually any C++ thing. They persist with the greatest of ease to simple IO objects. User interfaces are easy to build with this system. Content editors view it as a script. C++ programmers view the script as C++ objects. Again, I need to finish re-writing the system, and I need to document it. But I feel like it is a candidate to become another Boost library. What do you think?????

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RE: [Boost-Users] Subject: Poll results for Boost-Users
by Jim.Hyslop 23 Jan '02

23 Jan '02

Chris Little [SMTP:clittle@renlearn.ca] wrote: > When the question first came up of allowing members to view the membership > list, one of the moderators started a poll (around the beginning of > January). That'd be me. > Unfortunately polling in this group is limited to moderators. > The moderators then decided to discuss the issue amongst themselves and they > haven't reported back. Hoo, boy, I seem to have dropped the ball on several counts here. First, my apologies for not cancelling the poll after discovering polling was limited to moderators. Second, my apologies for not reporting back to the group on the results of our discussion (I'm taking responsibility for this, since I'm the one who opened the can of worms in the first place). We identified a potential problem with spam email harvesting. Granted, in the public pages emails are hidden, so that only the first letter of the domain appears (my address, for example, would appear as "jim.hyslop@l..." One of the moderators pointed out: > About half of the email addresses on > the first page start with either an a, h, or y. > ... the problem is that when harvesting email addresses you > don't need 100% accuracy. Just assume that a's are aol, all b's are > bigfoot, all e's are earthlink, all h's are hotmail.com, and all y's > are yahoo.com. These letters are going to be [greater than] half the list and you > will be correct [greater than] half the time. We could not come up with any compelling arguments in favour of opening the list. I believe the best summary was: > I'm not sure what the benefits of public membership would be. > Arguments such as "I need to know if X is a member of > the group" seem empty - this is a *mailing list* after all. > To access individuals, you should get hold of them in > other ways. If they are active members of the list, you'll > still know they're members. No moderators actually spoke out in favour of opening the list up, so the status quo remains. We moderators are, of course, open to suggestions, and if a reasonably strong argument comes up, then we will re-examine the issue. If anyone feels strongly about it, you can either post your rationale here or email the moderators at boost-users-owner(a)yahoogroups.com (the 'boost-users-owner' name is a bit misleading - email goes to all moderators, not just to the owner). Similarly, on the topic of polls themselves, the general consensus was that if or when we identify a good reason to run a poll, then we will open up the feature. Until then, there's no reason to change the status quo. -- Jim

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RE: [Boost-Users] Subject: Poll results for Boost-Users
by Chris Little 23 Jan '02

23 Jan '02

When the question first came up of allowing members to view the membership list, one of the moderators started a poll (around the beginning of January). Unfortunately polling in this group is limited to moderators. The moderators then decided to discuss the issue amongst themselves and they haven't reported back. Chris > -----Original Message----- > From: James Curran/MVP [mailto:jamescurran@mvps.org] > Sent: Wednesday, January 23, 2002 8:29 AM > To: Boost-Users(a)yahoogroups.com > Subject: RE: [Boost-Users] Subject: Poll results for Boost-Users > > > How long was that poll open for? > > Truth, > James Curran > > > -----Original Message----- > From: Boost-Users(a)yahoogroups.com > [mailto:Boost-Users@yahoogroups.com] > Subject: Poll results > for Boost-Users > > > The following Boost-Users poll is now closed. Here are the > final results: > > > CHOICES AND RESULTS > - I want only the moderators to be able to view the > membership list, 0 votes, 0.00% > - I want anyone to be able to view the membership list, 0 > votes, 0.00% > [Non-text portions of this message have been removed]

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RE: [Boost-Users] Subject: Poll results for Boost-Users
by James Curran/MVP 23 Jan '02

23 Jan '02

How long was that poll open for? Truth, James Curran -----Original Message----- From: Boost-Users(a)yahoogroups.com [mailto:Boost-Users@yahoogroups.com] Subject: Poll results for Boost-Users The following Boost-Users poll is now closed. Here are the final results: CHOICES AND RESULTS - I want only the moderators to be able to view the membership list, 0 votes, 0.00% - I want anyone to be able to view the membership list, 0 votes, 0.00%

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Ann: Forward lookahead asserts now supported by regex lib
by John Maddock 23 Jan '02

23 Jan '02

The regex lib, now has experimental support for perl style forward lookahead assertions, using the syntax extensions: (?=exp) positive zero width forward assertion on exp. (?!exp) negative zero width forward assertion on exp. I'm currently looking for anyone willing to test these, and for real world test cases to add to the regression tests, before documenting the extensions and making them "official". Many thanks. - John Maddock http://ourworld.compuserve.com/homepages/john_maddock/

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error with thread.hpp
by thrashmodule 19 Jan '02

19 Jan '02

I got this message: c:\boost_1_26_0\boost\thread\thread.hpp(17) : fatal error C1189: #error : Thread support is unavailable! I use VC++ on Win98 so now what??????????

