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  • What's the Difference Between These Two Ruby Class Initialaztion Definitions?

    - by michaelmichael
    I'm working through a book on Ruby, and the author used a slightly different form for writing a class initialization definition than he has in previous sections of the book. It looks like this: class Ticket attr_accessor :venue, :date def initialize(venue, date) self.venue = venue self.date = date end end In previous sections of the book, it would've been defined like this: class Ticket attr_accessor :venue, :date def initialize(venue, date) @venue = venue @date = date end end Is there any functional difference between using the setter method, as in the first example vs. using the instance variable in the second? They both seem to work. Even mixing them up seems to work: class Ticket attr_accessor :venue, :date def initialize(venue, date) @venue = venue self.date = date end end

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  • What's the Difference Between These Two Ruby Class Initialization Definitions?

    - by michaelmichael
    I'm working through a book on Ruby, and the author used a slightly different form for writing a class initialization definition than he has in previous sections of the book. It looks like this: class Ticket attr_accessor :venue, :date def initialize(venue, date) self.venue = venue self.date = date end end In previous sections of the book, it would've been defined like this: class Ticket attr_accessor :venue, :date def initialize(venue, date) @venue = venue @date = date end end Is there any functional difference between using the setter method, as in the first example, vs. using the instance variable as in the second? They both seem to work. Even mixing them up works: class Ticket attr_accessor :venue, :date def initialize(venue, date) @venue = venue self.date = date end end

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  • Virtual methods as Comp function to sort

    - by wilsongoncalo.mp
    Hello everyone! I'm new to C++ and i'm trying to use std::sort function to sort a vector of Solutions. The code is something like this (solution list is a *vector): void SolutionSet::sort(Comparator &comparator) { std::sort(solutionsList_->begin(), solutionsList_->end(), &comparator::compare); } The comparator param is a Comparator´s child class instance , and the compare method is virtual at Comparator class and implemented by all Comparator's child classes. And i want to use that function as a comparator function at std:sort(). Is this possible? If it is, can someone tell me how? Because with the previous code, it doesn't work. If i've not made myself clear, please just ask! Thank you guys!

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  • Create instance of generic type in Java?

    - by David Citron
    Is it possible to create an instance of a generic type in Java? I'm thinking based on what I've seen that the answer is "no" (due to type erasure), but I'd be interested if anyone can see something I'm missing: class SomeContainer<E> { E createContents() { return what??? } } EDIT: It turns out that Super Type Tokens could be used to resolve my issue, but it requires a lot of reflection-based code, as some of the answers below have indicated. I'll leave this open for a little while to see if anyone comes up with anything dramatically different than Ian Robertson's Artima Article.

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  • Objective C instance variables - Newbie

    - by Dwayne King
    OK - so I'm sure my confusion here is just a result of being stuck in a "Java mindset" and not understanding how Obj C differs in this case. In Java, I can declare a variable in a class, like this, and each instance of that class will have it's own: MyClass { String myVar; MyClass() { // constructor } } In Obj C I tried to do the same thing by declaring a variable only in the .m file like this: #import "MyClass.h" @implementation MyClass NSString *testVar; @end My expectation here was that this variable has a scope limited to this class. So I created a second class (identical): #import "MySecondClass.h" @implementation MySecondClass NSString *testVar; @end What I'm seeing (and has me baffled) is that changing the variable in one class, affects the value seen in the other class. In fact, if I set a breakpoint, and then "Jump to Definition" of the variable, it takes me to th I've created an extremely small XCode project that demonstrates the problem here Nothing more humbling than moving to a new language :) Thanks in advance.

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  • Java: Friendlier way to get an instance of FontMetrics

    - by Martijn Courteaux
    Hi people, Is there a friendlier way to get an instance of FontMetrics than FontMetrics fm = Graphics.getFontMetrics(Font); I hate this way because of the following example: If you want to create in a game a menu and you want all the menuitems in the center of the screen you need fontmetrics. But, mostly, menuitems are clickable. So I create an array of Rectangles and all the rectangles fits around the items, so when the mouse is pressed, I can simply use for (int i = 0; i < rects.length; i++) if (rects[i].contains(mouseX, mouseY)) { ... } But to create the rects I also need FontMetrics for their coordinates. So this mean that I have to construct all my rectangles in the paint-method of my menu. So I want a way to get the FontMetrics so I can construct the Rectangles in a method called by the constructor. Hope you understand. Thanks in advance.

