- Boost-users - lists.boost.org

condition variable predicate and lambda
by Christopher Pisz 19 Oct '11

19 Oct '11

I want to do something simple, but implementing it seems awefully complex. All I want to do is wait for a specified amount of time for a member variable of my class to equal a certain value. Can someone please help me with an example? I've tried several that came from Googling and read the documentation, but I get compile errors no matter what I try. Currently the compiler is complainging "term does not evaluate to a function taking 0 arguments" Here is the problem in all its simplicity: class A { public: enum STATE { HAPPY = 0, SAD, ANGRY, NUM_STATES }; Foo(boost::posix_time::millisec & timeout) { // I need to wait to return from this until the state is HAPPY } private: STATE state_; };

3 4

Wave doesn't recognize c++0x keywords ?
by 邓尧 19 Oct '11

19 Oct '11

Hi, I'm new to Boost.Wave. I followed the "quick start", but found that wave take the C++0x keyword "decltype" as an identifier instead of a keyword. The macro "BOOST_WAVE_SUPPORT_CPP0X" is defined as "1". Boost version: 1.47.0 Any suggestions ? Thanks. -Yao

2 2

Re: [Boost-users] Building boost with stlport?
by Brian Vandenberg 18 Oct '11

18 Oct '11

> STLport is not used much nowadays. Used to use it with msvc-6 and 7.1, but > those are loooong gone here. Keep in mind that msvc is not the only place someone might consider using a more portable STL implementation. Where I work we're using Sun Studio; at least in old implementations their support for STL was anything but standards compliant -- in particular, people were doing god-awful things that never should have passed peer review; stuff that stlport or gcc puke on. Using stlport in older versions of Sun Studio is all but necessary if you want to use boost. More recent releases of Sun Studio are less troublesome, but in our case we're porting between Solaris and Linux; the implementations of STL between SS for Solaris & SS for Linux appeared to have different behaviors for some things, and if we port to gcc there'll no doubt be issues with poorly written code that worked in SS that doesn't work under gcc. In short, I wouldn't discount stlport as an ancient, no-longer-used piece of software; for those of us trying to port/improve older and more fragile code, stlport is a boon. -Brian

2 1

Chrono System time Conversion to Since Epoch not working
by Michael Chrostowski 18 Oct '11

18 Oct '11

Hi, I'm using boost 1.47 on Visual Studio 2008 and cannot seem to get the time since epoch from the Chrono library. At first I noticed that boost::chrono::system_time::now() does not have to be represented in time since epoch format so I don't believe that's an issue. However, I tried calling boost::chrono::system_time::now().time_since_epoch() and I get the same return result as if I was only referencing now(). That is, it is not time since epoch. Calling the static method to_time_t() DOES return proper time since epoch but it is in seconds (as time_t generally is) and is not what I'm looking for. Michael Chrostowski

2 1

boost atomic query
by Sean Farrow 18 Oct '11

18 Oct '11

Hi: I'm just starting to use boost atomic. I need to protect an std::map. If I had: boost::atomic<std;:map<int, int> > test; Would I need to protect this with a mutex, or is the fact that the variable is atomic enough? Cheers SEean.

2 1

[BGL] problem using subgraph
by Avishay Ben Shabtai 18 Oct '11

18 Oct '11

Hey i am trying to use subgraph but i am having troubles one of them is the following scenario typedef adjacency_list_traits< vecS, vecS, directedS > Traits; typedef subgraph< adjacency_list< vecS, vecS, directedS, no_property, property< edge_index_t, int > > > Graph; Graph G0(6); boost::add_edge(0,1,G0); Graph G1 = G0.create_subgraph(); boost::add_vertex(0,G1); boost::add_vertex(1,G1); boost::remove_edge(boost::edge(0,1,G1).first,G1); My Analysis is that since the edge is added to G0 before creation of G1 it does not add the edge (0,1) to its m_local_edge is there a way to overcome it? or i need to create all my subgraphs upfront Thanks

1 0

[Bind] Finding the right syntax.
by Robert Jones 18 Oct '11

18 Oct '11

Hi All In the code below my objective is pass a nullary function object to apply, and for that nullary function object to be 'my_function()' called with each member of the vector. How can I recode the call to apply as a unary bind expression such that I can write the for loop as a for_each loop? Thx, - Rob. #include <vector> #include "boost/function.hpp" #include "boost/bind.hpp" void apply( boost::function<void()> f ) { f( ); } int main( ) { static boost::function<void(int)> my_function = 0; std::vector<int> v; for ( std::vector<int>::iterator i = v.begin( ); i != v.end( ); ++ i ) { apply( bind( my_function, * i ) ); } }

2 1

svn name / password?
by Benson Limketkai 17 Oct '11

17 Oct '11

SVN keeps asking me for a name and password. I'm not sure what to do about this, because it's not supposed to do that. Who should I ask to look into this? thanks, Benson

1 0

[boost::polygon::operators] Boolean operations compiler error
by Dimitris Dakopoulos 17 Oct '11

17 Oct '11

Hello all, I'm using a custom polygon set (PolygonCollection) according to the guidelines here: http://www.boost.org/doc/libs/1_47_0/libs/polygon/doc/gtl_custom_polygon_se… There is one case that I don't get any compiler error: PolygonCollection p1, p2; p1 & p2; There is this case that I do have an error: PolygonCollection p1, p2; PolygonCollection p3 = p1 & p2; The error is: error: conversion from 'boost::polygon::polygon_set_view<PolygonCollection, PolygonCollection, 1>' to non-scalar type 'PolygonCollection' requested There is also this case that I have a compiler error: PolygonCollection p1,p2,p3; p3 = p1 & p2; The error is:error: no match for 'operator=' in 'p3 = boost::polygon::operators::operator&(const geometry_type_1&, const geometry_type_2&) [with geometry_type_1 = PolygonCollection, geometry_type_2 = PolygonCollection](((const PolygonCollection&)((const PolygonCollection*)(& p1))))' /xxx/Polygon.hpp:182: note: candidates are: PolygonCollection& PolygonCollection::operator=(const PolygonCollection&) (You can notice that I have overloaded the operator= for my custom polygon set but I got the same error without the suggestion before my implementation) Any ideas are welcomed! Dimitris

3 2

Storing a Huge Graph
by Nouf M. 17 Oct '11

17 Oct '11

Hi, Regarding the Boost Graph Library, Will I be able to convert a huge text file to a graph with millions of nodes and edges? Can I store the graph somewhere in the hard disk and then upload it whenever I test my code (i.e. I don't have to convert the text file into a graph each time I run my program).

4 3