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• Forcing file redirection on x64 for a 32-bit application

  - by Paul Alexander

  The silent redirection of 64-bit system files to their 32-bit equivalents can be turned off and reverted with Wow64DisableWow64FsRedirection and Wow64RevertWow64FsRedirection. We use this for certain file identity checks in our application. The problem is that in performing some of theses tasks, we might call a framework or Windows API in a DLL that has not yet been loaded. If redirection is enabled at that time, the wrong version of the dll may be loaded resulting in a XXX is not a valid Win32 application error. I've identified the few API calls in question and what I'd like to do force the redirection on for the duration of that call then revert it back - just the opposite of the provided Win32 APIs. Unfortunately these calls do not provide any sort of WOW64 compatibility flag like some of the registry methods do. The obvious alternative is to use Wow64EnableWow64FsRedirection, pass TRUE for Wow64FsEanbledRedirection. However there are a variety of warnings about the use of this method and a note that it is not compatible with Disable/Revert combo methods that have replaced it. Is there a safe way to force redirection on for a give Win32 call? The docs state the redirection is thread specific so I've considered spinning up a new thread for the specific call with appropriate locks and waits, but I was hoping for a simpler solution.

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• How to read XML using XPath in Java

  - by kaibuki

  Hi guys, I want to read XML data using XPath in Java, so for the information I have gathered I am not able to parse XML according to my requirement. here is what I want to do: Get XML file from online via its URL, then use XPath to parse it, I want to create two methods in it. One is in which I enter a specific node attribute id, and I get all the child nodes as result, and second is suppose I just want to get a specific child node value only <?xml version="1.0"?><howto> <topic name="Java"> <url>http://www.rgagnonjavahowto.htm</url> <car>taxi</car> </topic> <topic ame="PowerBuilder"> <url>http://www.rgagnon/pbhowto.htm</url> <url>http://www.rgagnon/pbhowtonew.htm</url> </topic> <topic name="Javascript"> <url>http://www.rgagnon/jshowto.htm</url> </topic> <topic name="VBScript"> <url>http://www.rgagnon/vbshowto.htm</url> </topic></howto> In above example I want to read all the elements if I search via @name and also one function in which I just want the url from @name 'Javascript' only return one node element. I hope I cleared my question :) Thanks. Kai

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• When onblur occurs, how can I find out which element focus went *to*?

  - by Michiel Borkent

  Suppose I attach an onblur function to an html input box like this: <input id="myInput" onblur="function() { ... }"></input> Is there a way to get the ID of the element which caused the onblur event to fire (the element which was clicked) inside the function? How? For example, suppose I have a span like this: <span id="mySpan">Hello World</span> If I click the span right after the input element has focus, the input element will lose its focus. How does the function know that it was mySpan that was clicked? PS: If the onclick event of the span would occur before the onblur event of the input element my problem would be solved, because I could set some status value indicating a specific element had been clicked. PPS: The background of this problem is that I want to trigger an Ajax.AutoCompleter control externally (from a clickable element) to show its suggestions, without the suggestions disappearing immediately because of the onblur event on the input element. So I want to check in the OnBlur function if one specific element has been clicked, and if so, ignore the blur event.

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• Intercept Properties With Castle Windsor IInterceptor

  - by jeffn825

  Does anyone have a suggestion on a better way to intercept a properties with Castle DynamicProxy? Specifcally, I need the PropertyInfo that I'm intercepting, but it's not directly on the IInvocation, so what I do is: public static PropertyInfo GetProperty(this MethodInfo method) { bool takesArg = method.GetParameters().Length == 1; bool hasReturn = method.ReturnType != typeof(void); if (takesArg == hasReturn) return null; if (takesArg) { return method.DeclaringType.GetProperties() .Where(prop => prop.GetSetMethod() == method).FirstOrDefault(); } else { return method.DeclaringType.GetProperties() .Where(prop => prop.GetGetMethod() == method).FirstOrDefault(); } } Then in my IInterceptor: #region IInterceptor Members public void Intercept(IInvocation invocation) { bool doSomething = invocation.Method.GetProperty().GetCustomAttributes(true).OfType<SomeAttribute>().Count() > 0; } #endregion Thanks.