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  • Jquery scroll to first instance of a class (.error) for jquerytools validator

    - by Tommy Arnold
    I am using jquerytools validator on a clients website but the page using this plugin is very long so I would like to add a custom handler using the folowing code. $("#form").bind("onFail", function(e, errors) { // we are only doing stuff when the form is submitted if (e.originalEvent.type == 'submit') { $(".errormsg").html("Please scroll up and fix the highlighted errors."); //alert("Please fix the highlighted errors to continue"); } }); How would I get it to scroll up to the first instance of .error? Can you recommend any plugins for this?

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  • WPF Creating an instance of a class in xaml

    - by Cloverness
    Hi, I have a problem with creating the instance of a class in xaml file. I thought you can do it like this: in the resource part of the user control and then use it in the xaml file (for example bind to it). But even tough the class I created is located in the same namespace it says that: "The type was not found. Verfiy that all assemblies were built, etc". How to get it right? is there another method? Thanks for suggestions.

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  • Application.Current changes when using reflection to create an instance of another Application class

    - by markti
    Let's say I have the following Silverlight Applications: App1.xap App2.xap App3.xap Let's say that I start App1.xap as the default xap file. If I load App2.xap and App3.xap and instantiate an Application class within one of the other two XAPs. The Application.Current changes to be that new instance. System.Windows.Application obj = Activator.CreateInstance(type) as System.Windows.Application; I don't want the current application to change. I just want to get the merged Resource Dictionaries off the Application class.

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  • Object reference not set to an instance of an object

    - by Ste
    I have this function that create runtime textbox: int i = 0; private TextBox[] addressBox = new TextBox[100]; private void appendNewTab() { addressBox[i] = new TextBox(); addressBox[i].KeyPress += new KeyPressEventHandler(this.addressBox_KeyPress); i++; } void addressBox_KeyPress(object sender, KeyPressEventArgs e) { if (e.KeyChar == (char)13) { MessageBox.Show(addressBox[i].Text); } } but i have Object reference not set to an instance of an object here MessageBox.Show(addressBox[i].Text); any suggestion?

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  • Singelton restricted to instance of dll

    - by codeySmurf
    If I create a singleton class in the context of a dll, the singleton class is instantiated once and used by all instances of the dll. I am using a dll as a plug-in for an application. Now the following thing came to my mind: If I use a singleton Class, it will be shared across multiple instances of the plug-in. However, this makes it difficult to manage the lifetime of the singleton class efficiently. The only way I could think of would be to use a reference count and to make the singleton delete its self when the reference count is 0. Does anyone have any better ideas on that? Is there any good way to restrict the singleton object to one instance of the dll? Language is c++

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  • Obj-C memory management for an NSView * instance variable

    - by massimoperi
    My custom view has a subview as an instance variable. Here is a sample interface: @interface MyCustomView : NSView { NSView *aSubview; } @end Then, in the .m file, I initialize aSubView and add it to the custom view. - (id)init { self = [super initWithFrame:CGRectMakeFrame(0.0, 0.0, 320.0, 480.0); if (self) { aSubview = [[NSView alloc] initWithFrame(0.0, 0.0, 100.0, 100.0); [self addSubview:aSubview]; } return self; } Where should I release aSubView? In the -dealloc method? - (void)dealloc { [aSubView release]; [super dealloc]; } Or directly after adding it to the custom view in the -init method? - (id)init { [...] [self addSubview:aSubview]; [aSubview release]; [...] } Which one is the best implementation?

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  • Creating an instance in rails association

    - by Sandeep Rao
    I have three models where a basiccase has a form. Basic case can create a new form. class User < ActiveRecord::Base has_many :basiccases end class Basiccase < ActiveRecord::Base belongs_to :user has_one :basiccases end class Form3C < ActiveRecord::Base belongs_to :basiccases end I want to create an instance of form 3c in the form3c controller. Can any one explain me how I can carry the basiccase_id to the form3c controller to set the foreign key attribute. I can set the value using @basiccase.build_form3_c but I'm not sure how I can get the basiccase_id from the basiccase.

