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• Debugging .NET code called from X++ code in AX 2012

  - by ssmantha

  A very intriguing issue came to me to debug .Net code called from X++ code in AX 2012. This was indeed a challenge to be nailed down. Luckily the tools and some concepts helped me to achieve this task. Here it goes... We need to do a seamless debugging from AX debugger to Visual Studio back and forth. To enable this we need to first see if the dll to be debug is present in GAC then we might need to uninstall it from it due to the order of preference .NET loads the assemblies. The assemblies are first loaded from GAC and then the runtime checks for Public and Private Assemblies. Since the assembly in GAC is always compiled with runtime optimizations it is difficult to debug. We need to unhook this assembly from GAC and then move further relying on >NET assembly loading patterns. Step 1: Remove the target assembly to debug from GAC. Before that stop all the AOS servers and close all the instances of programs which rely on AOT e.g. all clients and even visual studio now. Step 2: Build your sample code which is present in AOT in debug mode and get the dll file along with PDB files. Step 3: Place these files in the Server\..\Bin and Client\bin directories of AX installation. Step 4: Configure Visual Studio: Step 4.1: Configure Debugging Options. In Visual Studio Go to Debug -> Options and Settings -> Debug node -> General sub node and disable “Enable Just My Code (managed)” Step 4.2: Specify the symbol loading directory options. Specify the locations for Client bin and server bin directories of the installation, remember to specify the correct instance of Server bin directory corresponding to your AOS. Step 4.3: Configure the project for debugging Step 5: Ready to go place your breakpoints in X++ and in .Net wherever necessary before this process... Run the Visual studio project and it will invoke the AX client with your breakpoint hitting X++ code.. and when you do a step-in using F11 the Visual studio debugger will be active and from here onwards you would be able to debug the complete flow. Debugging in seamless manner across debuggers is really very good feature and mostly underutilized, but by doing so we can have improved troubleshooting and saves a hell lot of time.. Stay tuned for more in Advanced Debugging..

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• An update on using Rosetta Stone: Studio now isn't very useful and is not great value as an add-on option

  - by Greg Low

  I had a surprisingly large number of responses from my previous posting about learning Chinese. An update for those considering Rosetta Stone (www.rosettastone.com) for Chinese, Spanish or any other language that they offer:I had to renew my "Studio" subscription today and it's now a much worse deal than it was.It's now $75 for 6 months for Studio sessions. Online classes used to be 45 mins. Recently they reduced them to 20 mins. Given how often people have connection issues, etc. that 20 mins can disappear very quickly.They've also reduced the number you can attend. You used to be able to have 2 scheduled at any point in time. Now they limit you to 2 "group sessions" per month during the period. (You can pay for additional private sessions). The combination of these two changes now makes it much less useful. Two x 20 min sessions per month is an almost meaningless amount of practice. They also now automatically change you to auto-renew when you subscribe. They tell you where to remove this auto-renewal but the first 4 or 5 times that I went into that screen, no such option appeared. Later, an option did appear and I used it.Overall, things just aren't what they used to be at Rosetta Stone. It's now pretty hard to recommend the Studio option where it was a no-brainer before.FURTHER UPDATE: <sigh>Even after I renewed, I could not even connect to their "new" service. Although the system processed the renewal, it still tells me it's expired. My online chat person "Siva S" tells me that the problem is that I've purchased all 5 levels of the program. I can't wait till they explain to me how making an extra purchase from them stops me from logging on. Siva told me that they had "renewed" the program. I'd have to speak to Customer Care; they aren't available and then disconnected himself. Impressive (not).Their website is now full of issues too. It insists that my billing address is in the USA, even though it pretends to accept changes to it.Overall, it's gone from something that could be recommended (with some limitations) to now being an app to avoid. That's a pity as I liked much of it before.

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• Registering InputListener in libGDX

  - by JPRO

  I'm just getting started with libGDX and have run into a snag registering an InputListener for a button. I've gone through many examples and this code appears correct to me but the associated callback never triggers ("touched" is not printed to console). I'm just posting the code with the abstract game screen and the implementing screen. The application starts successfully with a label of "Exit" in the bottom left hand corner, but clicking the button/label does nothing. I'm guessing the fix is something simple. What am I overlooking? public abstract class GameScreen<T> implements Screen { protected final T game; protected final SpriteBatch batch; protected final Stage stage; public GameScreen(T game) { this.game = game; this.batch = new SpriteBatch(); this.stage = new Stage(0, 0, true); } @Override public final void render(float delta) { update(delta); // Clear the screen with the given RGB color (black) Gdx.gl.glClearColor(0f, 0f, 0f, 1f); Gdx.gl.glClear(GL20.GL_COLOR_BUFFER_BIT); stage.act(delta); stage.draw(); } public abstract void update(float delta); @Override public void resize(int width, int height) { stage.setViewport(width, height, true); } @Override public void show() { Gdx.input.setInputProcessor(stage); } // hide, pause, resume, dipose } public class ExampleScreen extends GameScreen<MyGame> { private TextButton exitButton; public ExampleScreen(MyGame game) { super(game); } @Override public void show() { super.show(); TextButton.TextButtonStyle buttonStyle = new TextButton.TextButtonStyle(); buttonStyle.font = Font.getFont("Origicide", 32); buttonStyle.fontColor = Color.WHITE; exitButton = new TextButton("Exit", buttonStyle); exitButton.addListener(new InputListener() { @Override public void touchUp (InputEvent event, float x, float y, int pointer, int button) { System.out.println("touched"); } }); stage.addActor(exitButton); } @Override public void update(float delta) { } }

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• Time passage arithmetic explanation

