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  • Events + Adapter Pattern

    - by Stretto
    I have an adapter pattern on a generic class that essentially adapts between types: class A<T> { event EventHandler e; } class Aadapter<T1, T2> : A<T1> { A<T2> a; Aadapter(A<T2> _a) { a = _a; } } The problem is that A contains an event. I effectively want all event handlers assigned to Adapter to fall through to a. It would be awesome if I could assign the a's event handler to adapter's event handler but this is impossible? The idea here is that A is almost really just A but we need a way to adapt the them. Because of the way event's work I can't how to efficiently do it except manually add two event handlers and when they are called they "relay" the to the other event. This isn't pretty though and it would seem much nicer if I could have something like class A<T> { event EventHandler e; } class Aadapter<T1, T2> : A<T1> { event *e; A<T2> a; Aadapter(A<T2> _a) { a = _a; e = a.e; } } in a sense we have a pointer to the event that we can assign a2's event to. I doubt there is any simple way but maybe someone has some idea to make it work. (BTW, I realize this is possible with virtual events but I'd like to avoid this if at all possible)

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  • Why can a public class not inherit from a less visible one?

    - by Dan Tao
    I apologize if this question has been asked before. I've searched SO somewhat and wasn't able to find it. I'm just curious what the rationale behind this design was/is. Obviously I understand that private/internal members of a base type cannot, nor should they, be exposed through a derived public type. But it seems to my naive thinking that the "hidden" parts could easily remain hidden while some base functionality is still shared and a new interface is exposed publicly. I'm thinking of something along these lines: Assembly X internal class InternalClass { protected virtual void DoSomethingProtected() { // Let's say this method provides some useful functionality. // Its visibility is quite limited (only to derived types in // the same assembly), but at least it's there. } } public class PublicClass : InternalClass { public void DoSomethingPublic() { // Now let's say this method is useful enough that this type // should be public. What's keeping us from leveraging the // base functionality laid out in InternalClass's implementation, // without exposing anything that shouldn't be exposed? } } Assembly Y public class OtherPublicClass : PublicClass { // It seems (again, to my naive mind) that this could work. This class // simply wouldn't be able to "see" any of the methods of InternalClass // from AssemblyX directly. But it could still access the public and // protected members of PublicClass that weren't inherited from // InternalClass. Does this make sense? What am I missing? }

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  • Unit test approach for generic classes/methods

    - by Greg
    Hi, What's the recommended way to cover off unit testing of generic classes/methods? For example (referring to my example code below). Would it be a case of have 2 or 3 times the tests to cover testing the methods with a few different types of TKey, TNode classes? Or is just one class enough? public class TopologyBase<TKey, TNode, TRelationship> where TNode : NodeBase<TKey>, new() where TRelationship : RelationshipBase<TKey>, new() { // Properties public Dictionary<TKey, NodeBase<TKey>> Nodes { get; private set; } public List<RelationshipBase<TKey>> Relationships { get; private set; } // Constructors protected TopologyBase() { Nodes = new Dictionary<TKey, NodeBase<TKey>>(); Relationships = new List<RelationshipBase<TKey>>(); } // Methods public TNode CreateNode(TKey key) { var node = new TNode {Key = key}; Nodes.Add(node.Key, node); return node; } public void CreateRelationship(NodeBase<TKey> parent, NodeBase<TKey> child) { . . .

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  • refactoring my code. My headers (Header Guard Issues)

