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  • boost graph adjacency_list, retrieving a node's parents

    - by Juan
    I want to find in an adjacency graph from the bgl how give a Vertexdescriptor and get the set of nodes that are parents of this given node. i would like to do this in directed graph, it seems you could use a bidirectional graph but i want to be able to restrict it so that there are no cycles.

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  • boost::Spirit Grammar for unsorted schema

    - by Hassan Syed
    I have a section of a schema for a model that I need to parse. Lets say it looks like the following. { type = "Standard"; hostname="x.y.z"; port="123"; } The properties are: The elements may appear unordered. All elements that are part of the schema must appear, and no other. All of the elements' synthesised attributes go into a struct. (optional) The schema might in the future depend on the type field -- i.e., different fields based on type -- however I am not concerned about this at the moment.

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  • Partial string search in boost::multi_index_container

    - by user361699
    I have a struct to store info about persons and multi_index_contaider to store such objects struct person { std::string m_first_name; std::string m_last_name; std::string m_third_name; std::string m_address; std::string m_phone; person(); person(std::string f, std::string l, std::string t = "", std::string a = DEFAULT_ADDRESS, std::string p = DEFAULT_PHONE) : m_first_name(f), m_last_name(l), m_third_name(t), m_address(a), m_phone(p) {} }; typedef multi_index_container , ordered_non_unique, member, member persons_set; operator< and operator<< implementation for person bool operator<(const person &lhs, const person &rhs) { if(lhs.m_last_name == rhs.m_last_name) { if(lhs.m_first_name == rhs.m_first_name) return (lhs.m_third_name < rhs.m_third_name); return (lhs.m_first_name < rhs.m_first_name); } return (lhs.m_last_name < rhs.m_last_name); } std::ostream& operator<<(std::ostream &s, const person &rhs) { s << "Person's last name: " << rhs.m_last_name << std::endl; s << "Person's name: " << rhs.m_first_name << std::endl; if (!rhs.m_third_name.empty()) s << "Person's third name: " << rhs.m_third_name << std::endl; s << "Phone: " << rhs.m_phone << std::endl; s << "Address: " << rhs.m_address << std::endl; return s; } Add several persons into container: person ("Alex", "Johnson", "Somename"); person ("Alex", "Goodspeed"); person ("Petr", "Parker"); person ("Petr", "Goodspeed"); Now I want to find person by lastname (the first member of the second index in multi_index_container) persons_set::nth_index<1::type &names_index = my_set.get<1(); std::pair::type::const_iterator, persons_set::nth_index<1::type::const_iterator n_it = names_index.equal_range("Goodspeed"); std::copy(n_it.first ,n_it.second, std::ostream_iterator(std::cout)); It works great. Both 'Goodspeed' persons are found. Now lets try to find person by a part of a last name: std::pair::type::const_iterator, persons_set::nth_index<1::type::const_iterator n_it = names_index.equal_range("Good"); std::copy(n_it.first ,n_it.second, std::ostream_iterator(std::cout)); This returns nothing, but partial string search works as a charm in std::set. So I can't realize what's the problem. I only wraped strings by a struct. May be operator< implementation? Thanks in advance for any help.

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  • C++ boost thread id and Singleton

    - by aaa
    hi. Sorry to flood so many questions this week. I assume thread index returned by thread.get_id is implementation specific. In case of the pthreads, is index reused? IE, if thread 0 runs and joins, is thread launched afterwords going to have a different ID? the reason I ask this is a need to implement Singleton pattern with a twist: each thread gets its own instance. I know it sounds very crazy, but threads control hardware (cuda) which does not permit device memory sharing. What is a good way to implement such pattern?

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  • Boost ForEach Question

    - by bobber205
    Trying to use something like the below with a char array but it doesn't compile. But the example with short[] works fine. Any idea why? :) char someChars[] = {'s','h','e','r','r','y'}; BOOST_FOREACH(char& currentChar, someChars) { } short array_short[] = { 1, 2, 3 }; BOOST_FOREACH( short & i, array_short ) { ++i; }

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  • D_WIN32_WINNT compiler warning with Boost

    - by bobber205
    Not sure what to make of this error. Added -D_WIN32_WINNT=0x0501 to Visual Studio's "Command Line" options under Project Properties but it says it doesn't recognize it and the warning still appears. I am also not sure how to add the Preprocessor Definition. :) Thanks for any help! 1Please define _WIN32_WINNT or _WIN32_WINDOWS appropriately. For example: 1- add -D_WIN32_WINNT=0x0501 to the compiler command line; or 1- add _WIN32_WINNT=0x0501 to your project's Preprocessor Definitions.

