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• Scheme Homework Assignment

  - by user1704677

  In a course I am taking we recently had to learn the programming language Scheme. I get all of the basics, which is pretty much all that we have gone though. I'm just having trouble learning to think in the different way that Scheme consists of. I was given an assignment and really do not even know how to start. I have sat here for a few hours trying to figure out how to even get started, but I'm kind of stumped. For the record, I'm not asking for the code to solve this problem, but more of some thoughts to get me on the right track. Anyway, here is the gist of the assignment... We are given a list of ten numbers that represent a voter's votes. The numbers are -1, 0 or 1. Then we are given a list of lists of Candidates, with a name and then ten numbers corresponding to that candidate's votes. These numbers are also -1 0 and 1. So for example. '(0 0 0 -1 -1 1 0 1 0 -1) '(Adams 0 1 -1 0 1 1 0 -1 -1 0 0) We are asked to implement a function called best_candidates that will take in a list of numbers (Voter) and a list of lists of Candidates. Then we have to compare the votes of the voter against the list of each candidate and return a list of names with the most common votes. So far, I've come up with a few things. I'm just confused on how I will check the values and retain the name of the voter? I guess I'm still stuck in thinking C/Java and it's making this very tough. Any suggestions to help get me started?

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• Basic CSS question regarding background images for divs

  - by Mike

  I'm a programmer trying to learn some css and I've already run into a stumbling block. I have the following HTML: <div class="container"> <div class="span-24 last"> Header </div> <div class="span-4"> Left sidebar </div> <div class="span-16"> <div class="span-8"> Box1 </div> <div class="span-4"> Box2 </div> <div class="span-4 last"> Box3 </div> <div class="span-16 last"> Main content </div> </div> <div class="span-4 last"> Right sidebar </div> <div class="span-24 last"> Footer </div> </div> In my css I have the following: body { background-color:#FFFFFF; } div.container { background:url(/images/bck.jpg); } I just want to display an image for the background area for the container div but nothing shows up. If I remove the background section from the css and add background-color:#000000; then I see a black background for the container div. What am I overlooking?

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• php Getting the 'new' values in an array

  - by Mark

  Trying to learn about php's arrays today. I have a set of arrays like this: $a = array ( 0 => array ( 'value' => 'America', ), 1 => array ( 'value' => 'England', ), 2 => array ( 'value' => 'Australia', ), ) $b = array ( 0 => array ( 'value' => 'America', ), 1 => array ( 'value' => 'England', ), 2 => array ( 'value' => 'Canada', ), ) I need to get the 'new' subarrays that array b brings to the table. ie, I need to return array ( 'value' => 'Canada', ) I thought I could first merge $a+$b and then compare the result to $a. $merge = array_merge($a,$b); $result = array_diff($merge,$a); But somehow that does not work. It returns array() How come? And thanks!

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• C vs C++ function questions

  - by james

  I am learning C, and after starting out learning C++ as my first compiled language, I decided to "go back to basics" and learn C. There are two questions that I have concerning the ways each language deals with functions. Firstly, why does C "not care" about the scope that functions are defined in, whereas C++ does? For example, int main() { donothing(); return 0; } void donothing() { } the above will not compile in a C++ compiler, whereas it will compile in a C compiler. Why is this? Isn't C++ mostly just an extension on C, and should be mostly "backward compatible"? Secondly, the book that I found (Link to pdf) does not seem to state a return type for the main function. I check around and found other books and websites and these also commonly do not specify return types for the main function. If I try to compile a program that does not specify a return type for main, it compiles fine (although with some warnings) in a C compiler, but it doesn't compile in a C++ compiler. Again, why is that? Is it better style to always specify the return type as an integer rather than leaving it out? Thanks for any help, and just as a side note, if anyone can suggest a better book that I should buy that would be great!