    - by numerical25
    I had a post similar to this awhile ago based on a error I was getting. I was able to fix it but since then I been having trouble doing things because headers keep blocking other headers from using code. Honestly, these headers are confusing me and if anyone has any resources that will address these types of issues, that will be helpful. What I essentially want to do is be able to have rModel.h be included inside RenderEngine.h. every time I add rModel.h to RenderEngine.h, rModel.h is no longer able to use RenderEngine.h. (rModel.h has a #include of RenderEngine.h as well). So in a nutshell, RenderEngine and rModel need to use each others functionalities. On top of all this confusion, the Main.cpp needs to use RenderEngine. stdafx.h #include "targetver.h" #define WIN32_LEAN_AND_MEAN // Exclude rarely-used stuff from Windows headers // Windows Header Files: #include <windows.h> // C RunTime Header Files #include <stdlib.h> #include <malloc.h> #include <memory.h> #include <tchar.h> #include "resource.h" main.cpp #include "stdafx.h" #include "RenderEngine.h" #include "rModel.h" // Global Variables: RenderEngine go; rModel *g_pModel; ...code........... rModel.h #ifndef _MODEL_H #define _MODEL_H #include "stdafx.h" #include <vector> #include <string> #include "rTri.h" #include "RenderEngine.h" ........Code RenderEngine.h #pragma once #include "stdafx.h" #include "d3d10.h" #include "d3dx10.h" #include "dinput.h" #include "rModel.h" .......Code......

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  • C# Automatic Properties - Still null after +=?

    - by Sam Schutte
    This seems like a bug to me... I accept that automatic properties, defined as such: public decimal? Total { get; set; } Will be null when they are first accessed. They haven't been initialized, so of course they are null. But, even after setting their value through +=, this decimal? still remains null. So after: Total += 8; Total is still null. How can this be correct? I understand that it's doing a (null + 8), but seems strange that it doesn't pick up that it means it should just be set to 8... Addendums: I made the "null + 8" point in my question - but notice that it works with strings. So, it does null + "hello" just fine, and returns "hello". Therefore, behind the scenes, it is initializing the string to a string object with the value of "hello". The behavior should be the same for the other types, IMO. It might be because a string can accept a null as a value, but still, a null string is not an initialized object, correct? Perhaps it's just because a string isn't a nullable...

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  • short-cutting equality checking in F#?

    - by John Clements
    In F#, the equality operator (=) is generally extensional, rather than intensional. That's great! Unfortunately, it appears to me that F# does not use pointer equality to short-cut these extensional comparisons. For instance, this code: type Z = MT | NMT of Z ref // create a Z: let a = ref MT // make it point to itself: a := NMT a // check to see whether it's equal to itself: printf "a = a: %A\n" (a = a) ... gives me a big fat segmentation fault[*], despite the fact that 'a' and 'a' both evaluate to the same reference. That's not so great. Other functional languages (e.g. PLT Scheme) get this right, using pointer comparisons conservatively, to return 'true' when it can be determined using a pointer comparison. So: I'll accept the fact that F#'s equality operator doesn't use short-cutting; is there some way to perform an intensional (pointer-based) equality check? The (==) operator is not defined on my types, and I'd love it if someone could tell me that it's available somehow. Or tell me that I'm wrong in my analysis of the situation: I'd love that, too... [*] That would probably be a stack overflow on Windows; there are things about Mono that I'm not that fond of...

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  • Nginx Rails app can't deploy

    - by user3596718
    I have an issue with my rails application running with passenger and nginx hosted in Ubuntu 12.04. In the nginx.conf file below, my "example.com" (Regular HTML) and "redmine.example.com" (Rails app) are working perfectly, but my "crete.example.com" (Another Rails app) is showing "502 bad gateway". I have them both hosted in /var/data with the same permissions and ownerships, also tried different ports, I can't think of something else to try. worker_processes 1; events { worker_connections 1024; } http { passenger_root /usr/lib/ruby/vendor_ruby/phusion_passenger/locations.ini; include mime.types; default_type application/octet-stream; sendfile on; keepalive_timeout 65; server{ listen 80; server_name example.com; root /opt/nginx/html; } server{ server_name redmine.example.com; root /var/data/redmine/public; passenger_enabled on; location ~ ^/<SUBURI>(/.*|$){ alias /var/data/redmine/public$1; passenger_base_uri /redmine; passenger_app_root /var/data/redmine; passenger_document_root /var/data/redmine/public; passenger_enabled on;} } server{ server_name crete.example.com; root /var/data/crete/public; passenger_enabled on; location ~ ^/<SUBURI>(/.*|$){ alias /var/data/crete/public$1; passenger_base_uri /crete; passenger_app_root /var/data/crete; passenger_document_root /var/data/crete/public; passenger_enabled on;} } } This are my Ruby and Rails versions: ruby 2.0.0p451 (2014-02-24 revision 45167) [x86_64-linux] Rails 4.1.0 My nginx error.log 2014/05/02 12:29:50 [error] 3343#0: *4 upstream prematurely closed connection while reading response header from upstream, client: xxx.xx.xx.xx, server: crete.example.com, request: "GET / HTTP/1.1", upstream: "passenger:/tmp/passenger.1.0.3 323/generation-0/request:", host: "crete.example.com" Any other conf file you might need to solve this don't hesitate to ask.

