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  • Is there an appropriate coding style for implementing an algorithm during an interview?

    - by GlenPeterson
    I failed an interview question in C years ago about converting hex to decimal by not exploiting the ASCII table if (inputDigitByte > 9) hex = inputDigitByte - 'a'. The rise of Unicode has made this question pretty silly, but the point was that the interviewer valued raw execution speed above readability and error handling. They tell you to review algorithms textbooks to prepare for these interviews, yet these same textbooks tend to favor the implementation with the fewest lines of code, even if it has to rely on magic numbers (like "infinity") and a slower, more memory-intensive implementation (like a linked list instead of an array) to do that. I don't know what is right. Coding an algorithm within the space of an interview has at least 3 constraints: time to code, elegance/readability, and efficiency of execution. What trade-offs are appropriate for interview code? How much do you follow the textbook definition of an algorithm? Is it better to eliminate recursion, unroll loops, and use arrays for efficiency? Or is it better to use recursion and special values like "infinity" or Integer.MAX_VALUE to reduce the number of lines of code needed to write the algorithm? Interface: Make a very self-contained, bullet-proof interface, or sloppy and fast? On the one extreme, the array to be sorted might be a public static variable. On the other extreme, it might need to be passed to each method, allowing methods to be called individually from different threads for different purposes. Is it appropriate to use a linked-list data structure for items that are traversed in one direction vs. using arrays and doubling the size when the array is full? Implementing a singly-linked list during the interview is often much faster to code and easier remember for recursive algorithms like MergeSort. Thread safety - just document that it's unsafe, or say so verbally? How much should the interviewee be looking for opportunities for parallel processing? Is bit shifting appropriate? x / 2 or x >> 1 Polymorphism, type safety, and generics? Comments? Variable and method names: qs(a, p, q, r) vs: quickSort(theArray, minIdx, partIdx, maxIdx) How much should you use existing APIs? Obviously you can't use a java.util.HashMap to implement a hash-table, but what about using a java.util.List to accumulate your sorted results? Are there any guiding principals that would answer these and other questions, or is the guiding principal to ask the interviewer? Or maybe this should be the basis of a discussion while writing the code? If an interviewer can't or won't answer one of these questions, are there any tips for coaxing the information out of them?

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  • My grid based collision detection is slow

    - by Fibericon
    Something about my implementation of a basic 2x4 grid for collision detection is slow - so slow in fact, that it's actually faster to simply check every bullet from every enemy to see if the BoundingSphere intersects with that of my ship. It becomes noticeably slow when I have approximately 1000 bullets on the screen (36 enemies shooting 3 bullets every .5 seconds). By commenting it out bit by bit, I've determined that the code used to add them to the grid is what's slowest. Here's how I add them to the grid: for (int i = 0; i < enemy[x].gun.NumBullets; i++) { if (enemy[x].gun.bulletList[i].isActive) { enemy[x].gun.bulletList[i].Update(timeDelta); int bulletPosition = 0; if (enemy[x].gun.bulletList[i].position.Y < 0) { bulletPosition = (int)Math.Floor((enemy[x].gun.bulletList[i].position.X + 900) / 450); } else { bulletPosition = (int)Math.Floor((enemy[x].gun.bulletList[i].position.X + 900) / 450) + 4; } GridItem bulletItem = new GridItem(); bulletItem.index = i; bulletItem.type = 5; bulletItem.parentIndex = x; if (bulletPosition > -1 && bulletPosition < 8) { if (!grid[bulletPosition].Contains(bulletItem)) { for (int j = 0; j < grid.Length; j++) { grid[j].Remove(bulletItem); } grid[bulletPosition].Add(bulletItem); } } } } And here's how I check if it collides with the ship: if (ship.isActive && !ship.invincible) { BoundingSphere shipSphere = new BoundingSphere( ship.Position, ship.Model.Meshes[0].BoundingSphere.Radius * 9.0f); for (int i = 0; i < grid.Length; i++) { if (grid[i].Contains(shipItem)) { for (int j = 0; j < grid[i].Count; j++) { //Other collision types omitted else if (grid[i][j].type == 5) { if (enemy[grid[i][j].parentIndex].gun.bulletList[grid[i][j].index].isActive) { BoundingSphere bulletSphere = new BoundingSphere(enemy[grid[i][j].parentIndex].gun.bulletList[grid[i][j].index].position, enemy[grid[i][j].parentIndex].gun.bulletModel.Meshes[0].BoundingSphere.Radius); if (shipSphere.Intersects(bulletSphere)) { ship.health -= enemy[grid[i][j].parentIndex].gun.damage; enemy[grid[i][j].parentIndex].gun.bulletList[grid[i][j].index].isActive = false; grid[i].RemoveAt(j); break; //no need to check other bullets } } else { grid[i].RemoveAt(j); } } What am I doing wrong here? I thought a grid implementation would be faster than checking each one.

