December 2006 - Boost-users

ptime construct from string
by Delvaille Florent 11 Dec '06

11 Dec '06

Hi, I ve a problem with ptime. I'm doing a a project on Eclipse, and I need to create a ptime object from a string. Here's my code: std::string ts("2002-01-20 23:59:59.000"); ptime t(time_from_string(ts)) This code is exactly the same in the boost documentation. On compilation, no error is detected. But there's a problem with the linker. I paste here the error that Eclipse gives to me: Invoking: GCC C++ Linker g++ -o"brol" ./initmain.o ./initmain.o: dans la fonction « unsigned short boost::date_time::month_str_to_ushort<boost::gregorian::greg_month>(std::basic_string<char, std::char_traits<char>, std::allocator<char> >)»: /usr/include/boost/date_time/date_parsing.hpp:67: référence indéfinie vers « boost::gregorian::greg_month::get_month_map_ptr() » collect2: ld returned 1 exit status Do you have an idea?

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Re: [Boost-users] shared_ptr with custom free function
by Nat Goodspeed 11 Dec '06

11 Dec '06

From: boost-users-bounces(a)lists.boost.org [mailto:boost-users-bounces@lists.boost.org] On Behalf Of Sohail Somani Sent: Sunday, December 10, 2006 9:17 PM To: boost-users(a)lists.boost.org; boost-users(a)lists.boost.org Subject: Re: [Boost-users] shared_ptr with custom free function From: boost-users-bounces(a)lists.boost.org on behalf of Nat Goodspeed > > [Nat] It might be worth binding that knowledge into a specific > > shared-pointer-to-blob type so that the required deleter function is > > implicitly captured EVERY time you construct such a pointer. > > ------------- > > How do you encode that knowledge into the type? [Nat] I admit I haven't tried coding this. My thought is to derive your "blob pointer" type from shared_ptr<blob>, implementing a subset of the constructor variants that will be useful to you, and ensuring that the constructor that accepts a dumb blob* pointer implicitly passes free_blob to the base-class constructor. Something like this: class blob; void free_blob(blob*); class blob_ptr: public shared_ptr<blob> { typedef shared_ptr<blob> super; public: // should only need to implement (a subset of) constructors // ... // This constructor is the reason blob_ptr is a class rather // than a typedef. Since we MUST use free_blob() to free a // heap blob instance, always bind free_blob() as shared_ptr's // custom deleter. blob_ptr(blob* ptr): super(ptr, free_blob) {} // ... };

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Boost fusion: Bug in sample?
by Sohail Somani 11 Dec '06

11 Dec '06

Warning: MPL noob, still waiting for my book to arrive I'm reading the fusion library's documentation that was in the zip file for the announcement. If this is outdated, please ignore this email. The section in the quickstart: Print Only Pointers =================== Let's get a little cleverer. Say we wish to write a generic function that takes in an arbitrary sequence and XML prints only those elements which are pointers. Ah, easy. First, let's include the is_pointer boost type trait: #include <boost/type_traits/is_pointer.hpp> Then, simply: template <typename Sequence> void xml_print_pointers(Sequence const& seq) { for_each(filter_if<boost::is_pointer<Sequence> >(seq), print_xml()); } ==================== This doesn't seem to compile as is. I needed to do the following instead of the above: template <typename Sequence> void xml_print_pointers(Sequence const& seq) { using namespace mpl::placeholders; typedef mpl::lambda<boost::is_pointer<_1> >::type is_pointer; fusion::for_each(fusion::filter_if<is_pointer>(seq), print_xml()); } This is using boost 1.33.1. Did I miss something? Thanks! Sohail

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How can I find what I didn't install
by Bo Yang 11 Dec '06

11 Dec '06

Hi, I complile and installed boost 1.31 library today, I followd the instructions in the website and I got part of it installed. I have seen some messages in the process of compile which said , something is skiped and something is failed. Now , I think part of boost have already installed. And I want to know , which part I didn't install, How can I get such information? Thank you !

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Re: [Boost-users] shared_ptr with custom free function
by Nat Goodspeed 11 Dec '06

11 Dec '06

> -----Original Message----- > From: boost-users-bounces(a)lists.boost.org [mailto:boost-users- > bounces(a)lists.boost.org] On Behalf Of Peter Dimov > Sent: Sunday, December 10, 2006 7:00 PM > To: boost-users(a)lists.boost.org > Subject: Re: [Boost-users] shared_ptr with custom free function > > > Is > > there any way that I can create a shared_ptr that will call this > > special library free function when the last copy is destroyed? > > Yes, there is: > > shared_ptr< blob > pb( create_blob(), free_blob ); [Nat] It might be worth binding that knowledge into a specific shared-pointer-to-blob type so that the required deleter function is implicitly captured EVERY time you construct such a pointer.

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shared_ptr with custom free function
by Phil Endecott 10 Dec '06

10 Dec '06

Dear Boost experts, I have a C library that returns pointers to structs, and has special free functions that I must call to finalise and free these structs. Is there any way that I can create a shared_ptr that will call this special library free function when the last copy is destroyed? I was hoping that there would be some way of achieving this by overloading operator delete, but it seems not. Any ideas? Here's a more concrete example, in case it's not obvious: class Foo { public: Foo(struct blob* b): my_blob(b) {} ~Foo() {free_blob(my_blob);} private: struct blob* my_blob; }; Foo is not copyable, because the both copies will free the blob when they are destroyed. So: class Foo2 { public: Foo(struct blob* b): my_blob(b) {} private: boost::shared_ptr<struct blob> my_blob; }; Foo2 can be copied and the blob will be deleted exactly once when the last copy is destroyed, but the library's free_blob() function has not been used. inline void operator delete(struct blob* b) { free_blob(b); } Doesn't work; that's not how overloading of operator delete works. Thanks for any suggestions. Phil.

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multi_index + pure abstract
by fungos 10 Dec '06

10 Dec '06

Doesn't multi_index accept hold classes that has pure abstract methods? Even if these methods aren't used by the container? Is there a way to get the container to hold objects with same interface? -- Animal Frontline Liberation

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[filesystem] path to temporary file
by Chris Weed 10 Dec '06

10 Dec '06

Hi, Is there any support in filesystem to create paths to temporary files. I would like to make unit tests to test my file reader, by creating temporary files that are in some safe platform temp area that can be deleted at exit. Chris

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Boost Serialization make_binary & XML/ASCII
by Terence Wilson 09 Dec '06

09 Dec '06

I need to parse an XML file generated by Boost Serialization, part of the file is a section generated by make_binary. I was wondering which scheme was used to convert binary to ASCII, uuencode, Base64? Obviously I need to know in order that I can convert back. TIA Dr. Terence Wilson Principal, Bayside Technical email: tez(a)latte.com web: http://latte.com

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date-time New US daylight saving rules
by michael mathews 09 Dec '06

09 Dec '06

Hi All, Will /are the daylight savings time rules adjusted to reflect the new law taking effect in 2007? The rules in 1.33.1 are incorrect starting in 2007. thanks in advance michael __________________________________________________ Do You Yahoo!? Tired of spam? Yahoo! Mail has the best spam protection around http://mail.yahoo.com

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