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  • in haskell, why do I need to specify type constraints, why can't the compiler figure them out?

    - by Steve
    Consider the function, add a b = a + b This works: *Main> add 1 2 3 However, if I add a type signature specifying that I want to add things of the same type: add :: a -> a -> a add a b = a + b I get an error: test.hs:3:10: Could not deduce (Num a) from the context () arising from a use of `+' at test.hs:3:10-14 Possible fix: add (Num a) to the context of the type signature for `add' In the expression: a + b In the definition of `add': add a b = a + b So GHC clearly can deduce that I need the Num type constraint, since it just told me: add :: Num a => a -> a -> a add a b = a + b Works. Why does GHC require me to add the type constraint? If I'm doing generic programming, why can't it just work for anything that knows how to use the + operator? In C++ template programming, you can do this easily: #include <string> #include <cstdio> using namespace std; template<typename T> T add(T a, T b) { return a + b; } int main() { printf("%d, %f, %s\n", add(1, 2), add(1.0, 3.4), add(string("foo"), string("bar")).c_str()); return 0; } The compiler figures out the types of the arguments to add and generates a version of the function for that type. There seems to be a fundamental difference in Haskell's approach, can you describe it, and discuss the trade-offs? It seems to me like it would be resolved if GHC simply filled in the type constraint for me, since it obviously decided it was needed. Still, why the type constraint at all? Why not just compile successfully as long as the function is only used in a valid context where the arguments are in Num? Thank you.

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  • Overlay an image over video using OpenGL ES shaders

    - by BlueVoodoo
    I am trying to understand the basic concepts of OpenGL. A week into it, I am still far from there. Once I am in glsl, I know what to do but I find getting there is the tricky bit. I am currently able to pass in video pixels which I manipulate and present. I have then been trying to add still image as an overlay. This is where I get lost. My end goal is to end up in the same fragment shader with pixel data from both my video and my still image. I imagine this means I need two textures and pass on two pixel buffers. I am currently passing the video pixels like this: glGenTextures(1, &textures[0]); //target, texture glBindTexture(GL_TEXTURE_2D, textures[0]); glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR); glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR); glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE); glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE); glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, width, height, 0, GL_BGRA, GL_UNSIGNED_BYTE, buffer); Would I then repeat this process on textures[1] with the second buffer from the image? If so, do I then bind both GL_TEXTURE0 and GL_TEXTURE1? ...and would my shader look something like this? uniform sampler2D videoData; uniform sampler2D imageData; once I am in the shader? It seems no matter what combination I try, image and video always ends up being just video data in both these. Sorry for the many questions merged in here, just want to clear my many assumptions and move on. To clarify the question a bit, what do I need to do to add pixels from a still image in the process described? ("easy to understand" sample code or any types of hints would be appreciated).

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  • Why use shorter VARCHAR(n) fields?

    - by chryss
    It is frequently advised to choose database field sizes to be as narrow as possible. I am wondering to what degree this applies to SQL Server 2005 VARCHAR columns: Storing 10-letter English words in a VARCHAR(255) field will not take up more storage than in a VARCHAR(10) field. Are there other reasons to restrict the size of VARCHAR fields to stick as closely as possible to the size of the data? I'm thinking of Performance: Is there an advantage to using a smaller n when selecting, filtering and sorting on the data? Memory, including on the application side (C++)? Style/validation: How important do you consider restricting colunm size to force non-sensical data imports to fail (such as 200-character surnames)? Anything else? Background: I help data integrators with the design of data flows into a database-backed system. They have to use an API that restricts their choice of data types. For character data, only VARCHAR(n) with n <= 255 is available; CHAR, NCHAR, NVARCHAR and TEXT are not. We're trying to lay down some "good practices" rules, and the question has come up if there is a real detriment to using VARCHAR(255) even for data where real maximum sizes will never exceed 30 bytes or so. Typical data volumes for one table are 1-10 Mio records with up to 150 attributes. Query performance (SELECT, with frequently extensive WHERE clauses) and application-side retrieval performance are paramount.