  - by Cyber Axe

  I ported this from http://www.effectgames.com/effect/article.psp.html/joe/Old_School_Color_Cycling_with_HTML5 some time ago. However i'm now wanting to modify it for the purpose of changing it from floating point to fixed point maths for enhanced efficiency (for those who are going to talk about premature optimization and what not, i want to have my entire engine in fixed point both as a learning process for me and so i can port code more easily to systems in the future that dont have native floating points such as arm cpus) My initial conversion to fixed points just resulted in the cycling stuck on either the first or last frame of cycling. Plus it would be nice to understand better how it works so i can add more options and so forth in the future, my maths however sucks and the comments are limited so i don't really know how the maths work for determining the frame it shoud use (cycleAmount) I was also a beginner when i ported it as i had no idea between floating points and integers and what not. So in summary my question is, can anyone give an explination of the arithmatic used for determining the cycleAmount (which determings the "frame" of the cycle) This is the working floating point maths version of the code: public final void cycle(Colour[] sourceColours, double timeNow, double speedAdjust) { // Cycle all animated colour ranges in palette based on timestamp. sourceColours = sourceColours.clone(); int cycleSize; double cycleRate; double cycleAmount; Cycle cycle; for (int i = 0, len = cycles.length; i < len; ++i) { cycle = cycles[i]; cycleSize = (cycle.HIGH - cycle.LOW) + 1; cycleRate = cycle.RATE / (int) (CYCLE_SPEED / speedAdjust); cycleAmount = 0; if (cycle.REVERSE < 3) { // Standard Cycle cycleAmount = DFLOAT_MOD((timeNow / (1000 / cycleRate)), cycleSize); if (cycle.REVERSE < 1) { cycleAmount = cycleSize - cycleAmount; // If below 1 make sure its not reversed. } } else if (cycle.REVERSE == 3) { // Ping-Pong cycleAmount = DFLOAT_MOD((timeNow / (1000 / cycleRate)), cycleSize << 1); if (cycleAmount >= cycleSize) { cycleAmount = (cycleSize * 2) - cycleAmount; } } else if (cycle.REVERSE < 6) { // Sine Wave cycleAmount = DFLOAT_MOD((timeNow / (1000 / cycleRate)), cycleSize); cycleAmount = Math.sin((cycleAmount * 3.1415926 * 2) / cycleSize) + 1; if (cycle.REVERSE == 4) { cycleAmount *= (cycleSize / 4); } else if (cycle.REVERSE == 5) { cycleAmount *= (cycleSize >> 1); } } if (cycle.REVERSE == 2) { reverseColours(sourceColours, cycle); } if (USE_BLEND_SHIFT) { blendShiftColours(sourceColours, cycle, cycleAmount); } else { shiftColours(sourceColours, cycle, cycleAmount); } if (cycle.REVERSE == 2) { reverseColours(sourceColours, cycle); } } colours = sourceColours; } // This utility function allows for variable precision floating point modulus. private double DFLOAT_MOD(final double d, final double b) { return (Math.floor(d * PRECISION) % Math.floor(b * PRECISION)) / PRECISION; }

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• Congratulations to the 2012 Oracle Spatial Award Winners!

  - by Mandy Ho

  I just returned from the 2012 Location Intelligence and Oracle Spatial User conference in Washington, DC, held by Directions Magazine. It was a great conference with presentations from across the country and globe, networking with Oracle Spatial users and meeting new customers and partners. As part of the yearly event, Oracle recognizes special customers and partners for their contributions to advancing mainstream solutions using geospatial technology. This was the 8th year that Oracle has recognized innovative, industry leaders.   The awards were given in three categories: Education/Research, Innovator and Partnership. Here's a little on each of the award winners. Education and Research Award Winner: Technical University of Berlin The Institute for Geodesy and Geoinformation Science of the Technical University of Berlin (TU Berlin) was selected for its leading research work in mapping of urban and regional space onto virtual 3D-city and landscape models, and use of Oracle Spatial, including 3D Vector and Georaster type support, as the data management platform. Innovator Award Winner:  Istanbul Metropolitan Municipality Istanbul is the 3rd largest metropolitan area in Europe. One of their greatest challenges is organizing efficient public transportation for citizens and visitors. There are 15 types of transportations organized by 8 different agencies. To solve this problem, the Directorate of GIS of Istanbul Metropolitan Municipality has created a multi-model itinerary system to help citizens in their decision process for using public transport or their private cars. They choose to use Oracle Spatial Network Model as the solution in our system together with Java and SOAP web services.  Partnership Award Winners: CSoft Group and OSCARS. The Partnership award is given to the ISV or integrator who have demonstrated outstanding achievements in partnering with Oracle on the development side, in taking solutions to market.  CSoft Group- the largest Russion integrator and consultancy provider in CAD and GIS. CSoft was selected by the Oracle Spatial product development organization for the key role in delivering geospatial solutions based on Oracle Database and Fusion Middleware to the Russian market. OSCARS - Provides consulting/training in France, Belgium and Luxembourg. With only 3 full time staff, they have achieved significant success with leading edge customer implementations leveraging the latest Oracle Spatial/MapViewer technologies, and delivering training throughout Europe.  Finally, we also awarded two Special Recognition awards for two partners that helped contribute to the Oracle Partner Network Spatial Specialization. These two partners provided insight and technical expertise from a partner perspective to help launch the new certification program for Oracle Spatial Technologies. Award Winners: ThinkHuddle and OSCARS  For more pictures on the conference and the awards, visit our facebook page: http://www.facebook.com/OracleDatabase

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• Draw a never-ending line in XNA

  - by user2236165

  I am drawing a line in XNA which I want to never end. I also have a tool that moves forward in X-direction and a camera which is centered at this tool. However, when I reach the end of the viewport the lines are not drawn anymore. Here are some pictures to illustrate my problem: At the start the line goes across the whole screen, but as my tool moves forward, we reach the end of the line. Here are the method which draws the lines: private void DrawEvenlySpacedSprites (Texture2D texture, Vector2 point1, Vector2 point2, float increment) { var distance = Vector2.Distance (point1, point2); // the distance between two points var iterations = (int)(distance / increment); // how many sprites with be drawn var normalizedIncrement = 1.0f / iterations; // the Lerp method needs values between 0.0 and 1.0 var amount = 0.0f; if (iterations == 0) iterations = 1; for (int i = 0; i < iterations; i++) { var drawPoint = Vector2.Lerp (point1, point2, amount); spriteBatch.Draw (texture, drawPoint, Color.White); amount += normalizedIncrement; } } Here are the draw method in Game. The dots are my lines: protected override void Draw (GameTime gameTime) { graphics.GraphicsDevice.Clear(Color.Black); nyVector = nextVector (gammelVector); GraphicsDevice.SetRenderTarget (renderTarget); spriteBatch.Begin (); DrawEvenlySpacedSprites (dot, gammelVector, nyVector, 0.9F); spriteBatch.End (); GraphicsDevice.SetRenderTarget (null); spriteBatch.Begin (SpriteSortMode.Deferred, BlendState.AlphaBlend, null, null, null, null, camera.transform); spriteBatch.Draw (renderTarget, new Vector2 (), Color.White); spriteBatch.Draw (tool, new Vector2(toolPos.X - (tool.Width/2), toolPos.Y - (tool.Height/2)), Color.White); spriteBatch.End (); gammelVector = new Vector2 (nyVector.X, nyVector.Y); base.Draw (gameTime); } Here's the next vector-method, It just finds me a new point where the line should be drawn with a new X-coordinate between 100 and 200 pixels and a random Y-coordinate between the old vector Y-coordinate and the height of the viewport: Vector2 nextVector (Vector2 vector) { return new Vector2 (vector.X + r.Next(100, 200), r.Next ((int)(vector.Y - 100), viewport.Height)); } Can anyone point me in the right direction here? I'm guessing it has to do with the viewport.width, but I'm not quite sure how to solve it. Thank you for reading!

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• What source code organization approach helps improve modularity and API/Implementation separation?

