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  • Which Programming Language Should I Learn?

    - by Esteban Araya
    I've decided, for educational purposes, I want to learn a new language every 2 years or so. Which language should I learn first? Why? I'm proficient with C, C# and Java. Other than that, I really haven't done much with any other languages. Thanks! Edit: Thanks to all of those that recommended functional languages. Making the mental switch to a functional language seems hard. How did you overcome your instinct to keep doing things in a procedural manner?

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  • Transitive SQL query on same table

    - by MiKu
    Hey. consider d following table and data... in_timestamp | out_timestamp | name | in_id | out_id | in_server | out_server | status timestamp1 | timestamp2 | data1 |id1 | id2 | others-server1 | my-server1 | success timestamp2 | timestamp3 | data1 | id2 | id3 | my-server1 | my-server2 | success timestamp3 | timestamp4 | data1 | id3 | id4 | my-server2 | my-server3 | success timestamp4 | timestamp5 | data1 | id4 | id5 | my-server3 | others-server2 | success the above data represent log of a execution flow of some data across servers. e.g. some data has flowed from some 'outside-server1' to bunch of 'my-servers' and finally to destined 'others-server2'. Question : 1) I need to give this log in representable form to client where he doesn't need to know anything about the bunch of 'my-servers'. All i am supposed to give is timestamp of the data entered my infrastructure and when it left; drilling down to following info. in_timestamp (of 'others_server1' to 'my-server1') out_timestamp (of 'my-server3' to 'others-server2') name status I want to write sql for the same! Can someone help? NOTE : there might not be 3 'my-servers' all the time. It differs from situation to situation. e.g. there might be 4 'my-server' involved for, say, data2! 2) Are there any other alternatives to SQL? I mean stored procs/etc? 3) Optimizations? (The records are huge in number! As of now, it is around 5 million a day. And we are supposed to show records that are upto a week old.) In advance, THANKS FOR THE HELP! :)

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  • Entity Framework - Foreign key constraints not added for inherited entity

    - by Tri Q
    Hello, It appears to me that a strange phenomenon is occurring with inherited entities (TPT) in EF4. I have three entities. 1. Asset 2. Property 3. Activity Property is a derived-type of Asset. Property has many activities (many-to-many) When modeling this in my EDMX, everything seems fine until I try to insert a new Property into the database. If the property does not contain any Activity, it works, but all hell breaks loose when I add some new activities to the new Property. As it turns out after 2 days of crawling the web and fiddling around, I noticed that in the EF store (SSDL) some of the constraints between entities were not picked up during the update process. Property_Activity table which links properties and activities show only one constraint FK_Property_Activity_Activity but FK_Property_Activity_Property was missing. I knew this is an Entity Framework anomoly because when I switched the relationship in the database to: Asset <-- Asset_Activity <-- Activity After an update, all foreign key constraints are picked up and the save is successful, with or without activities in the new property. Is this intended or a bug in EF? How do I get around this problem? Should I abandon inheritance altogether?

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  • Some more multitasking java issues

    - by owca
    I had a task to write simple game simulating two players picking up 1-3 matches one after another until the pile is gone. I managed to do it for computer choosing random value of matches but now I'd like to go further and allow humans to play the game. Here's what I already have : http://paste.pocoo.org/show/200660/ Class Player is a computer player, and PlayerMan should be human being. Problem is, that thread of PlayerMan should wait until proper value of matches is given but I cannot make it work this way. When I type the values it sometimes catches them and decrease amount of matches but that's not exactly what I was up to :) Logics is : I check the value of current player. If it corresponds to this of the thread currently active I use scanner to catch the amount of matches. Else I wait one second (I know it's kinda harsh solution, but I have no other idea how to do it). Class Shared keeps the value of current player, and also amount of matches. By the way, is there any way I can make Player and Shared attributes private instead of public and still make the code work ? CONSOLE and INPUT-DIALOG is just for choosing way of inserting values. class PlayerMan extends Player{ static final int CONSOLE=0; static final int INPUT_DIALOG=1; private int input; public PlayerMan(String name, Shared data, int c){ super(name, data); input = c; } @Override public void run(){ Scanner scanner = new Scanner(System.in); int n = 0; System.out.println("Matches on table: "+data.matchesAmount); System.out.println("which: "+data.which); System.out.println("number: "+number); while(data.matchesAmount != 0){ if(number == data.which){ System.out.println("Choose amount of matches (from 1 to 3): "); n = scanner.nextInt(); if(data.matchesAmount == 1){ System.out.println("There's only 1 match left !"); while(n != 1){ n = scanner.nextInt(); } } else{ do{ n = scanner.nextInt(); } while(n <= 1 && n >= 3); } data.matchesAmount = data.matchesAmount - n; System.out.println(" "+ name+" takes "+n+" matches."); if(number != 0){ data.which = 0; } else{ data.which = 1; } } else{ try { Thread.sleep(1000); } catch(InterruptedException exc) { System.out.println("End of thread."); return; } } System.out.println("Matches on table: "+data.matchesAmount); } if(data.matchesAmount == 0){ System.out.println("Winner is player: "+name); stop(); } } }

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  • Best approach for coding ?