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• Mysterious combination

  - by pstone

  I decided to learn concurrency and wanted to find out in how many ways instructions from two different processes could overlap. The code for both processes is just a 10 iteration loop with 3 instructions performed in each iteration. I figured out the problem consisted of leaving X instructions fixed at a point and then fit the other X instructions from the other process between the spaces taking into account that they must be ordered (instruction 4 of process B must always come before instruction 20). I wrote a program to count this number, looking at the results I found out that the solution is n Combination k, where k is the number of instructions executed throughout the whole loop of one process, so for 10 iterations it would be 30, and n is k*2 (2 processes). In other words, n number of objects with n/2 fixed and having to fit n/2 among the spaces without the latter n/2 losing their order. Ok problem solved. No, not really. I have no idea why this is, I understand that the definition of a combination is, in how many ways can you take k elements from a group of n such that all the groups are different but the order in which you take the elements doesn't matter. In this case we have n elements and we are actually taking them all, because all the instructions are executed ( n C n). If one explains it by saying that there are 2k blue (A) and red (B) objects in a bag and you take k objects from the bag, you are still only taking k instructions when 2k instructions are actually executed. Can you please shed some light into this? Thanks in advance.

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• PHP | Online Notepad

  - by user2947423

  I recently made a Chat application in Visual Basic using PHP. I used this code: <?php $msg = $_GET['w']; $logfile= 'Chats.php'; $fp = fopen($logfile, "a"); fwrite($fp, $msg); fclose($fp); ?> I'm now trying to make a Online Notepad. What i want to do is in Visual Basic create a unique ID. That unique ID, has to be his filename. I'm not very good with PHP so what i want to know is: I want the unique ID to be the filename of the "Note". Like: $logfile= '{uniqueID.php}'; Whenever the user opens the program, it'll open his uniqueID.php file and he can edit that in my program. Long Story Short (TL;DR) Program generates uniqueID uniqueID is going to be a new file; {uniqueID}.php On next open it will check if {uniqueID}.php of him/her exists else it will make a new one. I know this isn't really secure but it's to learn something for myself.

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• Scientific Data processing (Graph comparison and interpretation)

  - by pinkynobrain

  Hi stackoverflow friends, I'm trying to write a program to automate one of my more boring and repetitive work tasks. I have some programming experience but none with processing or interpreting large volumes of data so I am seeking your advice (both suggestions of techniques to try and also things to read to learn more about doing this stuff). I have a piece of equipment that monitors an experiment by taking repeated samples and displays the readings on its screen as a graph. The input of experiment can be altered and one of these changes should produce a change in a section of the graph which I currently identify by eye and is what I'm looking for in the experiment. I want to automate it so that a computer looks at a set of results and spots the experiment input that causes the change. I can already extract the results from the machine. Currently they results for a run are in the form of an integer array with the index being the sample number and the corresponding value being the measurement. The overall shape of the graph will be similar for each experiment run. The change I'm looking for will be roughly the same and will occur in approximately the same place every time for the correct experiment input. Unfortunately there are a few gotchas that make this problem more difficult. There is some noise in the measuring process which mean there is some random variation in the measured values between different runs. Although the overall shape of the graph remains the same. The time the experiment takes varies slightly each run causing two effects. First, the a whole graph may be shifted slightly on the x axis relative to another run's graph. Second, individual features may appear slightly wider or narrower in different runs. In both these cases the variation isn't particularly large and you can assume that the only non random variation is caused by the correct input being found. Thank you for your time, Pinky

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• Help with 'simple' jQuery question

  - by user318573

  I am trying to get a simple effect working in jQuery, and only have a few hours of experience with it, so have a lot to learn. I managed to get this code working: <script type="text/javascript" > $(document).ready(function() { lastBlock = $("#a1"); maxWidth = 415; minWidth = 75; $("ul li a").hover(function() { $(lastBlock).animate({ width: minWidth + "px" }, { queue: false, duration: 600 }); $(this).animate({ width: maxWidth + "px" }, { queue: false, duration: 600 }); lastBlock = this; }); }); </script> Which gives me exactly what I want, a 6 pane horizontal accordion effect. Each pane however has a 75x75 image on the upper left, which is always visible no matter which pane is active (and it is this image that when hovered over caused the pane to open) - what I want to do is for the image on the selected 'pane', I want to drop the top margin down 10px, and then put it back to 0px when a new one is selected, i.e. so the selected panes image is always 10px lower than the other 5 images. I suspect this should be easy, but not quite grasping the syntax yet. Thanks.