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  • accumulator don't compile

    - by Abruzzo Forte e Gentile
    HI All I am using boost accumulators. These 2 lines use to work fine with current version of boost in LInux. accumulator_set< double, stats< tag::covariance<double, tag::covariate1> > > acc_cov; accumulator_set< double, stats< tag::variance > > acc_var; When I moved to a Sun machine where it is installed boost v1.40 I have this building error "/opt/boost/boost/accumulators/framework/depends_on.hpp", line 276: Error:<no tag> cannot be initialized in a constructor. "/opt/boost/boost/fusion/container/list/cons.hpp", line 85: Where: While instantiating "boost::accumulators::detail::accumulator_wrapper<int, int>::accumulator_wrapper(const boost::accumulators::detail::accumulator_wrapper<int, int>&)". "/opt/boost/boost/fusion/container/list/cons.hpp", line 85: Where: Instantiated from non-template code. 1 Error(s) Do you know how can I fix those errors and why I have this issue? Thanks AFG

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  • Issues with ILMerge, Lambda Expressions and VS2010 merging?

    - by John Blumenauer
    A little Background For quite some time now, it’s been possible to merge multiple .NET assemblies into a single assembly using ILMerge in Visual Studio 2008.  This is especially helpful when writing wrapper assemblies for 3rd-party libraries where it’s desirable to minimize the number of assemblies for distribution.  During the merge process, ILMerge will take a set of assemblies and merge them into a single assembly.  The resulting assembly can be either an executable or a DLL and is identified as the primary assembly. Issue During a recent project, I discovered using ILMerge to merge assemblies containing lambda expressions in Visual Studio 2010 is resulting in invalid primary assemblies.  The code below is not where the initial issue was identified, I will merely use it to illustrate the problem at hand. In order to describe the issue, I created a console application and a class library for calculating a few math functions utilizing lambda expressions.  The code is available for download at the bottom of this blog entry. MathLib.cs using System; namespace MathLib { public static class MathHelpers { public static Func<double, double, double> Hypotenuse = (x, y) => Math.Sqrt(x * x + y * y); static readonly Func<int, int, bool> divisibleBy = (int a, int b) => a % b == 0; public static bool IsPrimeNumber(int x) { { for (int i = 2; i <= x / 2; i++) if (divisibleBy(x, i)) return false; return true; }; } } } Program.cs using System; using MathLib; namespace ILMergeLambdasConsole { class Program { static void Main(string[] args) { int n = 19; if (MathHelpers.IsPrimeNumber(n)) { Console.WriteLine(n + " is prime"); } else { Console.WriteLine(n + " is not prime"); } Console.ReadLine(); } } } Not surprisingly, the preceding code compiles, builds and executes without error prior to running the ILMerge tool.   ILMerge Setup In order to utilize ILMerge, the following changes were made to the project. The MathLib.dll assembly was built in release configuration and copied to the MathLib folder.  The following folder hierarchy was used for this example:   The project file for ILMergeLambdasConsole project file was edited to add the ILMerge post-build configuration.  The following lines were added near the bottom of the project file:  <Target Name="AfterBuild" Condition="'$(Configuration)' == 'Release'"> <Exec Command="&quot;..\..\lib\ILMerge\Ilmerge.exe&quot; /ndebug /out:@(MainAssembly) &quot;@(IntermediateAssembly)&quot; @(ReferenceCopyLocalPaths->'&quot;%(FullPath)&quot;', ' ')" /> <Delete Files="@(ReferenceCopyLocalPaths->'$(OutDir)%(DestinationSubDirectory)%(Filename)%(Extension)')" /> </Target> The ILMergeLambdasConsole project was modified to reference the MathLib.dll located in the MathLib folder above. ILMerge and ILMerge.exe.config was copied into the ILMerge folder shown above.  The contents of ILMerge.exe.config are: <?xml version="1.0" encoding="utf-8" ?> <configuration> <startup useLegacyV2RuntimeActivationPolicy="true"> <requiredRuntime safemode="true" imageVersion="v4.0.30319" version="v4.0.30319"/> </startup> </configuration> Post-ILMerge After compiling and building, the MathLib.dll assembly will be merged into the ILMergeLambdasConsole executable.  Unfortunately, executing ILMergeLambdasConsole.exe now results in a crash.  The ILMerge documentation recommends using PEVerify.exe to validate assemblies after merging.  Executing PEVerify.exe against the ILMergeLambdasConsole.exe assembly results in the following error:    Further investigation by using Reflector reveals the divisibleBy method in the MathHelpers class looks a bit questionable after the merge.     Prior to using ILMerge, the same divisibleBy method appeared as the following in Reflector: It’s pretty obvious something has gone awry during the merge process.  However, this is only occurring when building within the Visual Studio 2010 environment.  The same code and configuration built within Visual Studio 2008 executes fine.  I’m still investigating the issue.  If anyone has already experienced this situation and solved it, I would love to hear from you.  However, as of right now, it looks like something has gone terribly wrong when executing ILMerge against assemblies containing Lambdas in Visual Studio 2010. Solution Files ILMergeLambdaExpression