    - by ahmed
    What should or how should I decide the best approach for coding as a smart programmer. I have just started programming last year in VB, and I keep on listening this statement. But I never could find by myself to choose the best approach for coding. When I search for a coding example on internet I find different types of approach to achieve the same target. So help me finding the best approach. (asp.net,vb.net)

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  • PyQt4, QThread and opening big files without freezing the GUI

    - by jmrbcu
    Hi, I would like to ask how to read a big file from disk and maintain the PyQt4 UI responsive (not blocked). I had moved the load of the file to a QThread subclass but my GUI thread get freezed. Any suggestions? I think it must be something with the GIL but I don't know how to sort it? EDIT: I am using vtkGDCMImageReader from the GDCM project to read a multiframe DICOM image and display it with vtk and pyqt4. I do this load in a different thread (QThread) but my app freeze until the image is loaded. here is an example code: class ReadThread(QThread): def __init__(self, file_name): super(ReadThread, self).__init__(self) self.file_name = file_name self.reader.vtkgdcm.vtkGDCMImageReader() def run(self): self.reader.SetFileName(self.file_name) self.reader.Update() self.emit(QtCore.SIGNAL('image_loaded'), self.reader.GetOutput())

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  • Infix to Postfix and unary/binary operators

    - by Jaapjan
    I have a piece of code that converts an infix expression to an expression tree in memory. This works just fine. There's just one small trouble. I just connect work out how to involve the unary operators correctly (the right associative ones). With the following infix expression : +1 + +2 - -3 - -4 I would expect an RPN of: 1+2++3-4-- Yet, none of the online infix-post converters I can find handle this example in the way I would expect. Does anyone have a clear explanation of handling right associative operators, specifically the binary ones that can be mistaken for the unary ones?

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  • What is the single most effective thing you did to improve your programming skills?

    - by Oded
    Looking back at my career and life as a programmer, there were plenty of different ways I improved my programming skills - reading code, writing code, reading books, listening to podcasts, watching screencasts and more. My question is: What is the most effective thing you have done that improved your programming skills? What would you recommend to others that want to improve? I do expect varied answers here and no single "one size fits all" answer - I would like to know what worked for different people. Edit: Wow - what great answers! Keep 'em coming people!!!

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  • Well written Perl Open Source to learn from ?

    - by Prix
    Hi, is there any well written perl open source out there (not using any kinda of framework) that i could use as sample for learning and good pratice of the perl... I've searched around and found many things for PHP, but nothing in perl that uses no framework. Thanks in advance.

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  • Blackberry - application settings save/load