  - by Berin Loritsch

  Few languages are as restrictive as Java with file naming standards and project structure. In that language, the file name must match the public class declared in the file, and the file must live in a directory structure matching the class package. I have mixed feelings about that approach. While I never have to guess where a file lives, there's still a lot of empty directories and artificial constraints. There's several languages that define everything about a class in one file, at least by convention. C#, Python (I think), Ruby, Erlang, etc. The commonality in most these languages is that they are object oriented, although that statement can probably be rebuffed (there is one non-OO language in the list already). Finally, there's quite a few languages mostly in the C family that have a separate header and implementation file. For C I think this makes sense, because it is one of the few ways to separate the API interface from implementations. With C it seems that feature is used to promote modularity. Yet, with C++ the way header and implementation files are split seems rather forced. You don't get the same clean API separation that you do with C, and you are forced to include some private details in the header you would rather keep only in the implementation. There's quite a few languages that have a concept that overlaps with interfaces like Java, C#, Go, etc. Some languages use what feels like a hack to provide the same concept like C# using pure virtual abstract classes. Still others don't really have an interface concept and rely on "duck" typing--for example Ruby. Ruby has modules, but those are more along the lines of mixing in behaviors to a class than they are for defining how to interact with a class. In OO terms, interfaces are a powerful way to provide separation between an API client and an API implementation. So to hurry up and ask the question, from a personal experience point of view: Does separation of header and implementation help you write more modular code, or does it get in the way? (it helps to specify the language you are referring to) Does the strict file name to class name scheme of Java help maintainability, or is it unnecessary structure for structure's sake? What would you propose to promote good API/Implementation separation and project maintenance, how would you prefer to do it?

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• How to: Show wait cursor in managed and native code

  - by TechTwaddle

  Someone on the MSDN forum asked about how to show a wait cursor, like when your application is loading or performing some (background) task. It’s pretty simple to show the wait cursor in both managed and native code, and in this post we will see just how. Managed Code (C#) Set Cursor.Current to Cursors.WaitCursor, and call Cursor.Show(). And to come back to normal cursor, set Cursor.Current to Cursors.Default and call Show() again. Below is a button handler for a sample app that I made, (watch the video below) private void button1_Click(object sender, EventArgs e) {     lblProgress.Text = "Downloading ether...";     lblProgress.Update();     Cursor.Current = Cursors.WaitCursor;     Cursor.Show();     //do some processing     for (int i = 0; i < 50; i++)     {         progressBar1.Value = 2 * (i + 1);         Thread.Sleep(100);     }     Cursor.Current = Cursors.Default;     Cursor.Show();     lblProgress.Text = "Download complete.";     lblProgress.Update(); }   Native Code In native code, call SetCursor(LoadCursor(NULL, IDC_WAIT)); to show the wait cursor; and SetCursor(LoadCursor(NULL, IDC_ARROW)); to come back to normal. The same button handler for native version of the app is below, case IDC_BUTTON_DOWNLOAD:     {         HWND temp;         temp = GetDlgItem(hDlg, IDC_STATIC_PROGRESS);         SetWindowText(temp, L"Downloading ether...");         UpdateWindow(temp);         SetCursor(LoadCursor(NULL, IDC_WAIT));         temp = GetDlgItem(hDlg, IDC_PROGRESSBAR);         for (int i=0; i<50; i++)         {             SendMessage(temp, PBM_SETPOS, (i+1)*2, 0);             Sleep(100);         }         SetCursor(LoadCursor(NULL, IDC_ARROW));         temp = GetDlgItem(hDlg, IDC_STATIC_PROGRESS);         SetWindowText(temp, L"Download Complete.");         UpdateWindow(temp);     }     break; Here is a video of the sample app running. First the managed version is deployed and the native version next,

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• MiniMax function throws null pointer exception

  - by Sven

  I'm working on a school project, I have to build a tic tac toe game with the AI based on the MiniMax algorithm. The two player mode works like it should. I followed the code example on http://ethangunderson.com/blog/minimax-algorithm-in-c/. The only thing is that I get a NullPointer Exception when I run the code. And I can't wrap my finger around it. I placed a comment in the code where the exception is thrown. The recursive call is returning a null pointer, what is very strange because it can't.. When I place a breakpoint on the null return with the help of a if statement, then I see that there ARE still 2 to 3 empty places.. I probably overlooking something. Hope someone can tell me what I'm doing wrong. Here is the MiniMax code (the tic tac toe code is not important): /* * To change this template, choose Tools | Templates * and open the template in the editor. */ package MiniMax; import Game.Block; import Game.Board; import java.util.ArrayList; public class MiniMax { public static Place getBestMove(Board gameBoard, Block.TYPE player) { Place bestPlace = null; ArrayList<Place> emptyPlaces = gameBoard.getEmptyPlaces(); Board newBoard; //loop trough all the empty places for(Place emptyPlace : emptyPlaces) { newBoard = gameBoard.clone(); newBoard.setBlock(emptyPlace.getRow(), emptyPlace.getCell(), player); //no game won and still room to move if(newBoard.getWinner() == Block.TYPE.NONE && newBoard.getEmptyPlaces().size() > 0) { //is an node (has children) Place tempPlace = getBestMove(newBoard, invertPlayer(player)); //ERROR is thrown here! tempPlace is null. emptyPlace.setScore(tempPlace.getScore()); } else { //is an leaf if(newBoard.getWinner() == Block.TYPE.NONE) { emptyPlace.setScore(0); } else if(newBoard.getWinner() == Block.TYPE.X) { emptyPlace.setScore(-1); } else if(newBoard.getWinner() == Block.TYPE.O) { emptyPlace.setScore(1); } //if this move is better then our prev move, take it! if((bestPlace == null) || (player == Block.TYPE.X && emptyPlace.getScore() < bestPlace.getScore()) || (player == Block.TYPE.O && emptyPlace.getScore() > bestPlace.getScore())) { bestPlace = emptyPlace; } } } //This should never be null, but it does.. return bestPlace; } private static Block.TYPE invertPlayer(Block.TYPE player) { if(player == Block.TYPE.X) { return Block.TYPE.O; } return Block.TYPE.X; } }

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• add collision detection to sprite?