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  • can I store an id value in array of float type ?

    - by srikanth rongali
    I used, for(id value in values) to get the value from an NSArray. Now I want to store it in 2 dimensional float array[][]. When I try to assign the values to array it is giving error:incompatible types in assignment. I tried to cast the value but I got error: pointer value used where a floating point value was expected. I need to store the values in an 2 dimensional array . How can I make it ? Thank You. @implementation fromFileRead1 NSString *fileNameString; int numberOfEnemies, numberOfValues; -(id)init { if( (self = [super init]) ) { NSString *path = @"/Users/sridhar/Desktop/Projects/exampleOnFile2/enemyDetals.txt"; NSString *contentsOfFile = [[NSString alloc] initWithContentsOfFile:path]; NSArray *lines = [contentsOfFile componentsSeparatedByString:@"\n"]; numberOfEnemies = [lines count]; NSLog(@"The number of Lines: %d", numberOfEnemies); for (id line in lines) { NSLog(@"Line %@", line ); NSString *string1 = line; NSArray *split1 = [string1 componentsSeparatedByString:@","]; numberOfValues = [split1 count]; NSLog(@"The number of values in Row: %d", numberOfValues); for (id value in split1) { NSLog(@"value %@", value); float value1; value1 = [split1 objectAtIndex:2]); NSLog(@"VAlue of Value1 at index 2: %f", value1 ); } } } return self; } @end In enemyDetal.txt I have 1,3,3 2,3,2.8 10,2,1.6

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  • Why do we need serialization in web service

    - by Cloud2010
    I have one webservice: public class Product { public int ProductId { get; set; } public string ProductName { get; set; } } public class Service : System.Web.Services.WebService { public Service () { //Uncomment the following line if using designed components //InitializeComponent(); } [WebMethod] public List<Product> GetItems() { List<Product> productList = new List<Product>() { new Product{ProductId=1,ProductName="Pencil"}, new Product{ProductId=2,ProductName="Pen"} }; return productList; } and in a asp.net application I am consuming it like: localhost.Service s = new localhost.Service(); List<localhost.Product> k = new List<localhost.Product>(); k = s.GetItems().ToList(); // i am getting the values here. now my question is do I need to serialize my webmethod as i am returning custom types? when should we serialize ? is it necessary at all, if yes , then what are the conditions?

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  • getting string.substring(N) not to choke when N > string.length

    - by aape
    I'm writing some code that takes a report from the mainframe and converts it to a spreadsheet. They can't edit the code on the MF to give me a delimited file, so I'm stuck dealing with it as fixed width. It's working okay now, but I need to get it more stable before I release it for testing. My problem is that in any given line of data, say it could have three columns of numbers, each five chars wide at positions 10, 16, and 22. If on this one particular row, there's no data for the last two cols, it won't be padded with spaces; rather, the length of the string will be only 14. So, I can't just blindly have dim s as string = someStream.readline a = s.substring(10, 5) b = s.substring(16, 5) c = s.substring(22, 5) because it'll choke when it substrings past the length of the string. I know I could test the length of the string before processing each row, and I have automated the filling of some of the vsariables using a counter and a loop, and using the counter*theWidthOfTheGivenVariable to jump around, but this project was a dog to start with (come on! turning a report into a spreadsheet?), but there are many different types of rows (it's not just a grid), and the code's getting ugly fast. I'd like this to be clean, clear, and maintainable for the poor sucker that gets this after me. If it matters, here's my code so far (it's really crufty at the moment). You can see some of my/its idiocy in the processSection#data subs So, I'm wondering 1) is there a way baked in to .NET to have string.substring not error when reading past the end of a string without wrapping it in a try...catch? and 2) would it be appropriate in this situation to write a new string class that inherits from string that has a more friendly substring function in it? ETA: Thanks for all the advice and knowledge everyone. I'll go with the extension. Hopefully one of these years, I'll get my chops up enough to pay someone back in kind. :)

