- Boost-users - lists.preview.boost.org

Bind problems
by judoka1981 23 Sep '02

23 Sep '02

Hi, I'm trying to find the first non-space character of a string using boost::bind, but I simply can't get this to compile: --- static void Trim(std::string& stringToTrim) { std::string::iterator firstNonSpace = std::find_if(stringToTrim.begin(), stringToTrim.end(), boost::bind(std::not_equal_to<int>(), boost::bind(&isspace, _1), 0)); .... --- Am I doing something seriously wrong, or is this a compiler limitation (VC.NET)? (If anyone has a method to do this without using isspace, I'd be happy to see it). Thanks // Johan

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Include directories
by sashang＠ihug.co.nz 23 Sep '02

23 Sep '02

This is a silly question. I feel silly asking it. How do I tell the compiler via the jamfile about extra directories to look in for include files? I've tried adding "-sHDRS=e:/mystuff/include" to the command line when invoking bjam. I've tried placing : <include>e:/mystuff/include at various places withing the jam file. Thanks Sashan

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shared_ptr documentation suggestion
by Brian 22 Sep '02

22 Sep '02

Thank you boost developers for your great work. I've already started using some smart_ptr's, regex, and the any type. I started to look at shared_ptr for my needs (working in a realtime embedded systems environment). I started wondering how it protects its reference count but was surprised to not see anything about this in the documentation. Examining the code I see it uses a platform specific mutex type mechanism if it is available. Otherwise the reference count is not thread safe. I was also alarmed to see that the #error "your reference count is not thread safe" was commented out! Just a suggestion: mention in the documentation whats going on here. The operating system I am using (VxWorks) is not supported by shared_count right now, and had I not been curious I would have not noticed this. Also, even if it was, it can be very expensive for a realtime embedded system (e.g. running on a very slow processor) to take a mutex, especially if done at a very high rate, which is a concern of mine in a few places in my code. BTW, can I submit a VxWorks version of shared_count? Does boost have an interest in expanding beyond Win32/Posix/Linux? Again, thanks for the great software, Brian Neal

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newbie question on tokenizer and unicode text
by elqed1 21 Sep '02

21 Sep '02

Hi all, I'm a newcomer to boost and am rewriting one of my text characterization programs to use some boost libraries. I'm running into a problem with non ascii text. I'm using MSVC 7.0 to compile my program and the project is setup to link to the unicode CRT. The problem is when boost::char_delimiters_separator<>::is_nonret is calling MSVC's CRT std::isspace() which takes an int; and isspace() is (of course) choking on a '©' (for example) in my training data. Is there something obvious I'm missing? Thanks in advance. -Eric Lucas

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RE: [Boost-Users] newsgroup
by Jim.Hyslop 20 Sep '02

20 Sep '02

Ihsan Ali Al Darhi [mailto:iad929@joinnet.com.jo] wrote: > how can i access the boost newsgroups? Boost and Boost Users are both mirrored through gmane.org. You should be able to point your newsreader at news.gmane.org. You can get more details at http://www.boost.org/more/mailing_lists.htm, or by going directly to gmane http://www.gmane.org -- Jim

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RE: [Boost-Users] Slightly Off-Topic, Books
by Jim.Hyslop 20 Sep '02

20 Sep '02

Your post is not "slightly" off topic, it is entirely off topic. -- Jim Hyslop moderator, boost-users(a)yahoogroups.com

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RE: [Boost-Users] Re: [BGL] Best way to abort an algorithm from w ithi n a visitor?
by Mark Storer 20 Sep '02

