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  • I've Heard Global Variables Are Bad, What Alternative Solution Should I Use?

    - by Jay
    I've read all over the place that global variables are bad and alternatives should be used. In Javascript specifically, what solution should I choose. I'm thinking of a function, that when fed two arguments (function globalVariables(Variable,Value)) looks if Variable exists in a local array and if it does set it's value to Value, else, Variable and Value are appended. If the function is called without arguments (function globalVariables()) it returns the array. Perhaps if the function is fired with just one argument (function globalVariables(Variable)) it returns the value of Variable in the array. What do you think? I'd like to hear your alternative solutions and arguments for using global variables.

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  • Using singleton instead of a global static instance

    - by Farstucker
    I ran into a problem today and a friend recommended I use a global static instance or more elegantly a singleton pattern. I spent a few hours reading about singletons but a few things still escape me. Background: What Im trying to accomplish is creating an instance of an API and use this one instance in all my classes (as opposed to making a new connection, etc). There seems to be about 100 ways of creating a singleton but with some help from yoda I found some thread safe examples. ..so given the following code: public sealed class Singleton { public static Singleton Instance { get; private set; } private Singleton() { APIClass api = new APIClass(); //Can this be done? } static Singleton() { Instance = new Singleton(); } } How/Where would you instantiate the this new class and how should it be called from a separate class? EDIT: I realize the Singleton class can be called with something like Singleton obj1 = Singleton.Instance(); but would I be able to access the methods within the APIs Class (ie. obj1.Start)? (not that I need to, just asking) EDIT #2: I might have been a bit premature in checking the answer but I do have one small thing that is still causing me problems. The API is launching just fine, unfortunately Im able to launch two instances? New Code public sealed class SingletonAPI { public static SingletonAPI Instance { get; private set; } private SingletonAPI() {} static SingletonAPI() { Instance = new SingletonAPI(); } // API method: public void Start() { API myAPI = new API();} } but if I try to do something like this... SingletonAPI api = SingletonAPI.Instance; api.Start(); SingletonAPI api2 = SingletonAPI.Instance; // This was just for testing. api2.Start(); I get an error saying that I cannot start more than one instance.

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  • Class generation on the fly

    - by James P.
    Is it possible to generate subclasses at runtime or while an application is running? If so, how is this achieved and what precautions should be taken to prevent a rogue object wreaking havoc inside an application?

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  • Using jquery append() in <head> (in a function/class)

    - by Anonymous
    I want to use the append() function from inside the <head>, in a function to be specific, like so: function custom_img(src_img) { $("div").append("<img src='"+src_img+"'>"); } var myimg = new custom_img("test.jpg"); This is a quick example that I just wrote out. I want my function to make a new image like that every time I create a new object like this. Obviously this doesn't work, since the append() requires to be in the body (I've tried this). How would I do this?

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  • How do you set a "Document class" from an SWC in Flash CS4?

    - by Flash Challenge
    I have an SWC with a class called Content. I want to set it as the "Document Class" in Flash. However, after setting up the SWC in the .fla, I am receiving an error message saying that "A definition for the document class could not be found in the classpath,..." Setting up the direct class folder works fine, but I need to distribute this SWC and do not want to include the sources. Is it possible to use a class as the Document Class if it resides in an SWC? I've found some links that seem to indicate no, but I need to find out definitively. http://balazs.sebesteny.com/document-class-from-swc/ forums.adobe.com/thread/452045

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  • How to terminate a particular Azure worker role instance

    - by Oliver Bock
    Background I am trying to work out the best structure for an Azure application. Each of my worker roles will spin up multiple long-running jobs. Over time I can transfer jobs from one instance to another by switching them to a readonly mode on the source instance, spinning them up on the target instance, and then spinning the original down on the source instance. If I have too many jobs then I can tell Azure to spin up extra role instance, and use them for new jobs. Conversely if my load drops (e.g. during the night) then I can consolidate outstanding jobs to a few machines and tell Azure to give me fewer instances. The trouble is that (as I understand it) Azure provides no mechanism to allow me to decide which instance to stop. Thus I cannot know which servers to consolidate onto, and some of my jobs will die when their instance stops, causing delays for users while I restart those jobs on surviving instances. Idea 1: I decide which instance to stop, and return from its Run(). I then tell Azure to reduce my instance count by one, and hope it concludes that the broken instance is a good candidate. Has anyone tried anything like this? Idea 2: I predefine a whole bunch of different worker roles, with identical contents. I can individually stop and start them by switching their instance count from zero to one, and back again. I think this idea would work, but I don't like it because it seems to go against the natural Azure way of doing things, and because it involves me in a lot of extra bookkeeping to manage the extra worker roles. Idea 3: Live with it. Any better ideas?

