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  • GestureListener's fling method doesn't get called

    - by nosferat
    I'm using SimpleGestureDetector from the libgdx-users Wiki as my InputProcessor. I set it in the created() method: Gdx.input.setInputProcess(new SimpleDirectionGestureDetector(charController)); charController is my class which implements the DirectionListener interface defined in the SimpleDirectionGestureDetector class and it is responsible for moving the player character. However the character doesn't change direction when I'm performing a fling action in any direction. I've checked and the fling() method in the SimpleDirectionGesture class doesn't get called and I have no idea why, since everything seems good. What am I doing wrong?

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  • Class design for calling "the same method" on different classes from one place

    - by betatester07
    Let me introduce my situation: I have Java EE application and in one package, I want to have classes which will act primarily as cache for some data from database, for example: class that will hold all articles for our website class that will hold all categories etc. Every class should have some update() method, which will update data for that class from database and also some other methods for data manipulation specific for that data type. Now, I would like to call update() method for all class instances (there will be exactly one class instance for every class) from one place. What is the best design?

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  • How to ensure that a member variable is initialized before calling a class method

    - by Omkar Ekbote
    There's a class with a parametrized constructor that initializes a member variable. All public methods of the class then use this member variable to do something. I want to ensure that the caller always creates an object using the parametrized constructor (there is also a setter for this member variable) and then call that object's methods. In essence, it should be impossible for the caller to call any method without setting a value to the member variable (either by using the parametrized constructor or the setter). Currently, a caller can simply make an object using the default constructor and then call that object's method - I want to avoid checking whether or not the member variable is set in each and every one of the 20-odd methods of the class (and throw an exception if it is not). Though a runtime solution is acceptable (better than the one I mentioned above); a compile-time solution is preferable so that any developer will not be allowed to make that mistake and then waste hours debuggging it!

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  • Is there a way to automaticly call all versions of an inherited method?

    - by Eric
    I'm writing a plug-in for a 3D modeling program. I have a custom class that wraps instances of elements in the 3D model, and in turn derives it's properties from the element it wraps. When the element in the model changes I want my class(es) to update their properties based on the new geometry. In the simplified example below. I have classes AbsCurveBasd, Extrusion, and Shell which are all derived from one another. Each of these classes implement a RefreshFromBaseShape() method which updates specific properties based on the current baseShape the class is wrapping. I can call base.RefreshFromBaseShape() in each implementation of RefreshFromBaseShape() to ensure that all the properties are updated. But I'm wondering if there is a better way where I don't have to remember to do this in every implementation of RefershFromBaseShape()? For example because AbsCurveBased does not have a parameterless constructor the code wont even compile unless the constructors call the base class constructors. public abstract class AbsCurveBased { internal Curve baseShape; double Area{get;set;} public AbsCurveBased(Curve baseShape) { this.baseShape = baseShape; RefreshFromBaseShape(); } public virtual void RefreshFromBaseShape() { //sets the Area property from the baseShape } } public class Extrusion : AbsCurveBased { double Volume{get;set;} double Height{get;set;} public Extrusion(Curve baseShape):base(baseShape) { this.baseShape = baseShape; RefreshFromBaseShape(); } public override void RefreshFromBaseShape() { base.RefreshFromBaseShape(); //sets the Volume property based on the area and the height } } public class Shell : Extrusion { double ShellVolume{get;set;} double ShellThickness{get;set;} public Shell(Curve baseShape): base(baseShape) { this.baseShape = baseShape; RefreshFromBaseShape(); } public void RefreshFromBaseShape() { base.RefreshFromBaseShape(); //sets this Shell Volume from the Extrusion properties and ShellThickness property } }

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  • What should I do if i have a factory method which requires different parameters for different implem

    - by Sam Holder
    I have an interface, IMessage and a class which have several methods for creating different types of message like so: class MessageService { IMessage TypeAMessage(param 1, param 2) IMessage TypeBMessage(param 1, param 2, param 3, param 4) IMessage TypeCMessage(param 1, param 2, param 3) IMessage TypeDMessage(param 1) } I don't want this class to do all the work for creating these messages so it simply delegates to a MessageCreatorFactory which produces an IMessageCreator depending on the type given (an enumeration based on the type of the message TypeA, TypeB, TypeC etc) interface IMessageCreator { IMessage Create(MessageParams params); } So I have 4 implementations of IMessageCreator: TypeAMessageCreator, TypeBMessageCreator, TypeCMessageCreator, TypeDMessageCreator I ok with this except for the fact that because each type requires different parameters I have had to create a MessageParams object which contains 4 properties for the 4 different params, but only some of them are used in each IMessageCreator. Is there an alternative to this? One other thought I had was to have a param array as the parameter in the Create emthod, but this seems even worse as you don't have any idea what the params are. Or to create several overloads of Create in the interface and have some of them throw an exception if they are not suitable for that particular implementation (ie you called a method which needs more params, so you should have called one of the other overloads.) Does this seem ok? Is there a better solution?

