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  • What does addListener do in node.js?

    - by Jeffrey
    I am trying to understand the purpose of addListener in node.js. Can someone explain please? Thanks! A simple example would be: var tcp = require('tcp'); var server = tcp.createServer(function (socket) { socket.setEncoding("utf8"); socket.addListener("connect", function () { socket.write("hello\r\n"); }); socket.addListener("data", function (data) { socket.write(data); }); socket.addListener("end", function () { socket.write("goodbye\r\n"); socket.end(); }); }); server.listen(7000, "localhost");

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  • Question About NerdDinner Controller Constructors

    - by Gavin Draper
    I've been looking at the Nerd Dinner app, more specifically how it handles its unit tests. The following constructors for the RSVPController are confusing my slightly public RSVPController() : this(new DinnerRepository()) { } public RSVPController(IDinnerRepository repository) { dinnerRepository = repository; } From what I can tell the second one is used by the unit tests so it can use Fake repositories. What I cant work out is what the first constructor does. It doesn't seem to ever set the dinnerRepository variable, it seems to imply its inheriting from something but I really don't get it. Can anyone explain? Thanks

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  • strenge exception phenomenon in win7

    - by Level 2
    Hello all, I spot some interesting artcles about exception handle in codeproject http://www.codeproject.com/KB/cpp/seexception.aspx after reading, I decided to do some experiment. The first time I try to excute the following code char *p; p[0] = 0; The program died without question. But After serveral time I execute the same problem binary code. It magically did fine. even the following code is doing well. any clue or explain? char *p p[1000] = 'd'; cout<<p[1000]<<endl; my os is windows 7 64bit and compiler is vs2008 rc1.

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  • an error "variable of field declared void"

    - by lego69
    I have this code: header - test.h Inside header I have some class Z and definitions of two functions test and test2 I call function test2 from test void test2(Z z, Z const *za); this is implementation of the function: void test2(Z z, Z const *za){ int i = z; //this row works cout << i << endl; } I call it from test: test2(z1, za1); // za1 is pinter to object and z1 is some object but in my header I receive an 3 errors: Multiple markers at this line - initializer expression list treated as compound expression - `A' was not declared in this scope - variable or field `quiz2' declared void can somebody please explain why? thanks in advance

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  • Send Email in iphone

    - by user559080
    Hi, I am new to iphone. I am working on first app..I could design Email view by using Interface Builder. My requirement is, I have to add contact list. And choose required contact, when i clicked on To UIButton, It will be placed on Address textfield. Finally, I can click the send UIButton, the email reach it's destination. How can I do this? Can anyone explain it and send me proper code. Image link is: http://img266.imageshack.us/img266/6447/emailau.png Thanks in Advance.

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  • Why isn't the eigenclass equivalent to self.class, when it looks so similar?

    - by The Wicked Flea
    I've missed the memo somewhere, and I hope you'll explain this to me. Why is the eigenclass of an object different from self.class? class Foo def initialize(symbol) eigenclass = class << self self end eigenclass.class_eval do attr_accessor symbol end end end My train of logic that equates the eigenclass with class.self is rather simple: class << self is a way of declaring class methods, rather than instance methods. It's a shortcut to def Foo.bar. So within the reference to the class object, returning self should be identical to self.class. This is because class << self would set self to Foo.class for definition of class methods/attributes. Am I just confused? Or, is this a sneaky trick of Ruby meta-programming?

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  • page_load another handler?

    - by joe doe
    can someone please explain why this code is not working as expected: using System; using System.Collections.Generic; using System.Linq; using System.Web; using System.Web.UI; using System.Web.UI.WebControls; public partial class temp : System.Web.UI.Page { protected void Page_Load(object sender, EventArgs e) { Response.Write("foo<br>"); this.Load += new EventHandler(temp_Load); } void temp_Load(object sender, EventArgs e) { Response.Write("bar<br>"); Response.End(); } } trying to add another handler for page Load event so that output would be: foo<br> bar<br>

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  • Creating DB views in Ruby on Rails

    - by Zigu
    Hey guys, I'm building a "reports" functionality to a project. 3 roles here: 1) Volunteers (they report what hours they volunteered) 2) Supervisors (they look at the reported stuff, note: one supervisor can view all projects) 3) Projects (Represents a work project that some collection of volunteers work on) To explain what it does: A report will be specified by the supervisor to generate based on a query of what he needs. These could be plausible reports: 1) The total number of volunteers, and the total amount of volunteer hours on this project 2) All the volunteer's names and emails associated with a project 3) The number of active projects vs. the total number of projects I was thinking maybe that creating a view in rails and storing the name of that view so Rails will just check the view whenever a supervisor wants to pull up the "report". Is a view really the answer or is it better to just save a query? Can Rails do this or is there an even better or more simple way of achieving this functionality? Cheers, -Jeremiah Tantongco

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  • Odd Segue Behaviour - Not Firing