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  • MATLAB is changing variables when I do not want it to.

    - by WVUstudent
    Here is my problem in a small bit of code used as an example, trial(0) function [] = trial(test) disp(test) if(test == 1) disp('test is one') test = 0; end disp(test) Matlab prints out this: 0 'test is one' 0 This is not my real code, there are over 500 lines of it, but this is a section of my code where the problem has risen. I have used the search function to see if I have been incrementing any variables anywhere, and have put in over 2 hours trying to see why MATLAB is changing my variables when I don't want it to.

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  • PHP multiuser login class or script

    - by FFish
    I am looking for a simple but secure login script with mySQL PHP: sessions, MD5 that I can use with my exsisting database. Cookies to store password + password recovery by email. Change login/pass. I do not need registering, I register the user myself with temp login/pass. table agents agent1 agent2 table albums album1, owner: agent1 album2, owner: agent1 album3, owner: agent2 ... login.php agent1 logs in and has access to his albums: - album1 - album2 agent1 can edit his albums: edit.php?ref=album1 but NOT edit.php?ref=album3 by changing the ?ref variable

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  • Class Cast Exception

    - by iaagty
    why do i get this exception? Map myHash = null myHash = (HashMap)Collections.synchronizedMap(new HashMap()); If i try to use this hashmap, i get java.lang.ClassCastException

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  • .net, using PowerShell class to invoke a "[namespace.class]::method" style command

    - by Marco
    Hello, I created a powershell object via .net to invoke commands. When I invoke normal commands like 'Get-Process' I had no problems: ps.AddCommand("Get-Process").AddParameter(...).Invoke() but I'm not able to invoke a .net method with the syntax "[namespace.class]::method", just to make an example to invoke [System.IO.File]::Exists("c:\boo.txt"). I tried with ps.AddCommand("[System.IO.File]::Exists(\"c:\boo.txt\")").Invoke() ps.AddCommand("[System.IO.File]::Exists").AddArgument("c:\boo.txt\").Invoke() and some others. It always throws an exception which says that the command specified is not recognized. There is a way to invoke that type of command? Thanks

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  • need help ,hp class and xml save load edit example.p

    - by jef
    http://www.sendspace.com/file/2zlfgn I have the php files i been trying to get them to save to xml. I have tried $product1=array(); $product1['id'] = new product( "19990","modrl","maf","purpose","war"); only the ID writes to xml. since model,maf etc are sub-elements is there a different way to create the objectarray?

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  • Initializing PHP class property declarations with simple expressions yields syntax error

    - by user171929
    According to the PHP docs, one can initialize properties in classes with the following restriction: "This declaration may include an initialization, but this initialization must be a constant value--that is, it must be able to be evaluated at compile time and must not depend on run-time information in order to be evaluated." I'm trying to initialize an array and having some issues. While this works fine: public $var = array( 1 => 4, 2 => 5, ); This creates a syntax error: public $var = array( 1 => 4, 2 => (4+1), ); Even this isn't accepted: public $var = 4+1; which suggests it's not a limitation of the array() language construct. Now, the last time I checked, "4+1" equated to a constant value that not only should be accepted, but should in fact be optimized away. In any case, it's certainly able to be evaluated at compile-time. So what's going on here? Is the limitation really along the lines of "cannot be any calculated expression at all", versus any expression "able to be evaluated at compile time"? The use of "evaluated" in the doc's language suggests that simple calculations are permitted, but alas.... If this is a bug in PHP, does anyone have a bug ID? I tried to find one but didn't have any luck.

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  • How to override inner class methods if the inner class is defined as a property of the top class

    - by Maddy
    I have a code snippet like this class A(object): class b: def print_hello(self): print "Hello world" b = property(b) And I want to override the inner class b (please dont worry about the lowercase name) behaviour. Say, I want to add a new method or I want to change an existing method, like: class C(A): class b(A.b): def print_hello(self): print "Inner Class: Hello world" b = property(b) Now if I create C's object as c = C(), and call c.b I get TypeError: 'property' object is not callable error. How would I get pass this and call print_hello of the extended inner class? Disclaimer: I dont want to change the code for A class.