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  • Modify game using external file

    - by Veehmot
    In Flash, for example, I can place an xml file along with the binary, then if I modify some variable the game will change for everyone. How to achieve something like that in Android? I know that for every change I make to the game, the player would need to download a new update. But the main goal I'm looking for, is modifying a game stats without the need for recompile the entire APK. I'm working with Haxe+OpenFL.

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  • SQL Server Substr Equivalent

    - by Derek D.
    The oracle function equivalent to the SQL Server function of Substr is: Substring. All spelled out. This function is actually identical to Oracle’s function.DECLARE @BaseString varchar(max)SET @BaseString = 'My grandmothers pillows are blue'SELECT SUBSTRING ( @BaseString -- The base string to extract from ,4 -- Start Position ,5 -- Length of Characters )The above query returns the value ‘grand’. Related Posts:»SQL Server Contains [...]

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  • Using Competition Information to Plan Your SEO Strategy

    There is no doubt about it, there is no better feeling than beating out your competition in search engine placement. It generally takes a certain length of time, but that day when you climb one step above your competition is a sweet victory. The easiest way to do this is to analyse just what exactly your competition is doing, and do it better.

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  • Explanation of the definition of interface inheritance as described in GoF book

    - by Geek
    I am reading the first chapter of the Gof book. Section 1.6 discusses about class vs interface inheritance: Class versus Interface Inheritance It's important to understand the difference between an object's class and its type. An object's class defines how the object is implemented.The class defines the object's internal state and the implementation of its operations.In contrast,an object's type only refers to its interface--the set of requests on which it can respond. An object can have many types, and objects of different classes can have the same type. Of course, there's a close relationship between class and type. Because a class defines the operations an object can perform, it also defines the object's type . When we say that an object is an instance of a class, we imply that the object supports the interface defined by the class. Languages like c++ and Eiffel use classes to specify both an object's type and its implementation. Smalltalk programs do not declare the types of variables; consequently,the compiler does not check that the types of objects assigned to a variable are subtypes of the variable's type. Sending a message requires checking that the class of the receiver implements the message, but it doesn't require checking that the receiver is an instance of a particular class. It's also important to understand the difference between class inheritance and interface inheritance (or subtyping). Class inheritance defines an object's implementation in terms of another object's implementation. In short, it's a mechanism for code and representation sharing. In contrast,interface inheritance(or subtyping) describes when an object can be used in place of another. I am familiar with the Java and JavaScript programming language and not really familiar with either C++ or Smalltalk or Eiffel as mentioned here. So I am trying to map the concepts discussed here to Java's way of doing classes, inheritance and interfaces. This is how I think of of these concepts in Java: In Java a class is always a blueprint for the objects it produces and what interface(as in "set of all possible requests that the object can respond to") an object of that class possess is defined during compilation stage only because the class of the object would have implemented those interfaces. The requests that an object of that class can respond to is the set of all the methods that are in the class(including those implemented for the interfaces that this class implements). My specific questions are: Am I right in saying that Java's way is more similar to C++ as described in the third paragraph. I do not understand what is meant by interface inheritance in the last paragraph. In Java interface inheritance is one interface extending from another interface. But I think the word interface has some other overloaded meaning here. Can some one provide an example in Java of what is meant by interface inheritance here so that I understand it better?

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  • 0xC0017011 and other error messages - what is the error message text?

