March 2006 - Boost - lists.preview.boost.org

more thoughts on c2_functions
by Marcus Mendenhall 27 Mar '06

27 Mar '06

I have started trying to templatize c2_functions, but I have a question for the Boost group. Realistically, this class is fairly meaningless for anything other than double and long double types. I also have a long, enduring distaste for c++ templates and, as a result, little deep competence with them. The process of making it into working template classes which are also fairly easy to use will be very slow for me. For the 99% of users who will always use this with double, also, the need to declare every items with <double> after it, or even with <> for things which can be defaulted, is ugly and will likely reduce the user base. Would it be objectionable to the Boost concept to release a basic version of the which is strictly for doubles, with the knowledge that, for the few people who want it for long doubles, this can be done with a global search & substitute, and then to plan later for a successor to this which is fully templatized? I see this as a package which, in its current, template-free form, can be essentially spun off except for improving the documentation. The algorithms in it are simple and robust, and the code should be highly portable, so I doubt it will every need much maintenance. I think there is a fairly decent reason to make it available soon, since there appears to be a significant need for it, and to learn if real users need it structured differently. Marcus

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Review schedule?
by Andy Little 27 Mar '06

27 Mar '06

Whats happening with regard to reviews? Whats next ? When does it start etc? regards Andy Little

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boost::gregorian::date_period,how to increment/decrement the period
by george 27 Mar '06

27 Mar '06

hello! boost::gregorian::days size(1); boost::gregorian::date_period tmp(period.begin()+=size,period.end()-=size); period=tmp; is there any better way to increment/decrement the period object I want period.begin+=size; period.end()-=size to be permanent to period but it doesn't,it returns an object... any idea?? thanks for any help.

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c2_functions templates
by Marcus Mendenhall 26 Mar '06

26 Mar '06

> Message: 11 > Date: Sun, 26 Mar 2006 13:37:11 -0500 > From: Neal Becker <ndbecker2(a)gmail.com> > Subject: Re: [boost] more thoughts on c2_functions > To: boost(a)lists.boost.org > Message-ID: <e06n0n$hr1$1(a)sea.gmane.org> > Content-Type: text/plain; charset=us-ascii > > Marcus Mendenhall wrote: > >> I have started trying to templatize c2_functions, but I have a >> question for the Boost group. Realistically, this class is fairly >> meaningless for anything other than double and long double types. I >> also have a long, enduring distaste for c++ templates and, as a >> result, little deep competence with them. The process of making it >> into working template classes which are also fairly easy to use will >> be very slow for me. For the 99% of users who will always use this >> with double, also, the need to declare every items with <double> >> after it, or even with <> for things which can be defaulted, is ugly >> and will likely reduce the user base. >> >> Would it be objectionable to the Boost concept to release a basic >> version of the which is strictly for doubles, with the knowledge >> that, for the few people who want it for long doubles, this can be >> done with a global search & substitute, and then to plan later for a >> successor to this which is fully templatized? >> >> I see this as a package which, in its current, template-free form, >> can be essentially spun off except for improving the documentation. >> The algorithms in it are simple and robust, and the code should be >> highly portable, so I doubt it will every need much maintenance. I >> think there is a fairly decent reason to make it available soon, >> since there appears to be a significant need for it, and to learn if >> real users need it structured differently. >> > > You've come to the right place. Here are the template experts. > Instead of > "release" without template support, why not collaborate with > someone to > help with the process? > > ** It's not just the data types that you would want to be generic. > It's the > containter types as well. There are hard-coded instances of > std::vector, > for example. From what I've seen in this code, fixing this aspect > is easy. > > Is that the sound of a volunteer I just heard :-) I would love to have someone collaborate on the template generation. I noticed the comment about containers earlier. In almost every case where I use std::vector, the data _really should be_ in an object with most of the detailed semantic behavior of a vector, since they are meaningful when defined as an ordered set with an integer index. Is there a compelling reason why more general containers are wanted? This, of course, nests the templatization even deeper, and thus makes the most common usage even harder. I know another commenter on this thread suggested defining the general template version of the class, and then generating shadow classes of every class in it with the templates already spelled out. I thought about this before, and it seems to me to be a nightmare, since one has to maintain a list of all the specific instances of the general classes. Although I would be willing to do it this way (if someone helps with the template generation in the first place), it isn't beautiful to me. Or am I missing a way to generate templates of everything at once (again, I am not a templates guru or even much more than a terrible template novice. The numerics are my specialty.) Thanks. Marcus Mendenhall