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• Get height of DIV and it's content with JQuery

  - by user1012403

  I have a div which contains several elements: <div class="menuItem designMenu" id="dMenu"> <ul class="menuList menu"> <li class="menuHeader">Design</li> <li class="projectHeader">Mother</li> <li class="projectBody">Some text here</li> <li class="more">More</li> </ul> </div> I need to get the height of the dMenu items that I can animate it upwards, including all the content inside. My Javascript currently: var designHeight = $("#dMenu").height(); Returns nothing. I've tried offsetHeight, scrollHeight, and everything else Google turns up. I'm running the JQuery at the end of the body, inside a document ready function. The reason to get the height to animate, instead of doing it manually, is that a: I'd like to learn how and b: I don't yet know how many items will be int he div. Thanks.

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• Understanding Basic Prototyping & Updating Key/Value pairs

  - by JordanD

  First time poster, long time lurker. I'm trying to learn some more advanced features of .js, and have two ojectives based on the pasted code below: I would like to add methods to a parent class in a specific way (by invoking prototype). I intend to update the declared key/value pairs each time I make an associated method call. execMTAction as seen in TheSuper will execute each function call, regardless. This is by design. Here is the code: function TheSuper(){ this.options = {componentType: "UITabBar", componentName: "Visual Browser", componentMethod: "select", componentValue: null}; execMTAction(this.options.componentType, this.options.componentName, this.options.componentMethod, this.options.componentValue); }; TheSuper.prototype.tapUITextView = function(val1, val2){ this.options = {componentType: "UITextView", componentName: val1, componentMethod: "entertext", componentValue: val2}; }; I would like to execute something like this (very simple): theSuper.executeMTAction(); theSuper.tapUITextView("a", "b"); Unfortunately I am unable to overwrite the "this.options" in the parent, and the .tapUITextView method throws an error saying it cannot find executeMTAction. All I want to do, like I said, is to update the parameters in the parent, then have executeMTAction run each time I make any method call. That's it. Any thoughts? I understand this is basic but I'm coming from a long-time procedural career and .js seems to have this weird confluence of oo/procedural that I'm having a bit of difficulty with. Thanks for any input!

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• Best strategies for reading J code

  - by estanford

  I've been using J for a few months now, and I find that reading unfamiliar code (e.g. that I didn't write myself) is one of the most challenging aspects of the language, particularly when it's in tacit. After a while, I came up with this strategy: 1) Copy the code segment into a word document 2) Take each operator from (1) and place it on a separate line, so that it reads vertically 3) Replace each operator with its verbal description in the Vocabulary page 4) Do a rough translation from J syntax into English grammar 5) Use the translation to identify conceptually related components and separate them with line breaks 6) Write a description of what each component from (5) is supposed to do, in plain English prose 7) Write a description of what the whole program is supposed to do, based on (6) 8) Write an explanation of why the code from (1) can be said to represent the design concept from (7). Although I learn a lot from this process, I find it to be rather arduous and time-consuming -- especially if someone designed their program using a concept I never encountered before. So I wonder: do other people in the J community have favorite ways to figure out obscure code? If so, what are the advantages and disadvantages of these methods?

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• Projecting an object into a scene based on world coordinates only

  - by user354862

  I want to place a 3D image into a scene base on world/global coordinates. I have an image of a scene. The image was captures at some global coordinate (x1, y1, z1). I am given an object that needs to be placed into this scene based on its global coordinate (x2, y2, y3). This object needs to be projected into the scene accurately similarly to perspective projection. An example may help to make this clear. Imagine there is a parking lot with some set of global coordinates. A picture is taken of a portion of the parking lot. The coordinates from the spot where the image was taken is recorded. The goal is to place a virtual vehicle into this image using the global coordinates for that vehicle. Because the global cooridnates for the vehicle may not be in the fov of the global coordinates for the image I am assuming that I will need the image coordinates, angle and possibly fov. 3D graphics is not my area so I have been looking at http://en.wikipedia.org/wiki/Perspective_projection#Perspective_projection. I have also been looking at Matrix3DProjection which seems to possibly be what I am looking for but it only works in Silverlight and I am trying to do this in WPF. In my mind it appears I need to determine the (X,Y,Z) coordinates that are in the fov of the image, determine the world coordinate to pixel conversion and then accurately project the vehicle into the image giving it the correct perspective such that is looks 3D i.e smaller the further away bigger closer Is there a function within WPF that can help with this or will I need to re-learn matrices and do this by hand?

