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  • Right multi object dependance design

    - by kenny
    I need some help with a correct design. I have a class called BufferManager. The push() method of this class reads data from a source and pushes it to a buffer repeatedly until there is no more data left in the source. There are also consumer threads that read data from this buffer, as soon as new data arrives. There is an option to sort the data before it comes to buffer. What I do right now is that BufferManager, instead of pushing data to the buffer, pushes it to another "sorting" buffer and starts a sorting thread. SorterManager class reads the data, sorts it in files and push()es the sorted data into the buffer. There will be a bottleneck (I use merge sort with files) but this is something I can't avoid. This is a bad design, because both BufferManager and SorterManager push data to a buffer (that consumers read from). I think only BufferManager should do it. How can I design it?

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  • Is there a Design Pattern for preventing dangling references?

    - by iFreilicht
    I was thinking about a design for custom handles. The thought is to prevent clients from copying around large objects. Now a regular handle class would probably suffice for that, but it doesn't solve the "dangling reference problem"; If a client has multiple handles of the same object and deletes the object via one of them, all the others would be invalid, but not know it, so the client could write or read parts of the memory he shouldn't have access to. Is there a design pattern to prevent this from happening? Two ideas: An observer-like pattern where the destructor of an object would notify all handles. "Handle handles" (does such a thing even exist?). All the handles don't really point to the object, but to another handle. When the object gets destroyed, this "master-handle" invalidates itself and therefore all that point to it.

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  • ms-access: DB engine cannot find input table or query

    - by every_answer_gets_a_point
    here's the query: SELECT * FROM (SELECT [Occurrence Number], [Occurrence Date], [1 0 Preanalytical (Before Testing)], [Cup Type], NULL as [2 0 Analytical (Testing Phase)], [2 0 Area], NULL as [3 0 Postanalytical ( After Testing)],NULL as [4 0 Other], [Practice Code], [Specimen ID #] FROM [Lab Occurrence Form] WHERE NOT ([1 0 Preanalytical (Before Testing)] IS NULL) UNION SELECT [Occurrence Number], [Occurrence Date],NULL, [Cup Type],[2 0 Analytical (Testing Phase)], [2 0 Area], NULL,NULL, [Practice Code], [Specimen ID #] FROM [Lab Occurrence Form] WHERE NOT ([2 0 Analytical (Testing Phase)] IS NULL) UNION SELECT [Occurrence Number], [Occurrence Date],NULL, [Cup Type],NULL, [2 0 Area], [3 0 Postanalytical ( After Testing)],NULL, [Practice Code], [Specimen ID #] FROM [Lab Occurrence Form] WHERE NOT ([3 0 Postanalytical ( After Testing)] IS NULL) UNION SELECT [Occurrence Number], [Occurrence Date],NULL, [Cup Type],NULL, [2 0 Area], NULL, [4 0 Other] FROM [Lab Occurrence Form], [Practice Code], [Specimen ID #] WHERE NOT ([4 0 Other] IS NULL) ) AS mySubQuery ORDER BY mySubQuery.[Occurrence Number]; for some reason it doesnt like [Practice Code]. it's definitely a column in the table so i dont understand the problem. the error is the microsoft office access database engine cannot find the input table or query 'Practice Code'........

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  • Make an object slide around an obstacle

    - by Isaiah
    I have path areas set up in a game I'm making for canvas/html5 and have got it working to keep the player within these areas. I have a function isOut(boundary, x, y) that returns true if the point is outside the boundary. What I do is check only the new position x/y separately with the corresponding old position x/y. Then if each one is out I assign them the past value from the frame before. The old positions are kept in a variable from a closure I made. like this: opos = [x,y];//old position npos = [x,y];//new position if(isOut(bound, npos[0], opos[1])){ npos[0] = opos[0]; //assign it the old x position } if(isOut(bound, opos[0], npos[1])){ npos[1] = opos[1]; //assign it the old y position } It looks nice and works good at certain angles, but if your boundary has diagonal regions it results in jittery motion. What's happening is the y pos exits the area while x doesn't and continues pushing the player to the side, once it has moved the player to the side a bit the player can move forward and then the y exits again and the whole process repeats. Anyone know how I may be able to achieve a smoother slide? I have access to the player's velocity vector, the angle, and the speed(when used with the angle). I can move the play with either angle/speed or x/yvelocities as I've built in backups to translate one to the other if either have been altered manually.