    Recently there was a bug raised against BIDS Helper which originated in my Expression Editor control. Thankfully the person that raised it kindly included a screenshot, so I had the error code (HRESULT 0xC0017011) and a stack trace that pointed the finger firmly at my control, but no error message text. The code itself looked fine so I searched on the error code but got no results. I’d expected to get a hit from Books Online with the Integration Services Error and Message Reference topic at the very least, but no joy. There is however a more accurate and definitive reference, namely the header file that defines all these codes dtsmsg.h which you can find at- C:\Program Files (x86)\Microsoft SQL Server\110\SDK\Include\dtsmsg.h Looking the code up in the header file gave me a much more useful error message. //////////////////////////////////////////////////////////////////////////// // The parameter is sensitive // // MessageId: DTS_E_SENSITIVEPARAMVALUENOTALLOWED // // MessageText: // // Accessing value of the parameter variable for the sensitive parameter "%1!s!" is not allowed. Verify that the variable is used properly and that it protects the sensitive information. // #define DTS_E_SENSITIVEPARAMVALUENOTALLOWED ((HRESULT)0xC0017011L) Unfortunately I’d forgotten all about this. By the time I had remembered about it, the person who raised the issue had managed to narrow it down to something to do with having  sensitive parameter. Putting that together with the error message I’d finally found, a quick poke around in the code and I found the new GetSensitiveValue method which seemed to do the trick. The HResult fields are also listed online but it only shows the short error message, and it doesn’t include that all so important HRESULT value itself. So let this be a lesson to you (and me!), if you need to check  SSIS error go straight to the horses mouth - dtsmsg.h. This is particularly true when working with early builds, or CTP releases when we expect the documentation to be a bit behind. There is also a programmatic approach to getting better SSIS error messages. I should to take another look at the error handling in the control, or the way it is hosted in BIDS Helper. I suspect that if I use an implementation of Microsoft.SqlServer.Dts.Runtime.Wrapper.IDTSInfoEvents100 I could catch the error itself and get the full error message text which I could then report back. This would obviously be a better user experience and also make it easier to diagnose any issues like this in the future. See ExprssionEvaluator.cs for an example of this in use in the Expression Editor control.

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  • Installed Sun Java 6 - configuration problem when running as sudo

    - by HorusKol
    I have install Sun Java 6 on an Ubuntu server and set an environment variable in the default profile as per the instructions at http://www.edugate.ie/workshop-guides/shibboleth-2-identity-provider-installation-linux-debian-or-ubuntu I then try to run an installer for a Java servlet - but when I run it as myself, it cannot create the required directory in /opt. When I run it as sudo, I am told that JAVA_HOME is not correct and it doesn't even start the installer - shouldn't this be coming from /etc/profile like it is for my normal user?

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  • Ubuntu 11.10 doesn't detect external usb hard drive

