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[serialization] Out of memory with Borland C++ Builder 60
by Federico Feller 02 Jul '06

02 Jul '06

Hi everyone. Im having problems compiling some code with Borland C++ Builder 6 that includes libboost serialization. In particular Im having troubles registrating a new class in order to be serialized. The new class, say A3, is a subclass of antother that is declared abstract, say A. A has already some subclases (A1, A2) that are serialized correctly. As I did for other subclasses on the same hierarchy, I added the instruction ar.register_type(static_cast<A3 *>(NULL)); in the load/save method of another class that serializes a pointer to the base class of the hierarchy. After doing that, I tried to compile the code and got the following error from the compiler: [C++ Fatal Error] if.hpp(72): F1008 Out of memory I really have no idea whats going on. Any ideas? Thanks Federico __________________________________________________ Do You Yahoo!? Tired of spam? Yahoo! Mail has the best spam protection around http://mail.yahoo.com

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Re: [Boost-users] Boost.Variant: char[], a bool or std::string ?
by Nindi Singh 01 Jul '06

01 Jul '06

This has the desired effects BUT ... I am not a software engineer .. so I would like to know is it would the proffessionals would consider ugly code ? #include<string> #include<boost/variant.hpp> typedef boost::variant< bool,std::string> BoostVariant; struct MyVariant:public BoostVariant { template<typename type> MyVariant(const type &theType):BoostVariant(theType){} MyVariant(const char *theCString):BoostVariant(std::string(theCString)){} }; int main () { MyVariant v("A String"); std::string &Sref(boost::get<std::string&>(v)); // NOw this does NOT throw bool &Bref(boost::get<bool&>(v)); // but this does return 0; }

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Re: [Boost-users] Boost.Variant: Is a char * really a bool ?
by Nindi Singh 01 Jul '06

01 Jul '06

Hi Yuval sorry .. i will ensure I put a RE: on my furtue replies ... but i have posted a reply with subject 'Boost.Variant: char[], a bool or std::string ? ' N

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Boost.Variant: char[], a bool or std::string ?
by Nindi Singh 01 Jul '06

01 Jul '06

I sort of guessed that this implicit conversion was taking place ... but unfortunatley it wil make my variant very error prone .. and on the other hand I do want the capability to construct from a C string appropriatley. I think one possible soultion would be to derive from boost::variant<bool,std::string> and put in an explicit constructor for const char *, this will also let me get around other similar problems. However deriving from boost::variant .... ??? not sure how healthy that is. >To answer the question in the subject line: char* isn't bool, but it's >implicitly convertible to bool, which is probably (haven't really >checked, just an educated guess) what's causing you trouble. > >Nindi wrote: >> When I have a Boost.Variant templated on a bool and a std::string, I get >> the following behaviour .. >> >> #include<string> >> >> #include<boost/variant.hpp> .> >> typedef boost::variant< bool,std::string> BoostVariant; >> >> int main () { >> >> BoostVariant v("A String"); >> >> bool &Bref(boost::get<bool&>(v)); // this is ok >> >> std::string &Sref(boost::get<std::string&>(v)); // But this throws >> >> return 0; >> >> } > >Instead of > BoostVariant v("A String"); >try > BoostVariant v(std::string("A String")); > >I think it will solve your problems.

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Boost.Variant: Is a char * really a bool ?
by Nindi 01 Jul '06

01 Jul '06

When I have a Boost.Variant templated on a bool and a std::string, I get the following behaviour .. #include<string> #include<boost/variant.hpp> typedef boost::variant< bool,std::string> BoostVariant; int main () { BoostVariant v("A String"); bool &Bref(boost::get<bool&>(v)); // this is ok std::string &Sref(boost::get<std::string&>(v)); // But this throws return 0; }

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Boost.Variant: char[], a bool or std::string ?
by Nindi Singh 01 Jul '06

01 Jul '06

... .. but this works fine .. #include<string> #include<boost/variant.hpp> typedef boost::variant<std::string> BoostVariant; int main () { BoostVariant v("A String"); std::string &Sref(boost::get<std::string&>(v)); // NOW this does NOT throw return 0; }