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  • Why use string.Empty over "" when assigning to a string object

    - by dreza
    I've been running StyleCop over my code and one of the recommendations SA1122 is to use string.Empty rather than "" when assigning an empty string to a value. My question is why is this considered best practice. Or, is this considered best practice? I assume there is no compiler difference between the two statements so I can only think that it's a readability thing? UPDATE: Thanks for the answers but it's been kindly pointed out this question has been asked many times already on SO, which in hind-sight I should have considered and searched first before asking here. Some of these especially forward links makes for interesting reading. SO question and answer Jon Skeet answer to question

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  • ASP.NET binding object to Request in asp.net mvc

    - by Alxandr
    I've created a object that I'd like to have accessible from wherever the request-object is accessible, and to "die" with the request, more or less like how you always in a mvc-application has access to the RouteData-collection. Especially it's important that I have access to this object in the execution of action-filters. And also there need to be created a new object of my class whenever a new request is made to the page (the object needs to be request-safe, ie. only one request modifies that one object). Any thoughts about how to achieve this?

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  • JPopupMenu getParent() returning a null?

    - by Zenzen
    Ok so I'm working on an Eclipse plugin based on the JGraph example. The problem is I can't really get the "save" method to work, here's how the program works in short: - I have a DiagramEditor class with an init() method, where I create a GraphEditor object and call the createFrame() methord of that object. - GraphEditor extends the BasicGraphEditor (which extends JPanel), the createFrame() method returns a JFrame and has a line "frame.setJMenuBar(menuBar)" - the "menuBar" is an object variable, which is initialized in the BasicGraphEditor. Till here everything is cool, the problem is with the action listener which is supposed to save a file. To get the graph I need to get the GraphEditor component, so I do a Component component = (Component) e.getSource() whitch is the ActionEvent passed to that action listener and at that stage is the JMenuItem "save", then I get the parent which is the JPopupMenu, then I want to get that JPopupMenu's parent which should be the GraphEdiotor, but instead I get a null. Any idea why? Here's some source code: DiagramEditor.java: @Override public void init(IEditorSite site, IEditorInput input) throws PartInitException { setSite(site); setInput(input); this.diagram = ((DiagramEditorInput)input).getDiagram(); setPartName(this.diagram.getName()); gEditor = new GraphEditor(); gEditor.createFrame().setVisible(true); } BasicGraphEditor.java: public JFrame createFrame() { JFrame frame = new JFrame(); frame.getContentPane().add(this); frame.setJMenuBar(menuBar); //frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); frame.setSize(870, 640); return frame; } In the constructor: menuBar = new JMenuBar(); menu = new JMenu("File"); menu.setMnemonic(KeyEvent.VK_F); menuBar.add(menu); JMenuItem openMenuItem = new JMenuItem("Open", KeyEvent.VK_O); // ADD FILE OPENING //openMenuItem.addActionListener(menuListener); menu.add(openMenuItem); JMenuItem saveMenuItem = new JMenuItem("Save", new ImageIcon("/images/save.gif")); saveMenuItem.setMnemonic(KeyEvent.VK_S); saveMenuItem.addActionListener( new SaveAction(false) ); menu.add(saveMenuItem); // menu.add(new SaveAction(false)); JMenuItem saveMenuItemAs = new JMenuItem("SaveAs", new ImageIcon("/images/saveas.gif")); //saveMenuItemAs.setMnemonic(KeyEvent.VK_S); saveMenuItemAs.addActionListener( new SaveAction(true) ); menu.add(saveMenuItemAs); //menu.add(new SaveAction(true)); JMenuItem closeMenuItem = new JMenuItem("Close", KeyEvent.VK_C); closeMenuItem.addActionListener( new ActionListener() { public void actionPerformed(ActionEvent e) { System.exit(0); } } ); menu.add(closeMenuItem);

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  • Object-Oriented OpenGL

    - by Sullivan
    I have been using OpenGL for a while and have read a large number of tutorials. Aside from the fact that a lot of them still use the fixed pipeline, they usually throw all the initialisation, state changes and drawing in one source file. This is fine for the limited scope of a tutorial, but I’m having a hard time working out how to scale it up to a full game. How do you split your usage of OpenGL across files? Conceptually, I can see the benefits of having, say, a rendering class that purely renders stuff to screen, but how would stuff like shaders and lights work? Should I have separate classes for things like lights and shaders?

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  • creating object parameters in {}?