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  • Methods for breaking up content client-side into multiple "pages"

    - by Tom Genoni
    I have a long HTML text-only article formatted with paragraph tags. What I'd like to do is break this content into N number of divs so that I can create individual pages. So, for instance, on an iPad/iPhone, instead of reading one long page the user could swipe right/left to navigate to pages. My initial javascript attempts have been somewhat convoluted: creating an array of the text, measuring line-heights, device window heights, adding closing/opening paragraph tags and the end/beginning of pages. Thoughts on a good way to approach this? I will not have access to server-side processing, this has to be a client-side solution.

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  • C# Making private instance variable accesable (jagged array)

    - by Chris
    Hello, In a attempt to put some more oop in a program i am looking to make a private instance variable in one class (object) accesable to a class. private byte [][] J; All those code refers to this jagged array with this. Now in the other class i putted all the for loops along with the consolewritlines to display the wanted results. Basicly it says "the name J does not exist in the current context" But how exactly do i make this J accesable? I have tried with get and set but i keep getting 'cannot convert to byte to byte[][]' Also what kind of cyntax would i need with get and set? Something along like this? Or would i need several more steps? : public Byte JArray get { return J; } //can converrt to byte here set { J = value; } //cannnot convert to byte here Kind regards

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  • Android HTTP get methods

    - by Nick
    I have written a number of applications for blackberry and am just starting in Android. It seems to me that android has a lot more built in functions. I am starting by recreating some of my BB apps on Android and on one I take a few xml sites and parse them out. On blackberry I implemented this by creating a class that extended a thread. I would construct a new instance of this class with the parameters of my http request and it would call a function back in my main class, sending it the results. I am tempted to reuse my code, but am curious if android has something better built in. I have been looking at the handler class as well as possible using a service. Bascially, I would like to start a new thread that will return a document of a specific url. Thanks!

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  • Javascript: adding methods using prototype descriptor

    - by LDK
    Sorter.prototype.init_bubblesort = function(){ console.log(this.rect_array); this.end = this.rect_array.length; this.bubblesort(); } Sorter.prototype.init = function(array,sort_type){ this.rect_array = array; this.init_bubblesort(); } The code above works as expected, but when I change the init function to: Sorter.prototype.init = function(array,sort_type){ var sort_types = {'bubblesort':this.init_bubblesort, 'quicksort':this.init_quicksort, 'liamsort':this.init_liamsort}; this.rect_array = array; sort_types[sort_type](); } the init_bubblesort function results in an error saying this.rect_array is undefined. I'm trying to wrap my head around why init_bubblesort no longer as access to it's instance's variables.

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  • TypeError: object not callable when making instance

    - by TSM
    I've searched around other threads with similar questions, but I'm not finding the answer. Basically, I have a class: import Android_Class class Android_Revision(object): def __init__(self): # dict for storing the classes in this revision # (format {name : classObject}): self.Classes = {} self.WorkingClass = Android_Class() self.RevisionNumber = '' def __call__(self): print "Called" def make_Class(self, name): newClass = Android_Class(name) self.Classes.update({name : newClass}) self.WorkingClass = newClass def set_Class(self, name): if not(self.Classes.has_key(name)): newClass = Android_Class(name) self.Classes.update({name : newClass}) self.WorkingClass = self.Classes.get(name) I'm trying to make an instance of this class: Revision = Android_Revision() and that's when I'm getting the error. I'm confused because I have another situation where I'm doing almost the exact same thing, and it's working fine. I can't figure out what differences between the two would lead to this error. Thanks.

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  • Load custom class properly

    - by LinusAn
    I have a custom class which I want to "load" inside the firstViewController and then access it from other classes by segues. My Problem is, I can't even access and change the instance variable inside the firstViewController. Somehow I'm "loading" it wrong. Here is the code I used until now: inside viewController.h @property (strong, nonatomic) myClass *newClass; inside viewController.m @synthesize newClass; I then try to access it by: self.newClass.string = @"myString"; if(newClass.string == @"myString"){ NSLog(@"didn't work"); } Well, I get "didn't work". Why is that? When I write myClass *newClass = [myClass new]; It does work. But the class and its properties gets overwritten every time the ViewController loads again. What would you recommend? Thank you very much.

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  • Are instance initializers good or bad?