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Boost.Variant: char[], a bool or std::string ?
by Nindi Singh 01 Jul '06

01 Jul '06

If I instantiate a Boost.Variant templated on a bool and a std::string , then I get the following behaviour ... not sure why #include <string> #include <Boost/Variant.hpp> typedef boost::variant< bool,std::string> BoostVariant; int main () { BoostVariant v("A String"); bool &Bref ( boost::get<bool &>(v)) ; // this is ok std::string &Sref ( boost::get<std::string> &(v) ) ; // but this throws return 0; } Is this what is supposed to happen ? Ninds

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[serialization] Error serializing std::wstring to text_oarchive on VC++
by William Kemper 01 Jul '06

01 Jul '06

The fill method on mb_from_wchar calls std::wctomb, which is backed by 'WideCharToMultiByte'. This function uses the codepage defined in the current locale, however, the utf-8 codepage does not function properly on VC++ 7 or 8. Would it be difficult to have the conversion use the code_cvt facet defined for the stream underlying the archive? It also seems that doing so would ensure serialization / deserialization would be more consistent and self-sufficient, since neither process would depend on a (mutable) global locale setting. At any rate, the serialization library works with certain window's codepages, but *not* with the utf-8 codepage (65001). It would be nice to have the library use its own utf8_code_cvt facet to translate wide characters to multibyte. If there is some work around I'm not aware of, I would appreciate any advice. Thanks.

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Compile-time constant CRCs
by Michael Marcin 01 Jul '06

01 Jul '06

I didn't tag this because I'm not sure if it should belong to [preprocessor], [mpl] or [crc]. Given the black-box (macro, function, class, whatever) I'll call ConstCRC32 that is assignable to a unsigned int is there a way to write: unsigned int hash = ConstCRC32( "HELLO" ); and have an optimized build yield the equivalent of: unsigned int hash = 0x58a10fc0; I had a solution (although obviously non-portable) in msvc7.1 but after moving to msvc8 and stepping through the code I noticed that msvc8's "improved" optimizing compiler cannot optimize away the calculation like msvc7.1's could. I also doubt that the code would work if I ever had to port it to another compiler. I tried using simple TMP techniques I've used in the past but couldn't find a way to access the characters of the string. So looking around I came upon boost.crc which is geared towards computing crcs of blocks of data which isn't really what I care about right now. I also found boost.mpl which is very cool but I have a hard time grasping still. The problems seems solvable with mpl if I could transform the data into boost::mpl::list_c<char,'H','E','L','L','O'> but I still coulnd't find a way to access the characters of the string and I think others at my company would rather revert to the old #define CRC( str, crc ) crc unsigned int hash = CRC( "HELLO", 0x58a10fc0 ); than move to that syntax directly. So looking further I found boost.preprocessor which I haven't explored enough to see if there is away to have PP calculate the CRC directly or have it transform the string into the boost::mpl::list_c form. Can anyone offer some advice? Thanks Mike P.S. The old version was actually fairly simple it just used a precomputed static const unsigned int lookup table and did a strlen and a for loop with a lookup into the table for each character (in a __forceinline function that took a const char * const string).

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Replacing C functions with boost::function for callback functions in OpenGL
by Stephen Torri 01 Jul '06

01 Jul '06

I have a main file from my OpenGL program which contains global variables and the functions that are used by OpenGL as callback functions. For example: int a; float b; void display () { .... display code calls ... } int main (int argc, char **argv) { glutDisplayFunc( display ); } Now I thought I would put all the variables and functions into a class and use that in the main. Here is where I am getting stuck on the use of boost::function. I changed the code to look something like the following: class MyMain { int a; float b; void display() { ... display code calls ... } } int main (int argc, char **argv) { MyMain m_ref; boost::function<void()> disp_func = boost::bind ( &MyMain::display, &m_ref ); glutDisplayFunc ( disp_func ); } What I am getting back from the g++ compiler is the following error message: error: cannot convert `boost::function<void ()(), std::allocator<void> >' to `void (*)()' for argument `1' to `void glutDisplayFunc(void (*)())' Any ideas where I am going wrong? Stephen

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