    - by RealityDysfunction
    I am trying to decode a piece of code from a book: List<Person> people = new List<Person>() { new Person {FirstName="Homer",LastName="Simpson",Age=47}, new Person {FirstName="Marge",LastName="Simpson",Age=45} }; Person is just a simple class they made, with a bunch of fields: Name, Last Name, etc... What I don't understand is, don't we send parameters to a constructor of Person in non-curly brackets? I tried replicating this code, but it doesn't seem to fly, any takers? Thanks for input.

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  • Numerical stability in continuous physics simulation

    - by Panda Pajama
    Pretty much all of the game development I have been involved with runs afoul of simulating a physical world in discrete time steps. This is of course very simple, but hardly elegant (not to mention mathematically inaccurate). It also has severe disadvantages when large values are involved (either very large speeds, or very large time intervals). I'm trying to make a continuous physics simulation, just for learning, which goes like this: time = get_time() while true do new_time = get_time() update_world(new_time - time) render() time = new_time end And update_world() is a continuous physical simulation. Meaning that for example, for an accelerated object, instead of doing object.x = object.x + object.vx * timestep object.vx = object.vx + object.ax * timestep -- timestep is fixed I'm doing something like object.x = object.x + object.vx * deltatime + object.ax * ((deltatime ^ 2) / 2) object.vx = object.vx + object.ax * deltatime However, I'm having a hard time with the numerical stability of my solutions, especially for very large time intervals (think of simulating a physical world for hundreds of thousands of virtual years). Depending on the framerate, I get wildly different solutions. How can I improve the numerical stability of my continuous physical simulations?

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  • How to move an object using X and Y coordinates in JavaScript

    - by Geroy290
    I am making a 2d game with JavaScript and HTML5 and am trying to move an image that I have drawn with JavaScript like so: //canvas var c = document.getElementById("gameCanvas"); var ctx = c.getContext("2d"); //baseball var baseball = new Image(); baseball.onload = function() { ctx.drawImage(baseball, 400, 425); }; baseball.src = "baseball2.png"; I'm not sure how I would move it though, I have seen many people seem to just type something like ballX and ballY but I don't understand where the actual x and y definition comes from. Here is my code so far: http://jsfiddle.net/xRfua/ I have a different image source but it is a local source so I couldn't include it. Thanks in a dvance for any help!

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  • Name user object and user table correctly

    - by Marc
    It's maybe simple but I think about this every time I build a new application. How do you name the class for the current user of the application and for the orm class of the user table? Usually I have something like CurrentUser: Logged-in user, stored in session, info for last activity etc User: ORM Class (C# EF CodeFirst, but it doesn't matter) And yes, they could have the same name in different namespaces, but I don't really like that.

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  • libgdx collision detection / bounding the object

    - by johnny-b
    i am trying to get collision detection so i am drawing a red rectangle to see if it is working, and when i do the code below in the update method. to check if it is going to work. the position is not in the right place. the red rectangle starts from the middle and not at the x and y point?Huh so it draws it wrong. i also have a getter method so nothing wrong there. bullet.set(getX(), getY(), getOriginX(), getOriginY()); this is for the render shapeRenderer.begin(ShapeType.Filled); shapeRenderer.setColor(Color.RED); shapeRenderer.rect(bullet.getX(), bullet.getY(), bullet.getOriginX(), bullet.getOriginY(), 15, 5, bullet.getRotation()); shapeRenderer.end(); i have tried to do it with a circle but the circle draws in the middle and i want it to be at the tip of the bullet. at the front of the bullet. x, y point. boundingCircle.set(getX() + getOriginX(), getY() + getOriginY(), 4.0f); shapeRenderer.begin(ShapeType.Filled); shapeRenderer.setColor(Color.RED); shapeRenderer.circle(bullet.getBoundingCircle().x, bullet.getBoundingCircle().y, bullet.getBoundingCircle().radius); shapeRenderer.end(); thank you need it to be of the x and y as the bullet is in the middle of the sprite when drawn originally via paint.