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  • Can I mix compile time string comparison with MPL templates?

    - by Negative Zero
    I got this compile time string comparison from another thread using constexpr and C++11 (http://stackoverflow.com/questions/5721813/compile-time-assert-for-string-equality). It works with constant strings like "OK" constexpr bool isequal(char const *one, char const *two) { return (*one && *two) ? (*one == *two && isequal(one + 1, two + 1)) : (!*one && !*two); } I am trying to use it in the following context: static_assert(isequal(boost::mpl::c_str<boost::mpl::string<'ak'>>::value, "ak"), "should not fail"); But it gives me an compilation error of static_assert expression is not an constant integral expression. Can I do this?

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  • CSV parser in C++

    - by User1
    All I need is a good CSV file parser for C++. At this point it can really just be a comma-delimited parser (ie don't worry about escaping new lines and commas). The main need is a line-by-line parser that will return a vector for the next line each time the method is called. I found this article which looks quite promising: http://www.boost.org/doc/libs/1_35_0/libs/spirit/example/fundamental/list_parser.cpp I've never used Boost's Spirit, but am willing to try it. Is it overkill/bloated or is it fast and efficient? Does anyone have faster algorithms using STL or anything else? Thanks!

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  • .NET: Best way to execute a lambda on UI thread after a delay?

    - by Scott Bussinger
    I had a situation come up that required running a lambda expression on the UI thread after a delay. I thought of several ways to do this and finally settled on this approach Task.Factory.StartNew(() => Thread.Sleep(1000)) .ContinueWith((t) => textBlock.Text="Done",TaskScheduler.FromCurrentSynchronizationContext()); But I'm wondering if there's an easier way that I missed. Any suggestions for a shorter, simpler or easier technique? Assume .NET 4 is available.

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  • How to declare a function that accepts a lambda?

    - by Andreas Bonini
    I read on the internet many tutorials that explained how to use lambdas with the standard library (such as std::find), and they all were very interesting, but I couldn't find any that explained how I can use a lambda for my own functions. For example: int main() { int test = 5; LambdaTest([&](int a) { test += a; }); return EXIT_SUCCESS; } How should I declare LambdaTest? What's the type of its first argument? And then, how can I call the anonymous function passing to it - for example - "10" as its argument?

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  • Lambda expressions - set the value of one property in a collection of objects based on the value of

    - by Michael Rut
    I'm new to lambda expressions and looking to leverage the syntax to set the value of one property in a collection based on another value in a collection Typically I would do a loop: class item{ public string name {get;set;} public string value {get;set;} } class business { item item1 = new item(name="name1"); item item2 = new item(name="name2"); item item3 = new item(name="name3"); Collection<item> items = new Collection() {item1,item2,item3}; //This is what I want to simplify for( int i = 0; i < items.count; i++) { if(items[i].item.name == "name2") { //set the value items[i].item.value = "value2"; } } }

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  • How do I use a Lambda expression to sort INTEGERS inside a object?

    - by punkouter
    I have a collection of objects and I know that I can sort by NAME (string type) by saying collEquipment.Sort((x, y) = string.Compare(x.ItemName, y.ItemName)); that WORKS. But I want to sort by a ID (integer type) and there is no such thing as Int32.Compare So how do I do this? This doesnt work collEquipment.Sort((x, y) = (x.ID < y.ID); //error I know the answer is going to be really simple. Lambda expressions confuse me.

