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Problems with boost::format and Visual C++ 7.0
by Tom Quarendon 07 Sep '04

07 Sep '04

I have trouble compiling code that makes use of the boost::format library. In particular I get compile errors from basic_format::operator= method (line 90 format_implementation.hpp). If I change the body to look like if(this == &x) return *this; basic_format<Ch, Tr> x1(x); // These 2 lines used x1.swap(*this); // to be 1 return *this; It compiles. --- Outgoing mail is certified Virus Free. Checked by AVG anti-virus system (http://www.grisoft.com) Version: 6.0.737 / Virus Database: 491 - Release Date: 11/08/2004

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output stream cloning?
by Jon Biggar 07 Sep '04

07 Sep '04

Is there any package in Boost (or upcoming in the Boost review queue) that would let me create an output stream that clones its output to one or more underlying output streams? -- Jon Biggar Levanta Inc jon(a)levanta.com

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Directory_Iterator causes MFC App to Freeze
by RYAN ROSARIO 06 Sep '04

06 Sep '04

Hi, I am writing an MFC program in MSVC7 that must pass a path from one dialog box to another upon pressing a button. I attempt to pass the path to the next dialog by using a directory iterator: fs::directory_iterator startIt(scanPath); (***) where scanPath is an object of type path. PICtoolProgressWnd temp(this,startIt); I pass the iterator into the constructor for the second dialog. When I attempt to run this program, my program just hangs after clicking the button and I cannot exit it. The second dialog never appears. The only way out is to Alt-Ctrl-Delete out of the program. The only other clue given is that when the program freezes, the "xstring" file opens with a green arrow pointing at what appears to be a definition of operator= or something of that sort. I have commented out practically all of my code in the button click event handler and determined that when the iterator is declared, (***) above, the program freezes. When this line is commented out, the program responds. What could I be doing wrong?? Below is some more code: //Creating the dialog if ( temp.DoModal() == IDOK) { //Display results. } else { //Are you sure you wish to cancel this process? } //Second dialog constructor. PICtoolProgressWnd::PICtoolProgressWnd(CWnd* pParent /*=NULL*/, fs::directory_iterator start) : CDialog(PICtoolProgressWnd::IDD, pParent) { startScanPath = start; } //startScanPath is a member variable of type fs::directory_iterator. Your help is greatly appreciated. Thanks in Advance, Ryan --------------------------------- Do you Yahoo!? Read only the mail you want - Yahoo! Mail SpamGuard.

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Using MPL to write is_derived_from_std_basic_ostream
by Angus Leeming 06 Sep '04

06 Sep '04

I'm trying to ascertain whether a given class is, or is derived from, std::basic_ostream, but I've ground to a halt. The attached code successfully reports those classes that do derive from std::basic_ostream but fails to compile when I test std::string, bool, char etc. I can see what is going wrong, but have run out of ideas about how to fix it. I'm also painfully aware that my attempts are just plain ugly. Can someone show me the way forward? Regards, Angus

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global stream manipulators for the format library
by Justin Findlay 05 Sep '04

05 Sep '04

I've got some code that uses the format library to format output, not out of necessity, but rather out of a wanton enjoyment derived from using the syntax, having lately (relatively) discovered boost, prefering the boost::format simple syntax to the posix printf and std::ostringstream flavored solutions. The "problem" I have is that for the output of every double, I have to specify the precision: int main() { cout << setprecision(18); cout << format("Bunner p' air: %1% torr\t\tN$_2$: %2% torr\n" " C air: %3%\t\tN$_2$: %4%") % group(setprecision(18), bunner::air::pp_av) % group(setprecision(18), bunner::N2::pp_av) % group(setprecision(18), bunner::air::c_av) % group(setprecision(18), bunner::N2::c_av) << endl; //... return 0; } Is there a graceful solution, or am I using this library beyond what it was intended for? Something like the following naturally suggests itself, but I don't think it is standard compliant: the constructor doesn't seem to like using a static object, actually the linker couldn't find the 'prmanip' object. class Fmt { public: Fmt() { cout << "duh" << endl << prmanip << constants::pi << endl; } static std::_Setprecision setpr(const int&pr) { prmanip = std::setprecision(pr); return std::setprecision(pr); } static std::_Setprecision prmanip; }; int main() { cout << setprecision(18); Fmt::setpr(18); //... Justin