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• How to remove background of a image and copy into another?

  - by Gustavo Pinent

  I'm researching about captchas. In this idea, the task is: create a image from a JPEG and remove the white background, than create another image from another JPEG, than create the final image by adding the second as a background, and copying the first one over this background preserving the transparent area created, of course. Here is the code: header("Content-Type: image/jpeg"); $nFundo = rand(0,4); $Dirs = array(rand(0,7), rand(0,7), rand(0,7), rand(0,7)); // Will be four times all $_SESSION["form_captcha"] = $Dirs; $image = ImageCreatetruecolor(320, 80); ImageAlphaBlending($image, FALSE); ImageSaveAlpha($image, TRUE); $image_seta = ImageCreateFromJPEG("_captcha-seta.jpg"); // Image do copy over $image_fundo = ImageCreateFromJPEG("_captcha-fundo-".$nFundo.".jpg"); // Image to make the background for($i=0; $i<4; $i++){ ImageCopy($image, $image_fundo, $i*80, 0, 0, 0, 80, 80); } // So far so good, a background with a pattern repeated four times $color_white = ImageColorAllocate($image_seta, 255, 255, 255); ImageColorTransparent($image_seta, $color_white); ImageSaveAlpha($image_seta, TRUE); for($i=0; $i<4; $i++){ $image_seta_rot = imageRotate($image_seta, $Dirs[$i]*45, $color_white); ImageCopyResampled($image, $image_seta_rot, $i*80, 0, 0, 0, 80, 80, 80, 80); // Try } echo(imagejpeg($image)); imagedestroy($image); I tried to replace $image_seta_rot by $image_seta ("Try" line) to see if the rotation is the problem, but even without rotation, the white wasn't removed and the image just "erase" the background created before. So the copy is failing or the white were never removed... I may create a PNG with transparent background, but will be interesting to learn how to make it dynamically, don't you think? Any ideas?

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• Change $mailTo variable based on select input value (array)

  - by Dirty Bird Design

  I have the following select list: <form action="mail.php" method="POST"> <select name="foo" id="foo"> <option value="sales">Sales</option> <option value="salesAssist">Sales Assist</option> <option value="billing">Billing</option> <option value="billingAssist">Billing Assist</option> </select> </form> I need to route the $mailTo variable depending on which option they select, Sales and Sales Assist go to [email protected], while Billing and Billing Assist go to [email protected] PHP pseudeo code! <? php $_POST['foo'] if inArray(sales, salesAssist) foo="[email protected]"; else if inArray(billing, billingAssist) foo="[email protected]"; mailTo="foo" ?> I know there is nothing correct about the above, but you can see what I am trying to do, change a variable's value based on the selected value. I don't want to do this with JS, would rather learn more PHP here. Thank you.

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• Dependency Injection: How to pass DB around?

  - by Stephane

  Edit: This is a conceptual question first and foremost. I can make applications work without knowing this, but I'm trying to learn the concept. I've seen lots of videos with related classes and that makes sense, but when it comes to classes wrapping around other classes, I can't seem to grasp where things should be instantiated/passed around. =-=-=-=-=-=-= Question: Let's say I have a simple page that loads data from a table, manipulates the result and displays it. Simple. I'm going to use '=' for instantiating a class and '-' for passing a class in using constructor injection. It seems to me that the database has to be passed from one end of the application to the other which doesn't seem right. Here's how I would do it if I wanted to separate concerns: index =>Controller =>Model Layer =>Database =>DAO->Database I have this rule in my head that says I'm not supposed to create objects inside other objects. So what do I do with the Database? Or even the Model for that matter? I'm obviously missing something so basic about this. I would love a simplified example so that I can move forward in my code. I feel really hamstrung by this.