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• Locking behaviour is different via network shares

  - by MattH

  I have been trying to lock a file so that other cloned services cannot access the file. I then read the file, and then move the file when finished. The Move is allowed by using FileShare.Delete. However in later testing, we found that this approach does not work if we are looking at a network share. I appreciate my approach may not have been the best, but my specific question is: Why does the below demo work against the local file, but not against the network file? The more specific you can be the better, as I've found very little information in my searches that indicates network shares behave differently to local disks. string sourceFile = @"C:\TestFile.txt"; string localPath = @"C:\MyLocalFolder\TestFile.txt"; string networkPath = @"\\MyMachine\MyNetworkFolder\TestFile.txt"; File.WriteAllText(sourceFile, "Test data"); if (!File.Exists(localPath)) File.Copy(sourceFile, localPath); foreach (string path in new string[] { localPath, networkPath }) { using (FileStream fsLock = File.Open(path, FileMode.Open, FileAccess.ReadWrite, (FileShare.Read | FileShare.Delete))) { string target = path + ".out"; File.Move(path, target); //This is the point of failure, when working with networkPath if (File.Exists(target)) File.Delete(target); } if (!File.Exists(path)) File.Copy(sourceFile, path); }

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• C++ Serialization Clean XML Similar to XSTREAM

  - by disown

  I need to write a linux c++ app which saves it settings in XML format (for easy hand editing) and also communicates with existing apps through XML messages over sockets and HTTP. Problem is that I haven't been able to find any intelligent libs to help me, I don't particular feel like writing DOM or SAX code just to write and read some very simple messages. Boost Serialization was almost a match, but it adds a lot of boost-specific data to the xml it generates. This obviously doesn't work well for interchange formats. I'm wondering if it is possible to make Boost Serialization or some other c++ serialization library generate clean xml. I don't mind if there are some required extra attributes - like a version attribute, but I'd really like to be able to control their naming and also get rid of 'features' that I don't use - tracking_level and class_id for instance. Ideally I would just like to have something similar to xstream in Java. I am aware of the fact that c++ lacks introspection and that it is therefore necessary to do some manual coding - but it would be nice if there was a clean solution to just read and write simple XML without kludges! If this cannot be done I am also interested in tools where the XML schema is the canonical resource (contract first) - a good JAXB alternative to C++. So far I have only found commercial solutions like CodeSynthesis XSD. I would prefer open source solutions. I have tried gSoap - but it generates really ugly code and it is also SOAP-specific. In desperation I also started looking at alternative serialization formats for protobuffers. This exists - but only for Java! It really surprises me that protocol buffers seems to be a better supported data interchange format than XML. I'm going mad just finding libs for this app and I really need some new ideas. Anyone?

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• How can I apply a PSSM efficiently?

  - by flies

  I am fitting for position specific scoring matrices (PSSM aka Position Specific Weight Matrices). The fit I'm using is like simulated annealing, where I the perturb the PSSM, compare the prediction to experiment and accept the change if it improves agreement. This means I apply the PSSM millions of times per fit; performance is critical. In my particular problem, I'm applying a PSSM for an object of length L (~8 bp) at every position of a DNA sequence of length M (~30 bp) (so there are M-L+1 valid positions). I need an efficient algorithm to apply a PSSM. Can anyone help improve performance? My best idea is to convert the DNA into some kind of a matrix so that applying the PSSM is matrix multiplication. There are efficient linear algebra libraries out there (e.g. BLAS), but I'm not sure how best to turn an M-length DNA sequence into a matrix M x 4 matrix and then apply the PSSM at each position. The solution needs to work for higher order/dinucleotide terms in the PSSM - presumably this means representing the sequence-matrix for mono-nucleotides and separately for dinucleotides. My current solution iterates over each position m, then over each letter in word from m to m+L-1, adding the corresponding term in the matrix. I'm storing the matrix as a multi-dimensional STL vector, and profiling has revealed that a lot of the computation time is just accessing the elements of the PSSM (with similar performance bottlenecks accessing the DNA sequence). If someone has an idea besides matrix multiplication, I'm all ears.

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• Setting up ehcache replication - what multicast settings do I need?