    - by Andrew
    I have been batting with this issue for a bit and cannot find the answer to it. So the Dmesg see's the device, being Symwave WDC WD64.... media@Media-pc:~$ dmesg | tail -n 20 [78678.719497] scsi 10:0:0:0: Direct-Access Generic- USB3.0 CRW -0 1.00 PQ: 0 ANSI: 0 CCS [78678.725621] scsi 10:0:0:1: Direct-Access Generic- USB3.0 CRW -1 1.00 PQ: 0 ANSI: 0 CCS [78684.073837] scsi 11:0:0:0: Direct-Access SYMWAVE WDC WD6400AAKS-0 3B01 PQ: 0 ANSI: 4 [78691.008126] scsi 11:0:0:0: uas_eh_abort_handler tag 0 [78691.008139] scsi 11:0:0:0: uas_eh_device_reset_handler tag 0 [78691.008147] scsi 11:0:0:0: uas_eh_target_reset_handler tag 0 [78691.008154] scsi 11:0:0:0: uas_eh_bus_reset_handler tag 0 [78691.080307] usb 2-2.4: reset high speed USB device number 9 using ehci_hcd [78691.221427] scsi 11:0:0:0: Device offlined - not ready after error recovery [78691.221498] scsi 11:0:0:0: rejecting I/O to offline device [78691.221519] scsi 11:0:0:0: rejecting I/O to offline device [78691.222952] scsi 11:0:0:1: Enclosure SYMWAVE SES 3B01 PQ: 0 ANSI: 4 [78691.223156] scsi 11:0:0:2: uas_sense_old: urb length 26 disagrees with IU sense data length 510, using 18 bytes of sense data [78691.225061] sd 11:0:0:0: Attached scsi generic sg3 type 0 [78691.225344] ses 11:0:0:1: Attached Enclosure device [78691.225495] ses 11:0:0:1: Attached scsi generic sg4 type 13 [78691.226266] sd 10:0:0:0: Attached scsi generic sg5 type 0 [78691.226653] sd 10:0:0:1: Attached scsi generic sg6 type 0 [78691.241647] sd 10:0:0:0: [sdd] Attached SCSI removable disk [78691.243832] sd 10:0:0:1: [sde] Attached SCSI removable disk It looks like it attaches sdd and sde. Now when i look in the disk utility it shows "Hard disk Symwave WD6400AAKS-0 device /dev/sdc doesn't show any other info then that, if i format, it says that it cannot open /dev/sdc no device or address error. Underneeth the device it does show two general usb3.0 CRW that are sdd and sde. Now if I do a fdisk -l it doesn't show the device: media@Media-pc:~$ sudo fdisk -l Disk /dev/sda: 80.0 GB, 80026361856 bytes 255 heads, 63 sectors/track, 9729 cylinders, total 156301488 sectors Units = sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disk identifier: 0x000247de Device Boot Start End Blocks Id System /dev/sda1 * 2048 152176639 76087296 83 Linux /dev/sda2 152178686 156301311 2061313 5 Extended /dev/sda5 152178688 156301311 2061312 82 Linux swap / Solaris Disk /dev/sdb: 1000.2 GB, 1000204886016 bytes 255 heads, 63 sectors/track, 121601 cylinders, total 1953525168 sectors Units = sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disk identifier: 0x948fc822 Device Boot Start End Blocks Id System /dev/sdb1 63 1953520064 976760001 7 HPFS/NTFS/exFAT So now I am confused. Any ideas how I get fdisk to see the device?

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  • music for an arcade game?

    - by user717572
    I'm thinking about music for my brick breaker game, but I don't know how to choose any. If I'd make a loop from a few seconds, I think it would get annoying very quickly. I also found some longer length tracks (about 2 minutes), but when this is over, it's going to be repeated anyway, just like when you'd select a new level, you'd have to listen to the same beginning of the song again. I can't put an hour of music in my application, so what would you recommend I'd do for the music?

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  • SharpDX/D3D: How to implement and draw fonts/text

    - by Dmitrij A
    I am playing with SharpDX (Direct3D for .NET) without using "Toolkit", already finished with basic rendering 3D models. But now i am wondering how to program/create fonts for game (2D), or how to simple draw variable text to output with Direct3D? (it is not as SharpDX question as common Direct3D question, how to start with game GUIs? And what should i do to program simple GUI's like menu for a game (generally i understand that it's shaders).

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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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  • How to motivate team for knowledge sharing sessions

    - by ring bearer
    I work in a team with wide range of expertise and experience. I have been trying to introduce weekly knowledge sharing sessions. Sessions of 30-60 min length where everybody gets a chance to present something and talk about it. This will contribute in improving presentational and language skills. However, the team is not motivated towards this, either the attendance is too low or none. How to get a team work towards such an idea?

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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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  • We've completed the first iteration

