September 2004 - Boost-users

boost::shared_ptr and stl algorithms
by Bill Eidson 15 Apr '05

15 Apr '05

std::vector< boost::shared_ptr<T> > TVec; I want to write a function object to run std::for_each. to do somework against members of T and accumulate results in functor. My attempts have failed in VC7 with memory errors in my operator() method. struct fo { bool operator()( boost::shared_ptr<T>& t ) { return true; } }; Thanks in advance bille

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Will libraries built on WinNT run on Win98? (MinGW)
by Reed Hedges 31 Mar '05

31 Mar '05

I know that Win98 is not really supported, but is there any chance that libraries (specifically thread and regex) that were build on WinNT using MinGW work on Win98 (in MinGW)? My guess is no, but has anyone tried it? thanks reed

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Bug in lexical_cast<> with doubles
by Leon Raj 29 Jan '05

29 Jan '05

I think I've found a bug in the boost::lexical_cast<> library (v1.31.0) on WinXP SP1, MSVC 6.0 (sp5) and MSVC.NET 2003. --- Start code snippet --- #include <boost/lexical_cast.hpp> #include <iostream> int main( int argc, char* argv[] ) { double dMax = = std::numeric_limits< double >::max(); // On a Win32 x86 system, dMax is now 1.7976931348623157e+308 // This is successful and strMax is "1.797693134862316e+308" std::string strMax = boost::lexical_cast< std::string >( dMax ); try { double newDMax = boost::lexical_cast< double >( strMax ); std::cout << "Successfuly" << std::endl; } catch ( boost::bad_lexical_cast& ) { std::cout << "Failed to cast" << std::endl; } // On a Win32 x86 system, this always fails, // because (I think) strMax overflows a double, // because 1.7976931348623157e+308 is *rounded UP* // to 1.797693134862316e+308, which cannot be // represented by a double } --- End code snippet --- ----------------------------------------------------- Leon Raj Senior Engineer Invetech Pty. Ltd. Phone: +61 3 9211 7000 (Switchboard) +61 3 9211 7938 (DDI) leon.raj(a)invetech.com.au IMPORTANT - This e-mail and any attachments may be confidential. Any retransmissions, dissemination or other use of these materials by persons or entities other than the intended recipient is prohibited. If received in error, please contact us and delete all copies. Before opening or using attachments, check them for viruses and defects. Our liability is limited to resupplying any affected attachments. [Any representations or opinions expressed in this e-mail are those of the individual sender, and not necessarily those of Vision Systems Limited].

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"Compiler threading support not turned on" error
by Glen Simmons 12 Oct '04

12 Oct '04

I'm attempting to use Boost.threads on Mac OS X 10.3 and am getting the error "Compiler threading support is not turned on" when trying to compile. I'm using Xcode, which is Apple's IDE, so I'm not sure what to do when the error text helpfully suggests I set the correct command line option. As far as I know, there's nothing extra that you have to do to enable threading support in the compiler. I've written multi-threaded apps using pthreads and never had to deal with command line options. Any suggestions? Thanks, Glen Simmons

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C++ Parsing - oops
by Foster, Gareth 03 Oct '04