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  • Detect that the onscreen keyboard has been displayed on Windows Phone 7

    - by David_001
    Simple question: How do I detect that the onscreen keyboard has been displayed on windows mobile 7? Is there an event I can add a listener to? It takes up about half the screen and I want to scroll the view up when it gets displayed... EDIT: A comment below indicates more clearly what I'm trying to do: I have a textbox input, and as the user types into it an autocomplete dropdown appears below it (like google suggest). By default, the active control (the textbox) scrolls into view when focussed, and the onscreen keyboard is directly below it. The onscreen keyboard appears in front of my autocomplete dropdown - what I want to do is make the screen scroll a little further up, so there's some room for my dropdown to be shown. The windows phone UI design guidelines say: "When the keyboard is deployed, the application should scroll to ensure the active edit control and the caret are in view". This happens fine, it's just the non-active dropdown gets hidden behind the onscreen keyboard. The guidelines also say that an application can choose to show the onscreen keyboard, and can also choose to close it. At the moment i'm stuck, and I don't think (based on my research and the replies to this question) that it's possible to detect that the onscreen keyboard has been displayed. I'm moving my investigation to see if it's possible to determine the "visible area" of the page (width & height in pixels for example), and combine this with an onfocus for the textbox... not sure if this will prove fruitful though.

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  • How to filter List<T> with LINQ and Reflection

    - by Ehsan Sajjad
    i am getting properties via reflection and i was doing like this to iterate on the list. private void HandleListProperty(object oldObject, object newObject, string difference, PropertyInfo prop) { var oldList = prop.GetValue(oldObject, null) as IList; var newList = prop.GetValue(newObject, null) as IList; if (prop.PropertyType == typeof(List<DataModel.ScheduleDetail>)) { List<DataModel.ScheduleDetail> ScheduleDetailsOld = oldList as List<DataModel.ScheduleDetail>; List<DataModel.ScheduleDetail> ScheduleDetailsNew = newList as List<DataModel.ScheduleDetail>; var groupOldSchedules = ScheduleDetailsOld .GroupBy(x => x.HomeHelpID) .SelectMany(s => s.DistinctBy(d => d.HomeHelpID) .Select(h => new { h.HomeHelpID, h.HomeHelpName })); } } Now i am making it generic because there will be coming different types of Lists and i don't want to put if conditions this way i want to write generic code to handle any type of list. I came up with this way: private void HandleListProperty(object oldObject, object newObject, string difference, PropertyInfo prop) { var oldList = prop.GetValue(oldObject, null) as IList; var newList = prop.GetValue(newObject, null) as IList; var ListType = prop.PropertyType; var MyListInstance = Activator.CreateInstance(ListType); MyListInstance = oldList; } i am able to get the items in MyListInstance but as the type will come at runtime i am not getting how to write linq query to filter them, any ideah how to do.

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  • C++ universal data type

    - by Gokul
    I have a universal data type, which is passed by value, but does not maintain the type information. We store only pointers and basic data types(like int, float etc) inside this. Now for the first time, we need to store std::string inside this. So we decided to convert it into std::string* and store it. Then comes the problem of destruction. We don't like to copy the std::string every time. So i am thinking of an approach like this. Say the data type looks like this class Atom { public : enum flags { IS_STRING, IS_EMPTY, HAS_GOT_COPIED, MARKER }; private: void* m_value; std::bitset<MARKER> m_flags; public: ..... Atom( Atom& atm ) { atm.m_flags.set( HAS_GOT_COPIED ); ..... } ..... ~Atom() { if( m_flags.test(IS_STRING) && !m_flags.test(HAS_GOT_COPIED) ) { std::string* val = static_cast<std::string*>(m_value); delete val; } } }; Is this a good approach to find out whether there is no more reference to std::string*? Any comments.. Thanks, Gokul.