    - by CliveT
    There are a lot of features in C# that are implemented by the compiler and not by the underlying platform. One such feature is a lambda expression. Since local variables cannot be accessed once the current method activation finishes, the compiler has to go out of its way to generate a new class which acts as a home for any variable whose lifetime needs to be extended past the activation of the procedure. Take the following example:     Random generator = new Random();     Func func = () = generator.Next(10); In this case, the compiler generates a new class called c_DisplayClass1 which is marked with the CompilerGenerated attribute. [CompilerGenerated] private sealed class c__DisplayClass1 {     // Fields     public Random generator;     // Methods     public int b__0()     {         return this.generator.Next(10);     } } Two quick comments on this: (i)    A display was the means that compilers for languages like Algol recorded the various lexical contours of the nested procedure activations on the stack. I imagine that this is what has led to the name. (ii)    It is a shame that the same attribute is used to mark all compiler generated classes as it makes it hard to figure out what they are being used for. Indeed, you could imagine optimisations that the runtime could perform if it knew that classes corresponded to certain high level concepts. We can see that the local variable generator has been turned into a field in the class, and the body of the lambda expression has been turned into a method of the new class. The code that builds the Func object simply constructs an instance of this class and initialises the fields to their initial values.     c__DisplayClass1 class2 = new c__DisplayClass1();     class2.generator = new Random();     Func func = new Func(class2.b__0); Reflector already contains code to spot this pattern of code and reproduce the form containing the lambda expression, so this is example is correctly decompiled. The use of compiler generated code is even more spectacular in the case of iterators. C# introduced the idea of a method that could automatically store its state between calls, so that it can pick up where it left off. The code can express the logical flow with yield return and yield break denoting places where the method should return a particular value and be prepared to resume.         {             yield return 1;             yield return 2;             yield return 3;         } Of course, there was already a .NET pattern for expressing the idea of returning a sequence of values with the computation proceeding lazily (in the sense that the work for the next value is executed on demand). This is expressed by the IEnumerable interface with its Current property for fetching the current value and the MoveNext method for forcing the computation of the next value. The sequence is terminated when this method returns false. The C# compiler links these two ideas together so that an IEnumerator returning method using the yield keyword causes the compiler to produce the implementation of an Iterator. Take the following piece of code.         IEnumerable GetItems()         {             yield return 1;             yield return 2;             yield return 3;         } The compiler implements this by defining a new class that implements a state machine. This has an integer state that records which yield point we should go to if we are resumed. It also has a field that records the Current value of the enumerator and a field for recording the thread. This latter value is used for optimising the creation of iterator instances. [CompilerGenerated] private sealed class d__0 : IEnumerable, IEnumerable, IEnumerator, IEnumerator, IDisposable {     // Fields     private int 1__state;     private int 2__current;     public Program 4__this;     private int l__initialThreadId; The body gets converted into the code to construct and initialize this new class. private IEnumerable GetItems() {     d__0 d__ = new d__0(-2);     d__.4__this = this;     return d__; } When the class is constructed we set the state, which was passed through as -2 and the current thread. public d__0(int 1__state) {     this.1__state = 1__state;     this.l__initialThreadId = Thread.CurrentThread.ManagedThreadId; } The state needs to be set to 0 to represent a valid enumerator and this is done in the GetEnumerator method which optimises for the usual case where the returned enumerator is only used once. IEnumerator IEnumerable.GetEnumerator() {     if ((Thread.CurrentThread.ManagedThreadId == this.l__initialThreadId)               && (this.1__state == -2))     {         this.1__state = 0;         return this;     } The state machine itself is implemented inside the MoveNext method. private bool MoveNext() {     switch (this.1__state)     {         case 0:             this.1__state = -1;             this.2__current = 1;             this.1__state = 1;             return true;         case 1:             this.1__state = -1;             this.2__current = 2;             this.1__state = 2;             return true;         case 2:             this.1__state = -1;             this.2__current = 3;             this.1__state = 3;             return true;         case 3:             this.1__state = -1;             break;     }     return false; } At each stage, the current value of the state is used to determine how far we got, and then we generate the next value which we return after recording the next state. Finally we return false from the MoveNext to signify the end of the sequence. Of course, that example was really simple. The original method body didn't have any local variables. Any local variables need to live between the calls to MoveNext and so they need to be transformed into fields in much the same way that we did in the case of the lambda expression. More complicated MoveNext methods are required to deal with resources that need to be disposed when the iterator finishes, and sometimes the compiler uses a temporary variable to hold the return value. Why all of this explanation? We've implemented the de-compilation of iterators in the current EAP version of Reflector (7). This contrasts with previous version where all you could do was look at the MoveNext method and try to figure out the control flow. There's a fair amount of things we have to do. We have to spot the use of a CompilerGenerated class which implements the Enumerator pattern. We need to go to the class and figure out the fields corresponding to the local variables. We then need to go to the MoveNext method and try to break it into the various possible states and spot the state transitions. We can then take these pieces and put them back together into an object model that uses yield return to show the transition points. After that Reflector can carry on optimising using its usual optimisations. The pattern matching is currently a little too sensitive to changes in the code generation, and we only do a limited analysis of the MoveNext method to determine use of the compiler generated fields. In some ways, it is a pity that iterators are compiled away and there is no metadata that reflects the original intent. Without it, we are always going to dependent on our knowledge of the compiler's implementation. For example, we have noticed that the Async CTP changes the way that iterators are code generated, so we'll have to do some more work to support that. However, with that warning in place, we seem to do a reasonable job of decompiling the iterators that are built into the framework. Hopefully, the EAP will give us a chance to find examples where we don't spot the pattern correctly or regenerate the wrong code, and we can improve things. Please give it a go, and report any problems.