20 Sep '02

Using exceptions in this way just bugs me. Religious reasons I guess. As the Esteemed Mr. Hylsop ;) mentioned earlier, exceptions are for "oops". This seems alot like the whole "do{}while(0)" with various 'break' statements sprinkled in to avoid multiple returns/nested ifs. Useful, but Just Not Right. Your code has cooties! Nobody's going to want to sit next to it during recess... >So there's no way to affect feedback to the algorithm's dispatcher >without actually making modifications to the algorithm code. So modify away. Seems like a "breath_first_until" sort of thing would be quite useful. Pass in some sort of predicate, and away you go. I'm sure the community at large would be grateful. --Mark Storer Software Engineer Cardiff Software #include <disclaimer> typedef std::disclaimer<Cardiff> Discard; -----Original Message----- From: Chris Russell [mailto:cdr@encapsule.com] Sent: Wednesday, September 18, 2002 1:27 PM To: boost-users(a)yahoogroups.com Subject: [Boost-Users] Re: [BGL] Best way to abort an algorithm from withi n a visitor? > Now if you've got more than a hundred or so entries left to go, exceptions > really are the greener grass. > The size of the graph is not known a-priori (not at coding time anyway) but is likely to be quite large. > What's wrong with 'return', perhaps along-side some sort of 'done' status > variable? I'm only vaguely familiar with the visitor pattern, but these > would seem to be the obvious choice. > See my earlier reply. In this case I'm deriving my visitor from a base and overriding "event" handlers that receive their marching orders via const references and return void. So there's no way to affect feedback to the algorithm's dispatcher without actually making modifications to the algorithm code. "Mark Storer" <mstorer(a)cardiff.com> wrote in message news:E840F0B7E6189547BDB91DA8BF2228AB016255F8@csmail.cardiff.com... > If efficiency is your goal, exceptions are not the answer. Just enabling > exceptions at compile time makes a noticable performance hit. Actually > throwing an exception can gobble up a 1000 cycles, give or take. That's per > throw. If you catch and throw again, you'll pay again. > > Now if you've got more than a hundred or so entries left to go, exceptions > really are the greener grass. > > What's wrong with 'return', perhaps along-side some sort of 'done' status > variable? I'm only vaguely familiar with the vistor pattern, but these > would seem to be the obvious choice. > > --Mark Storer > Software Engineer > Cardiff Software > > #include <disclaimer> > typedef std::disclaimer<Cardiff> Discard; > 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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Slightly Off-Topic, Books
by James Zappia 20 Sep '02

20 Sep '02

Hello, I'm a long time C/Perl programming and would like to transition into C++. What are some books I should pick up? I have the C++ Complete Reference for all the syntax sugar. I'm more interested in books that teach how to program in the mindset of objects. Also, books that don't read like RFCs ;) I learn better with examples and such -- not just brain dumps. Thank you in advance. Regards, James

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boost::shared_ptr confusion...
by someuserat 20 Sep '02

20 Sep '02

First, many thanks to Peter Dimov for answering my earlier questions. I've gotten hung up on something that may not be directly related to shared_ptr, but it's in the mix here. I suspect the real problem is my lack of experience using the STL algorithms, but I'm making an effort not to go back to writing my own loops with this project. Using my Widget theme, here's what I've got. A WidgetManager class contains a stl::list of shared_ptr<Widget> objects. It also contains a stl::vector of shared_ptr<WidgetMap> objects. WidgetMap objects contain a B+tree. (I know, I should probably change this to stl::map or multimap, I'll do that later) The index maps a data member of a Widget to a shared_ptr to the Widget for fast lookups. It is possible that new data members can be added or removed from the Widgets, and we have functions for handling that. Additional WidgetMap objects are added to the WidgetManager for Widget data members as needed. When adding a new WidgetMap, I need to loop through the existing set of Widgets and add them to the new WidgetMap. This is the simplest example I can think of as to what I'm trying to do, however obviously this does not work... void WidgetManager::addMap(const WidgetMapPtr i){ maps_.push_back(i); // have to write a function adapter here? for_each(widgetset_.begin(),widgetset_.end(),i->insert); } Along a similar line, when a Widget's data member collection is changed, I need to remove any WidgetMap objects fromm the WidgetManager that referenced the member being deleted. void WidgetManager::dropWidgetMember(const DataMemberPtr d){ // delete any maps using the target member // how to fix this bloody line? getIndexedMember returns a DataMemberPtr to the member it is keyed on. maps_.erase(remove_if(maps_.begin(),maps_.end(),(boost::mem_fn(&WidgetMap::getIndexedMember)).equals(d))); // get rid of the member itself members_.erase(remove_if(members_.begin(),members_.end(),boost::bind(&DataMember::equals,_1,d))); // rewrite the data file, we're all dirty anyway. this->compact(); } I feel like I understand what I want to do, but I cannot find a reference that explains how to do it the 'correct' way. At least not that I can grasp. Can someone point me in the right direction? Thanks, Mark

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Regex and Unicode
by Fr�d�ric Mayot 20 Sep '02

20 Sep '02

Hi, I'm trying to use Unicode with Regex in an MFC app. The preprocessor variable UNICODE is defined. But I obtain an error on the line : regex_search(sText, oResults, pRegExp); error C2665: none of the 4 overloads can convert parameter 1 from type 'class CString' sText is a CString which has a "const wchar_t*" operator. The problem is why doesn't the regex_search prototype require a "const wchar_t*" when UNICODE is defined ? Thanks. Fred (I read the documentation, but maybe I missed something...)

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