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  • Invoking public method on a class in a different package via reflection

    - by KARASZI István
    I ran into the following problem. I have two different packages in package a I would like to call the implemented method of an interface in a package b but the implementing class has package visibility. So a simplifed code looks like this: package b; public final class Factory { public static B createB() { return new ImplB(); } public interface B { void method(); } static class ImplB implements B { public void method() { System.out.println("Called"); } } } and the Invoker: package a; import java.lang.reflect.Method; import b.Factory; import b.Factory.B; public final class Invoker { private static final Class<?>[] EMPTY_CLASS_ARRAY = new Class<?>[] {}; private static final Object[] EMPTY_OBJECT_ARRAY = new Object[] {}; public static void main(String... args) throws Exception { final B b = Factory.createB(); b.method(); final Method method = b.getClass().getDeclaredMethod("method", EMPTY_CLASS_ARRAY); method.invoke(b, EMPTY_OBJECT_ARRAY); } } When I start the program it prints out Called as expected and throws an Exception because the package visibility prohibits the calling of the discovered method. So my question is any way to solve this problem? Am I missing something in Java documentation or this is simply not possible although simply calling an implemented method is possible without reflection.

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  • Haskell: monadic takeWhile?

    - by Mark Rushakoff
    I have some functions written in C that I call from Haskell. These functions return IO (CInt). Sometimes I want to run all of the functions regardless of what any of them return, and this is easy. For sake of example code, this is the general idea of what's happening currently: Prelude> let f x = print x >> return x Prelude> mapM_ f [0..5] 0 1 2 3 4 5 Prelude> I get my desired side effects, and I don't care about the results. But now I need to stop execution immediately after the first item that doesn't return my desired result. Let's say a return value of 4 or higher requires execution to stop - then what I want to do is this: Prelude> takeWhile (<4) $ mapM f [0..5] Which gives me this error: <interactive:1:22: Couldn't match expected type `[b]' against inferred type `IO a' In the first argument of `mapM', namely `f' In the second argument of `($)', namely `mapM f ([0 .. 5])' In the expression: takeWhile (< 4) $ mapM f ([0 .. 5]) And that makes sense to me - the result is still contained in the IO monad, and I can't just compare two values contained in the IO monad. I know this is precisely the purpose of monads -- chaining results together and discarding operations when a certain condition is met -- but is there an easy way to "wrap up" the IO monad in this case to stop executing the chain upon a condition of my choosing, without writing an instance of MonadPlus? Can I just "unlift" the values from f, for the purposes of the takeWhile? Is this a solution where functors fit? Functors haven't "clicked" with me yet, but I sort of have the impression that this might be a good situation to use them. Update: @sth has the closest answer to what I want - in fact, that's almost exactly what I was going for, but I'd still like to see whether there is a standard solution that isn't explicitly recursive -- this is Haskell, after all! Looking back on how I worded my question, now I can see that I wasn't clear enough about my desired behavior. The f function I used above for an example was merely an example. The real functions are written in C and used exclusively for their side effects. I can't use @Tom's suggestion of mapM_ f (takeWhile (&lt;4) [0..5]) because I have no idea whether any input will really result in success or failure until executed. I don't actually care about the returned list, either -- I just want to call the C functions until either the list is exhausted or the first C function returns a failure code. In C-style pseudocode, my behavior would be: do { result = function_with_side_effects(input_list[index++]); } while (result == success && index < max_index); So again, @sth's answer performs the exact behavior that I want, except that the results may (should?) be discarded. A dropWhileM_ function would be equivalent for my purposes. Why isn't there a function like that or takeWhileM_ in Control.Monad? I see that there was a similar discussion on a mailing list, but it appears that nothing has come of that.

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  • What feature is at play when Ctrl+Shift+Alt+U,E "types" an unprintable hex 000E?