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[1.34][date-time][format][tokenizer] -Wshadow And -Wcast-qual Warnings, With Patches
by Stephan T. Lavavej 26 Mar '06

26 Mar '06

Hi, I downloaded RC_1_34_0 from CVS on 20060324 and found -Wshadow and -Wcast-qual warnings (from GCC 3.4.2) in three files. My patch is here: http://stl.nuwen.net/boost-RC_1_34_0-20060324.patch This patch supersedes my patch for 1.33.1; I verified that Jeff Garland's and John Maddock's date-time and regex fixes, respectively, work in RC_1_34_0 (thanks again!), and found that the C cast in boost/range/detail/implementation_help.hpp was fixed 7 months ago. [date-time] * boost/date_time/gregorian/gregorian_io.hpp This file contains several instances of a smaller-scope output_itr shadowing a larger-scope output_itr. My local patch renames each larger-scope output_itr to big_output_itr. (The larger-scope variable is the safer one to rename in cases of local-local shadowing.) [format] * boost/format/format_implementation.hpp This file has contained shadowing since at least 1.33.0. [tokenizer] * boost/token_iterator.hpp This file has lacked a "const" since at least 1.33.0, which causes a *nasty* -Wcast-qual warning: http://stl.nuwen.net/boost-warning.txt This warning is nasty because its cause isn't immediately obvious. Can the appropriate maintainers please take a look at these patches? It'd be really nice if people could use -Wshadow and -Wcast-qual with Boost without having to patch it first. Thanks! Stephan T. Lavavej

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[shared_ptr] Best Practices - new_shared_ptr
by Vaclav Vesely 26 Mar '06

26 Mar '06

Hi, In Best Practices section of shared_ptr is an example: void f(shared_ptr<int>, int); int g(); void ok() { shared_ptr<int> p(new int(2)); f(p, g()); } void bad() { f(shared_ptr<int>(new int(2)), g()); } Best Practices refers to http://www.gotw.ca/gotw/056.htm (it deals with auto_ptr, but for shared_ptr the conclusion is same). The article proposes following solution: template<typename T, typename A1> shared_ptr<Type> new_shared_ptr(A1 a1) { return shared_ptr<Type>(new Type(a1)); } void ok2() { f(new_shared_ptr<int>(2), g()); } However the conclusion of the article is, that ok1() is better than ok2() because you have to write helper functions. I don't agree. IMHO ok2 IS better and the helper functions should be in the library (so the uses doesn't have to write them. What do you think? Regards, Vaclav

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[optional] from_optional
by Václav Veselý 26 Mar '06

26 Mar '06

Hi, There is a common need of getting a value from an optional with possibility to define a default value in case of the optional is uninitialized. I suggest two alternatives: optional<int> o; int i = o.get(123); // a meber function get with an additional parameter int j = from_optional(o, 123); // a free function Both alternatives can be implemented simultaneously. What do you think about it? Regards, Vaclav

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Regex alignment changed warning with VC2005 amd64 platform
by George M. Garner Jr. 26 Mar '06

26 Mar '06

I am getting the following warning when I compile Regex 1-33-1 with VC2005 for amd64 platform: --> # include BOOST_ABI_SUFFIX alignment changed after including header, may be due to missing #pragma pack(pop) Does anyone know what this is all about? Regards, George.

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"Top Downloads" tips from a veteran
by Andy Little 26 Mar '06

26 Mar '06

BTW A very trivial general point, but something to think about before uploading a library to the vault. I noticed that adding versions to the zip file (as I do) means you dont get into the Top downloads section of boost. I decided to continue as it helps my organisation so I can tell whats what, but its a slight niggle. I think there has been around 300-400 downloads of my pqs library but because I change the name each version its never going to appear in the "Top 10". Of course if you dont add version info then I think it makes life more difficult for the user. Its possible to add version info in the accompanying text, but the user will of course lose it once downloaded. Anyway that seems to be the choice. Does it matter? Not much... But just a reminder to anyone starting at the Top downloads section of boost. They dont tell the whole story. "Theres gold in them thar hills ..." ;-) regards Andy Little

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c2_functions first submission materials uploaded
by Marcus Mendenhall 26 Mar '06

26 Mar '06

I have uploaded c2_functions.zip to the file vault. It contains the code for c2_functions (header & source), an html folder with Doxygen documentation, and a white paper describing the theory of this package. Anyone who is interested, look over this and let me know how the group wishes to proceed. Marcus Mendenhall

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