  - by xBroak

  bassically im trying to add collision detection to the sprite below, using the following: self.rect = bounds_rect collide = pygame.sprite.spritecollide(self, wall_list, False) if collide: # yes print("collide") However it seems that when the collide is triggered it continuously prints 'collide' over and over when instead i want them to simply not be able to walk through the object, any help? def update(self, time_passed): """ Update the creep. time_passed: The time passed (in ms) since the previous update. """ if self.state == Creep.ALIVE: # Maybe it's time to change the direction ? # self._change_direction(time_passed) # Make the creep point in the correct direction. # Since our direction vector is in screen coordinates # (i.e. right bottom is 1, 1), and rotate() rotates # counter-clockwise, the angle must be inverted to # work correctly. # self.image = pygame.transform.rotate( self.base_image, -self.direction.angle) # Compute and apply the displacement to the position # vector. The displacement is a vector, having the angle # of self.direction (which is normalized to not affect # the magnitude of the displacement) # displacement = vec2d( self.direction.x * self.speed * time_passed, self.direction.y * self.speed * time_passed) self.pos += displacement # When the image is rotated, its size is changed. # We must take the size into account for detecting # collisions with the walls. # self.image_w, self.image_h = self.image.get_size() global bounds_rect bounds_rect = self.field.inflate( -self.image_w, -self.image_h) if self.pos.x < bounds_rect.left: self.pos.x = bounds_rect.left self.direction.x *= -1 elif self.pos.x > bounds_rect.right: self.pos.x = bounds_rect.right self.direction.x *= -1 elif self.pos.y < bounds_rect.top: self.pos.y = bounds_rect.top self.direction.y *= -1 elif self.pos.y > bounds_rect.bottom: self.pos.y = bounds_rect.bottom self.direction.y *= -1 self.rect = bounds_rect collide = pygame.sprite.spritecollide(self, wall_list, False) if collide: # yes print("collide") elif self.state == Creep.EXPLODING: if self.explode_animation.active: self.explode_animation.update(time_passed) else: self.state = Creep.DEAD self.kill() elif self.state == Creep.DEAD: pass #------------------ PRIVATE PARTS ------------------# # States the creep can be in. # # ALIVE: The creep is roaming around the screen # EXPLODING: # The creep is now exploding, just a moment before dying. # DEAD: The creep is dead and inactive # (ALIVE, EXPLODING, DEAD) = range(3) _counter = 0 def _change_direction(self, time_passed): """ Turn by 45 degrees in a random direction once per 0.4 to 0.5 seconds. """ self._counter += time_passed if self._counter > randint(400, 500): self.direction.rotate(45 * randint(-1, 1)) self._counter = 0 def _point_is_inside(self, point): """ Is the point (given as a vec2d) inside our creep's body? """ img_point = point - vec2d( int(self.pos.x - self.image_w / 2), int(self.pos.y - self.image_h / 2)) try: pix = self.image.get_at(img_point) return pix[3] > 0 except IndexError: return False def _decrease_health(self, n): """ Decrease my health by n (or to 0, if it's currently less than n) """ self.health = max(0, self.health - n) if self.health == 0: self._explode() def _explode(self): """ Starts the explosion animation that ends the Creep's life. """ self.state = Creep.EXPLODING pos = ( self.pos.x - self.explosion_images[0].get_width() / 2, self.pos.y - self.explosion_images[0].get_height() / 2) self.explode_animation = SimpleAnimation( self.screen, pos, self.explosion_images, 100, 300) global remainingCreeps remainingCreeps-=1 if remainingCreeps == 0: print("all dead")

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• Is throwing an error in unpredictable subclass-specific circumstances a violation of LSP?

  - by Motti Strom

  Say, I wanted to create a Java List<String> (see spec) implementation that uses a complex subsystem, such as a database or file system, for its store so that it becomes a simple persistent collection rather than an basic in-memory one. (We're limiting it specifically to a List of Strings for the purposes of discussion, but it could extended to automatically de-/serialise any object, with some help. We can also provide persistent Sets, Maps and so on in this way too.) So here's a skeleton implementation: class DbBackedList implements List<String> { private DbBackedList() {} /** Returns a list, possibly non-empty */ public static getList() { return new DbBackedList(); } public String get(int index) { return Db.getTable().getRow(i).asString(); // may throw DbExceptions! } // add(String), add(int, String), etc. ... } My problem lies with the fact that the underlying DB API may encounter connection errors that are not specified in the List interface that it should throw. My problem is whether this violates Liskov's Substitution Principle (LSP). Bob Martin actually gives an example of a PersistentSet in his paper on LSP that violates LSP. The difference is that his newly-specified Exception there is determined by the inserted value and so is strengthening the precondition. In my case the connection/read error is unpredictable and due to external factors and so is not technically a new precondition, merely an error of circumstance, perhaps like OutOfMemoryError which can occur even when unspecified. In normal circumstances, the new Error/Exception might never be thrown. (The caller could catch if it is aware of the possibility, just as a memory-restricted Java program might specifically catch OOME.) Is this therefore a valid argument for throwing an extra error and can I still claim to be a valid java.util.List (or pick your SDK/language/collection in general) and not in violation of LSP? If this does indeed violate LSP and thus not practically usable, I have provided two less-palatable alternative solutions as answers that you can comment on, see below. Footnote: Use Cases In the simplest case, the goal is to provide a familiar interface for cases when (say) a database is just being used as a persistent list, and allow regular List operations such as search, subList and iteration. Another, more adventurous, use-case is as a slot-in replacement for libraries that work with basic Lists, e.g if we have a third-party task queue that usually works with a plain List: new TaskWorkQueue(new ArrayList<String>()).start() which is susceptible to losing all it's queue in event of a crash, if we just replace this with: new TaskWorkQueue(new DbBackedList()).start() we get a instant persistence and the ability to share the tasks amongst more than one machine. In either case, we could either handle connection/read exceptions that are thrown, perhaps retrying the connection/read first, or allow them to throw and crash the program (e.g. if we can't change the TaskWorkQueue code).

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• Segmentation fault 11 in MacOS X- C++ [migrated]

  - by Marcos Cesar Vargas Magana

  all. I have a "segmentation fault 11" error when I run the following code. The code actually compiles but I get the error at run time. //** Terror.h ** #include <iostream> #include <string> #include <map> using std::map; using std::pair; using std::string; template<typename Tsize> class Terror { public: //Inserts a message in the map. static Tsize insertMessage(const string& message) { mErrorMessages.insert( pair<Tsize, string>(mErrorMessages.size()+1, message) ); return mErrorMessages.size(); } private: static map<Tsize, string> mErrorMessages; } template<typename Tsize> map<Tsize,string> Terror<Tsize>::mErrorMessages; //** error.h ** #include <iostream> #include "Terror.h" typedef unsigned short errorType; typedef Terror<errorType> error; errorType memoryAllocationError=error::insertMessage("ERROR: out of memory."); //** main.cpp ** #include <iostream> #include "error.h" using namespace std; int main() { try { throw error(memoryAllocationError); } catch(error& err) { } } I have kind of debugging the code and the error happens when the message is being inserted in the static map member. An observation is that if I put the line: errorType memoryAllocationError=error::insertMessage("ERROR: out of memory."); inside the "main()" function instead of at global scope, then everything works fine. But I would like to extend the error messages at global scope, not at local scope. The map is defined static so that all instances of "error" share the same error codes and messages. Do you know how can I get this or something similar. Thank you very much.

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• What's the best way to create a static utility class in python? Is using metaclasses code smell?