    - by Zak
    So I've noticed some very weird behaviour from my program. Here's a simplified code snippet and then I'll explain what occurs when built and ran. -(void)viewDidLoad { [super viewDidLoad]; ... if (self.sampleBool) { [self performSegueWithIdentifier:@"mySegue" sender:self]; } else { // do stuff } } ... -(IBAction)myMethod:(UITapGestureRecognizer*)sender { ... [self performSegueWithIdentifier:@"mySegue" sender:self]; } The segue triggers via the UITapGestureRecognizer fine - so I know the segue is linked correctly. However, when self.sampleBool is true and performSegueWithIdentifier is called within viewDidLoad, the segue does not fire. Anyone have any guesses? Any help or advice is appreciated. Thanks

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  • PHP inheriting/extending a particular instance of an Object

    - by delta9
    Is there any way to force PHP to extend an existing/particular (and for that matter, already instantiated) instance of an object? This imaginary code should explain what I am wondering: class Base { public $var; function __construct($var){ $this->var = $name; } } class Extender extends Base { function __construct($parent) { parent = $parent; } } $base = new Base('yay!'); $extender = new Extender($base); echo 'Extended base var value: '.$extender->var.'<br/>'; Output (would be): Extended base var value: yay! To be clear, I am wanting to instantiate an object that extends a PARTICULAR INSTANCE of another object, one that has already been instantiated. I am aware that I can pass a reference to an object to another object (via it's constructor function) and then add it as a property of the receiving object, I'm wondering if there is a real way to do this?

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  • Uploading or writing to files contained within s3

    - by Chase
    We have a widget that needs to be hosted on s3 due to a bunch of hoopla that isn't relevant to the issue. I'd explain if it was worth the time. Problem is it calls an external XML file for part of its content. The XML file is accessible if it is local on s3 but I cannot get my php file to write to it on s3. The widget could also be useful if I could access the xml file elsewhere but s3 does not seem to permit this. Suggestions? Here's the error I'm getting when trying to write to S3. [function.fopen]: failed to open stream: HTTP wrapper does not support writeable connections.

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  • Compilation Error related

    - by aparna
    Given: 11. public static void test(String str) { 12. int check = 4; 13. if (check = str.length()) { 14. System.out.print(str.charAt(check -= 1) +", "); 15. } else { 16. System.out.print(str.charAt(0) + ", "); 17. } 18. } and the invocation: 21. test("four"); 22. test("tee"); 23. test("to"); What is the result? A. r, t, t, B. r, e, o, C. Compilation fails. D. An exception is thrown at runtime. Answer: C Can you explain why the compilation fails please?

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  • How to search for a specific word in a row in MYSQL?

    - by user220755
    I have a row that has keywords in this way (keyword1, keyword2, keyword3) separated by commas as shown. When a user signs in, you know that he wants information about (keyword1, keyword3). Now, I have another table that has bunch of information related to different keywords, this table has a row called (keywords) which indicates if this information is suitable for which keyword. How do I render for the user the information he needs depending on the keywords. In other words, if the user wants information about (keyword3, keyword1) how do I go to the (information) table and find all the information that has the word (keyword1) or the word (keyword3) in the row (keyword)? Sorry if this is complicated (my explanation) but I tried my best to explain it. Thank you in advance :)

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  • convert int into string with certain length of char

    - by Tommy
    If the title wasn't clear, ill try to explain it well here. I have a bunch of integers, ranging from 1 to 999, and i need to convert these into strings, but when i do that, i need them to be 3 characters long. so for instance, if i had: int i1 = 45; then when i turned that into a string, i'd need this: "045" or similarly, if i had an int of 8 then that would have to turn into "008", and if anything had 3 places, such as 143, then it would just be outputted as 143. is this easily possible? Thanks for responses in advance. :)

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  • I just can't figure out strcat.

    - by Anonymous
    I know I shouldn't be using that function, and I don't care. Last time I checked the spec for strcat, it said something along the lines of updating the first value as well as returning the same. Now, this is a really stupid question, and I want you to explain it like you're talking to a really stupid person. Why won't this work? char* foo="foo"; printf(strcat(foo,"bar")); EDIT: I don't know the difference between char[] and char*. How would I allocate a string of 255 characters? EDIT 2: OK, OK, so char[number] allocates a string of that many bytes? Makes sense. Thanks.

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  • Comparison question string vs int

    - by Mike
    Can someone explain to me why these comparisons work they way the do. I had a bug in one of my scripts that took me a little bit to work through. I was using read-host and typing a number. It was storing it as a string. Write-Host "(`'2`' -gt 9 ) = " ('2' -gt 9 ) Write-Host "(2 -gt 9 ) = " (2 -gt 9 ) Write-Host "(`'2`' -gt 10 ) = " ('2' -gt 10 ) If you are comparing a string to an Int does it use the Ascii value? If so why does the first one show $false, it should be $true. Then how is it when you chage it to an int of 10 it because $true.

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  • Global JavaScript Variable Scope: Why doesn't this work?