    - by Peter.O
    I tend to use Ctrl+Shift+Alt for my customized system-wide keybindings. When I tried Ctrl+Shift+Alt+U it printed an underscored u and waited for more keyboard input!... Some keys were accepted and some were not... eg. Numbers were accepted and they too were underlined, but only a few keys allowed me to break out. I then tried Ctrl+Shift+Alt+U immediately followed by Ctrl+Shift+Alt+E. This produced an unprintable hex 000E(?) and broke out of the loop... The unprintable character got me thinking that this may be Unicode related. If so, how so? What is happening here? Is this underscored u a trigger for an Input Method Editor? This behaviour occurs: Here (as I type), "gedit", text-edit fields... (but not in the Terminal)... and "gvim" reported "pattern not found"...

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  • C# vector class - Interpolation design decision

    - by Benjamin
    Currently I'm working on a vector class in C# and now I'm coming to the point, where I've to figure out, how i want to implement the functions for interpolation between two vectors. At first I came up with implementing the functions directly into the vector class... public class Vector3D { public static Vector3D LinearInterpolate(Vector3D vector1, Vector3D vector2, double factor) { ... } public Vector3D LinearInterpolate(Vector3D other, double factor { ... } } (I always offer both: a static method with two vectors as parameters and one non-static, with only one vector as parameter) ...but then I got the idea to use extension methods (defined in a seperate class called "Interpolation" for example), since interpolation isn't really a thing only available for vectors. So this could be another solution: public class Vector3D { ... } public static class Interpolation { public static Vector3D LinearInterpolate(this Vector3D vector, Vector3D other, double factor) { ... } } So here an example how you'd use the different possibilities: { var vec1 = new Vector3D(5, 3, 1); var vec2 = new Vector3D(4, 2, 0); Vector3D vec3; vec3 = vec1.LinearInterpolate(vec2, 0.5); //1 vec3 = Vector3D.LinearInterpolate(vec1, vec2, 0.5); //2 //or with extension-methods vec3 = vec1.LinearInterpolate(vec2, 0.5); //3 (same as 1) vec3 = Interpolation.LinearInterpolation(vec1, vec2, 0.5); //4 } So I really don't know which design is better. Also I don't know if there's an ultimate rule for things like this or if it's just about what someone personally prefers. But I really would like to hear your opinions, what's better (and if possible why ).

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  • How to prevent duplicate data access methods that retrieve similar data?

    - by Ronald Wildenberg
    In almost every project I work on with a team, the same problem seems to creep in. Someone writes UI code that needs data and writes a data access method: AssetDto GetAssetById(int assetId) A week later someone else is working on another part of the application and also needs an AssetDto but now including 'approvers' and writes the following: AssetDto GetAssetWithApproversById(int assetId) A month later someone needs an asset but now including the 'questions' (or the 'owners' or the 'running requests', etc): AssetDto GetAssetWithQuestionsById(int assetId) AssetDto GetAssetWithOwnersById(int assetId) AssetDto GetAssetWithRunningRequestsById(int assetId) And it gets even worse when methods like GetAssetWithOwnerAndQuestionsById start to appear. You see the pattern that emerges: an object is attached to a large object graph and you need different parts of this graph in different locations. Of course, I'd like to prevent having a large number of methods that do almost the same. Is it simply a matter of team discipline or is there some pattern I can use to prevent this? In some cases it might make sense to have separate methods, i.e. getting an asset with running requests may be expensive so I do not want to include these all the time. How to handle such cases?

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  • Trying to implement pre/post method code: better to use methods or a parent class?

    - by Will
    I'm finding it difficult to frame this question so ... I want to execute code both before and after a method runs in PHP. There are, as far as I know, two ways to implement this: Method One: pre and post methods class Model { function find($id) { $this->_precode(); // ... do stuff $this->post_code(); } } Add the calls to _precode() and _postcode() to each method where I need this functionality. Method Two: __call and method naming class Model extends PrePost { function prepost_find($id) { // ... do stuff ... } } class PrePost { function __call($method,$param) { $method = "prepost_$method"; // .. precode here .. $result = $this->$method($param); // .. postcode here .. } } This relies on naming a method in a specific way in the inheriting class. Is there a preferred way of doing this? The call method can be made to only handle its specific cases and even defer to a child class's call if there is one. I'm not looking for opinions; I'm looking to find out if there are valid reasons to choose one way over another.

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  • Is "If a method is re-used without changes, put the method in a base class, else create an interface" a good rule-of-thumb?