    - by Max Gontar
    Hi! I know two ways to save/load application settings: use PersistentStore use filesystem (store, since SDCard is optional) I'd like to know what are you're practicies of working with application settings? Using PersistentStore to save/load application settings The persistent store provides a means for objects to persist across device resets. A persistent object consists of a key-value pair. When a persistent object is committed to the persistent store, that object's value is stored in flash memory via a deep copy. The value can then be retrieved at a later point in time via the key. Example of helper class for storing and retrieving settings: class PSOptions { private PersistentObject mStore; private LongHashtableCollection mSettings; private long KEY_URL = 0; private long KEY_ENCRYPT = 1; private long KEY_REFRESH_PERIOD = 2; public PSOptions() { // "AppSettings" = 0x71f1f00b95850cfeL mStore = PersistentStore.getPersistentObject(0x71f1f00b95850cfeL); } public String getUrl() { Object result = get(KEY_URL); return (null != result) ? (String) result : null; } public void setUrl(String url) { set(KEY_URL, url); } public boolean getEncrypt() { Object result = get(KEY_ENCRYPT); return (null != result) ? ((Boolean) result).booleanValue() : false; } public void setEncrypt(boolean encrypt) { set(KEY_ENCRYPT, new Boolean(encrypt)); } public int getRefreshPeriod() { Object result = get(KEY_REFRESH_PERIOD); return (null != result) ? ((Integer) result).intValue() : -1; } public void setRefreshRate(int refreshRate) { set(KEY_REFRESH_PERIOD, new Integer(refreshRate)); } private void set(long key, Object value) { synchronized (mStore) { mSettings = (LongHashtableCollection) mStore.getContents(); if (null == mSettings) { mSettings = new LongHashtableCollection(); } mSettings.put(key, value); mStore.setContents(mSettings); mStore.commit(); } } private Object get(long key) { synchronized (mStore) { mSettings = (LongHashtableCollection) mStore.getContents(); if (null != mSettings && mSettings.size() != 0) { return mSettings.get(key); } else { return null; } } } } Example of use: class Scr extends MainScreen implements FieldChangeListener { PSOptions mOptions = new PSOptions(); BasicEditField mUrl = new BasicEditField("Url:", "http://stackoverflow.com/"); CheckboxField mEncrypt = new CheckboxField("Enable encrypt", false); GaugeField mRefresh = new GaugeField("Refresh period", 1, 60 * 10, 10, GaugeField.EDITABLE|FOCUSABLE); ButtonField mLoad = new ButtonField("Load settings", ButtonField.CONSUME_CLICK); ButtonField mSave = new ButtonField("Save settings", ButtonField.CONSUME_CLICK); public Scr() { add(mUrl); mUrl.setChangeListener(this); add(mEncrypt); mEncrypt.setChangeListener(this); add(mRefresh); mRefresh.setChangeListener(this); HorizontalFieldManager hfm = new HorizontalFieldManager(USE_ALL_WIDTH); add(hfm); hfm.add(mLoad); mLoad.setChangeListener(this); hfm.add(mSave); mSave.setChangeListener(this); loadSettings(); } public void fieldChanged(Field field, int context) { if (field == mLoad) { loadSettings(); } else if (field == mSave) { saveSettings(); } } private void saveSettings() { mOptions.setUrl(mUrl.getText()); mOptions.setEncrypt(mEncrypt.getChecked()); mOptions.setRefreshRate(mRefresh.getValue()); } private void loadSettings() { mUrl.setText(mOptions.getUrl()); mEncrypt.setChecked(mOptions.getEncrypt()); mRefresh.setValue(mOptions.getRefreshPeriod()); } }

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  • Is Programming Right for me?

    - by L1th1um
    I'm interested in programming, but it seems to me that I can't get into it. Every time I've tried to learn a language and stuff by looking through tutorials or books I'd never get past the part where I use the syntax to make something. And by interest, I mean that I read stack overflow a lot, coding horror, and stuff but the actual coding part is hard for me to get into. Did anybody start this way? How did you get past this block?

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  • collision with moving objects