  - by rsimp

  Ok so I need to create a bunch of utility classes in python. Normally I would just use a simple module for this but I need to be able to inherit in order to share common code between them. The common code needs to reference the state of the module using it so simple imports wouldn't work well. I don't like singletons, and classes that use the classmethod decorator do not have proper support for python properties. One pattern I see used a lot is creating an internal python class prefixed with an underscore and creating a single instance which is then explicitly imported or set as the module itself. This is also used by fabric to create a common environment object (fabric.api.env). I've realized another way to accomplish this would be with metaclasses. For example: #util.py class MetaFooBase(type): @property def file_path(cls): raise NotImplementedError def inherited_method(cls): print cls.file_path #foo.py from util import * import env class MetaFoo(MetaFooBase): @property def file_path(cls): return env.base_path + "relative/path" def another_class_method(cls): pass class Foo(object): __metaclass__ = MetaFoo #client.py from foo import Foo file_path = Foo.file_path I like this approach better than the first pattern for a few reasons: First, instantiating Foo would be meaningless as it has no attributes or methods, which insures this class acts like a true single interface utility, unlike the first pattern which relies on the underscore convention to dissuade client code from creating more instances of the internal class. Second, sub-classing MetaFoo in a different module wouldn't be as awkward because I wouldn't be importing a class with an underscore which is inherently going against its private naming convention. Third, this seems to be the closest approximation to a static class that exists in python, as all the meta code applies only to the class and not to its instances. This is shown by the common convention of using cls instead of self in the class methods. As well, the base class inherits from type instead of object which would prevent users from trying to use it as a base for other non-static classes. It's implementation as a static class is also apparent when using it by the naming convention Foo, as opposed to foo, which denotes a static class method is being used. As much as I think this is a good fit, I feel that others might feel its not pythonic because its not a sanctioned use for metaclasses which should be avoided 99% of the time. I also find most python devs tend to shy away from metaclasses which might affect code reuse/maintainability. Is this code considered code smell in the python community? I ask because I'm creating a pypi package, and would like to do everything I can to increase adoption.

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• Retrieving Custom Attributes Using Reflection

  - by Scott Dorman

  The .NET Framework allows you to easily add metadata to your classes by using attributes. These attributes can be ones that the .NET Framework already provides, of which there are over 300, or you can create your own. Using reflection, the ways to retrieve the custom attributes of a type are: System.Reflection.MemberInfo public abstract object[] GetCustomAttributes(bool inherit); public abstract object[] GetCustomAttributes(Type attributeType, bool inherit); public abstract bool IsDefined(Type attributeType, bool inherit); System.Attribute public static Attribute[] GetCustomAttributes(MemberInfo member, bool inherit); public static bool IsDefined(MemberInfo element, Type attributeType, bool inherit); If you take the following simple class hierarchy: public abstract class BaseClass { private bool result;   [DefaultValue(false)] public virtual bool SimpleProperty { get { return this.result; } set { this.result = value; } } }   public class DerivedClass : BaseClass { public override bool SimpleProperty { get { return true; } set { base.SimpleProperty = value; } } } Given a PropertyInfo object (which is derived from MemberInfo, and represents a propery in reflection), you might expect that these methods would return the same result. Unfortunately, that isn’t the case. The MemberInfo methods strictly reflect the metadata definitions, ignoring the inherit parameter and not searching the inheritance chain when used with a PropertyInfo, EventInfo, or ParameterInfo object. It also returns all custom attribute instances, including those that don’t inherit from System.Attribute. The Attribute methods are closer to the implied behavior of the language (and probably closer to what you would naturally expect). They do respect the inherit parameter for PropertyInfo, EventInfo, and ParameterInfo objects and search the implied inheritance chain defined by the associated methods (in this case, the property accessors). These methods also only return custom attributes that inherit from System.Attribute. This is a fairly subtle difference that can produce very unexpected results if you aren’t careful. For example, to retrieve the custom  attributes defined on SimpleProperty, you could use code similar to this: PropertyInfo info = typeof(DerivedClass).GetProperty("SimpleProperty"); var attributeList1 = info.GetCustomAttributes(typeof(DefaultValueAttribute), true)); var attributeList2 = Attribute.GetCustomAttributes(info, typeof(DefaultValueAttribute), true));   The attributeList1 array will be empty while the attributeList2 array will contain the attribute instance, as expected. Technorati Tags: Reflection,Custom Attributes,PropertyInfo

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• Evaluating Scrum - is it okay to have people with multiple roles in a Scrum team?

  - by Wayne M

  I'm evaluating some Agile-style methodologies for possible introduction to my team. With Scrum, is it allowable to have the same person perform multiple roles? We have a small team of four developers and a web designer; we don't really have a lead (I fulfill this role), QA testers or business analysts, and all of our development tasks come from the CIO. Automated testing is seen as a total waste of time, and everything focuses on speed and not quality. What will happen is the CIO will come up with a development task (whether a feature or a bug) and give it to a developer (not to the whole team, to an individual, often in private or out of the blue) who is then expected to get it completed. The CIO doesn't gather requirements beyond the initial idea (and this has bitten us before as we'll implement something only to find out that none of the end users can use the feature, because they weren't consulted or even informed about it before we developed it, and in a panic we'll be told to revert the change) but requires say in/approval of everything that we do. First things first, is a Scrum style something to consider to introduce some standards and practices? From reading, Scrum seems to rely on a bit more trust and communication and focuses more on project management than on development, which is something we are completely devoid of as we don't have any semblance of project management at present. Second, if it can work is it unreasonable for someone, let's say myself, to act as both ScrumMaster and a developer? Or for a developer to also be the Product Owner (although chances are this will be the CIO, who isn't a developer)? I realize the Scrum Master and the Product Owner should be different people but at the same time I don't think we have anyone who has the qualities of a Product Owner (chances are it would turn into a "I need all these stories, I don't care how but get it done" type of deal and/or any freeze would be unfrozen on a whim). It seems to me that I might need to pick and choose pieces of Scrum/XP/Lean to compensate for how things are done currently, as it's highly unlikely that the mentality can be changed; for instance Pair Programming would never fly (seen as a waste, you get half the tasks done if you need two people for everything), TDD would be a hard sell, but short cycles would be welcomed.

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• Your interesting code tricks/ conventions? [closed]

  - by Paul

  What interesting conventions, rules, tricks do you use in your code? Preferably some that are not so popular so that the rest of us would find them as novelties. :) Here's some of mine... Input and output parameters This applies to C++ and other languages that have both references and pointers. This is the convention: input parameters are always passed by value or const reference; output parameters are always passed by pointer. This way I'm able to see at a glance, directly from the function call, what parameters might get modified by the function: Inspiration: Old C code int a = 6, b = 7, sum = 0; calculateSum(a, b, &sum); Ordering of headers My typical source file begins like this (see code below). The reason I put the matching header first is because, in case that header is not self-sufficient (I forgot to include some necessary library, or forgot to forward declare some type or function), a compiler error will occur. // Matching header #include "example.h" // Standard libraries #include <string> ... Setter functions Sometimes I find that I need to set multiple properties of an object all at once (like when I just constructed it and I need to initialize it). To reduce the amount of typing and, in some cases, improve readability, I decided to make my setters chainable: Inspiration: Builder pattern class Employee { public: Employee& name(const std::string& name); Employee& salary(double salary); private: std::string name_; double salary_; }; Employee bob; bob.name("William Smith").salary(500.00); Maybe in this particular case it could have been just as well done in the constructor. But for Real WorldTM applications, classes would have lots more fields that should be set to appropriate values and it becomes unmaintainable to do it in the constructor. So what about you? What personal tips and tricks would you like to share?