    - by exizt
    A colleague of mine came up with a rule-of-thumb for choosing between creating a base class or an interface. He says: Imagine every new method that you are about to implement. For each of them, consider this: will this method be implemented by more than one class in exactly this form, without any change? If the answer is "yes", create a base class. In every other situation, create an interface. For example: Consider the classes cat and dog, which extend the class mammal and have a single method pet(). We then add the class alligator, which doesn't extend anything and has a single method slither(). Now, we want to add an eat() method to all of them. If the implementation of eat() method will be exactly the same for cat, dog and alligator, we should create a base class (let's say, animal), which implements this method. However, if it's implementation in alligator differs in the slightest way, we should create an IEat interface and make mammal and alligator implement it. He insists that this method covers all cases, but it seems like over-simplification to me. Is it worth following this rule-of-thumb?

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  • BAD ARCHIVE MIRROR using PXE BOOT method

    - by omkar
    i m trying to automatically install UBUNTU on a client PC by using the method of PXE BOOT method....my Objectives are below:- i m following the steps given in this link installation using PXE BOOT 1:-the server will have a KICKSTART config file which contains the parameters for the OS installation and the files which are required for the OS installations. 2:-the client will have to detect this configuration along with the setup files and complete the installation without any input from the user. In my server i have installed DHCP3-server,Apache2 and TFTP for helping me with the installation. i have nearly achieved my first objective,i m able to boot my client using the files stored in the server,but during the installation stage it is asking me to "CHOOSE A MIRROR of UBUNTU ARCHIVE".i gave the server's IP address and the path in the server where the files are located but then too its giving me error "BAD ARCHIVE MIRROR". so is it possible that instead of downloading all the files from the internet and storing them on my disk , can i use the files which comes with the UBUNTU-CD, and how to store this files in what format (should i zip them ) on the disk. secondly i am also generating the ks.cfg which i wanted to give to the client for automatic installation of the OS ,so how should the configuration file be given to the installation process.

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  • TakeWhile and SkipWhile method in LINQ

    - by vik20000in
     In my last post I talked about how to use the take and the Skip keyword to filter out the number of records that we are fetching. But there is only problem with the take and skip statement. The problem lies in the dependency where by the number of records to be fetched has to be passed to it. Many a times the number of records to be fetched is also based on the query itself. For example if we want to continue fetching records till a certain condition is met on the record set. Let’s say we want to fetch records from the array of number till we get 7. For this kind of query LINQ has exposed the TakeWhile Method.     int[] numbers = { 5, 4, 1, 3, 9, 8, 6, 7, 2, 0 };     var firstNumbersLessThan6 = numbers.TakeWhile(n => n < 7);   In the same way we can also use the SkipWhile statement. The skip while statement will skip all the records that do not match certain condition provided. In the example below we are skiping all those number which are not divisible by 3. Remember we could have done this with where clause also, but SkipWhile method can be useful in many other situation and hence the example and the keyword.     int[] numbers = { 5, 4, 1, 3, 9, 8, 6, 7, 2, 0 };     var allButFirst3Numbers = numbers.SkipWhile(n => n % 3 != 0); Vikram

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  • Adding Vertices to a dynamic mesh via Method Call