    - by berry120
    I personally quite like instance initializers - I use them to assign default values to things such as collections so when writing constructors I don't have to remember to assign them the same default values each time. It seems quite elegant to me - avoids annoying NPE's popping up and avoids duplicate code. A private method doesn't seem as nice because a) it can't assign values to final fields, b) it could be run elsewhere in code and c) the method still needs to be explicitly called at the start of each constructor. However, the flip side with others I have spoken to is that they're confusing, some people reading the code might not understand what they do or when they're called and thus they could cause more problems than they solve. Are proper use of these initializers something to be encouraged or avoided? Or is it an "each to their own" case?

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  • DataContractSerializer does not properly deserialize, values for methods in object are missing

    - by sachin
    My SomeClass [Serializable] [DataContract(Namespace = "")] public class SomeClass { [DataMember] public string FirstName { get; set; } [DataMember] public string LastName { get; set; } [DataMember] private IDictionary<long, string> customValues; public IDictionary<long, string> CustomValues { get { return customValues; } set { customValues = value; } } } My XML File: <?xml version="1.0" encoding="UTF-8"?> <SomeClass> <FirstName>John</FirstName> <LastName>Smith</LastName> <CustomValues> <Value1>One</Value1> <Value2>Two</Value2> </CustomValues > </SomeClass> But my problem is for the class, i am only getting some of the data for my methods when i deserialize. var xmlRoot = XElement.Load(new StreamReader( filterContext.HttpContext.Request.InputStream, filterContext.HttpContext.Request.ContentEncoding)); XmlDictionaryReader reader = XmlDictionaryReader.CreateDictionaryReader(xmlRoot.CreateReader()); DataContractSerializer ser = new DataContractSerializer(typeof(SomeClass)); //Deserialize the data and read it from the instance. SomeClass someClass = (SomeClass)ser.ReadObject(reader, true); So when I check "someClass", FirstName will have the value john, But the LastName will be null. Mystery is how can i get some of the data and not all of the data for the class. So DataContractSerializer is not pulling up all the data from xml when deserializing. Am i doing something wrong. Any help is appreciated. Thanks in advance. Let me know if anyone has the same problem or any one has solution

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  • Constant NSDictionary/NSArray for class methods.

    - by Jeff B
    I am trying to code a global lookup table of sorts. I have game data that is stored in character/string format in a plist, but which needs to be in integer/id format when it is loaded. For instance, in the level data file, a "p" means player. In the game code a player is represented as the integer 1. This let's me do some bitwise operations, etc. I am simplifying greatly here, but trying to get the point across. Also, there is a conversion to coordinates for the sprite on a sprite sheet. Right now this string-integer, integer-string, integer-coordinate, etc. conversion is taking place in several places in code using a case statement. This stinks, of course, and I would rather do it with a dictionary lookup. I created a class called levelInfo, and want to define the dictionary for this conversion, and then class methods to call when I need to do a conversion, or otherwise deal with level data. NSString *levelObjects = @"empty,player,object,thing,doohickey"; int levelIDs[] = [0,1,2,4,8]; // etc etc @implementation LevelInfo +(int) crateIDfromChar: (char) crateChar { int idx = [[crateTypes componentsSeparatedByString:@","] indexOfObject: crateChar]; return levelIDs[idx]; } +(NSString *) crateStringFromID: (int) crateID { return [[crateTypes componentsSeparatedByString:@","] objectAtIndex: crateID]; } @end Is there a better way to do this? It feels wrong to basically build these temporary arrays, or dictionaries, or whatever for each call to do this translation. And I don't know of a way to declare a constant NSArray or NSDictionary. Please, tell me a better way....

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  • Twitter-OAuth update_profile_*_image methods problem [EpiTwitter]