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  • Looping in Python and keeping current line after sub routine [migrated]

    - by Brendan
    I've been trying to nut out an issue when looping in python 3. When returning from sub routine the "line" variable has not incremented. How do I get the script to return the latest readline from the subsroutine? Code below def getData(line): #print(line) #while line in sTSDP_data: while "/service/content/test" not in line: line = sTSDP_data.readline() import os, sys sFileTSDP = "d:/ess/redo/Test.log" sTSDP_data = open(sFileTSDP, "r") for line in sTSDP_data: if "MOBITV" in line: getData(line) #call sub routine print(line)

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  • bashrc script not accepting space in directory name

    - by faizal
    I have added a variable at the end of my ~/.basrc file : export xyz = /home/faizal/DEV/ADT workspace/xyz But if i open a new terminal, i get the error : bash: export: 'workspace/xyz': not a valid identifier So i try a variety of alternatives : export xyz=/home/faizal/DEV/ADT\ workspace/xyz export xyz="/home/faizal/DEV/ADT workspace/xyz" export xyz="/home/faizal/DEV/ADT\ workspace/xyz" export xyz='/home/faizal/DEV/ADT workspace/xyz' export xyz='/home/faizal/DEV/ADT\ workspace/xyz' They all give me the error when i try cd $xyz: bash: cd: /home/faizal/DEV/ADT: No such file or directory What am i doing wrong?

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  • Get Info From Database, or Build Inferred Info?

    - by Zaemz
    Does it make more sense to store and retrieve properties or information directly related to an item in a database, or, say in such a case that a product's ID could describe information about it, should the information be gathered from that? Example: Item SKU -- 4HBU12 4 - is the number of motors H - the voltage B - the color, blue U - the model 12 - the length Should I store those individual attributes as well as the SKU, or should I store only the SKU and build the attributes from it?

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  • <meta name="robots" content="noindex"> in "Fetch as Google"

    - by Rodrigo Azevedo
    I don't know why but when I execute "fetch as Google" it returns me HTTP/1.1 200 OK Cache-Control: private Content-Type: text/html Content-Encoding: gzip Vary: Accept-Encoding Server: Microsoft-IIS/7.5 Set-Cookie: ASPSESSIONIDQACRADAQ=ECAINNFBMGNDEPAEBKBLOBOP; path=/ X-Powered-By: ASP.NET Date: Wed, 26 Jun 2013 15:18:29 GMT Content-Length: 153 <meta name="robots" content="noindex"> The noindex doesn't exist. Does anybody know what could be wrong?

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  • Checking if an Unloaded Collection Contains Elements

    - by Ricardo Peres
    If you want to know if an unloaded collection in an entity contains elements, or count them, without actually loading them, you need to use a custom query; that is because the Count property (if the collection is not mapped with lazy=”extra”) and the LINQ Count() and Any() methods force the whole collection to be loaded. You can use something like these two methods, one for checking if there are any values, the other for actually counting them: 1: public static Boolean Exists(this ISession session, IEnumerable collection) 2: { 3: if (collection is IPersistentCollection) 4: { 5: IPersistentCollection col = collection as IPersistentCollection; 6:  7: if (col.WasInitialized == false) 8: { 9: String[] roleParts = col.Role.Split('.'); 10: String ownerTypeName = String.Join(".", roleParts, 0, roleParts.Length - 1); 11: String ownerCollectionName = roleParts.Last(); 12: String hql = "select 1 from " + ownerTypeName + " it where it.id = :id and exists elements(it." + ownerCollectionName + ")"; 13: Boolean exists = session.CreateQuery(hql).SetParameter("id", col.Key).List().Count == 1; 14:  15: return (exists); 16: } 17: } 18:  19: return ((collection as IEnumerable).OfType<Object>().Any()); 20: } 21:  22: public static Int64 Count(this ISession session, IEnumerable collection) 23: { 24: if (collection is IPersistentCollection) 25: { 26: IPersistentCollection col = collection as IPersistentCollection; 27:  28: if (col.WasInitialized == false) 29: { 30: String[] roleParts = col.Role.Split('.'); 31: String ownerTypeName = String.Join(".", roleParts, 0, roleParts.Length - 1); 32: String ownerCollectionName = roleParts.Last(); 33: String hql = "select count(elements(it." + ownerCollectionName + ")) from " + ownerTypeName + " it where it.id = :id"; 34: Int64 count = session.CreateQuery(hql).SetParameter("id", col.Key).UniqueResult<Int64>(); 35:  36: return (count); 37: } 38: } 39:  40: return ((collection as IEnumerable).OfType<Object>().Count()); 41: } Here’s how: 1: MyEntity entity = session.Load(100); 2:  3: if (session.Exists(entity.SomeCollection)) 4: { 5: Int32 count = session.Count(entity.SomeCollection); 6: //... 7: }