    - by Raven Dreamer
    I have a C# Struct with a static method, "Get Shape" which populates a List with the vertices of a polyhedron. Method Signature: public static void GetShape(Block b, int x, int y, int z, List<Vector3> vertices, List<int> triangles, List<Vector2> uvs, List<Vector2> uv2s) Adding directly to the vertices list (via vertices.Add(vector3) ), the code works as expected, and the new polyhedron appears when I trigger the method. However, I want to do some processing on the vertices I'm adding (a rotation), and the most sensible way I can think to do that is by creating a separate list of Vector3s, and then combining the lists when I'm done. However, vertices.AddRange(newVerts) does not add the shape to the mesh, nor does a foreach loop with verts.Add(vertices[i]). And this is before I've added in any of the processing! I have a feeling this might stem from passing the list of vertices in as a parameter, rather than returning a list and then adding to the vertices in the calling object, but since I'm filling 4 lists, I was trying to avoid having to create a data struct to return all four at once. Any ideas? The working version of the method is reprinted below, in full: public static void GetShape(Block b, int x, int y, int z, List<Vector3> vertices, List<int> triangles, List<Vector2> uvs, List<Vector2> uv2s) { //List<Vector3> vertices = new List<Vector3>(); int l_blockShape = b.blockShape; int l_blockType = b.blockType; //CheckFace checks if the block is empty //if this block is empty, don't draw anything. int vertexIndex; //only y faces need to be hidden. //if((l_blockShape & BlockShape.NegZFace) == BlockShape.NegZFace) { vertexIndex = vertices.Count; //top left, top right, bottom right, bottom left vertices.Add(new Vector3(x+.2f, y + 1, z+.2f)); vertices.Add(new Vector3(x+.8f, y + 1, z+.2f)); vertices.Add(new Vector3(x+.8f, y , z+.2f)); vertices.Add(new Vector3(x+.2f, y , z+.2f)); // first triangle for the face triangles.Add(vertexIndex); triangles.Add(vertexIndex+1); triangles.Add(vertexIndex+3); // second triangle for the face triangles.Add(vertexIndex+1); triangles.Add(vertexIndex+2); triangles.Add(vertexIndex+3); //UVs for the face uvs.Add( new Vector2(0,1)); uvs.Add( new Vector2(1,1)); uvs.Add( new Vector2(1,0)); uvs.Add( new Vector2(0,0)); //UV2s (lightmapping?) uv2s.Add( new Vector2(0,1)); uv2s.Add( new Vector2(1,1)); uv2s.Add( new Vector2(1,0)); uv2s.Add( new Vector2(0,0)); } //XY Z+1 face //if((l_blockShape & BlockShape.PosZFace) == BlockShape.PosZFace) { vertexIndex = vertices.Count; //top left, top right, bottom right, bottom left vertices.Add(new Vector3(x+.8f, y + 1, z+.8f)); vertices.Add(new Vector3(x+.2f, y + 1, z+.8f)); vertices.Add(new Vector3(x+.2f, y , z+.8f)); vertices.Add(new Vector3(x+.8f, y , z+.8f)); // first triangle for the face triangles.Add(vertexIndex); triangles.Add(vertexIndex+1); triangles.Add(vertexIndex+3); // second triangle for the face triangles.Add(vertexIndex+1); triangles.Add(vertexIndex+2); triangles.Add(vertexIndex+3); //UVs for the face uvs.Add( new Vector2(0,1)); uvs.Add( new Vector2(1,1)); uvs.Add( new Vector2(1,0)); uvs.Add( new Vector2(0,0)); //UV2s (lightmapping?) uv2s.Add( new Vector2(0,1)); uv2s.Add( new Vector2(1,1)); uv2s.Add( new Vector2(1,0)); uv2s.Add( new Vector2(0,0)); } //ZY face //if((l_blockShape & BlockShape.NegXFace) == BlockShape.NegXFace) { vertexIndex = vertices.Count; //top left, top right, bottom right, bottom left vertices.Add(new Vector3(x+.2f, y + 1, z+.8f)); vertices.Add(new Vector3(x+.2f, y + 1, z+.2f)); vertices.Add(new Vector3(x+.2f, y , z+.2f)); vertices.Add(new Vector3(x+.2f, y , z+.8f)); // first triangle for the face triangles.Add(vertexIndex); triangles.Add(vertexIndex+1); triangles.Add(vertexIndex+3); // second triangle for the face triangles.Add(vertexIndex+1); triangles.Add(vertexIndex+2); triangles.Add(vertexIndex+3); //UVs for the face uvs.Add( new Vector2(0,1)); uvs.Add( new Vector2(1,1)); uvs.Add( new Vector2(1,0)); uvs.Add( new Vector2(0,0)); //UV2s (lightmapping?) uv2s.Add( new Vector2(0,1)); uv2s.Add( new Vector2(1,1)); uv2s.Add( new Vector2(1,0)); uv2s.Add( new Vector2(0,0)); } //ZY X+1 face // if((l_blockShape & BlockShape.PosXFace) == BlockShape.PosXFace) { vertexIndex = vertices.Count; //top left, top right, bottom right, bottom left vertices.Add(new Vector3(x+.8f, y + 1, z+.2f)); vertices.Add(new Vector3(x+.8f, y + 1, z+.8f)); vertices.Add(new Vector3(x+.8f, y , z+.8f)); vertices.Add(new Vector3(x+.8f, y , z+.2f)); // first triangle for the face triangles.Add(vertexIndex); triangles.Add(vertexIndex+1); triangles.Add(vertexIndex+3); // second triangle for the face triangles.Add(vertexIndex+1); triangles.Add(vertexIndex+2); triangles.Add(vertexIndex+3); //UVs for the face uvs.Add( new Vector2(0,1)); uvs.Add( new Vector2(1,1)); uvs.Add( new Vector2(1,0)); uvs.Add( new Vector2(0,0)); //UV2s (lightmapping?) uv2s.Add( new Vector2(0,1)); uv2s.Add( new Vector2(1,1)); uv2s.Add( new Vector2(1,0)); uv2s.Add( new Vector2(0,0)); } //ZX face if((l_blockShape & BlockShape.NegYFace) == BlockShape.NegYFace) { vertexIndex = vertices.Count; //top left, top right, bottom right, bottom left vertices.Add(new Vector3(x+.8f, y , z+.8f)); vertices.Add(new Vector3(x+.8f, y , z+.2f)); vertices.Add(new Vector3(x+.2f, y , z+.2f)); vertices.Add(new Vector3(x+.2f, y , z+.8f)); // first triangle for the face triangles.Add(vertexIndex+3); triangles.Add(vertexIndex+1); triangles.Add(vertexIndex); // second triangle for the face triangles.Add(vertexIndex+3); triangles.Add(vertexIndex+2); triangles.Add(vertexIndex+1); //UVs for the face uvs.Add( new Vector2(0,1)); uvs.Add( new Vector2(1,1)); uvs.Add( new Vector2(1,0)); uvs.Add( new Vector2(0,0)); //UV2s (lightmapping?) uv2s.Add( new Vector2(0,1)); uv2s.Add( new Vector2(1,1)); uv2s.Add( new Vector2(1,0)); uv2s.Add( new Vector2(0,0)); } //ZX + 1 face if((l_blockShape & BlockShape.PosYFace) == BlockShape.PosYFace) { vertexIndex = vertices.Count; //top left, top right, bottom right, bottom left vertices.Add(new Vector3(x+.8f, y+1 , z+.2f)); vertices.Add(new Vector3(x+.8f, y+1 , z+.8f)); vertices.Add(new Vector3(x+.2f, y+1 , z+.8f)); vertices.Add(new Vector3(x+.2f, y+1 , z+.2f)); // first triangle for the face triangles.Add(vertexIndex+3); triangles.Add(vertexIndex+1); triangles.Add(vertexIndex); // second triangle for the face triangles.Add(vertexIndex+3); triangles.Add(vertexIndex+2); triangles.Add(vertexIndex+1); //UVs for the face uvs.Add( new Vector2(0,1)); uvs.Add( new Vector2(1,1)); uvs.Add( new Vector2(1,0)); uvs.Add( new Vector2(0,0)); //UV2s (lightmapping?) uv2s.Add( new Vector2(0,1)); uv2s.Add( new Vector2(1,1)); uv2s.Add( new Vector2(1,0)); uv2s.Add( new Vector2(0,0)); } }