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  • Turn based synchronization between threads

    - by Amarus
    I'm trying to find a way to synchronize multiple threads having the following conditions: * There are two types of threads: 1. A single "cyclic" thread executing an infinite loop to do cyclic calculations 2. Multiple short-lived threads not started by the main thread * The cyclic thread has a sleep duration between each cycle/loop iteration * The other threads are allowed execute during the inter-cycle sleep of the cyclic thread: - Any other thread that attempts to execute during an active cycle should be blocked - The cyclic thread will wait until all other threads that are already executing to be finished Here's a basic example of what I was thinking of doing: // Somewhere in the code: ManualResetEvent manualResetEvent = new ManualResetEvent(true); // Allow Externally call CountdownEvent countdownEvent = new CountdownEvent(1); // Can't AddCount a CountdownEvent with CurrentCount = 0 void ExternallyCalled() { manualResetEvent.WaitOne(); // Wait until CyclicCalculations is having its beauty sleep countdownEvent.AddCount(); // Notify CyclicCalculations that it should wait for this method call to finish before starting the next cycle Thread.Sleep(1000); // TODO: Replace with actual method logic countdownEvent.Signal(); // Notify CyclicCalculations that this call is finished } void CyclicCalculations() { while (!stopCyclicCalculations) { manualResetEvent.Reset(); // Block all incoming calls to ExternallyCalled from this point forward countdownEvent.Signal(); // Dirty workaround for the issue with AddCount and CurrentCount = 0 countdownEvent.Wait(); // Wait until all of the already executing calls to ExternallyCalled are finished countdownEvent.Reset(); // Reset the CountdownEvent for next cycle. Thread.Sleep(2000); // TODO: Replace with actual method logic manualResetEvent.Set(); // Unblock all threads executing ExternallyCalled Thread.Sleep(1000); // Inter-cycles delay } } Obviously, this doesn't work. There's no guarantee that there won't be any threads executing ExternallyCalled that are in between manualResetEvent.WaitOne(); and countdownEvent.AddCount(); at the time the main thread gets released by the CountdownEvent. I can't figure out a simple way of doing what I'm after, and almost everything that I've found after a lengthy search is related to producer/consumer synchronization which I can't apply here.

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  • Const Discards Qualifers: C++

    - by user991673
    I'm using OpenGL to render camera perspectives, and a one point in my code I'm trying to take the direction of the light (shown here as type "Vector4") and multiply it by a matrix of type "Matrix4x4" that represents the Modelview transformation (sorry if this is not making any sense, this is for a school project, as such I'm still learning about this stuff) Anyway, my code goes as follows... Vector4 lightDirection = data->dir * follow->getModelviewMatrix().getInverse().getTranspose(); data->dir = lightDirection; setLight(*data); this give me the following error: passing 'const vec4<double>' as 'this' argument of 'vec4<T>& vec4<T>::operator=(const vec4<T>&)[with T = double]' discards qualifiers Again, much of this code is prewritten for the class (namely the vector and matrix types) but if someone could just help me decipher what the error means it would be much appreciated! I can give more information as needed. I figured 'data' or 'data-dir' were const, however I can find no mention of either of them to be. 'dir' is of type SceneLightData, and when its added on I'm doing this: void Scene::addLight(const SceneLightData &sceneLight) { SceneLightData light = sceneLight; m_lights.push_back(&light); } The error occurs on this line: data->dir = lightDirection; EDIT problem solved. thanks everyone! solution: void Scene::addLight(const SceneLightData &sceneLight) { SceneLightData* light = new SceneLightData; *light = sceneLight; m_lights.push_back(light); } and SceneLightData* data = m_lights[i]; data->dir = data->dir * follow->getModelviewMatrix().getInverse().getTranspose(); setLight(*data);

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  • How do I populate an NSMutableArray in one class with another object?