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• rotate sprite and shooting bullets from the end of a cannon

  - by Alberto

  Hi all i have a problem in my Andengine code, I need , when I touch the screen, shoot a bullet from the cannon (in the same direction of the cannon) The cannon rotates perfectly but when I touch the screen the bullet is not created at the end of the turret This is my code: private void shootProjectile(final float pX, final float pY){ int offX = (int) (pX-canon.getSceneCenterCoordinates()[0]); int offY = (int) (pY-canon.getSceneCenterCoordinates()[1]); if (offX <= 0) return ; if(offY>=0) return; double X=canon.getX()+canon.getWidth()*0,5; double Y=canon.getY()+canon.getHeight()*0,5 ; final Sprite projectile; projectile = new Sprite( (float) X, (float) Y, mProjectileTextureRegion,this.getVertexBufferObjectManager() ); mMainScene.attachChild(projectile); int realX = (int) (mCamera.getWidth()+ projectile.getWidth()/2.0f); float ratio = (float) offY / (float) offX; int realY = (int) ((realX*ratio) + projectile.getY()); int offRealX = (int) (realX- projectile.getX()); int offRealY = (int) (realY- projectile.getY()); float length = (float) Math.sqrt((offRealX*offRealX)+(offRealY*offRealY)); float velocity = (float) 480.0f/1.0f; float realMoveDuration = length/velocity; MoveModifier modifier = new MoveModifier(realMoveDuration,projectile.getX(), realX, projectile.getY(), realY); projectile.registerEntityModifier(modifier); } @Override public boolean onSceneTouchEvent(Scene pScene, TouchEvent pSceneTouchEvent) { if (pSceneTouchEvent.getAction() == TouchEvent.ACTION_MOVE){ double dx = pSceneTouchEvent.getX() - canon.getSceneCenterCoordinates()[0]; double dy = pSceneTouchEvent.getY() - canon.getSceneCenterCoordinates()[1]; double Radius = Math.atan2(dy,dx); double Angle = Radius * 180 / Math.PI; canon.setRotation((float)Angle); return true; } else if (pSceneTouchEvent.getAction() == TouchEvent.ACTION_DOWN){ final float touchX = pSceneTouchEvent.getX(); final float touchY = pSceneTouchEvent.getY(); double dx = pSceneTouchEvent.getX() - canon.getSceneCenterCoordinates()[0]; double dy = pSceneTouchEvent.getY() - canon.getSceneCenterCoordinates()[1]; double Radius = Math.atan2(dy,dx); double Angle = Radius * 180 / Math.PI; canon.setRotation((float)Angle); shootProjectile(touchX, touchY); } return false; } Anyone know how to calculate the coordinates (X,Y) of the end of the barrel to draw the bullet?

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• x axis detection issues platformer starter kit

  - by dbomb101

  I've come across a problem with the collision detection code in the platformer starter kit for xna.It will send up the impassible flag on the x axis despite being nowhere near a wall in either direction on the x axis, could someone could tell me why this happens ? Here is the collision method. /// <summary> /// Detects and resolves all collisions between the player and his neighboring /// tiles. When a collision is detected, the player is pushed away along one /// axis to prevent overlapping. There is some special logic for the Y axis to /// handle platforms which behave differently depending on direction of movement. /// </summary> private void HandleCollisions() { // Get the player's bounding rectangle and find neighboring tiles. Rectangle bounds = BoundingRectangle; int leftTile = (int)Math.Floor((float)bounds.Left / Tile.Width); int rightTile = (int)Math.Ceiling(((float)bounds.Right / Tile.Width)) - 1; int topTile = (int)Math.Floor((float)bounds.Top / Tile.Height); int bottomTile = (int)Math.Ceiling(((float)bounds.Bottom / Tile.Height)) - 1; // Reset flag to search for ground collision. isOnGround = false; // For each potentially colliding tile, for (int y = topTile; y <= bottomTile; ++y) { for (int x = leftTile; x <= rightTile; ++x) { // If this tile is collidable, TileCollision collision = Level.GetCollision(x, y); if (collision != TileCollision.Passable) { // Determine collision depth (with direction) and magnitude. Rectangle tileBounds = Level.GetBounds(x, y); Vector2 depth = RectangleExtensions.GetIntersectionDepth(bounds, tileBounds); if (depth != Vector2.Zero) { float absDepthX = Math.Abs(depth.X); float absDepthY = Math.Abs(depth.Y); // Resolve the collision along the shallow axis. if (absDepthY < absDepthX || collision == TileCollision.Platform) { // If we crossed the top of a tile, we are on the ground. if (previousBottom <= tileBounds.Top) isOnGround = true; // Ignore platforms, unless we are on the ground. if (collision == TileCollision.Impassable || IsOnGround) { // Resolve the collision along the Y axis. Position = new Vector2(Position.X, Position.Y + depth.Y); // Perform further collisions with the new bounds. bounds = BoundingRectangle; } } //This is the section which deals with collision on the x-axis else if (collision == TileCollision.Impassable) // Ignore platforms. { // Resolve the collision along the X axis. Position = new Vector2(Position.X + depth.X, Position.Y); // Perform further collisions with the new bounds. bounds = BoundingRectangle; } } } } } // Save the new bounds bottom. previousBottom = bounds.Bottom; }

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• Less than 50 Lines of Code to Create a Java Palette in NetBeans