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  • Optimization ended up in casting an object at each method call

    - by Aybe
    I've been doing some optimization for the following piece of code : public void DrawLine(int x1, int y1, int x2, int y2, int color) { _bitmap.DrawLineBresenham(x1, y1, x2, y2, color); } After profiling it about 70% of the time spent was in getting a context for drawing and disposing it. I ended up sketching the following overload : public void DrawLine(int x1, int y1, int x2, int y2, int color, BitmapContext bitmapContext) { _bitmap.DrawLineBresenham(x1, y1, x2, y2, color, bitmapContext); } Until here no problems, all the user has to do is to pass a context and performance is really great as a context is created/disposed one time only (previously it was a thousand times per second). The next step was to make it generic in the sense it doesn't depend on a particular framework for rendering (besides .NET obvisouly). So I wrote this method : public void DrawLine(int x1, int y1, int x2, int y2, int color, IDisposable bitmapContext) { _bitmap.DrawLineBresenham(x1, y1, x2, y2, color, (BitmapContext)bitmapContext); } Now every time a line is drawn the generic context is casted, this was unexpected for me. Are there any approaches for fixing this design issue ? Note : _bitmap is a WriteableBitmap from WPF BitmapContext is from WriteableBitmapEx library DrawLineBresenham is an extension method from WriteableBitmapEx

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  • What is the ideal length of a method?

    - by iPhoneDeveloper
    In object-oriented programming, there is no exact rule on the maximum length of a method , but I still found these two qutes somewhat contradicting each other, so I would like to hear what you think. In Clean Code: A Handbook of Agile Software Craftsmanship, Robert Martin says: The first rule of functions is that they should be small. The second rule of functions is that they should be smaller than that. Functions should not be 100 lines long. Functions should hardly ever be 20 lines long. and he gives an example from Java code he sees from Kent Beck: Every function in his program was just two, or three, or four lines long. Each was transparently obvious. Each told a story. And each led you to the next in a compelling order. That’s how short your functions should be! This sounds great, but on the other hand, in Code Complete, Steve McConnell says something very different: The routine should be allowed to grow organically up to 100-200 lines, decades of evidence say that routines of such length no more error prone then shorter routines. And he gives a reference to a study that says routines 65 lines or long are cheaper to develop. So while there are diverging opinions about the matter, is there a functional best-practice towards determining the ideal length of a method for you?