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• CoffeeScript 2 Dimensional Array Usage

  - by Chris

  I feel like I'm missing something with CoffeeScript and 2 dimensional arrays. I'm simply attempting to make a grid of spaces (think checkers). After some searching and a discovery with the arrays.map function, I came up with this: @spaces = [0...20].map (x)-> [0...20].map (y) -> new Elements.Space() And this seems to work great, I have a nice 2 dimensional array with my Space object created in each. But now I want to send the created space constructor the x,y location. Because I'm two layers deep, I lost the x variable when I entered the map function for y. Ideally I would want to do something like: @spaces = [0...20].map (x)-> [0...20].map (y) -> new Elements.Space(x, y) or something that feels more natural to me like: for row in rows for column in row @spaces[row][column] = new Elements.Space(row, column) I'm really open to any better way of doing this. I know how I would do it in standard JavaScript, but really would like to learn how to do it in CoffeeScript.

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• format, iomanip, c++

  - by Crystal

  I'm trying to learn to use namespaces declarations more definitive than not just say "using namespace std". I'm trying to format my data to 2 decimal places, and set the format to be fixed and not scientific. This is my main file: #include <iostream> #include <iomanip> #include "SavingsAccount.h" using std::cout; using std::setprecision; using std::ios_base; int main() { SavingsAccount *saver1 = new SavingsAccount(2000.00); SavingsAccount *saver2 = new SavingsAccount(3000.00); SavingsAccount::modifyInterestRate(.03); saver1->calculateMonthlyInterest(); saver2->calculateMonthlyInterest(); cout << ios_base::fixed << "saver1\n" << "monthlyInterestRate: " << saver1->getMonthlyInterest() << '\n' << "savingsBalance: " << saver1->getSavingsBalance() << '\n'; cout << "saver2\n" << "monthlyInterestRate: " << saver2->getMonthlyInterest() << '\n' << "savingsBalance: " << saver2->getSavingsBalance() << '\n'; } On Visual Studio 2008, when I run my program, I get an output of "8192" before the data I want. Is there a reason for that? Also, I don't think I am setting the fixed part or 2 decimal places correctly since I seem to get scientific notation once I added the setprecision(2). Thanks.

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• seriouosly elusive for loop (racking my brains!)

  - by user1693359

  I've got a loop issue in Python 2.72 that's really frustrating me. Basically the loop is not iterating fast the first index (j), and I've tried all sorts of ways to fix it with no luck. def learn(dataSet): for i in dataSet.getNext(): recall = raw_input("Enter all members of %s you are able to recall >>> (separated by commas) " % (i.getName())) missed = i.getMembers() missedString = [] for a in missed: missedString.append(a.getName()) Here is the loop I can't get to iterate. The first for loop only goes through the first iteration of 'j' in the split string list, then removes it from 'missedString'. I would like for all members of the split-string 'recall' to be removed from 'missedString'. for j in string.split(recall, ','): if j in missedString: missedString.remove(j) continue for b in missed: if b.getName() not in missedString: missed.remove(b) print 'You missed %d. ' % (len(missed)) if (len(missed)) > 0: print 'Maybe a hint or two will help...' for miss in missed: remind(miss.getSecs(), i.getName(), missed) I really have no clue, help would be appreciated!