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Class destructor invocation - possible by hand?
by Jonathan Brownell 19 Jan '02

19 Jan '02

I have a question for all you C++ gurus. I'm writing a class that I would like to use the following technique in, and I'm not sure if it's portable or even legal, although VC++6 and VC++.NET, which I'm compiling in, work beautifully with it. Consider the following class, a very simplified example that I wrote to demonstrate: class House { public: explicit House(const int rooms) : m_rooms(rooms) { } ~House() { } private: const int m_rooms; }; Pretty straightforward. I'd like m_rooms to remain const to protect it from accidental modification by member functions, since it will *never* be changed during operation. Now, the first problem that arises is that this is illegal: House housingComplex[100]; Because, obviously, the constructor requires that the number of rooms be passed to it. (Yes, we could create it as an array of House pointers and create them dynamically, but in my case that will require inconveniences by everybody using my class.) So, we make it a default parameter and add an assignment operator: class House { public: explicit House(const int rooms = -1) : m_rooms(rooms) { } ~House() { } House& operator =(const House& source); private: const int m_rooms; }; When rooms == -1, the House is considered to be uninitialized. Now, we can do the following: House housingComplex[100]; housingComplex[0] = House(5); housingComplex[1] = House(4); (etc) The question is, how to implement the assignment operator? This is my method: House& House::operator =(const House& source) { assert(m_rooms == -1); this->~House(); new(this) House(source); return *this; } Yikes! I know this looks weird. First, assert verifies in debug mode that the object is in its uninitialized state. Then, the destructor is called manually to destruct the class and its contents. (In the actual class I'm working on, there are numerous member variables that must be appropriately destructed, and all of them are - I've checked.) Simply calling ~House(); will not compile, because the compiler assumes I'm trying to use the ~ operator illegally, so I have to call it through the 'this' pointer. Then, the placement new operator is used to create a new House in exactly the same space in memory as the old one, using the default copy constructor so that all the const variables are (re)initialized. Finally, a technicality for all assignment operators, a reference to the object is returned. (This is so C-style expressions like "var1 = var2 = var3 = 5;" can be used.) Now, this works beautifully on my VC++. But... is it legal C++?? Am I entering the realm of "undefined behavior", or is this a perfectly legitimate technique? Is there an obviously better solution to my problem? Are there caveats that I should be looking out for? Please, someone with more knowledge of the C++ standards, give me a hand here. Thanks! -Jonathan

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RE: [Boost-Users] Class destructor invocation - possible by hand ?
by Tom Matelich 17 Jan '02

17 Jan '02

> > > > Also, I would recommend that you either reconsider > > > having the constant member variable, or use a > > > vector<>. > > > > Using a vector<T> won't work in this case, because the STL uses > > T::operator = in order to copy vector contents into new > locations during > > memory reallocation. And there's no logical way to > implement operator = > > when a const data member is present, which is the cause of this > > conversation. > > I could use std::list, since it doesn't do reallocation, but clients > > using this class in containers will most likely need random access > > iterators. > > > > Any other ideas? > > Easy option: Use a vector<shared_ptr<T> >. This will give you > basically > the behavior you want, with the ability to initialize the elements > directly. The drawback is that the data will be dynamically allocated. Another drawback is the interface is now pointers, not references. If you don't mind the dynamic allocation, the vector<shared_ptr<T> > can be contained by another class, overloading operator[], etc. The Boost Iterator Adapter library works very nicely for providing vector<T>::iterator behavior from a vector<shared_ptr<T> >::iterator. I can send you our vector-like class which uses adapted iterators if you would like. Re: the moderation. Yes, this is not a boost question, but it is a question boost can provide good solutions for, so where do you draw the line?

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