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  • MatheMagics - Guess My Age - Method 2

    - by PointsToShare
    © 2011 By: Dov Trietsch. All rights reserved MatheMagic – Guess My Age – Method 2 The Mathemagician stands on the stage and asks an adult to do the following: ·         Do the next few steps on your calculator, or the calculator in your phone, or even on a piece of paper. ·         Do it silently! Don’t tell me the results until I ask for them directly ·         Multiply your age by 2. ·         Add 7 to the result ·         Multiply the result by 5. ·         Tell me the result. I will nonetheless immediately tell you what your age is. How do I do this? Let’s do the algebra. Let A denote your age (2A + 7) 5 = 10A + 35 so it is of the 3 digit form XY5 Now make two numbers out of the result - The last digit and the number before it. The Last digit is obviously 5, the other 2 (or 3 for a centenarian) and this number is the age + 3. Example: I am 76 years old and here is what happens when I do the steps 76 x 2 = 152 152 + 7 = 159 159 x 5 = 795 This is made of 79 and 5. And … 79 – 3 = 76 A note to the socially aware mathemagician – it is safer to do it with a man. The chances of a veracious answer are much, much higher! The trick may be accomplished on any 2 or 3 digit number, not just one’s age, but if you want to know your date’s age, it’s a good way to elicit it. That’s All Folks PS for more Ageless “Age” mathemagics go to www.mgsltns.com/games.htm and also here: http://geekswithblogs.net/PointsToShare/archive/2011/11/15/mathemagics---guess-my-age-method-1.aspx

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  • Should you create a class within a method?

    - by Amndeep7
    I have made a program using Java that is an implementation of this project: http://nifty.stanford.edu/2009/stone-random-art/sml/index.html. Essentially, you create a mathematical expression and, using the pixel coordinate as input, make a picture. After I initially implemented this in serial, I then implemented it in parallel due to the fact that if the picture size is too large or if the mathematical expression is too complex (especially considering the fact that I made the expression recursively), it takes a really long time. During this process, I realized that I needed two classes which implemented the Runnable interface as I had to put in parameters for the run method, which you aren't allowed to do directly. One of these classes ended up being a medium sized static inner class (not large enough to make an independent class file for it though). The other though, just needed a few parameters to determine some indexes and the size of the for loop that I was making run in parallel - here it is: class DataConversionRunnable implements Runnable { int jj, kk, w; DataConversionRunnable(int column, int matrix, int wid) { jj = column; kk = matrix; w = wid; } public void run() { for(int i = 0; i < w; i++) colorvals[kk][jj][i] = (int) ((raw[kk][jj][i] + 1.0) * 255 / 2.0); increaseCounter(); } } My question is should I make it a static inner class or can I just create it in a method? What is the general programming convention followed in this case?

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  • Dependency Injection and method signatures

    - by sunwukung
    I've been using YADIF (yet another dependency injection framework) in a PHP/Zend app I'm working on to handle dependencies. This has achieved some notable benefits in terms of testing and decoupling classes. However,one thing that strikes me is that despite the sleight of hand performed when using this technique, the method names impart a degree of coupling. Probably not the best example -but these methods are distinct from ... say the PEAR Mailer. The method names themselves are a (subtle) form of coupling //example public function __construct($dic){ $this->dic = $dic; } public function example(){ //this line in itself indicates the YADIF origin of the DIC $Mail= $dic->getComponent('mail'); $Mail->setBodyText($body); $Mail->setFrom($from); $Mail->setSubject($subject); } I could write a series of proxies/wrappers to hide these methods and thus promote decoupling from , but this seems a bit excessive. You have to balance purity with pragmatism... How far would you go to hide the dependencies in your classes?