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• Just a small help about switch's use

  - by Laurent Fournier

  If an answer on this already exist, my apologies i've not found on this question... is this statement correct if i want presice actions on integers from -2 to 0, and for those between 1 and 6 apply the same methods with only my integer who'll change ? Like this: public void setCaseGUI(Point pt, int i, boolean b){ plateau.cellule[(int)pt.getAbs()][(int)pt.getOrd()].setSelected(b); plateau.cellule[(int)pt.getAbs()][(int)pt.getOrd()].setIcon(null); switch(i) { case -2: plateau.cellule[(int)pt.getAbs()][(int)pt.getOrd()].setText("F"); plateau.cellule[(int)pt.getAbs()][(int)pt.getOrd()].setForeground(Color.red); break; case -1: plateau.cellule[(int)pt.getAbs()][(int)pt.getOrd()].setText("B"); plateau.cellule[(int)pt.getAbs()][(int)pt.getOrd()].setForeground(Color.red); break; case 0: plateau.cellule[(int)pt.getAbs()][(int)pt.getOrd()].setText(""); plateau.cellule[(int)pt.getAbs()][(int)pt.getOrd()].setForeground(null); break; case 1: case 2: case 3: case 4: case 5: case 6: case 7: case 8: plateau.cellule[(int)pt.getAbs()][(int)pt.getOrd()].setText(String.valueOf(i)); plateau.cellule[(int)pt.getAbs()][(int)pt.getOrd()].setForeground(null); break; default: System.out.println("Erreur de changement d'état/case !"); } } Please don't be too harsh on me i've started to learn dev only a few month ago

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• F# why my recursion is faster than Seq.exists?

  - by user38397

  I am pretty new to F#. I'm trying to understand how I can get a fast code in F#. For this, I tried to write two methods (IsPrime1 and IsPrime2) for benchmarking. My code is: // Learn more about F# at http://fsharp.net open System open System.Diagnostics #light let isDivisible n d = n % d = 0 let IsPrime1 n = Array.init (n-2) ((+) 2) |> Array.exists (isDivisible n) |> not let rec hasDivisor n d = match d with | x when x < n -> (n % x = 0) || (hasDivisor n (d+1)) | _ -> false let IsPrime2 n = hasDivisor n 2 |> not let SumOfPrimes max = [|2..max|] |> Array.filter IsPrime1 |> Array.sum let maxVal = 20000 let s = new Stopwatch() s.Start() let valOfSum = SumOfPrimes maxVal s.Stop() Console.WriteLine valOfSum Console.WriteLine("IsPrime1: {0}", s.ElapsedMilliseconds) ////////////////////////////////// s.Reset() s.Start() let SumOfPrimes2 max = [|2..max|] |> Array.filter IsPrime2 |> Array.sum let valOfSum2 = SumOfPrimes2 maxVal s.Stop() Console.WriteLine valOfSum2 Console.WriteLine("IsPrime2: {0}", s.ElapsedMilliseconds) Console.ReadKey() IsPrime1 takes 760 ms while IsPrime2 takes 260ms for the same result. What's going on here and how I can make my code even faster?

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• Infrastructure for high transactional system (language & hosting suggestion help)

  - by RPS

  Some of our friends (University students) are trying to develop a twitter type application, I want to plan for at least 1000 transactions per second (I know it's wishful thinking) for initial launch. This involves several people connecting and getting updates and posting (text + images) to site. In the back end db will server the data and also calculates rankings of what to push to user based on complex algorithm on the fly real-time. Our group is familiar with Java and Tomcat/MySQL. We can also easily learn/code in PHP/MySQL. What is the best suited platform for our purpose ? Though Java seem to be easy to implement for us I am afraid that hosting will be a bit difficult. I could find cloud based php hosting services (like rackspace cloudsites) at reasonable cost. Amazon EC2 is a bit over our heads to manage on day-to-day. Also any recommendation on hosting ? (PHP or Java) We don't have millions in seed money but about $20K to start with. Any advice on above or any thing in general approach is much appreciated.

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• What is the "x = x || {}" technique in JavaScript - and how does it affect this IIFE?

  - by Micky Hulse

  First, a pseudo code example: ;(function(foo){ foo.init = function(baz) { ... } foo.other = function() { ... } return foo; }(window.FOO = window.FOO || {})); Called like so: FOO.init(); My question: What is the technical name/description of: window.FOO = window.FOO || {}? I understand what the code does... See below for my reason(s) for asking. Reason for asking: I'm calling the passed in global like so: ;(function(foo){ ... foo vs. FOO, anyone else potentially confused? ... }(window.FOO = window.FOO || {})); ... but I just don't like calling that lowercase "foo", considering that the global is called capitalized FOO... It just seems confusing. If I knew the technical name of this technique, I could say: ;(function(technicalname){ ... do something with technicalname, not to be confused with FOO ... }(window.FOO = window.FOO || {})); I've seen a recent (awesome) example where they called it "exports": ;(function(exports){ ... }(window.Lib = window.Lib || {})); I guess I'm just trying to standardize my coding conventions... I'd like to learn what the pros do and how they think (that's why I'm asking here)!