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  • Write Null/Nothing value with Databinding

    - by clawson
    I have extended a MaskedTextBox component to add some functionality. The text property of the extended MaskedTextBox is bound to a DateTime? property and the format of binding is set to a time format of "HH:mm:ss" (i.e. 24hr time). So that this masked text box will capture the display a time. The extra functionality I have added is to make the component readonly unless the component is double clicked or the enter button is pressed (the back color of the control helps to inform the users if the component is locked/readonly or not). When the enter button is pressed I also suspend the bindings so that bound data is updated the users input won't be lost. The information is then written back to the value and databindings resumed when the user presses the enter key again. This all works fine up to here, with values written and displayed as would be expected. However, I also want to write the null or nothing value to the DateTime? property if the user hasn't entered any text (or invalid text but let's just stick with no text) when enter key is pressed to submit the new value. Unlike with other valid entries in the MaskedTextBox, with no text entered when i execute: Me.DataBindings("Text").WriteValue() (when 'locking' the MaskedTextBox) it then branches to the bound properties Get method as I step into each line of code in the debugger (as opposed to the Set method with other valid entries) How can I write this null/nothing/"" value to the DateTime? property when no text "" is entered into the MaskedTextBox? Thanks for the help!

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  • How do I implement Unreal-like object serialization?

    - by MrWiggels
    Recently, I've been working on the core of my engine, and as I'm moving forward I find myself developing throwaway code to read files and simple data into the engine. This got me thinking about how I should implement a file management system. After a bit of googleing I came across the Unreal Package format, and boy does it look like the perfect one. I think it's good because the way how it allows you to separate different assets into different packages and allow something like a level to reference the different packages. I was just wondering, is this possible with C#? Because the built-in serialization API in .NET does not seem to support any form of this, only reading and writing to a single file.

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  • object detection in bitmmap javacanvas

    - by user1538127
    i want to detect clicks on canvas elements which are drawn using paths. so far i have think of to store elements path in javascript data structure and then check the cordinates of hits which matches the elements cordinates. i belive there is algorithm already for thins kind o cordinate search. rendering each of element path and checking the hits would be inefficient when elements number is larger. can anyone point on me that?

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  • JavaScript inheritance

    - by Tower
    Hi, Douglas Crockford seems to like the following inheritance approach: if (typeof Object.create !== 'function') { Object.create = function (o) { function F() {} F.prototype = o; return new F(); }; } newObject = Object.create(oldObject); It looks OK to me, but how does it differ from John Resig's simple inheritance approach? Basically it goes down to newObject = Object.create(oldObject); versus newObject = Object.extend(); And I am interested in theories. Implementation wise there does not seem to be much difference.

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  • What should a domain object's validation cover?

    - by MarcoR88
    I'm trying to figure out how to do validation of domain objects that need external resources, such as data mappers/dao Firstly here's my code class User { const INVALID_ID = 1; const INVALID_NAME = 2; const INVALID_EMAIL = 4; int getID(); void setID(Int i); string getName(); void setName(String s); string getEmail(); void setEmail(String s); int getErrorsForInsert(); // returns a bitmask for INVALID_* constants int getErrorsForUpdate(); } My worries are about the uniqueness of the email, checking it would require the storage layer. Reading others' code seems that two solutions are equally accepted: both perform the unique validation in data mapper but some set an error state to the DO user.addError(User.INVALID_EMAIL) while others prefer to throw a totally different type of exception that covers only persistence, like: UserStorageException { const INVALID_EMAIL = 1; const INVALID_CITY = 2; } What are the pros and cons of these solutions?

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  • This for array colllision function doesn't work with anything but first object in array

    - by Zee Bashew
    For some reason, this simple simple loop is totally broken. (characterSheet is my character Class, it's just a movieClip with some extra functionality) (hitBox, is basically a square movieclip) Anyway: every time hitBox make contact with a characterSheet in a different order than they were created: Nothing happens. The program only seems to be listening to collisions that are made with o2[0]. As soon as another hitBox is created, it pushes the last one out of o2[0] and the last one becomes totally useless. What's super weird is that I can hit characterSheets in any order I like.... public function collisions(o1:Array, o2:Array) { if((o1.lenght>=0)&&(o2.length>=0)){ for (var i = 0; i < o1.length; i++) { var ob1 = o1[i]; for (var f = 0; f < o1.length; f++) { var ob2 = o2[f]; if (ob1 is characterSheet) { if (ob2.hitTestObject(ob1)) { var right:Boolean = true; if (ob1.x < hitBox(ob2).origin.x) right = false; characterSheet(ob1).specialDamage(hitBox(ob2).damageType, hitBox(ob2).damage, right); }}}}}} Also it might be somewhat helpful to see the function for creating a new hitBox public function SpawnHitBox(targeted, following, atype, xoff, yoff, ... args) { var newHitBox = new hitBox(targeted, following, atype, xoff, yoff, args); badCollisionObjects.push(newHitBox); arraydictionary[newHitBox] = badCollisionObjects; addChild(newHitBox); }