  - by Darren Greaves

  I am trying to set up ehcache replication as documented here: http://ehcache.sourceforge.net/EhcacheUserGuide.html#id.s22.2 This is on a Windows machine but will ultimately run on Solaris in production. The instructions say to set up a provider as follows: <cacheManagerPeerProviderFactory class="net.sf.ehcache.distribution.RMICacheManagerPeerProviderFactory" properties="peerDiscovery=automatic, multicastGroupAddress=230.0.0.1, multicastGroupPort=4446, timeToLive=32"/> And a listener like this: <cacheManagerPeerListenerFactory class="net.sf.ehcache.distribution.RMICacheManagerPeerListenerFactory" properties="hostName=localhost, port=40001, socketTimeoutMillis=2000"/> My questions are: Are the multicast IP address and port arbitrary (I know the address has to live within a specific range but do they have to be specific numbers)? Do they need to be set up in some way by our system administrator (I am on an office network)? I want to test it locally so am running two separate tomcat instances with the above config. What do I need to change in each one? I know both the listeners can't listen on the same port - but what about the provider? Also, are the listener ports arbitrary too? I've tried setting it up as above but in my testing the caches don't appear to be replicated - the value added in one tomcat's cache is not present in the other cache. Is there anything I can do to debug this situation (other than packet sniffing)? Thanks in advance for any help, been tearing my hair out over this one!

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• Why aren't google api clients built on top of Apache's Abdera project ?

  - by lisak

  Hey, Could anybody please explain that to me? As far as I can see, the developers of java's google api client library are reinventing the wheel. It's like writing a new JDK for a Java project. I'm aware of the fact that google data protocol is a little specific re atom publishing, but if one needs to use some of the fancy extensions and features that Apache Abdera project offers for this protocol, it is better not to use google api client library and implement the client from scratch with Abdera... And I'm sure that in a lot of cases its features such as Abdera's JCR adapter would become very handy for google docs, google translator toolkit and others. Now it's great that there is a google api client library to be used for google docs, but what am I going to do with the documents? I believe that in more than a half cases there is also a repository or database on the other side. And in that case, abdera is needed, not the simple google api clients that are only marshalling/unmarshalling the feeds... In fact, there is something to persist in all of the google APIs. It would make sense, if google decided to invest the effort into Abdera enhancement... This doesn't... Also for the question to be more specific: How are you developing google api clients, that need entry persistence (JCR for instance) ? What would be the best way to integrate a google api client library with Apache Abdera ?

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• Turing Machine & Modern Computer

  - by smwikipedia

  I heard a lot that modern computers are based on Turing machine. I'd like to share my understanding and hear your comments. I think the computer is a big general-purpose Turing machine. Each program we write is a small specific-purpose Turing machine. The classical Turing machine do its job based on the input and its current state inside and so do our programs. Let's take a running program (a process) as an example. We know that in the process's address space, there's areas for stack, heap, and code. A classical Turing machine doesn't have the ability to remember many things, so we borrow the concept of stack from the push-down automaton. The heap and stack areas contains the state of our specific-purpose Turing machine (our program). The code area represents the logic of this small Turing machine. And various I/O devices supply input to this Turing machine. The above is my naive understanding about the working paradigm of modern computer. I couln't wait to hear your comments. Thanks very much.

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• Windows Task Scheduler: IAction.QueryInterface() returns an error I cannot find a definition for

  - by Sascha

  Hello I am attempting to schedule a task (to open an .exe at a specific time) using C++ win32. But at one specific point I am getting an error, I have searched & searched to try & find the definition of this error but I cannot find it? Do you know what this error means: Hexadecimal: 80004003 Decimal: 2147500035 I wont post the whole function because its rather long (unless you may need it to determine the error context?). The code I am using (that causes the error) is the following: // QI for the executable task pointer. hr = action -> QueryInterface( IID_IExecAction, (void**) execAction ); action -> Release(); if( FAILED(hr) ) { printf("QueryInterface call failed for IExecAction: %x %X %u \n", hr, hr, hr ); rootFolder -> Release(); task -> Release(); CoUninitialize(); return false; } The output is: QueryInterface call failed for IExecAction: 80004003 80004003 2147500035

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• Embedding Lua functions as member variables in Java

