- Boost-users - lists.boost.org

upgrading lock
by Igor R 21 Feb '13

21 Feb '13

Hello, Just wanted to be sure that I'm doing this correctly. typedef boost::upgrade_lock<boost::shared_mutex> upgrade_lock; typedef boost::upgrade_to_unique_lock<boost::shared_mutex> upgrade_to_unique_lock; upgrade_lock readLock(mutex_); // accessing shared resources in read-only mode //... upgrade_to_unique_lock writeLock(readLock); // modifying shared resources Is the above correct? In particular, upgrade_lock acquires "read" lock in raii style (similarly to shared_lock), right? Thanks.

2 2

Re: [Boost-users] Can boost help me organize/parse lots of binary data?
by Gabriel Bizzotto 21 Feb '13

21 Feb '13

Chris, > class Item > { > virtual void Decode(istream& Stream) = 0; > } > class Double : public Item > class String : public Item > class EmployeePacket > { > std::vector<Item*> Items; ... Maybe boost::any will do better here ? http://www.boost.org/doc/libs/1_53_0/doc/html/any.html

2 1

[lockfree] compile-time capacity vs. run-time capacity
by Akira Takahashi 21 Feb '13

21 Feb '13

Hi, I confused with boost::lockfree::queue behavior. Fist, run-time capacity: #include <iostream> #include <boost/lockfree/queue.hpp> int main() { boost::lockfree::queue<int, boost::lockfree::fixed_sized<true>> que(3); std::cout << std::boolalpha; std::cout << que.push(1) << std::endl; // true std::cout << que.push(2) << std::endl; // true std::cout << que.push(3) << std::endl; // true std::cout << que.push(4) << std::endl; // false } I think this behavior is correct. But, compile-time capacity: #include <iostream> #include <boost/lockfree/queue.hpp> int main() { boost::lockfree::queue<int, boost::lockfree::capacity<3>> que; std::cout << std::boolalpha; std::cout << que.push(1) << std::endl; // true std::cout << que.push(2) << std::endl; // true std::cout << que.push(3) << std::endl; // false : why? std::cout << que.push(4) << std::endl; // false } Is this bug or specification? Thanks, Akira >>======================== Akira Takahashi mailto:faithandbrave@gmail.com site: https://sites.google.com/site/faithandbrave/about/en

1 1

Coroutine documentation question
by Brian Wood 21 Feb '13

21 Feb '13

I have a question about a sentence on this page: http://www.boost.org/doc/libs/1_53_0/libs/coroutine/doc/html/coroutine/intr… "The principal difference between coroutines and routines is that a coroutine enables explicit suspend and resume their progress via additional operations by preserving local state ..." I'm wondering if it would be accurate/helpful to change that to this: "The principal difference between coroutines and routines is that coroutines enable explicit suspend and resume of their progress via additional operations by preserving local state ..." Shalom Brian Wood Ebenezer Enterprises - so far G-d has helped us. http://webEbenezer.net (651) 251-9384

1 0

Boost.Geometry: Correct use of multi-part polygons
by John Lilley 20 Feb '13

20 Feb '13

Greetings, I am looking for some guidance around the correct creation and use of multi-part polygons. I am a bit confused about when to use each of the following: * Polygon with multiple rings * Vector of polygons * Polygon set * Set/vector of polygons, each potentially containing multiple rings I gather from this example picture: http://geometrylibrary.geodan.nl/03__polygon__example_8cpp-example.html That if one wants holes to be opened as a result of intersection, they need to be rings as opposed to polygon sets or vectors of polygons? An example would be polygon(s) representing an island chain. Some of the islands are atolls and as such have a hole in the middle. What would a representation of this set of islands look like? And, what If I don't know if I have "real" rings (interior) vs just a collection of polygons (like I got this from an external source that doesn't have the same model). If I just throw a pile of points at a polygon and call clean(), will that magic everything up for me? john

2 4

Boost.geometry intersection / difference question
by John Lilley 20 Feb '13

20 Feb '13

What types are the intersection and difference algorithms implemented for? In particular: Can polygons intersect with non-polygons (e.g. point sets to produce clipped point sets, or linestrings to produce clipped linestrings)? Similar question for difference, where polygon is the second input. Thanks John

2 1

Re: [Boost-users] [Atomic] [Tread] Proposal for Synchronized<T>
by Gabriel Bizzotto 20 Feb '13

20 Feb '13

Hi, > I've been working already on a synchronized_value class that is in trunk [1]. I plan to merge it to release branch as soon as I have finished the tests and the documentation. You can see some examples in [2] and [3]. > I've take a look to your class and I think my class provides everything yours provide. Surely your version has been given more thought. > My class allows in addition to lock several synchronized values using the deadlock free lock algorithm as e.g. I did not understand the unique_synchronize part, though. > Please could you compare your class to mine and let me know what do you think? I can't see any flaw right now, but I'm still playing with it. If anything shows up I'll let you know. Thanks !

2 1

Re: [Boost-users] [Atomic] [Tread] Proposal for, Synchronized<T>
by Gabriel Bizzotto 20 Feb '13

20 Feb '13

> I have one that does reader/writer locking. I'll pass it along for comparison along with design notes (it was done partially for teaching), if it's OK to send a zip file to you. > ?John Sure, let's take a look ! You also want to carbon-copy to vicente.botet(a)wanadoo.fr, which is putting the finishing touch on the future boost::synchronized_value.

2 1

Directed cycle detection in a DAG between two nodes
by Amanullah Yasin 20 Feb '13

20 Feb '13

Hi, In Hill Climbing algorithm, before applying an operation "add_edge", "reverse_edge" or "remove_edge", I need to check whether the graph will be a Directed Acyclic Graph (DAG) or not. So there is recursive function but in some cases it goes in infinite loop and gives "stack overflow" error. //======= Function ======= bool myAlgo::remainsADAG(const Node_type& nodeInit, const Node_type& node, const Graph_type& graph) { graph_traits<Graph_type>::adjacency_iterator vi, vi_end; tie(vi, vi_end) = adjacent_vertices(node, graph); for (; vi != vi_end; ++vi) { if ((*vi == nodeInit) || (!remainsADAG(nodeInit, *vi, graph))) return false; } return true; } ============== e.g. for Graph 12->19->20->23 19->24->31->18>19 18->32 To test if there is a directed path between v12 and v32 it goes as: 12->19->20->23 24->31->18>19 *There is an infinite loop{18->19->20->23, 24->31->18}.* ================= Can some one help me or is there any other easy way to find a directed path between two nodes in boost graph? Thanks in advance. YASIN

4 3

[Preprocessor] Generate #include directive with preprocessor
by Adam Badura 20 Feb '13

20 Feb '13

Is it possible to use preprocessor to generate #include directives (or in any other way include the files)? For example if I would have a sequence of strings (being file paths) what to do to include all those files? It is possible at all?

4 3