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  • Modelling multiple simultaneous states

    - by James P.
    How can you go about modelling an object that can have multiple simultaneous states? For example, you could have a person that's waiting for a bus. That's one state. But they could also be reading a newspaper while waiting for the bus. Furthermore, they could be thinking about something while reading the newspaper. They could also be sniffing their nose because they have a cold. That's a four states in all taking place at the same time. Obviously using booleans would be tedious and unflexible. Also, a conventional state pattern would mean that states are exclusive and can't be simultaneous in nature. The only thing I can think of is a State pattern combined with a Composite. Would this do or is there a way of taking things further?

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  • Offset Forward vector of object based on Rotation

    - by Taylor
    I'm using the Bullet 3D physics engine in a iOS application running openGL ES 1.1 Currently I'm accepting info from the gyroscope to allow the user to "look around" a 3d world that follows a bouncing ball (note: it only takes in the yaw to look around 360 degrees). Im also accepting information from the accelerometer based on the tilt to push the ball. As of right now, to move forward, the user tilts the devise forward (using the accelerometer); to move to the right, the user tilts the devise to the right and so on. The forward vector is currently along it's local Z-axis. The problem is that I want to change the ball bounce based on where the user has changed the view. If I change the view, the ball bounces in the fixed direction. I want to change the forward facing direction so that when a user changes the view (say to the look at the right of the world, the user rotates the device), tilting the devise forward will result in a forward force in that direction. Basically, I want the forward vector to take the rotation into consideration. Sorry if I didn't explain the issue well enough, its kind of confusing to write down.

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  • Periodic updates of an object in Unity

    - by Blue
    I'm trying to make a collider appear every 1 second. But I can't get the code right. I tried enabling the collider in the Update function and putting a yield to make it update every second or so. But it's not working (it gives me an error: Update() cannot be a coroutine.) How would I fix this? Would I need a timer system to toggle the collider? var waitTime : float = 1; var trigger : boolean = false; function Update () { if(!trigger){ collider.enabled = false; yield WaitForSeconds(waitTime); } if(trigger){ collider.enabled = true; yield WaitForSeconds(waitTime); } } }

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  • C++: Checking if an object faces a point (within a certain range)

    - by bojoradarial
    I have been working on a shooter game in C++, and am trying to add a feature whereby missiles shot must be within 90 degrees (PI/2 radians) of the direction the ship is facing. The missiles will be shot towards the mouse. My idea is that the ship's angle of rotation is compared with the angle between the ship and the mouse (std::atan2(mouseY - shipY, mouseX - shipX)), and if the difference is less than PI/4 (45 degrees) then the missile can be fired. However, I can't seem to get this to work. The ship's angle of rotation is increased and decreased with the A and D keys, so it is possible that it isn't between 0 and 2*PI, hence the use of fmod() below. Code: float userRotation = std::fmod(user->Angle(), 6.28318f); if (std::abs(userRotation - missileAngle) > 0.78f) return; Any help would be appreciated. Thanks!

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  • getPackage() returning null when my JUnit test is run from Ant

    - by philharvey
    I'm having problems running a JUnit test. It runs fine in Eclipse, but now I'm trying to run it from the command-line using Ant. The problem is that the following code is returning null: getClass().getPackage(). I'm running my JUnit test like so: <junit fork="no" printsummary="yes" haltonfailure="no"> <classpath refid="junit.classpath" /> <batchtest fork="yes" todir="${reports.junit}"> <fileset dir="${junit.classdir}"> <include name="**/FileHttpServerTest.class" /> <exclude name="**/*$*" /> </fileset> </batchtest> <formatter type="xml" /> ... I Googled for this sort of error, and found a number of references to classloader misbehaviour. But I've found nothing gave me enough information to solve my problem. I really need getClass().getPackage() to not return null. Can anyone help me? Thanks, Phil

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  • New Whitepaper: Sales Cloud Business Object Cheatsheet

    - by Richard Bingham
    Ever tried coding groovy in Application Composer and found it hard to remember the API names for the standard objects and their fields? To help we have created this short set of ERD-like diagrams for the most regularly used Business Objects with along with their key attributes. As a handy PDF we hope this quick-reference guide will make this easier and save you some time. Please let us know in the comments below if this is useful or any enhancements you'd like us to add.

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