  - by Zarion

  Although the program I'm working on is in Java, answering this from a C perspective is also fine, considering that most of this is either language-agnostic, or happens on the Lua side of things. In the outline I have for the architecture of a game I'm programming, individual types of game objects within a particular class (eg: creatures, items, spells, etc.) are loaded from a data file. Most of their properties are simple data types, but I'd like a few of these members to actually contain simple scripts that define, for example, what an item does when it's used. The scripts will be extremely simple, since all fundamental game actions will be exposed through an API from Java. The Lua is simply responsible for stringing a couple of these basic functions together, and setting arguments. The question is largely about the best way to store a reference to a specific Lua function as a member of a Java class. I understand that if I store the Lua code as a string and call lua_dostring, Lua will compile the code fresh every time it's called. So the function needs to be defined somehow, and a reference to this specific function wrapped in a Java function object. One possibility that I've considered is, during the data loading process, when the loader encounters a script definition in a data file, it extracts this string, decorates the function name using the associated object's unique ID, calls lua_dostring on the string containing a full function definition, and then wraps the generated function name in a Java function object. A function declared in script run with lua_dostring should still be added to the global function table, correct? I'm just wondering if there's a better way of going about this. I admit that my knowledge of Lua at this point is rather superficial and theoretical, so it's possible that I'm overlooking something obvious.

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• vim opens my folds on paste. how to prevent that ?

  - by Stefano Borini

  There's something weird going on in my fortran folding. This is the example file module foo contains subroutine hello() end subroutine hello subroutine hello() end subroutine subroutine hello() end subroutine end module foo subroutine hello() end subroutine subroutine hello() end subroutine subroutine hello() end subroutine and this is the vimrc syntax on au! BufRead,BufNewFile *.f90 setfiletype fortran set foldmethod=syntax let fortran_fold=1 The annoying thing is the following. If I cut (dd) and paste (P) a folded subroutine outside the module/end module block, the freshly pasted fold stay closed. If I paste it inside the module/end module block, the newly pasted folded region appears instead unfolded. Can you reproduce the issue (vim 7.2 here) and do you know any workaround/fix ?

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• How to design this class hierarchy?

  - by devoured elysium

  I have defined an Event class: Event and all the following classes inherit from Event: AEvent BEvent CEvent DEvent Now, with the info I gather from all these Event classes, I will make a chart. With AEvent and BEvent, I will generate points for that chart, while with CEvent and DEvent I will paint certain regions of the chart. Now, how should I signal this in my class hierarchy? Should I make AEvent and BEvent inherit from PointEvent while CEvent and DEvent inherit from RegionEvent, being that both RegionEvent and PointEvent inherit from Event? Should I add a field with an Enum to Event with 2 values, Point and Region, and each of the child classes set their value to it? Should I use some kind of pattern here? Which one? Thanks.

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• Simple ASP.NET MVC views without writing a controller

  - by Jake Stevenson

  We're building a site that will have very minimal code, it's mostly just going to be a bunch of static pages served up. I know over time that will change and we'll want to swap in more dynamic information, so I've decided to go ahead and build a web application using ASP.NET MVC2 and the Spark view engine. There will be a couple of controllers that will have to do actual work (like in the /products area), but most of it will be static. I want my designer to be able to build and modify the site without having to ask me to write a new controller or route every time they decide to add or move a page. So if he wants to add a "http://mysite.com/News" page he can just create a "News" folder under Views and put an index.spark page within it. Then later if he decides he wants a /News/Community page, he can drop a community.spark file within that folder and have it work. I'm able to have a view without a specific action by making my controllers override HandleUnknownAction, but I still have to create a controller for each of these folders. It seems silly to have to add an empty controller and recompile every time they decide to add an area to the site. Is there any way to make this easier, so I only have to write a controller and recompile if there's actual logic to be done? Some sort of "master" controller that will handle any requests where there was no specific controller defined?

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• How to determine which source files are required for an Eclipse run configuration

  - by isme

  When writing code in an Eclipse project, I'm usually quite messy and undisciplined in how I create and organize my classes, at least in the early hacky and experimental stages. In particular, I create more than one class with a main method for testing different ideas that share most of the same classes. If I come up with something like a useful app, I can export it to a runnable jar so I can share it with friends. But this simply packs up the whole project, which can become several megabytes big if I'm relying on large library such as httpclient. Also, if I decide to refactor my lump of code into several projects once I work out what works, and I can't remember which source files are used in a particular run configuration, all I can do it copy the main class to a new project and then keep copying missing types till the new project compiles. Is there a way in Eclipse to determine which classes are actually used in a particular run configuration? EDIT: Here's an example. Say I'm experimenting with web scraping, and so far I've tried to scrape the search-result pages of both youtube.com and wrzuta.pl. I have a bunch of classes that implement scraping in general, a few that are specific to each of youtube and wrzuta. On top of this I have a basic gui common to both scrapers, but a few wrzuta- and youtube-specific buttons and options. The WrzutaGuiMain and YoutubeGuiMain classes each contain a main method to configure and show the gui for each respective website. Can Eclipse look at each of these to determine which types are referenced?