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  • getting bone base and tip positions from a transform matrix?

    - by ddos
    I need this for a Blender3d script, but you don't really need to know Blender to answer this. I need to get bone head and tip positions from a transform matrix read from a file. The position of base is the location part of the matrix, length of the bone (distance from base to tip) is the scale, position of the tip is calculated from the scale (distance from bone base) and rotation part of the matrix. So how to calculate these? bone.base([x,y,z]) # x,y,z - floats bone.tip([x,y,z])

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  • Yet another use of OUTER APPLY in defensive programming

    - by Alexander Kuznetsov
    When a SELECT is used to populate variables from a subquery, it fails to change them if the subquery returns nothing - and that can lead to subtle bugs. We shall use OUTER APPLY to eliminate this problem. Prerequisites All we need is the following mock function that imitates a subquery: CREATE FUNCTION dbo.BoxById ( @BoxId INT ) RETURNS TABLE AS RETURN ( SELECT CAST ( 1 AS INT ) AS [Length] , CAST ( 2 AS INT ) AS [Width] , CAST ( 3 AS INT ) AS [Height] WHERE @BoxId = 1 ) ; Let us assume that this...(read more)

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  • Understanding clojure keywords

    - by tjb1982
    I'm taking my first steps with Clojure. Otherwise, I'm somewhat competent with JavaScript, Python, Java, and a little C. I was reading this artical that describes destructuring vectors and maps. E.g. => (def point [0 0]) => (let [[x y] point] => (println "the coordinates are:" x y)) the coordinates are: 0 0 but I'm having a difficult time understanding keywords. At first glance, they seem really simple, as they just evaluate to themselves: => :test :test But they seem to be used is so many different ways and I don't understand how to think about them. E.g., you can also do stuff like this: => (defn full-name [& {first :first last :last}] => (println first last)) => (full-name :first "Tom" :last "Brennan") Tom Brennan nil This doesn't seem intuitive to me. I would have guessed the arguments should have been something more like: (full-name {:first "Tom" :last "Brennan"}) because it looks like in the function definition that you're saying "no required arguments, but a variable number of arguments comes in the form of a single map". But it seems more like you're saying "no required arguments, but a variable number of arguments comes which should be a list of alternating keywords and values... ?" I'm not really sure how to wrap my brain around this. Also, things like this confuse me too: => (def population {:humans 5 :zombies 1000}) => (:zombies population) 1000 => (population :zombies) 1000 How do maps and keywords suddenly become functions? If I could get some clarification on the use of keywords in these two examples, that would be really helpful. Update I've also seen http://stackoverflow.com/questions/3337888/clojure-named-arguments and while the accepted answer is a great demonstration of how to use keywords with destructuring and named arguments, I'm really looking more for understanding how to think about them--why the language is designed this way and how I can best internalize their use.

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  • How does a "Variables introduce state"?

    - by kunj2aan
    I was reading the "C++ Coding Standards" and this line was there: Variables introduce state, and you should have to deal with as little state as possible, with lifetimes as short as possible. Doesn't anything that mutates eventually manipulate state? What does "you should have to deal with little state as possible" mean? In an impure language such as C++, isn't state management really what you are doing? And what are other ways to "deal with as little state as possible" other than limiting variable lifetime?

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