    - by AngeloS
    Hello, I know this is a simple answer, but I can't seem to find the solution. I created an object in its own class and I am trying to populate it with data from another class. For simple data types like NSString, I have no problem, but when trying make an NSMutableArray equal to another NSMutableArray or when I try to populate a NSMutableArray with another objects (like strings), I keep getting exception errors... Here is the object I am trying to populate: #import <Foundation/Foundation.h> @interface RSSFeedList : NSObject { NSString *subject; NSMutableArray *rssfeedDetail; } @property (nonatomic, retain) NSString *subject; @property (nonatomic, retain) NSMutableArray *rssfeedDetail; @end This is how I was able to populate the NSString 'subject' in another class: rssFeedList.subject = @"test"; However, if I follow similar convention within that same class with respect to an Array, it throws an exception: rssFeedList.rssfeedDetail = rssItemDetailArray; Where rssItemDetailArray is a NSMutableArray that I have built in the same class. I have also tried to add items (i tried strings for testing) to the NSMutableArray directly like so to no avail: [rssFeedList.rssfeedDetail addObject:@"test"]; Any ideas?? Thanks in advance!!

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  • How to get a category listing from Magento?

    - by alex
    I want to create a page in Magento that shows a visual representation of the categories.. example CATEGORY product 1 product 2 ANOTHER CATEGORY product 3 My problem is, their database is organised very differently to what I've seen in the past. They have tables dedicated to data types like varchar, int, etc. I assume this is for performance or similiar. I haven't found a way to use MySQL to query the database and get a list of categories. I'd then like to match these categories to products, to get a listing of products for each category. Unfortunately Magento seems to make this very difficult. Also I have not found a method that will work from within a page block.. I have created showcase.phtml and put it in the XML layout and it displays and runs it's PHP code. I was hoping for something easy like looping through $this-getAllCategories(); and then a nested loop inside with something like $category-getChildProducts(); Can anyone help me? Thank you!

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  • "pseudo-atomic" operations in C++

    - by dan
    So I'm aware that nothing is atomic in C++. But I'm trying to figure out if there are any "pseudo-atomic" assumptions I can make. The reason is that I want to avoid using mutexes in some simple situations where I only need very weak guarantees. 1) Suppose I have globally defined volatile bool b, which initially I set true. Then I launch a thread which executes a loop while(b) doSomething(); Meanwhile, in another thread, I execute b=true. Can I assume that the first thread will continue to execute? In other words, if b starts out as true, and the first thread checks the value of b at the same time as the second thread assigns b=true, can I assume that the first thread will read the value of b as true? Or is it possible that at some intermediate point of the assignment b=true, the value of b might be read as false? 2) Now suppose that b is initially false. Then the first thread executes bool b1=b; bool b2=b; if(b1 && !b2) bad(); while the second thread executes b=true. Can I assume that bad() never gets called? 3) What about an int or other builtin types: suppose I have volatile int i, which is initially (say) 7, and then I assign i=7. Can I assume that, at any time during this operation, from any thread, the value of i will be equal to 7? 4) I have volatile int i=7, and then I execute i++ from some thread, and all other threads only read the value of i. Can I assume that i never has any value, in any thread, except for either 7 or 8? 5) I have volatile int i, from one thread I execute i=7, and from another I execute i=8. Afterwards, is i guaranteed to be either 7 or 8 (or whatever two values I have chosen to assign)?

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  • How should I map an abstract class with simple xml in Java?

    - by spderosso
    Hi, I want to achieve the following xml using simple xml framework (http://simple.sourceforge.net/): <events> <course-added date="01/01/2010"> ... </course-added> <course-removed date="01/02/2010"> .... </course-removed> <student-enrolled date="01/02/2010"> ... </student-enrolled> </events> I have the following (but it doesn't achieve the desired xml): @Root(name="events") class XMLEvents { @ElementList(inline=true) ArrayList<XMLEvent> events = Lists.newArrayList(); ... } abstract class XMLEvent { @Attribute(name="date") String dateOfEventFormatted; ... } And different type of XMLNodes that have different information (but are all different types of events) @Root(name="course-added") class XMLCourseAdded extends XMLEvent{ @Element(name="course") XMLCourseLongFormat course; .... } @Root(name="course-removed") class XMLCourseRemoved extends XMLEvent { @Element(name="course-id") String courseId; ... } How should I do the mapping or what should I change in order to be able to achieve de desired xml? Thanks!