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• PHP - "Fat Free Framework" Find Methods and Showing Results in Template

  - by user1672808

  Just started trying the "Fat Free Framework" I'm building a site using a MySQL DB with 265 fields, and 5000+ rows in the DB; I can load() a specific record easily, no problems. When using find(), afind(), and even "select()", template will show blank lines or lines with "filler" text, with the correct number of rows for the query results, but no text/data from the DB itself; Same problem whether using objects or simply arrays from result (afind() and find()). I've copied/pasted the code verbatim from examples and from documentation, with only the DB specific items changed. Still, no luck. CODE IN PHP FILE (function from CLASS): static function home() { $featured=new Axon('boats'); $F3::set('boatlist',$featured->afind('D_CustomerID=173')); F3::set('content',TEMPLATE_DIR .'/home.html'); echo Template::serve(TEMPLATE_DIR .'/layout.html'); } TEMPLATE home.html: <div class="span8"> <h3> Featured Boats </h3> <F3:repeat group="{{@boatlist}}" value="{{@boat}}"> <div style="margin-left: 2em" class="thumbnails"> <p> <a href="boat/{{@boat['D_BoatNum']}}">{{trim(@boat['D_Description'])}}</a> by {{@boat['D_CustomerID']}} </p> <p> {{@boat['D_Price']}} </p> </div> </F3:repeat> </div> The number of rows this produces coincides with the correct number of rows in the DB. However, the actual data from each field does not show. Any ideas?

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• wopen calls when porting to Linux

  - by laura

  I have an application which was developed under Windows, but for gcc. The code is mostly OS-independent, with very few classes which are Windows specific because a Linux port was always regarded as necessary. The API, especially that which gets called as a direct result of user interaction, is using wide char arrays instead of char arrays (as a side note, I cannot change the API itself - at this point, std::wstring cannot be used). These are considered as encoded in UTF-16. In some places, the code opens files, mostly using the windows-specific _wopen function call. The problem with this is there is no wopen-like substitute for Linux because Linux "only deals with bytes". The question is: how do I port this code ? What if I wanted to open a file with the name "something™.log", how would I go about doing so in Linux ? Is a cast to char* sufficient, would the wide chars be picked up automatically based on the locale (probably not) ? Do I need to convert manually ? I'm a bit confused regarding this, perhaps someone could point me to some documentation regarding the matter.

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• How do I get the collection of Model State Errors in ASP.NET MVC?

  - by Ryan Montgomery

  How do I get the collection of errors in a view? I don't want to use the Html Helper Validation Summary or Validation Message. Instead I want to check for errors and if any display them in specific format. Also on the input controls I want to check for a specific property error and add a class to the input. P.S. I'm using the Spark View Engine but the idea should be the same. So I figured I could do something like... <if condition="${ModelState.Errors.Count > 0}"> DispalyErrorSummary() </if> ....and also... <input type="text" value="${Model.Name}" class="?{ModelState.Errors["Name"] != string.empty} error" /> .... Or something like that. UPDATE My final solution looked like this: <input type="text" value="${ViewData.Model.Name}" class="text error?{!ViewData.ModelState.IsValid && ViewData.ModelState["Name"].Errors.Count() > 0}" id="Name" name="Name" /> This only adds the error css class if this property has an error.

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• Setting a "dependency property" in code

  - by Matt B

  I'm on a roll today... I have the following code delaring a dependency property inside a class called ActionScreen: #region Dependency Properties & Methods public string DescriptionHeader { get { return (string)GetValue(DescriptionHeaderProperty); } set { SetValue(DescriptionHeaderProperty, value); } } // Using a DependencyProperty as the backing store for DescriptionHeader. This enables animation, styling, binding, etc... public static readonly DependencyProperty DescriptionHeaderProperty = DependencyProperty.Register("DescriptionHeader", typeof(string), typeof(ActionScreen), new UIPropertyMetadata("xxx")); #endregion I bind to this property in my Xaml as so: <GridViewColumn DisplayMemberBinding="{Binding Description}" Header="{Binding DescriptionHeader}" Width="350" /> Now I want to be able to set the parameter from my code behind when I recieve an event - but it's not working: public string DescColText { set { this.Dispatcher.Invoke(DispatcherPriority.Normal, new Action(delegate() { DescriptionHeader = value; })); } }

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• Basic syntax for an animation loop?