  - by Geertjan

  Want to drag and drop Java code snippets into the palette, in the same way as can be done for HTML files? If so, create a new module and add a class with the content below and you're done. You'll be able to select a piece of Java code, drag it into the palette (Ctrl-Shift-8 to open it), where you'll be able to set a name, tooltip, and icons for the snippet, and then you'll be able to drag it out of the palette into any Java files you like. The palette content is persisted across restarts of the IDE. package org.netbeans.modules.javasourcefilepalette; import java.io.IOException; import javax.swing.Action; import org.netbeans.api.editor.mimelookup.MimeRegistration; import org.netbeans.spi.palette.DragAndDropHandler; import org.netbeans.spi.palette.PaletteActions; import org.netbeans.spi.palette.PaletteController; import org.netbeans.spi.palette.PaletteFactory; import org.openide.util.Exceptions; import org.openide.util.Lookup; import org.openide.util.datatransfer.ExTransferable; public class JavaSourceFileLayerPaletteFactory { private static PaletteController palette = null; @MimeRegistration(mimeType = "text/x-java", service = PaletteController.class) public static PaletteController createPalette() { try { if (null == palette) { return PaletteFactory.createPalette( //Folder: "JavaPalette", //Palette Actions: new PaletteActions() { @Override public Action[] getImportActions() {return null;} @Override public Action[] getCustomPaletteActions() {return null;} @Override public Action[] getCustomCategoryActions(Lookup lkp) {return null;} @Override public Action[] getCustomItemActions(Lookup lkp) {return null;} @Override public Action getPreferredAction(Lookup lkp) {return null;} }, //Palette Filter: null, //Drag and Drop Handler: new DragAndDropHandler(true) { @Override public void customize(ExTransferable et, Lookup lkp) {} }); } } catch (IOException ex) { Exceptions.printStackTrace(ex); } return null; } } In my layer file, I have this content: <folder name="JavaPalette"> <folder name="Snippets"/> </folder> That's all. Run the module. Open a Java source file and the palette will automatically open. Drag some code into the palette and a dialog will pop up asking for some details like display name and icons. Then the snippet will be in the palette and you'll be able to drag and drop it anywhere you like. Use the Palette Manager, which is automatically integrated, to add new categories and show/hide palette items. Related blog entry, for which the above is a big simplification: Drag/Drop Snippets into Palette .

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• Get Specific depth values in Kinect (XNA)

  - by N0xus

  I'm currently trying to make a hand / finger tracking with a kinect in XNA. For this, I need to be able to specify the depth range I want my program to render. I've looked about, and I cannot see how this is done. As far as I can tell, kinect's depth values only work with pre-set ranged found in the depthStream. What I would like to do is make it modular so that I can change the depth range my kinect renders. I know this has been down before but I can't find anything online that can show me how to do this. Could someone please help me out? I have made it possible to render the standard depth view with the kinect, and the method that I have made for converting the depth frame is as follows (I've a feeling its something in here I need to set) private byte[] ConvertDepthFrame(short[] depthFrame, DepthImageStream depthStream, int depthFrame32Length) { int tooNearDepth = depthStream.TooNearDepth; int tooFarDepth = depthStream.TooFarDepth; int unknownDepth = depthStream.UnknownDepth; byte[] depthFrame32 = new byte[depthFrame32Length]; for (int i16 = 0, i32 = 0; i16 < depthFrame.Length && i32 < depthFrame32.Length; i16++, i32 += 4) { int player = depthFrame[i16] & DepthImageFrame.PlayerIndexBitmask; int realDepth = depthFrame[i16] >> DepthImageFrame.PlayerIndexBitmaskWidth; // transform 13-bit depth information into an 8-bit intensity appropriate // for display (we disregard information in most significant bit) byte intensity = (byte)(~(realDepth >> 8)); if (player == 0 && realDepth == 00) { // white depthFrame32[i32 + RedIndex] = 255; depthFrame32[i32 + GreenIndex] = 255; depthFrame32[i32 + BlueIndex] = 255; } // omitted other if statements. Simple changed the color of the pixels if they went out of the pre=set depth values else { // tint the intensity by dividing by per-player values depthFrame32[i32 + RedIndex] = (byte)(intensity >> IntensityShiftByPlayerR[player]); depthFrame32[i32 + GreenIndex] = (byte)(intensity >> IntensityShiftByPlayerG[player]); depthFrame32[i32 + BlueIndex] = (byte)(intensity >> IntensityShiftByPlayerB[player]); } } return depthFrame32; } I have a strong hunch it's something I need to change in the int player and int realDepth values, but i can't be sure.

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• Storing game objects with generic object information

  - by Mick

  In a simple game object class, you might have something like this: public abstract class GameObject { protected String name; // other properties protected double x, y; public GameObject(String name, double x, double y) { // etc } // setters, getters } I was thinking, since a lot of game objects (ex. generic monsters) will share the same name, movement speed, attack power, etc, it would be better to have all that information shared between all monsters of the same type. So I decided to have an abstract class "ObjectData" to hold all this shared information. So whenever I create a generic monster, I would use the same pre-created "ObjectData" for it. Now the above class becomes more like this: public abstract class GameObject { protected ObjectData data; protected double x, y; public GameObject(ObjectData data, double x, double y) { // etc } // setters, getters public String getName() { return data.getName(); } } So to tailor this specifically for a Monster (could be done in a very similar way for Npcs, etc), I would add 2 classes. Monster which extends GameObject, and MonsterData which extends ObjectData. Now I'll have something like this: public class Monster extends GameObject { public Monster(MonsterData data, double x, double y) { super(data, x, y); } } This is where my design question comes in. Since MonsterData would hold data specific to a generic monster (and would vary with what say NpcData holds), what would be the best way to access this extra information in a system like this? At the moment, since the data variable is of type ObjectData, I'll have to cast data to MonsterData whenever I use it inside the Monster class. One solution I thought of is this, but this might be bad practice: public class Monster extends GameObject { private MonsterData data; // <- this part here public Monster(MonsterData data, double x, double y) { super(data, x, y); this.data = data; // <- this part here } } I've read that for one I should generically avoid overwriting the underlying classes variables. What do you guys think of this solution? Is it bad practice? Do you have any better solutions? Is the design in general bad? How should I redesign this if it is? Thanks in advanced for any replies, and sorry about the long question. Hopefully it all makes sense!

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• What is the correct way to use g_signal_connect() in C++ for dynamic unity quicklists?

  - by hakermania

  I want to make my application use dynamic unity quicklists. For building my application I am using C++ and the QtCreator IDE. When a menu action is triggered I want to be able to have access to a non-static function of my MainWindow class so as to be able to update the Graphical User Interface which can be accessed from inside 'normal' MainWindow's functions. So, I am building up my quicklist like this (mainwindow.cpp): void MainWindow::enable_unity_quicklist(){ Unity_Menu = dbusmenu_menuitem_new(); dbusmenu_menuitem_property_set_bool (Unity_Menu, DBUSMENU_MENUITEM_PROP_VISIBLE, FALSE); Unity_Stop = dbusmenu_menuitem_new(); dbusmenu_menuitem_property_set(Unity_Stop, DBUSMENU_MENUITEM_PROP_LABEL, "Stop"); dbusmenu_menuitem_child_append (Unity_Menu, Unity_Stop); g_signal_connect (Unity_Stop, DBUSMENU_MENUITEM_SIGNAL_ITEM_ACTIVATED, G_CALLBACK(&fake_callback), (gpointer)this); if(!unity_entry) unity_entry = unity_launcher_entry_get_for_desktop_id("myapp.desktop"); unity_launcher_entry_set_quicklist(unity_entry, Unity_Menu); dbusmenu_menuitem_property_set_bool(Unity_Menu, DBUSMENU_MENUITEM_PROP_VISIBLE, true); dbusmenu_menuitem_property_set_bool(Unity_Stop, DBUSMENU_MENUITEM_PROP_VISIBLE, true); } void MainWindow::fake_callback(gpointer data){ MainWindow* m = (MainWindow*)data; m->on_stopButton_clicked(); } void MainWindow::on_stopButton_clicked(){ //stopping the process... } mainwindow.h: private slots: void enable_unity_quicklist(); void on_stopButton_clicked(); public slots: static void fake_callback(gpointer data); This suggestion was taken from http://old.nabble.com/Using-g_signal_connect-in-class-td18461823.html The program crashes immediately after I choose the 'Stop' action from the Unity Quicklist. Debugging the program shows that I am not able to access anything MainWindow related inside the on_stopButton_clicked() without crashing. For example, it crashes when doing this check (which is the first 2 lines of code inside this function): if (!ui->stopButton->isEnabled()) return; I have also tested lots of other things that I found at the internet, but nothing of them worked. One interesting solution would be to use gtkmm (http://developer.gnome.org/gtkmm-tutorial/stable/sec-connecting-signal-handlers.html.en) but I am not used at all working on GTK applications (I work solely in Qt) and I don't know if this even suits to my occasion. A compilable example indicating what the problem is can be found at: http://ubuntuone.com/7iKA3wnPmWVp8YNNDLlVQI (3.2Kb) If you are not familiar with the QtCreator IDE, you can compile with the following commands, as long as you have all the needed libraries: cd dynamic_unity_quicklists_test; qmake -project; qmake; make