03 Oct '04

Hello John, Joel, I didn't mean to knock your work with that last email John, it might have come across badly, it was meant more as a compliment to spirit and a reference to the fact that it 'appears' to fit the bill for what I want to do better, not to bash regex, I like regex too. For the record it needn't be 'perfect' indexing of the C++ code, I don't mind if I get two hits for the same classname for example. I used regex for a tool to index the C++ and C files themselves, so I could quickly search for file names using regular expressions, it works great! So thank you both, no offence caused I hope. So, will spirit be the best way then? Glad to hear its already a part of boost btw, congratulations mate. Cheers! Gaz -----Original Message----- From: boost-users-bounces(a)lists.boost.org [mailto:boost-users-bounces@lists.boost.org] On Behalf Of John Maddock Sent: 30 September 2004 11:33 To: Subject: Re: [Boost-users] Boost:regex and C++ Parsing - Clarification > Thank you Caleb and Hartmut for your replies. You both seem to think regex > is a bad way to go, I will explain better what I want to write just to be > clear. > > I want to write a tool (cli probably) where I can say, here you go, here > is > a large folder full of code, go and parse it. I will store the results in > XML format somewhere, then, I can do say, "<myapp> class someclass" and > the > program will go and find where that class is declared/defined using its > database, saving me headache. > > So I thought I could use one of the C++ expat wrappers, and boost regex > looked powerful enough to do the parsing if only I were handy enough with > regular expression syntax. > > Anyway, I don't know if that better explanation will make any difference > to > you recommendations, I look forward to reading you opinions. > > Oh, and the example I looked at is here Hartmut: > http://boost.org/libs/regex/example/snippets/regex_search_example.cpp - > that > is what got me thinking I might actually be able to take on this > challenge. It depends what you want to do: if you want to use a "real" C++ parser then you will also have to preprocess the code (including the includes) and then parse the code. In theory this gives you a "perfect" result, but only if you know what include paths to use, and what predefined macros should be set (think about conditional code blocks). Regexes on the other hand, don't require you to preprocess the code, but can get confused by macros and the like. So you have to choose the way that best meets your expectations, and live with the defects either which way ;-) To solve your problem BTW, why not scan through the file for line starts (keeping count obviously!), and at each line start see if it's also the start of the regex you are interested in (one that matches a class definition for example), if you do this don't forget to either: prefix your expression with \A or Pass the match_continuous flag to regex_search, Either will anchor the search at the start of the line you are checking, and prevent the whole text being searched. John. _______________________________________________ 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:regex and C++ Parsing - Spirit!
by Foster, Gareth 03 Oct '04

03 Oct '04

Wow, I just read through the 1st few pages of the spirit docs, and I can safely say, that is as close to naked women as C++ code will ever be, its such a sexy idea. One library, and you can parse any sort of config file, code or anything! Amazing. Well, any lingering desire to use regex for my pet project has now left the building, I can't wait to have a play with spirit. When will it be a part of boost? Is it worth installing it seperately (I'd hate to do that and have a new boost appear the day after). Also, reading this made up my mind that I should get a nice magazine about STL and C++ matters, can anyone recommend one (UK based preferable, but all sugestions welcome). Interetsing stuff, thank you all! Gaz

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Are BOOST_BUILD_PATH && BOOST_ROOT necessary?
by Steven T. Hatton 01 Oct '04

01 Oct '04

>From reading the documentation on boost.org, I have gotten the impression I don't need to set $BOOST_BUILD_PATH and $BOOST_ROOT. I'm more than a little confused about how I should use the boost libraries. Part of this comes from the fact that it is not clear to me exactly where the demarkation is between using the build system to build boost, and using it to build my own programs. Some of my confusion comes from the appearant change in configuration requirements described in the documentation. It is suggested I don't need the environment variable used with earlier releases. One of these variables is $BOOST_ROOT, which the documentation used as an example of how to build boost. That example was exactly what I successfully (I believe) build the libraries with. I'm using SuSE Linux 9.1 on a P4 box. Some basic questions are these: When I downloaded and built boost, I first fetched the source for bjam. This is the name of the file I downloaded: boost-jam-3.1.10.tgz It compiled quite nicely, and I copied the resulting bjam jam mkjambase and yyacc to a location in my path. Are there anything other things such as configuration files I need to reside with the binary executables? Are there necessary configuration file that I need to have visible to these programs, even if they are not colocated? I then build boost with the command: bjam --prefix=$BOOST_ROOT "-sTOOLS=gcc" install after setting my BOOST_ROOT the way I wanted it. That resulted in two directories being placed in $BOOST_ROOT/ one is called $BOOST_ROOT/include/ the other is called $BOOST_ROOT/lib/. Under $BOOST_ROOT/include/ I have <path>/boost-1_31/boost/ which contains dozens of header files. I added $BOOST_ROOT/include/boost-1_31 to my $INCLUDE_PATH, and $BOOST_ROOT/lib to my $LIBRARY_PATH and $LD_LIBRARY_PATH variables. Is this the correct way to configure my system to use boost? Is there anything else I need to do in order to compile my programs against the boost headers and libraries? Will the boost libraries work as well as other, comperable libraries using autotools rather than bjam? Are there any special accommodations I need to make in order to use boost with the gnu build tools? Do I need to do anything special to use boost with bjam that does not involve placing files in my current project directories? For example, do I need to provide a global configuration file of some kind? Is it a preferred option, even if not strictly required? There is much remaining in the source directory where I compiled boost. Is that something I need to also put in an accessible place on my system? If so, what so I need to put where, and how to I modify my environment variable to facilitate its use? -- Regards, Steven