  - by Moshe

  I know that jQuery, for example, can do animation of sorts. I also know that at the very core of the animation, there must me some sort of loop doing the animation. What is an example of such a loop? A complete answer should ideally answer the following questions: What is a basic syntax for an effective animation recursion that can animate a single property of a particular object at a time? The function should be able to vary its target object and property of the object. What arguments/parameters should it take? What is a good range of reiterating the loop? In milliseconds? (Should this be a parameter/argument to the function?) REMEMBER: The answer is NOT necessarily language specific, but if you are writing in a specific language, please specify which one. Error handling is a plus. {Nothing is more irritating (for our purposes) than an animation that does something strange, like stopping halfway through.} Thanks!

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• Adaptive user interface/environment algorithm

  - by WowtaH

  Hi all, I'm working on an information system (in C#) that (while my users use it) gathers statistical data on what pieces of information (tables & records) each user is requesting the most, and what parts of the interface he/she uses most. I'm using this statistical data to make the application adaptive to the user's needs, both in the way the interface presents itself (eg: tab/pane-ordering) as in the way of using the frequently viewed information to (eg:) show higher in search results/suggestion-lists. What i'm looking for is an algorithm/formula to determine the current 'hotness'/relevance of these objects for a specific user. A simple 'hitcounter' for each object won't be sufficient because the user might view some information quite frequently for a period of time, and then moving on to the next, making the old information less relevant. So i think my algorithm also needs some sort of sliding/historical principle to account for the changing popularity of the objects in the application over time. So, the question is: Does anybody have some sort of algorithm that accounts for that 'popularity over time' ? Preferably with some explanation on the parameters :) Thanks! PS I've looked at other posts like http://stackoverflow.com/questions/32397/popularity-algorithm but i could't quite port it to my specific case. Any help is appreciated.

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• Windsor Method interception (AOP)

  - by Allan

  Hi there guys, I'm trying to create interceptors for specific methods but I'm having a hard time. I can't bind an aspect to a specific method. I create the faicilities most of examples show but it still doesn't work. Can anyone give me an example of how to do this? I prefer xml conifguration, if possible. Another question, I have this code: <component id="SampleAspect" service="WindsorSample.Aspect.SampleAspect, WindsorSample" type="WindsorSample.Aspect.SampleAspect, WindsorSample"> </component> <component id="HtmlTitleRetriever" type="WindsorSample.DummyObject, WindsorSample"> <parameters> <interceptors> <interceptor>${SampleAspect}</interceptor> </interceptors> </parameters> </component> Then... IWindsorContainer container = new WindsorContainer(new XmlInterpreter()); IDummyObject retriever = container.Resolve<DummyObject>(); retriever.SomeMethod(); This aspect is not executed. Am I missing something? Am I using the wrong approach for aop? Thanks

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• Emulating Dynamic Dispatch in C++ based on Template Parameters

  - by Jon Purdy

  This is heavily simplified for the sake of the question. Say I have a hierarchy: struct Base { virtual int precision() const = 0; }; template<int Precision> struct Derived : public Base { typedef Traits<Precision>::Type Type; Derived(Type data) : value(data) {} virtual int precision() const { return Precision; } Type value; }; I want a function like: Base* function(const Base& a, const Base& b); Where the specific type of the result of the function is the same type as whichever of first and second has the greater Precision; something like the following pseudocode: template<class T> T* operation(const T& a, const T& b) { return new T(a.value + b.value); } Base* function(const Base& a, const Base& b) { if (a.precision() > b.precision()) return operation((A&)a, A(b.value)); else if (a.precision() < b.precision()) return operation(B(a.value), (B&)b); else return operation((A&)a, (A&)b); } Where A and B are the specific types of a and b, respectively. I want f to operate independently of how many instantiations of Derived there are. I'd like to avoid a massive table of typeid() comparisons, though RTTI is fine in answers. Any ideas?

