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[optional] How to make boost::optional throw if trying to access uninitialized value
by dariomt＠gmail.com 10 Jul '09

10 Jul '09

Hi list, I've seen in the docs that boost::optional asserts if you try to access an uninitialized value. Is it possible to make it throw an exception instead? Even in release mode? TIA

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How can I save the values in lambda expression? Can any one with kindness help me?
by fmingu 10 Jul '09

10 Jul '09

I am using Dev-C++ with boost lambda expression, I wrote: .................... int nnumber; int switchvalue; typedef std::map<int, int> IIPrimemap; IIPrimemap primemapvec; # define BetaKGre2 1 # define EqualToOne 2 #define ProductOfKPrime 3 ..................... if_then_else(var(nnumber)==1,var(switchvalue)=EqualToOne, if_then_else(constant(count_if(primemapvec.begin(),primemapvec.end(), bind(&IIPrimemap::value_type::second,_1)>2)>0), var(switchvalue)=BetaKGre2,var(switchvalue)=ProductOfKPrime)); std::cout<<" the var(switchvalue) is "<<var(switchvalue)<<"\n"; .............. and the program ran and showed: the var(switchvalue) is without any expression of var(switchvalue). I do not know how to save the values in lambda expression and where is wrong? Can I use *var(switchvalue) instead of var(switchvalue)? Can anyone with kindness help me?

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bootstrap.sh generates incorrect libdir in project-config.jam
by Andreas Klöckner 10 Jul '09

10 Jul '09

Hi all, When I ran bootstrap.sh --prefix=$HOME/pool, it did generate a broken project- config.jam--it used option.set libdir : /lib ; instead of option.set libdir : /home/andreas/pool/lib ; Has anybody else run into the issue described here? Any chance for fixed tarballs? Thanks, Andreas

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[Boost.Program_options] zero or one tokens with zero_tokens()?
by Marti Cuquet 09 Jul '09

09 Jul '09

Hello, I am trying to use an option that can have either zero or one arguments. I have seen an example in the documentation claiming that the following code would allow the user to provide either zero or one tokens to option 'verbose', but instead it throws an exception "extra parameter" when one token is given. So the question is, does zero_tokens() allow the user to specify a value? options_description desc; desc.add_options() ("help", "produce help message") ("compression", value<string>(), "compression level") ("verbose", value<string>()->zero_tokens(), "verbosity level") ("email", value<string>()->multitoken(), "email to send to") ; Thanks, Marti

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[Tuple] Addressing by named tag?
by Robert Jones 09 Jul '09

09 Jul '09

Am I correct in believing that tuples have to be accessed by element index, as in tuple.get<0>() Multi-Index container has a really nice facility to use named (well typed really) tags in these kind of expressions, but it seems tuples do not. Anyone fancy adding it to tuple? - Rob.

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boost programmer_option.hpp
by Narendra R 09 Jul '09

09 Jul '09

Hi, i was trying to use boost program option I can compile the code written using the program_option.hpp, but i am getting linker error can any one help me? Using gcc compiler

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Possible to put path to boost library somewhere else than Jamroot file?
by s seelenluft 09 Jul '09

09 Jul '09

Hi, my question is whether I can put the path to the boost library in a another file than the Jamroot file (eg, boost-build.jam)? I run run longish simulations on multiple workstations, essentially Debian and Mac OS X machines. For good or bad reasons, the path to the boost library is differs between machines. I give the path via an <include> in the Jamroot file. Thus the Jamroot file has to be different on each machine. However, my code is synchronized via Subversion between the machines which poses a problem for the Jamroot file. Thus, I either can only do one-way synchronisation from one master computer and edit the Jamroot file on the other machines locally (marking the conflict as resolved after the first update after this edit) or exclude the Jamroot file from Subversion. Since I probably do modify the Jamroot file from time to time, it would be nice to include it in Subversion. Currently, I solve the problem by sticking to one-way synchronisation but if there would be another place to put the path, this would be nicer. Thanks. Markus

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[BGL] Large graphs
by Sebastian Weber 09 Jul '09

09 Jul '09

Hi! I am using the BGL to represent a fractal structure which I iteratevley grow. As I intend to handle large structures I usually preallocate the required space for the final fractal in the beginning. My construction process then uses the graph object to put in new edges into the same graph object. Now, if I always use the same graph object things get messed up for large fractals. However, if I use 2 graph structures, one which represents the last and one the comming generation, everything is ok (which doubles memory requirements for nothing). I have no clue what the problem here is. For small fractals both schemes produce correct fractals, but not for large ones. I suspect that there are some really strange problems here with allocated memory going on. BTW, is there a way to preallocate the required memory for the edges of a adjacency_list graph? I do know ahaed how many edges in total and how many edges per vertex will be in the final graph, so that I could preallocate memory if it is possible. Preallocating vertices is easy... In case someone may have an idea, but needs the code I am having trouble with, no problem, just contact me. Thanks in advance, Sebastian

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[graph] named vertices?
by Noah Roberts 09 Jul '09

09 Jul '09

I notice that in the changes for the newest boost that "named vertexes" is now supported in adjacency_list. I can't find anything on this feature though. I have the book, have searched the web. Only thing I find is comments in adjacency_list.hpp that maybe refers to a NamedGraph concept? I don't see that in the docs either: http://www.boost.org/doc/libs/1_39_0/libs/graph/doc/table_of_contents.html Could someone give me an overview of what this feature is and why I might use it? Probably better...point me to some place that documents it?

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[boost-build][doc][boostbook][doxygen] Problems with using boost documenting tools
by Andrey Torba 09 Jul '09

09 Jul '09

I've attached simple project with documentation. There are two problems:1. doxygen generates documentation with full paths to headers <D:/c++/my_project/include/my_project/h1.hpp> instead of <my_project/h1.hpp> As you can see in attachment, i configure doxygen by defining STRIP_FROM... directives, where $(TOP)/include = D:/c++/project/include: <doxygen:param>STRIP_FROM_PATH=$(TOP)/include <doxygen:param>STRIP_FROM_INC_PATH=$(TOP)/include TOP variable i define in Jamroot as: path-constant TOP : . ; What do i do wrong? 2. Paths to images looks like <img src="../../doc/html/images/next.png" alt="Next">. Path goes up by two directories and then down, it seem through the Jamroot I need simple <img src="images/next.png" alt="Next"> How to generate forward relative paths? -- Regards, Andrey

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