    - by blacksheep
    tried to write a collision with the moving "floats" but did not succeed. maybe wrong place of the "collision" code? thanx 4 help! // // FruitsView.m // import "FruitsView.h" import "Constants.h" import "Utilities.h" define kFloat1Speed 0.15 define kFloat2Speed 0.3 define kFloat3Speed 0.2 @interface FruitsView (Private) - (void) stopTimer; @end @implementation FruitsView @synthesize apple, float1, float2, float3, posFloat1, posFloat2, posFloat3; -(void)onTimer { float1.center = CGPointMake(float1.center.x+posFloat1.x,float1.cen ter.y+posFloat1.y); if(float1.center.x 380 || float1.center.x < -60) posFloat1.x = -posFloat1.x; if(float1.center.y 100 || float1.center.y < -40) posFloat1.y = -posFloat1.y; float2.center = CGPointMake(float2.center.x+posFloat2.x,float2.cen ter.y+posFloat2.y); if(float2.center.x 380 || float2.center.x < -50) posFloat2.x = -posFloat2.x; if(float2.center.y 150 || float2.center.y < -30) posFloat2.y = -posFloat2.y; float3.center = CGPointMake(float3.center.x+posFloat3.x,float3.cen ter.y+posFloat3.y); if(float3.center.x 380 || float3.center.x < -70) posFloat3.x = -posFloat3.x; if(float3.center.y 100 || float3.center.y < -20) posFloat3.y = -posFloat3.y; if(CGRectIntersectsRect(apple.frame,float1.frame)) { if(apple.center.y float1.center.y) { posApple.y = -posApple.y; } } if(CGRectIntersectsRect(apple.frame,float2.frame)) { if(apple.center.y float2.center.y) { posFloat2.y = -posFloat2.y; } } if(CGRectIntersectsRect(apple.frame,float3.frame)) { if(apple.center.y float3.center.y) { posFloat3.y = -posFloat3.y; } } } pragma mark Initialisation/destruction (void)awakeFromNib { [NSTimer scheduledTimerWithTimeInterval:0.0001 target:self selector:@selector(onTimer) userInfo:nil repeats:YES]; posFloat1 = CGPointMake(kFloat1Speed, 0); posFloat2 = CGPointMake(kFloat2Speed, 0); posFloat3 = CGPointMake(kFloat3Speed, 0); timer = nil; modeLock = lockNotYetChosen; defaultSize = self.bounds.size.width; modal = self.tag; [[UIAccelerometer sharedAccelerometer] setDelegate:self]; [UIView beginAnimations:nil context:nil]; [UIView setAnimationRepeatCount:1]; eadbea.transform = CGAffineTransformMakeScale(0.5,0.5); [UIView commitAnimations]; [UIView beginAnimations:nil context:nil]; [UIView setAnimationRepeatCount:1]; apple.transform = CGAffineTransformMakeScale(0.5,0.5); [UIView commitAnimations]; } pragma mark Background animation processing (void) startTimer { if (!timer) { timer = [[NSTimer scheduledTimerWithTimeInterval:1.0/60.0 target:self selector:@selector(timerTick:) userInfo:nil repeats:YES] retain]; } } (void) stopTimer { [timer invalidate]; [timer release]; timer = nil; } (void) check:(CGPoint*)position delta:(CGSize*)delta halfSize:(CGSize)halfSize forBouncingAgainst:(CGSize)containerSize { if ((position-x - halfSize.width)<0) { delta-width = fabsf(delta-width)*BOUNCE_DAMPING; position-x = halfSize.width; } if ((position-x + halfSize.width)containerSize.width) { delta-width = fabsf(delta-width)*-BOUNCE_DAMPING; position-x = containerSize.width - halfSize.width; } if ((position-y - halfSize.height)<0) { delta-height = fabsf(delta-height)*BOUNCE_DAMPING; position-y = halfSize.height; } if ((position-y + halfSize.height)containerSize.height) { delta-height = fabsf(delta-height)*-BOUNCE_DAMPING; position-y = containerSize.height - halfSize.height; } } (void) timerTick: (NSTimer*)timer { dragDelta = CGSizeScale(dragDelta, INERTIAL_DAMPING); if ((fabsf(dragDelta.width)DELTA_ZERO_THRESHOLD) || (fabsf(dragDelta.height)DELTA_ZERO_THRESHOLD)) { CGPoint ctr = CGPointApplyDelta(self.center, dragDelta); CGSize halfSize = CGSizeMake(self.bounds.size.width/4, self.bounds.size.height/4); [self check:&ctr delta:&dragDelta halfSize:halfSize forBouncingAgainst:self.superview.bounds.size]; self.center = ctr; } else { [self stopTimer]; } } pragma mark Input Handling (void)touchesMoved:(NSSet *)touches withEvent:(UIEvent )event { NSSet allTouches = [event touchesForView:self]; if ([allTouches count]==1) { if (modeLocklockNotYetChosen) return; UITouch* anyTouch = [touches anyObject]; lastMove = anyTouch.timestamp; CGPoint now = [anyTouch locationInView: self.superview]; CGPoint then = [anyTouch previousLocationInView: self.superview]; dragDelta = CGPointDelta(now, then); self.center = CGPointApplyDelta(self.center, dragDelta); [self stopTimer]; } } (void)touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event { NSSet* allTouches = [event touchesForView:self]; if ([touches count]==[allTouches count]) { modeLock = lockNotYetChosen; if ((event.timestamp - lastMove) MOVEMENT_PAUSE_THRESHOLD) return; if ((fabsf(dragDelta.width)INERTIA_THRESHOLD) || (fabsf(dragDelta.height)INERTIA_THRESHOLD)) { [self startTimer]; } } } (void)touchesCancelled:(NSSet *)touches withEvent:(UIEvent *)event { modeLock = lockNotYetChosen; [self stopTimer]; } (void)dealloc { [float1 release]; [float2 release]; [float3 release]; [apple release]; [bear_head release]; [self stopTimer]; [super dealloc]; } @end

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  • What skills are needed to be successful at robotics?