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• Dont understand the concept of extends in URL.openConnection() in JAVA

  - by user1722361

  Hi I am trying to learn JAVA deeply and so I am digging into the JDK source code in the following lines: URL url = new URL("http://www.google.com"); URLConnection tmpConn = url.openConnection(); I attached the source code and set the breakpoint at the second line and stepped into the code. I can see the code flow is: URL.openConnection() - sun.net.www.protocol.http.Handler.openConnection() I have two questions about this First In URL.openConnection() the code is: public URLConnection openConnection() throws java.io.IOException { return handler.openConnection(this); } handler is an object of URLStreamHandler, define as blow transient URLStreamHandler handler; But URLStreamHandler is a abstract class and method openConnection() is not implement in it so when handler calls this method, it should go to find a subclass who implement this method, right? But there are a lot classes who implement this methods in sun.net.www.protocol (like http.Hanlder, ftp.Handler ) How should the code know which "openConnection" method it should call? In this example, this handler.openConnection() will go into http.Handler and it is correct. (if I set the url as ftp://www.google.com, it will go into ftp.Handler) I cannot understand the mechanism. second. I have attached the source code so I can step into the JDK and see the variables but for many classes like sun.net.www.protocol.http.Handler, there are not source code in src.zip. I googled this class and there is source code online I can get but why they did not put it (and many other classes) in the src.zip? Where can I find a comprehensive version of source code? Thanks!

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• Placing elements (panels) within a wx.GridBagSizer

  - by JHarris

  I'm using a gridbagsizer to place two panels within a frame. control_panel = wx.Panel(self, id=ID_CONTROL_PANEL) main_panel = wx.Panel(self, id=ID_MAIN_PANEL) frame_sizer = wx.GridBagSizer(1, 1) frame_sizer.Add(control_panel, (0, 0), (2, 5), flag=wx.EXPAND) frame_sizer.Add(main_panel, (2, 0), (5, 5), flag=wx.EXPAND) frame_sizer.AddGrowableRow(0) frame_sizer.AddGrowableCol(0) self.SetSizer(frame_sizer) I want the control_panel to be above the main_panel (as you can see above). However this is the output I get: I don't know why the top panel is so much larger than the bottom panel, when I've specified the opposite. (2, 5) for the top and (5, 5) for the bottom. It also has a strange behaviour when I resize it smaller, it basically gives me what I want (see image below), but I don't know how to maintain the ratio when I make it larger again. However when you start resizing larger (even by a small amount) you can see (below) the shapes and ratio change dramatically in the other direction (with the bottom becoming much smaller and the top much larger). Still trying to learn this sizers and can't really find this problem with any of the examples I've seen. Also tried experimenting with all the parameters and doing some tests and I can't figure out what's going on here. Any help would be much appreciated.

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• What does the `new` keyword do

  - by Mike

  I'm following a Java tutorial online, trying to learn the language, and it's bouncing between two semantics for using arrays. long results[] = new long[3]; results[0] = 1; results[1] = 2; results[2] = 3; and: long results[] = {1, 2, 3}; The tutorial never really mentioned why it switched back and forth between the two so I searched a little on the topic. My current understanding is that the new operator is creating an object of "array of longs" type. What I do not understand is why do I want that, and what are the ramifications of that? Are there certain "array" specific methods that won't work on an array unless it's an "array object"? Is there anything that I can't do with an "array object" that I can do with a normal array? Does the Java VM have to do clean up on objects initialized with the new operator that it wouldn't normally have to do? I'm coming from C, so my Java terminology, may not be correct here, so please ask for clarification if something's not understandable.

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