    - by CoryDorning
    So I'm playing around with JavaScript and came across what I think to be an oddity. Is anyone able to explain the following? (i've included the alerted values as comments) Why is the first alert(msg) inside foo() returning undefined and not outside? var msg = 'outside'; function foo() { alert(msg); // undefined var msg = 'inside'; alert(msg); // inside } foo(); alert(msg); // outside Considering these both work fine: var msg = 'outside'; function foo() { alert(msg); // outside } alert(msg); // outside and: var msg = 'outside'; function foo() { var msg = 'inside'; alert(msg); // inside } alert(msg); // outside

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  • What technologies to use for a particle system with enormous calculation demand?

    - by Amir Rezaei
    I have a particle system with X particles. Each particle tests for collision with other particles. This gives X*X = X^2 collision tests per frame. For 60f/s, this corresponds to 60*X^2 collision detection per second. What is the best technological approach for these intensive calculations? Should I use F#, C, C++ or C#, or something else? The following are constraints The code is written in C# with the latest XNA Multi-threaded may be considered No special algorithm that tests the collision with the nearest neighbors or that reduces the problem The last constraint may be strange, so let me explain. Regardless constraint 3, given a problem with enormous computational requirement what would be the best approach to solve the problem. An algorithm reduces the problem; still the same algorithm may behave different depending on technology. Consider pros and cons of CLR vs native C.

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  • Python built-in id() not consistent:

    - by Dannellyz
    Hoping someone can explain the following discrepancy: >>> s1 = "Cyber security" >>> s2 = "Cyber security" >>> id(s1) == id(s1) True >>> id(s1) == id(s2) False >>> s1 = "cyber" >>> s2 = "cyber" >>> id(s1) == id(s2) True >>> s2 = "cyber " >>> s2 = "cyber " >>> id(s1) == id(s2) False Why does the space make the id() False, yet different variables with no spaces are True?

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  • Rails: How to have dynamic association

    - by Aaron Dufall
    I'll use an example to explain what behaviour I would like to achieve. If you had a project management app and you added a task, but not all the contributors are users of the app. So when you adding contributors to the task you can enter a user name or email address. Here is the part that I'm finding a little tricky. The task model has many contributors which are linked through the user model, but from this point on I want to achieve 2 things. Store the non members email(this would obviously be quite simple) If that email address was to create an account it would then link that user to the task and remove the temporally saved email. This way, when that user creates an account all the related tasks will already be associated with their email. Is this something that i could achieve with a polymorphic association? or is there something else I should be looking at?

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  • Android TranslateAnimation resets after animation

    - by monmonja
    I'm creating something like a SlideDrawer but with most customization, basically the thing is working but the animation is flickering at the end. To further explain, I got an TranslateAnimation then after this animation it returns back to the original position, if i set setFillAfter then the buttons inside the layout stops working. If i listen to onAnimationEnd and set other's layout to View.GONE the layout fickers. Judging from it is that on animation end, the view goes back to original position before the View.GONE is called. Any advice would be awesome. Thanks

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  • Why are some programs writing on stderr instead of stdout their output?

    - by Zagorax
    I've recently added to my .bashrc file an ssh-add command. I found that ssh-add $HOME/.ssh/id_rsa_github > /dev/null results on a message "identity added and something else" every time I open a shell. While ssh-add $HOME/.ssh/id_rsa_github > /dev/null 2>&1 did the trick and my shell is now 'clean'. Reading on internet, I found that other command do it, (for example time). Could you please explain why it's done?

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  • How to understand the functional programming code for converting IP string to a number?

    - by zfz
    In a python discusion, I saw a way to convert IP string to a integer in functional progamming way. Here is the Link . The function is implemented in a single line. def ipnumber(ip): return reduce(lambda sum, chunk: sum <<8 | chunk, map(int, ip.split("."))) However, I have few ideas of funcional programming. Could anybody explain the function in detail? I've some knowledg of "map" and "reduce". But I don't konw what "|" and "chunk" mean here? Thanks.

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  • How to call a custom php file on magento product page

    - by David
    if getChildHtml('product_type_data') ? maps directly to catalog/product/view/type/simple.phtml by default, how do I map to my own file? If I wanted to create a file that would produce a small image to place on the product page, right under "availability" how would I tell magento to map to where I have put the file? From what I understand getChildHtml('product_type_data') ? defaults to the file path: catalog/product/view/type/simple.phtml so how can I customize the magento defaults and tell it to map to my custom files i've created? I hope I have explained this well enough, if not, please let me know and I will try to explain more. Any help or guidance would be awesome. Thanks.

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  • write to xml file using objective c

    - by Mith
    Hi, ok, I managed to read from xml file using NSXMLParser but now i don't know how to write to xml file. I have a xml file , say <?xml version="1.0" encoding="UTF-8"?> <root> <user id="abcd" password="pass1"/> <user id="efg" password="pass2"/> </root> Now when a new user enters details, I want to store them in a new tag.. lets say like, the id is "hhhh" and password is"pass3" I want to add a new tag with attributes as such <user id="hhhh" password="pass3"/> to the xml file. How should I do this. Please explain in an elaborate way . I am a newbie here. Any links to tutorials or examples will be much helpful. Thanks

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