    - by Click Upvote
    I'm considering studying to be a robotics engineer. The desire to work in that field is definitely there.. but I'm wondering what my chances of success would be. Generally I'm good with mental tasks of any sort such as programming, maths, physics, etc, and I think i'd be able to do electrical work such as soldering wires, changing batteries, etc. However, I'm not so good with things of a physical nature where I have to use my hands. For example, if you give me some vegetables to slice and dice, all of them will be diced un-evenly and some will look ugly. This might be because I have poor mind-hand coordination or because of a lack of concentration. Thoughts?

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  • Clientside going serverside with node.js

    - by Sveisvei
    Hello, I`ve been looking for a serverside language for some time, and python got my attention somewhat. But as I already know and love javascript, I now want learn to code on the server with js and node.js. Now, what books and what subjects do I need to learn to understand the serverside world better? (let me know if Im to vague)

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  • How can I learn to set up a build process?

    - by Satoru.Logic
    Hi, all. What I was taught at school is all about programming languages, software design, but hardly anything about how to automatically build a software, probably with unit testing integrated. Please tell me how do one start learning to set up a build process for his project.

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  • How do you beat procrastination?

    - by Armentia
    I have had horrible procrastination habits since gradeschool, and now that I'm in college, I still am having a hard time beating this bad habit. I find myself easily distracted from doing real "work" and find myself wandering off doing something else that I enjoy more. Tell me how you personally beat procrastination; or share your struggles.

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  • Coding for fun

    - by Klelky
    I would describe myself as a career coder - i.e. a developer at work but never really coded for fun. Early in my career I've hit the management track though. I really like my current job and can't see me going back to coding anytime soon so: Whats the best way to develop my coding skills and learn new languages in my spare time?

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  • Hobbies/Careers that complement programming

    - by Cherian
    Do you cultivate an alternative career/hobby which complements or refreshes your primary role as a developer? If so, what is it and why? Also see these related questions: If you weren't a programmer what would you be doing How do you vent stress as a programmer? What are some exercises you do to make you a better programmer? How do you reward yourself when you've overcome a monster task

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  • What is this particular type of revelation called?

    - by Lars Haugseth
    After struggling with a particular problem or bug in some part of my code for hours, without getting anywhere, I often get a sudden revelation as soon as I try to explain the problem to one of my coworkers, or while formulating it in writing for posting to some forum. Does this kind of experience have a name? Where can I read more about it and how to train it? Do any of you use this consciously in your day-to-day work?

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  • Asymptotic runtime of list-to-tree function

    - by Deestan
    I have a merge function which takes time O(log n) to combine two trees into one, and a listToTree function which converts an initial list of elements to singleton trees and repeatedly calls merge on each successive pair of trees until only one tree remains. Function signatures and relevant implementations are as follows: merge :: Tree a -> Tree a -> Tree a --// O(log n) where n is size of input trees singleton :: a -> Tree a --// O(1) empty :: Tree a --// O(1) listToTree :: [a] -> Tree a --// Supposedly O(n) listToTree = listToTreeR . (map singleton) listToTreeR :: [Tree a] -> Tree a listToTreeR [] = empty listToTreeR (x:[]) = x listToTreeR xs = listToTreeR (mergePairs xs) mergePairs :: [Tree a] -> [Tree a] mergePairs [] = [] mergePairs (x:[]) = [x] mergePairs (x:y:xs) = merge x y : mergePairs xs This is a slightly simplified version of exercise 3.3 in Purely Functional Data Structures by Chris Okasaki. According to the exercise, I shall now show that listToTree takes O(n) time. Which I can't. :-( There are trivially ceil(log n) recursive calls to listToTreeR, meaning ceil(log n) calls to mergePairs. The running time of mergePairs is dependent on the length of the list, and the sizes of the trees. The length of the list is 2^h-1, and the sizes of the trees are log(n/(2^h)), where h=log n is the first recursive step, and h=1 is the last recursive step. Each call to mergePairs thus takes time (2^h-1) * log(n/(2^h)) I'm having trouble taking this analysis any further. Can anyone give me a hint in the right direction?

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  • What should a conference newbie bring to make the most out of their first conference?

    - by skarnis
    I am planning to attend my first developer conference (Microsoft TechDays 2008 in Toronto). I have been looking around for suggestions so that I can prepare and make the most out of my first developer conference. Many articles make suggestions about asking questions, getting involved, being social. These are great! I am also wondering about physical items. I have seen many conference photos with most of the audience having their laptops. Are they just taking notes? Are they working on a problem during the session? Are these photos just during a break and everyone is catching up on blogs/email/outside contact? Thank you StackOverflow-ers (StackOverflow-ites?)

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