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• OpenGL render vs. own Phong Illumination Implementation

  - by Myx

  Hello: I have implemented a Phong Illumination Scheme using a camera that's centered at (0,0,0) and looking directly at the sphere primitive. The following are the relevant contents of the scene file that is used to view the scene using OpenGL as well as to render the scene using my own implementation: ambient 0 1 0 dir_light 1 1 1 -3 -4 -5 # A red sphere with 0.5 green ambiance, centered at (0,0,0) with radius 1 material 0 0.5 0 1 0 0 1 0 0 0 0 0 0 0 0 10 1 0 sphere 0 0 0 0 1 The resulting image produced by OpenGL. The image that my rendering application produces. As you can see, there are various differences between the two: The specular highlight on my image is smaller than the one in OpenGL. The diffuse surface seems to not diffuse in the correct way, resulting in the yellow region to be unneccessarily large in my image, whereas in OpenGL there's a nice dark green region closer to the bottom of the sphere The color produced by OpenGL is much darker than the one in my image. Those are the most prominent three differences that I see. The following is my implementation of the Phong illumination: R3Rgb Phong(R3Scene *scene, R3Ray *ray, R3Intersection *intersection) { R3Rgb radiance; if(intersection->hit == 0) { radiance = scene->background; return radiance; } R3Vector normal = intersection->normal; R3Rgb Kd = intersection->node->material->kd; R3Rgb Ks = intersection->node->material->ks; // obtain ambient term R3Rgb intensity_ambient = intersection->node->material->ka*scene->ambient; // obtain emissive term R3Rgb intensity_emission = intersection->node->material->emission; // for each light in the scene, obtain calculate the diffuse and specular terms R3Rgb intensity_diffuse(0,0,0,1); R3Rgb intensity_specular(0,0,0,1); for(unsigned int i = 0; i < scene->lights.size(); i++) { R3Light *light = scene->Light(i); R3Rgb light_color = LightIntensity(scene->Light(i), intersection->position); R3Vector light_vector = -LightDirection(scene->Light(i), intersection->position); // calculate diffuse reflection intensity_diffuse += Kd*normal.Dot(light_vector)*light_color; // calculate specular reflection R3Vector reflection_vector = 2.*normal.Dot(light_vector)*normal-light_vector; reflection_vector.Normalize(); R3Vector viewing_vector = ray->Start() - intersection->position; viewing_vector.Normalize(); double n = intersection->node->material->shininess; intensity_specular += Ks*pow(max(0.,viewing_vector.Dot(reflection_vector)),n)*light_color; } radiance = intensity_emission+intensity_ambient+intensity_diffuse+intensity_specular; return radiance; } Here are the related LightIntensity(...) and LightDirection(...) functions: R3Vector LightDirection(R3Light *light, R3Point position) { R3Vector light_direction; switch(light->type) { case R3_DIRECTIONAL_LIGHT: light_direction = light->direction; break; case R3_POINT_LIGHT: light_direction = position-light->position; break; case R3_SPOT_LIGHT: light_direction = position-light->position; break; } light_direction.Normalize(); return light_direction; } R3Rgb LightIntensity(R3Light *light, R3Point position) { R3Rgb light_intensity; double distance; double denominator; if(light->type != R3_DIRECTIONAL_LIGHT) { distance = (position-light->position).Length(); denominator = light->constant_attenuation + light->linear_attenuation*distance + light->quadratic_attenuation*distance*distance; } switch(light->type) { case R3_DIRECTIONAL_LIGHT: light_intensity = light->color; break; case R3_POINT_LIGHT: light_intensity = light->color/denominator; break; case R3_SPOT_LIGHT: R3Vector from_light_to_point = position - light->position; light_intensity = light->color*( pow(light->direction.Dot(from_light_to_point), light->angle_attenuation)); break; } return light_intensity; } I would greatly appreciate any suggestions as to any implementation errors that are apparent. I am wondering if the differences could be occurring simply because of the gamma values used for display by OpenGL and the default gamma value for my display. I also know that OpenGL (or at least tha parts that I was provided) can't cast shadows on objects. Not that this is relevant for the point in question, but it just leads me to wonder if it's simply display and capability differences between OpenGL and what I am trying to do. Thank you for your help.

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