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Problem using Boost Signals HPP file
by Brian Braatz 05 Sep '04

05 Sep '04

I am using vc7.1 MS Visual Studio 2003. I have tried using the boost signals (boost/signal.hpp) library in both my application and a Visual Stuido project file using the signal_test.cpp file. (made a blank C++ win32 console app project file- and then added the include dir for boost- I did nothing else). in either case I get: Compiling... signal_test.cpp Linking... LINK : fatal error LNK1104: cannot open file 'libboost_signals-vc71-sgd-1_31.lib' Build log was saved at file://c:\Rmtg\Root\_Common\_Lib\Boost\V_1_31\libs\signals\test\signal_test\signal_test\Debug\BuildLog.htm signal_test - 1 error(s), 0 warning(s) ---------------------- Done ---------------------- Build: 0 succeeded, 1 failed, 0 skipped My project file is quite bare other than pointing to boost as an include dir. I am perplexed on how visual studio is even AWARE of the lib name (since I did not tell it). On the machine I am using, I have not built boost static or dll libs. That would solve my problem, but not completely as what I *need* to do is use the hpp and *not* link to the lib. My questions: has anyone run into this before? Is Boost::signals supposed to work by just being able to #include the hpp? Any thoughts here? (one of those situations where I am really scratching my head). **ANY** thoughts or suggestions greatly appreciated

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generic factory creator
by Stephen torri 04 Sep '04

04 Sep '04

In my example data is passed between objects using a Data_Source. I want to hide the method data is passed from what the value is of the data. So a object receiving it does not need to be concerned with whether the data is coming from a file or database. In my situation I have three data sources for information: a file, memory pointer or database. Each of these data sources can handle a std::string, a Memory_Object, and a Graph_Object type as its internal data structure. The question I want to understand is how to create a generic interface to create the appropriate factory. Here is the table of the possible data source combinations (3 types * 3 sources = 9 possible). So more types and more sources can make creating the right Data_Source an ugly experience for maintaining the code. I don't want to have to have 9 separate functions. ----------------------------------------------------------- | File_Data_Src | Memory_Data_Src | Graph_Data_Src ----------------------------------------------------------------------- std::string | x | x | x ------------------------------------------------------------------------ Memory Obj | x | x | x ------------------------------------------------------------------------ Graph Obj | x | x | x ------------------------------------------------------------------------ At initialization I give a interger the Data_Source_Factory_Creator to represent what kind of factory I want. When a call is made to the Data_Source_Factory_Creator::get_Factory I want the apporpriate factory returned based upon the integer value given during initialization. Right now I get the right compilor error for Data_Source_Factory_Creator::get_Factory() because given Data_Source_Factory is a template class I need to instantiate this template correctly. I don't know how to make this function return a generic type so that I can do: Data_Source_Factory<File_Data_Source>* m_factory = Data_Source_Factory_Creator::get_Factory(); Any ideas? Stephen -- Email: storri(a)torri.org

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Signals - last call
by Georgios Diamantopoulos 04 Sep '04

04 Sep '04

Hello everyone, I have a question concerning signals. I wanted to force one of the callbacks to be called last. Obviously this needs to be done in an agnostic way since the calling function will probably not know how many other callbacks are connected and so on. I could not find anything in the documentation - only about numbered calls. Any ideas? Thanks in advance. Georgios

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Is there a binary serialization class ?
by Raj 03 Sep '04

03 Sep '04

Hi, Is there a binary serialization class in any of the boost file lib ? Also, how do I re-target and compile the boost libraries with the newly released Visual Studio Express edition ( VC 8.0 ) ? Thank in advance. Raja

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How to find min-cut?
by Daniele Carlucci 03 Sep '04

03 Sep '04

Hi, How can I find the min-cut (max-flow) in a graph undirected with all the weights of the edges equal one. Thanks Daniele

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