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  • How do I make lambda functions generic in Scala?

    - by Electric Coffee
    As most of you probably know you can define functions in 2 ways in scala, there's the 'def' method and the lambda method... making the 'def' kind generic is fairly straight forward def someFunc[T](a: T) { // insert body here what I'm having trouble with here is how to make the following generic: val someFunc = (a: Int) => // insert body here of course right now a is an integer, but what would I need to do to make it generic? val someFunc[T] = (a: T) => doesn't work, neither does val someFunc = [T](a: T) => Is it even possible to make them generic, or should I just stick to the 'def' variant?

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  • Boost Netbook Speed with an SD Card & ReadyBoost

    - by Matthew Guay
    Looking for a way to increase the performance of your netbook?  Here’s how you can use a standard SD memory card or a USB flash drive to boost performance with ReadyBoost. Most netbooks ship with 1Gb of Ram, and many older netbooks shipped with even less.  Even if you want to add more ram, often they can only be upgraded to a max of 2GB.  With ReadyBoost in Windows 7, it’s easy to boost your system’s performance with flash memory.  If your netbook has an SD card slot, you can insert a memory card into it and just leave it there to always boost your netbook’s memory; otherwise, you can use a standard USB flash drive the same way. Also, you can use ReadyBoost on any desktop or laptop; ones with limited memory will see the most performance increase from using it. Please Note:  ReadyBoost requires at least 256Mb of free space on your flash drive, and also requires minimum read/write speeds.  Most modern memory cards or flash drives meet these requirements, but be aware that an old card may not work with it. Using ReadyBoost Insert an SD card into your card reader, or connect a USB flash drive to a USB port on your computer.  Windows will automatically see if your flash memory is ReadyBoost capable, and if so, you can directly choose to speed up your computer with ReadyBoost. The ReadyBoost settings dialog will open when you select this.  Choose “Use this device” and choose how much space you want ReadyBoost to use. Click Ok, and Windows will setup ReadyBoost and start using it to speed up your computer.  It will automatically use ReadyBoost whenever the card is connected to the computer. When you view your SD card or flash drive in Explorer, you will notice a ReadyBoost file the size you chose before.  This will be deleted when you eject your card or flash drive. If you need to remove your drive to use elsewhere, simply eject as normal. Windows will inform you that the drive is currently being used.  Make sure you have closed any programs or files you had open from the drive, and then press Continue to stop ReadyBoost and eject your drive. If you remove the drive without ejecting it, the ReadyBoost file may still remain on the drive.  You can delete this to save space on the drive, and the cache will be recreated when you use ReadyBoost next time. Conclusion Although ReadyBoost may not make your netbook feel like a Core i7 laptop with 6GB of RAM, it will still help performance and make multitasking even easier.  Also, if you have, say, a memory stick and a flash drive, you can use both of them with ReadyBoost for the maximum benefit.  We have even noticed better battery life when multitasking with ReadyBoost, as it lets you use your hard drive less.  SD cards and thumb drives are relatively cheap today, and many of us have several already, so this is a great way to improve netbook performance cheaply. Similar Articles Productive Geek Tips Speed up Your Windows Vista Computer with ReadyBoostSet the Speed Dial as the Opera Startup PageAsk the Readers: What are Your Computer’s Hardware Specs?Understanding Windows Vista Aero Glass RequirementsReplace Google Chrome’s New Tab Page with Speed Dial TouchFreeze Alternative in AutoHotkey The Icy Undertow Desktop Windows Home Server – Backup to LAN The Clear & Clean Desktop Use This Bookmarklet to Easily Get Albums Use AutoHotkey to Assign a Hotkey to a Specific Window Latest Software Reviews Tinyhacker Random Tips DVDFab 6 Revo Uninstaller Pro Registry Mechanic 9 for Windows PC Tools Internet Security Suite 2010 Recycle ! Find That Elusive Icon with FindIcons Looking for Good Windows Media Player 12 Plug-ins? Find Out the Celebrity You Resemble With FaceDouble Whoa ! Use Printflush to Solve Printing Problems

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  • Is complete boost going to be included in C++0x?