    - by KPL
    People, I have been struggling over the two methods - Update Profile Image and Update Background Image I am using EpiTwitter library. I am uploading GIFs, Twitter returns the expected result for update_profile_background_image but returns 401 for update_profile_image , but the image is not changed. Here are the headers catched from $apiObj-headers in my case while using the update_profile_background_image Array ( [Date] = Sat, 24 Apr 2010 17:51:36 GMT [Server] = hi [Status] = 200 OK [X-Transaction] = 1272131495-55190-23911 [ETag] = b6a421c01936f3547802ae6b59ee7ef3" [Last-Modified] = Sat, 24 Apr 2010 17:51:36 GMT [X-Runtime] = 0.13990 [Content-Type] = application/json; charset=utf-8 [Content-Length] = 1272 [Pragma] = no-cache [X-Revision] = DEV [Expires] = Tue, 31 Mar 1981 05:00:00 GMT [Cache-Control] = no-cache, no-store, must-revalidate, pre- check=0, post-check=0 [Set-Cookie] = *REMOVED* [Vary] = Accept-Encoding [Connection] = close ) and for update_profile_image - Array ( [Date] => Sat, 24 Apr 2010 17:57:58 GMT [Server] => hi [Status] => 401 Unauthorized [WWW-Authenticate] => Basic realm="Twitter API" [X-Runtime] => 0.02263 [Content-Type] => text/html; charset=utf-8 [Content-Length] => 152 [Cache-Control] => no-cache, max-age=300 [Set-Cookie] => *REMOVED* [Expires] => Sat, 24 Apr 2010 18:02:58 GMT [Vary] => Accept-Encoding [Connection] => close ) Can somebody help me out?

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  • WPF: UnauthorizedAccessException using anonymous methods.

    - by Diego Pacheco Pedemonte
    Here is the thing, I want to create a simply app that copy many files from one site, and move them to another; but using async methods and create a new thread. private void button3_Click(object sender, RoutedEventArgs e) { //progressBar1.Maximum = _FileInfoArray.Count; DispatcherTimer dt1 = new DispatcherTimer(); foreach (FileInfo Fi in _FileInfoArray) { Thread t = new Thread(new ThreadStart(delegate() { DispatcherOperation _dispOp = progressBar1.Dispatcher.BeginInvoke(DispatcherPriority.Loaded, new Action(delegate() { File.Copy(txtdestino.Text, Fi.FullName, true); //progressBar1.Value = n; //txtstatus.Content = ("Copiados " + n.ToString() + " archivos"); //Thread.Sleep(100); } )); _dispOp.Completed += new EventHandler(_dispOp_Completed); } )); t.Start(); } } UnauthorizedAccessException is throw! It says that I can't access to txtdestino content. Some clues? -------------------------------------------------------------------------------Edited This is the version with all the changes, get the same error :( any clues? private void button4_Click(object sender, RoutedEventArgs e) { //First: Build mynames List<string> mynames = new List<string>(); foreach (FileInfo fi in _FileInfoArray) { mynames.Add(fi.FullName); } Thread t = new Thread(new ThreadStart(delegate() { foreach (string fullname in mynames) { DispatcherOperation _dispOp = progressBar1.Dispatcher.BeginInvoke(DispatcherPriority.Loaded, new Action(delegate() { string destino = System.IO.Path.Combine(@"C:\", System.IO.Path.GetFileName(fullname)); File.Copy(fullname, destino, true); //Some progressbar changes } )); _dispOp.Completed += new EventHandler(_dispOp_Completed); } } )); t.Start(); } File.Copy(txtdestino.Text, Fi.FullName, true); // here the exception is throw

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  • Accessing bean object methods from xhtml in RichFaces

    - by Mark Lewis
    Hello When I use (1) in my xhtml, I get an error as in (2). How can I access the size of an array in my bean? (1) A List of objects of a custom class type, accessed through the following h:outputText in a rich:column in a rich:subTable in a rich:dataTable: <h:outputText value="Info: #{f.filemask.size()}" /> (2) Caused by: com.sun.facelets.tag.TagAttributeException: /nodeConfig.xhtml @190,91 value="Info: #{f.filemask.size()" Error Parsing: Info:  #{f.filemask.size()} at com.sun.facelets.tag.TagAttribute.getValueExpression(TagAttribute.java:259) ... Caused by: org.apache.el.parser.ParseException: Encountered " "(" "( "" at line 1, column 41. Was expecting one of: "}" ... "." ... "[" ... ">" ... "gt" ... "<" ... "lt" ... ">=" ... "ge" ... "<=" ... "le" ... "==" ... "eq" ... "!=" ... "ne" ... "&&" ... "and" ... "||" ... "or" ... "*" ... "+" ... "-" ... "/" ... "div" ... "%" ... "mod" ... Any help greatly appreciated. I cannot seem to find references to using methods like this but this reference reported it working fine

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