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  • Returning JSON or XML for Exceptions in Jersey

    - by Dominic
    My goal is to have an error bean returned on a 404 with a descriptive message when a object is not found, and return the same MIME type that was requested. I have a look up resource, which will return the specified object in XML or JSON based on the URI (I have setup the com.sun.jersey.config.property.resourceConfigClass servlet parameter so I dont need the Accept header. My JAXBContextResolver has the ErrorBean.class in its list of types, and the correct JAXBContext is returned for this class because I can see in the logs). eg: http://foobar.com/rest/locations/1.json @GET @Path("{id}") @Produces({MediaType.APPLICATION_JSON, MediaType.APPLICATION_XML}) public Location getCustomer(@PathParam("id") int cId) { //look up location from datastore .... if (location == null) { throw new NotFoundException("Location" + cId + " is not found"); } } And my NotFoundException looks like this: public class NotFoundException extends WebApplicationException { public NotFoundException(String message) { super(Response.status(Response.Status.NOT_FOUND). entity(new ErrorBean( message, Response.Status.NOT_FOUND.getStatusCode() ) .build()); } } The ErrorBean is as follows: @XmlRootElement(name = "error") public class ErrorBean { private String errorMsg; private int errorCode; //no-arg constructor, property constructor, getter and setters ... } However, I'm always getting a 204 No Content response when I try this. I have hacked around, and if I return a string and specify the mime type this works fine: public NotFoundException(String message) { super(Response.status(Response.Status.NOT_FOUND). entity(message).type("text/plain").build()); } I have also tried returning an ErrorBean as a resource. This works fine: {"errorCode":404,"errorMsg":"Location 1 is not found!"}

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  • C vs C++ function questions

    - by james
    I am learning C, and after starting out learning C++ as my first compiled language, I decided to "go back to basics" and learn C. There are two questions that I have concerning the ways each language deals with functions. Firstly, why does C "not care" about the scope that functions are defined in, whereas C++ does? For example, int main() { donothing(); return 0; } void donothing() { } the above will not compile in a C++ compiler, whereas it will compile in a C compiler. Why is this? Isn't C++ mostly just an extension on C, and should be mostly "backward compatible"? Secondly, the book that I found (Link to pdf) does not seem to state a return type for the main function. I check around and found other books and websites and these also commonly do not specify return types for the main function. If I try to compile a program that does not specify a return type for main, it compiles fine (although with some warnings) in a C compiler, but it doesn't compile in a C++ compiler. Again, why is that? Is it better style to always specify the return type as an integer rather than leaving it out? Thanks for any help, and just as a side note, if anyone can suggest a better book that I should buy that would be great!

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  • Is this a good way to generically deserialize objects?

    - by Damien Wildfire
    I have a stream onto which serialized objects representing messages are dumped periodically. The objects are one of a very limited number of types, and other than the actual sequence of bytes that arrives, I have no way of knowing what type of message it is. I would like to simply try to deserialize it as an object of a particular type, and if an exception is thrown, try again with the next type. I have an interface that looks like this: public interface IMessageHandler<T> where T : class, IMessage { T Handle(string message); } // elsewhere: // (These are all xsd.exe-generated classes from an XML schema.) public class AppleMessage : IMessage { ... } public class BananaMessage : IMessage { ... } public class CoconutMessage : IMessage { ... } Then I wrote a GenericHandler<T> that looks like this: public class GenericHandler<T> : IMessageHandler<T> where T: class, IMessage { public class MessageHandler : IMessageHandler { T IMessageHandler.Handle(string message) { T result = default(T); try { // This utility method tries to deserialize the object with an // XmlSerializer as if it were an object of type T. result = Utils.SerializationHelper.Deserialize<T>(message); } catch (InvalidCastException e) { result = default(T); } return result; } } } Two questions: Using my GenericHandler<T> (or something similar to it), I'd now like to populate a collection with handlers that each handle a different type. Then I want to invoke each handler's Handle method on a particular message to see if it can be deserialized. If I get a null result, move onto the next handler; otherwise, the message has been deserialized. Can this be done? Is there a better way to deserialize data of unknown (but restricted) type?

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