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BOOST_CHECK_CLOSE apparent misbehavior
by Ross Boylan 01 Oct '04

01 Oct '04

I get the following error Specification_test.cc(22): error in "specsimple": difference between spec(i, j){0.206788} and results[k]{0.206788} exceeds 1e-05% The numbers agree to all printed digits. I get a maximum relative error (assuming the printed values are rounded from extremes)*(see footnote) of .000001/.206787 = 4.8e-6 < 1e-5. Even doubling this is under the tolerance. As I read the documentation, this should pass. 1e-6 tolerance produces a lot more discrepancies; 1e-4 says they are all OK. Have I misunderstood something, or is something funny going on? In particular, the "%" after "1e-5" in the error message suggests the tolerances are supposed to be in percentage terms, i.e, 1e-5 implies a real tolerance of 1e-7. That would explain things, but I see nothing in the documentation to suggest the tolerance value is a percent. (Well, the docs do say the tolerance can be an integer.) The relevant line is BOOST_CHECK_CLOSE(spec(i, j), results[k], tol); All relevant quantities are doubles. It may be relevant that the program under test includes <cmath>. Debian package libboost-dev 1.31.0-7 on an Athlon system. # g++ --version g++.real (GCC) 3.3.4 (Debian 1:3.3.4-6sarge1) Linux kernel 2.4.26 * In fact, the results value is coded as 0.2067880 in the program, so my calculation likely gives double the possible discrepancy.

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Forgot to add
by Foster, Gareth 01 Oct '04

01 Oct '04

I also was going to say Joel, you ought to moan about the description of spirit in the docs, I can see it is there in the list of libraries now, and whilst it probably does describe what the library does, it doesn't do it in a way that is very identifiable for those who don't know about the subject, I just plain missed it, despite the fact that I was looking to parse C++. spirit <file:///C:/boost/boost_1_31_0/libs/spirit/index.html> - LL parser framework represents parsers directly as EBNF grammars in inlined C++, from Joel de Guzman and team. Why not something like ... spirit <file:///C:/boost/boost_1_31_0/libs/spirit/index.html> - A customisable framework for parsing any syntax. You will know what I mean and how to describe it properly etc I'm sure. Just a thought :) Gaz

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Boost:regex and C++ Parsing - Clarification
by Foster, Gareth 30 Sep '04

30 Sep '04

Hello, Thank you Caleb and Hartmut for your replies. You both seem to think regex is a bad way to go, I will explain better what I want to write just to be clear. I want to write a tool (cli probably) where I can say, here you go, here is a large folder full of code, go and parse it. I will store the results in XML format somewhere, then, I can do say, "<myapp> class someclass" and the program will go and find where that class is declared/defined using its database, saving me headache. So I thought I could use one of the C++ expat wrappers, and boost regex looked powerful enough to do the parsing if only I were handy enough with regular expression syntax. Anyway, I don't know if that better explanation will make any difference to you recommendations, I look forward to reading you opinions. Oh, and the example I looked at is here Hartmut: http://boost.org/libs/regex/example/snippets/regex_search_example.cpp - that is what got me thinking I might actually be able to take on this challenge. Okay lads, thanks again, cheers Gaz -----Original Message----- From: boost-users-bounces(a)lists.boost.org [mailto:boost-users-bounces@lists.boost.org] On Behalf Of Hartmut Kaiser Sent: 29 September 2004 18:41 To: boost-users(a)lists.boost.org Subject: RE: [Boost-users] Boost:regex and C++ Parsing Foster, Gareth wrote: > I have a couple of questions, firstly, how might I extend the > example for parsing C++ code for class names so that it > records the line number on which the class is defined? I > thought maybe I could extend the regular expression so that > it has "|(\n)" at the end, or maybe there is another way. In > any case I am not sure if that is the correct way to extend > the regex and I am unsure how to check the regex_match result > to see if it was a new line character I encountered or a class name. Which example you're referring to? > Secondly, are there any efforts anywhere to parse C++ for > other keywords by this approach? I don't know of any efforts going on regarding C++ parsing with the help of regex (non-authoritative answer). But there is the Wave library (Boost review is due shortly), which is a C/C++ preprocessor containing different C++ lexing components, which may be helpful for you during writing a class name extraction tool. Regards Hartmut _______________________________________________ Boost-users mailing list Boost-users(a)lists.boost.org http://lists.boost.org/mailman/listinfo.cgi/boost-users

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