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  • Difference between Factory Method and Abstract Factory design patterns using C#.Net

    - by nijhawan.saurabh
    First of all I'll just put both these patterns in context and describe their intent as in the GOF book: Factory Method: Define an interface for creating an object, but let subclasses decide which class to instantiate. Factory Method lets a class defer instantiation to subclasses.   Abstract Factory: Provide an interface for creating families of related or dependent objects without specifying their concrete classes.   Points to note:   Abstract factory pattern adds a layer of abstraction to the factory method pattern. The type of factory is not known to the client at compile time, this information is passed to the client at runtime (How it is passed is again dependent on the system, you may store this information in configuration files and the client can read it on execution). While implementing Abstract factory pattern, the factory classes can have multiple factory methods. In Abstract factory, a factory is capable of creating more than one type of product (Simpilar products are grouped together in a factory)   Sample implementation of factory method pattern   Let's see the class diagram first:                   ProductFactory.cs // ----------------------------------------------------------------------- // <copyright file="ProductFactory.cs" company=""> // TODO: Update copyright text. // </copyright> // -----------------------------------------------------------------------   namespace FactoryMethod {     using System;     using System.Collections.Generic;     using System.Linq;     using System.Text;       /// <summary>     /// TODO: Update summary.     /// </summary>     public abstract class ProductFactory     {         /// <summary>         /// </summary>         /// <returns>         /// </returns>         public abstract Product CreateProductInstance();     } }     ProductAFactory.cs // ----------------------------------------------------------------------- // <copyright file="ProductAFactory.cs" company=""> // TODO: Update copyright text. // </copyright> // -----------------------------------------------------------------------   namespace FactoryMethod {     using System;     using System.Collections.Generic;     using System.Linq;     using System.Text;       /// <summary>     /// TODO: Update summary.     /// </summary>     public class ProductAFactory:ProductFactory     {         public override Product CreateProductInstance()         {             return new ProductA();         }     } }         // ----------------------------------------------------------------------- // <copyright file="ProductBFactory.cs" company=""> // TODO: Update copyright text. // </copyright> // -----------------------------------------------------------------------   namespace FactoryMethod {     using System;     using System.Collections.Generic;     using System.Linq;     using System.Text;       /// <summary>     /// TODO: Update summary.     /// </summary>     public class ProductBFactory:ProductFactory     {         public override Product CreateProductInstance()         {             return new ProductB();           }     } }     // ----------------------------------------------------------------------- // <copyright file="Product.cs" company=""> // TODO: Update copyright text. // </copyright> // -----------------------------------------------------------------------   namespace FactoryMethod {     using System;     using System.Collections.Generic;     using System.Linq;     using System.Text;       /// <summary>     /// TODO: Update summary.     /// </summary>     public abstract class Product     {         public abstract string Name { get; set; }     } }     // ----------------------------------------------------------------------- // <copyright file="ProductA.cs" company=""> // TODO: Update copyright text. // </copyright> // -----------------------------------------------------------------------   namespace FactoryMethod {     using System;     using System.Collections.Generic;     using System.Linq;     using System.Text;       /// <summary>     /// TODO: Update summary.     /// </summary>     public class ProductA:Product     {         public ProductA()         {               Name = "ProductA";         }           public override string Name { get; set; }     } }       // ----------------------------------------------------------------------- // <copyright file="ProductB.cs" company=""> // TODO: Update copyright text. // </copyright> // -----------------------------------------------------------------------   namespace FactoryMethod {     using System;     using System.Collections.Generic;     using System.Linq;     using System.Text;       /// <summary>     /// TODO: Update summary.     /// </summary>     public class ProductB:Product     {          public ProductB()         {               Name = "ProductA";         }         public override string Name { get; set; }     } }     Program.cs using System; using System.Collections.Generic; using System.Linq; using System.Text;   namespace FactoryMethod {     class Program     {         static void Main(string[] args)         {             ProductFactory pf = new ProductAFactory();               Product product = pf.CreateProductInstance();             Console.WriteLine(product.Name);         }     } }       Normal 0 false false false false EN-US X-NONE X-NONE /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-parent:""; mso-padding-alt:0in 5.4pt 0in 5.4pt; mso-para-margin-top:0in; mso-para-margin-right:0in; mso-para-margin-bottom:10.0pt; mso-para-margin-left:0in; line-height:115%; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Calibri","sans-serif"; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin; mso-bidi-font-family:"Times New Roman"; mso-bidi-theme-font:minor-bidi;}

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  • Xcode Objective-c warnings "creating selector for nonexistent method" with OCUnit (SenTestingKit)

    - by niblha
    I started getting getting warnings like the following in XCode when trying to write some unit tests with OCUnit (SenTestingKit). warning: creating selector for nonexistent method 'myMethodName1:' warning: creating selector for nonexistent method 'myMethodName2:' ... warning: creating selector for nonexistent method 'release' warning: creating selector for nonexistent method 'retain' warning: creating selector for nonexistent method 'alloc' warning: creating selector for nonexistent method 'init' Is it something I should worry about, or can I somehow disable these types of warnings by some compiler flag?

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