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• What are some reasonable stylistic limits on type inference?

  - by Jon Purdy

  C++0x adds pretty darn comprehensive type inference support. I'm sorely tempted to use it everywhere possible to avoid undue repetition, but I'm wondering if removing explicit type information all over the place is such a good idea. Consider this rather contrived example: Foo.h: #include <set> class Foo { private: static std::set<Foo*> instances; public: Foo(); ~Foo(); // What does it return? Who cares! Just forward it! static decltype(instances.begin()) begin() { return instances.begin(); } static decltype(instances.end()) end() { return instances.end(); } }; Foo.cpp: #include <Foo.h> #include <Bar.h> // The type need only be specified in one location! // But I do have to open the header to find out what it actually is. decltype(Foo::instances) Foo::instances; Foo() { // What is the type of x? auto x = Bar::get_something(); // What does do_something() return? auto y = x.do_something(*this); // Well, it's convertible to bool somehow... if (!y) throw "a constant, old school"; instances.insert(this); } ~Foo() { instances.erase(this); } Would you say this is reasonable, or is it completely ridiculous? After all, especially if you're used to developing in a dynamic language, you don't really need to care all that much about the types of things, and can trust that the compiler will catch any egregious abuses of the type system. But for those of you that rely on editor support for method signatures, you're out of luck, so using this style in a library interface is probably really bad practice. I find that writing things with all possible types implicit actually makes my code a lot easier for me to follow, because it removes nearly all of the usual clutter of C++. Your mileage may, of course, vary, and that's what I'm interested in hearing about. What are the specific advantages and disadvantages to radical use of type inference?

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• #SSAS #Tabular Workshop and Community Events in Netherlands and Denmark

  - by Marco Russo (SQLBI)

  Next week I will finally start the roadshow of the SSAS Tabular Workshop, a 2-day seminar about the new BISM Tabular model for Analysis Services that has been introduced in SQL Server 2012. During these roadshows, we always try to arrange some speeches at local community events in the evening - we already defined for Copenhagen, we have some logistic issue in Amsterdam that we're trying to solve. Here is the timetable: Netherlands SSAS Workshop in Amsterdam, NL – April 16-17, 2012 2-day seminar, I and Alberto will be the trainers for this event, register here We're trying to manage a Community event but we still don't have a confirmation, stay tuned        Denmark SSAS Workshop in Copenhagen, DK – April 26-27, 2012 2-day seminar, I and Alberto will be the trainers for this event, register here Community event on April 26, 2012 This event will run in Hellerup, at Microsoft venue All details available here: http://msbip.dk/events/26/msbip-mode-nr-5/ People from Sweden are welcome! Just register to this private group on LinkedIn in order to announce your presence, so we’ll know how many people will attend In community events we’ll deliver two speeches – here are the descriptions: Inside xVelocity (VertiPaq) PowerPivot and BISM Tabular models in Analysis Services share a great columnar-based database engine called xVelocity in-memory analytics engine (VertiPaq). If you want to improve performance and optimize memory used, you have to understand some basic principles about how this engine works, how data is compressed, and how you can design a data model for better optimization. Prepare yourself to change your mind. xVelocity optimization techniques might seem counterintuitive and are absolutely different than OLAP and SQL ones! Choosing between Tabular and Multidimensional You have a new project and you have to make an important decision upfront. Should you use Tabular or Multidimensional? It is not easy to answer, because sometime there is a clear choice, but most of the times both decisions might be correct, at least at the beginning. In this session we’ll help you making an informed decision, correctly evaluating pros and cons of each one according to common scenarios, considering both short-term and long-term consequences of your choice. I hope to meet many people in this first dates. We have many other events coming in May and June, including an online event (for US time zones), and you can also attend our PreCon Day at TechEd US in Orland (PRC06) or TechEd Europe in Amsterdam. I’ll be a good customer for airline companies in the next three months! I’m just sorry that I hadn’t time to write other articles in the last month, but I’m accumulating material that I will need to write down during some flight – stay tuned…

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• Loading levels from .txt or .XML for XNA

  - by Dave Voyles

  I'm attemptin to add multiple levels to my pong game. I'd like to simply exchange a few elements with each level, nothing crazy. Just the background texture, the color of the AI paddle (the one on the right side), and the music. It seems that the best way to go about this is by utilizing the StreamReader to read and write the files from XML. If there is a better, or more efficient alternative way then I'm all for it. In looking over the XNA Starter Platformer Kit provided by MS it seems that they've done it in this manner as well. I'm perplexed by a few things, however, namely parts within the Level class which aren't commented. /// <summary> /// Iterates over every tile in the structure file and loads its /// appearance and behavior. This method also validates that the /// file is well-formed with a player start point, exit, etc. /// </summary> /// <param name="fileStream"> /// A stream containing the tile data. /// </param> private void LoadTiles(Stream fileStream) { // Load the level and ensure all of the lines are the same length. int width; List<string> lines = new List<string>(); using (StreamReader reader = new StreamReader(fileStream)) { string line = reader.ReadLine(); width = line.Length; while (line != null) { lines.Add(line); if (line.Length != width) throw new Exception(String.Format("The length of line {0} is different from all preceeding lines.", lines.Count)); line = reader.ReadLine(); } } What does width = line.Length mean exactly? I mean I know how it reads the line, but what difference does it make if one line is longer than any of the others? Finally, their levels are simply text files that look like this: .................... .................... .................... .................... .................... .................... .................... .........GGG........ .........###........ .................... ....GGG.......GGG... ....###.......###... .................... .1................X. #################### It can't be that easy..... Can it?

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