    - by iammilind
    Many utilities of boost have been included as part of extended C++ TR1 currently. Is the complete boost library going to be included once the standard is officially out ? In other words, do I need boost library, if I have complete standard conforming C++11 compiler ? If not then any reason for that (Reliability cannot be an issue; as far as I know it's written by many people from standard committee) ?

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  • What is the easiest way to get the property value from a passed lambda expression in an extension me

    - by Andrew Siemer
    I am writing a dirty little extension method for HtmlHelper so that I can say something like HtmlHelper.WysiwygFor(lambda) and display the CKEditor. I have this working currently but it seems a bit more cumbersome than I would prefer. I am hoping that there is a more straight forward way of doing this. Here is what I have so far. public static MvcHtmlString WysiwygFor<TModel, TProperty>(this HtmlHelper<TModel> helper, Expression<Func<TModel, TProperty>> expression) { return MvcHtmlString.Create(string.Concat("<textarea class=\"ckeditor\" cols=\"80\" id=\"", expression.MemberName(), "\" name=\"editor1\" rows=\"10\">", GetValue(helper, expression), "</textarea>")); } private static string GetValue<TModel, TProperty>(HtmlHelper<TModel> helper, Expression<Func<TModel, TProperty>> expression) { MemberExpression body = (MemberExpression)expression.Body; string propertyName = body.Member.Name; TModel model = helper.ViewData.Model; string value = typeof(TModel).GetProperty(propertyName).GetValue(model, null).ToString(); return value; } private static string MemberName<T, V>(this Expression<Func<T, V>> expression) { var memberExpression = expression.Body as MemberExpression; if (memberExpression == null) throw new InvalidOperationException("Expression must be a member expression"); return memberExpression.Member.Name; } Thanks!

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  • 5 ways the Exceptional DBA Award could boost your career

    - by Rebecca Amos
    Winning the Exceptional DBA Award won’t just get you full conference registration for the PASS Summit – it could also change your life and career. With a little help from our past winners, here are the top 5 ways the Exceptional DBA Award could take your career to the next level: 1. Recognition from your peers As 2009 winner Josef Richberg says, “Being recognized by your peers is the highest honor one can receive.” Whether you enter yourself, or are nominated by a friend or colleague, the fact that the winner is selected by the SQL Server community is a great chance for your peers to recognize your achievements as a DBA. 2. Boost your CV Winning the Exceptional DBA Award not only shows that you excel as a DBA, but that SQL Server experts think so too – a huge vote of confidence for any prospective employer. 2008 winner Dan McClain agrees, “It brings another level of 'wow' to my resume”. 3. Networking opportunities within the community Whether you want to increase your experience as a writer, speaker or blogger, winning the Exceptional DBA Award can open up new opportunities within the SQL Server community. Plus you’ll make new friends along the way, as Josef has discovered: “It is an unbelievable community that has become an extended family.” 4. Award ceremony at the world's largest technical SQL Server conference The Exceptional DBA Award is presented at the PASS Summit, giving you great networking opportunities and a chance to be seen by people throughout the SQL Server community. 5. Increased personal confidence Finally, the Exceptional DBA Award should give a huge boost to your personal confidence. Last year’s winner, Tracy Hamlin has certainly found this: “The recognition has given me new confidence and the drive to accomplish even loftier goals.” Read the full interview with our past winners to find out how why they’re encouraging you to enter this year’s Exceptional DBA Awards. Already inspired? Then why not get started on your entry straightaway: www.exceptionaldba.com

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  • How to implement generic callbacks in C++

    - by Kylotan
    Forgive my ignorance in asking this basic question but I've become so used to using Python where this sort of thing is trivial that I've completely forgotten how I would attempt this in C++. I want to be able to pass a callback to a function that performs a slow process in the background, and have it called later when the process is complete. This callback could be a free function, a static function, or a member function. I'd also like to be able to inject some arbitrary arguments in there for context. (ie. Implementing a very poor man's coroutine, in a way.) On top of that, this function will always take a std::string, which is the output of the process. I don't mind if the position of this argument in the final callback parameter list is fixed. I get the feeling that the answer will involve boost::bind and boost::function but I can't work out the precise invocations that would be necessary in order to create arbitrary callables (while currying them to just take a single string), store them in the background process, and invoke the callable correctly with the string parameter.

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