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  • Objective-C Basic class related question, retaining the value of a specific object using a class fil

    - by von steiner
    Members, scholars, code gurus. My background is far from any computer programming thus my question may seems basic and somewhat trivial to you. Nevertheless it seems that I can't put my head around it. I have googled and searched for the answer, just to get myself confused even more. With that, I would kindly ask for a simple explanation suitable for a non technical person such as myself and for other alike arriving to this thread. I have left a comment with the text "Here is the issue" below, referring to my question. // character.h #import <Foundation/Foundation.h> @interface character : NSObject { NSString *name; int hitPoints; int armorClass; } @property (nonatomic,retain) NSString *name; @property int hitPoints,armorClass; -(void)giveCharacterInfo; @end // character.m #import "character.h" @implementation character @synthesize name,hitPoints,armorClass; -(void)giveCharacterInfo{ NSLog(@"name:%@ HP:%i AC:%i",name,hitPoints,armorClass); } @end // ClassAtLastViewController.h #import <UIKit/UIKit.h> @interface ClassAtLastViewController : UIViewController { } -(void)callAgain; @end // ClassAtLastViewController.m #import "ClassAtLastViewController.h" #import "character.h" @implementation ClassAtLastViewController - (void)viewDidLoad { //[super viewDidLoad]; character *player = [[character alloc]init]; player.name = @"Minsc"; player.hitPoints = 140; player.armorClass = 10; [player giveCharacterInfo]; [player release]; // Up until here, All peachy! [self performSelector:@selector(callAgain) withObject:nil afterDelay:2.0]; } -(void)callAgain{ // Here is the issue, I assume that since I init the player again I loss everything // Q1. I loss all the data I set above, where is it than? // Q2. What is the proper way to implement this character *player = [[character alloc]init]; [player giveCharacterInfo]; } Many thanks in advance, Kindly remember that my background is more related to Salmons breeding than to computer code, try and lower your answer to my level if it's all the same to you.

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  • Strange Java Coding??? Class in class???

    - by poeschlorn
    Hi guys, I got a question about Java coding in general... In some sample codes there are methods and classes declared WITHIN other methods and/or classes.... I've never heard/red about this...what effect does this kind of programming have? Wouldn't it be better to write down classes in a seperate file and methods side by side and not within each other (like every book tells you)? What are the advantages and disadvantages of this kind of programming? Here's an example of what I mean: Handler mHandler = new Handler() { public void handleMessage(android.os.Message msg) { TextView textView = (TextView) findViewById(R.id.description); textView.setText(mRoad.mName + " " + mRoad.mDescription); MapOverlay mapOverlay = new MapOverlay(mRoad, mapView); List<Overlay> listOfOverlays = mapView.getOverlays(); listOfOverlays.clear(); listOfOverlays.add(mapOverlay); mapView.invalidate(); }; };

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  • How should I declare default values for instance variables in Python?

    - by int3
    Should I give my class members default values like this: class Foo: num = 1 or like this? class Foo: def __init__(self): self.num = 1 In this question I discovered that in both cases, bar = Foo() bar.num += 1 is a well-defined operation. I understand that the first method will give me a class variable while the second one will not. However, if I do not require a class variable, but only need to set a default value for my instance variables, are both methods equally good? Or one of them more 'pythonic' than the other? One thing I've noticed is that in the Django tutorial, they use the second method to declare Models. Personally I think the second method is more elegant, but I'd like to know what the 'standard' way is.

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  • Using PowerShell class to invoke a "[namespace.class]::method" style command

    - by Marco
    Hello, I created a powershell object via .net to invoke commands. When I invoke normal commands like 'Get-Process' I had no problems: ps.AddCommand("Get-Process").AddParameter(...).Invoke() but I'm not able to invoke a .net method with the syntax "[namespace.class]::method", just to make an example to invoke [System.IO.File]::Exists("c:\boo.txt"). I tried with ps.AddCommand("[System.IO.File]::Exists(\"c:\\boo.txt\")").Invoke() ps.AddCommand("[System.IO.File]::Exists").AddArgument("c:\\boo.txt").Invoke() and some others. It always throws an exception which says that the command specified is not recognized. There is a way to invoke that type of command? Thanks

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  • need help ,php class and xml save load edit example.p

    - by jef
    http://www.sendspace.com/file/2zlfgn I have the php files i been trying to get them to save to xml. I have tried $product1=array(); $product1['id'] = new product( "19990","modrl","maf","purpose","war"); only the ID writes to xml. since model,maf etc are sub-elements is there a different way to create the objectarray?

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  • Why doesn't my UIViewController class keep track of an NSArray instance variable.

    - by TaoStoner
    Hey, I am new to Objective-C 2.0 and Xcode, so forgive me if I am missing something elementary here. Anyways, I am trying to make my own UIViewController class called GameView to display a new view. To work the game I need to keep track of an NSArray that I want to load from a plist file. I have made a method 'loadGame' which I want to load the correct NSArray into an instance variable. However it appears that after the method executes the instance variable loses track of the array. Its easier if I just show you the code.... @interface GameView : UIViewController { IBOutlet UIView *view IBOutlet UILabel *label; NSArray *currentGame; } -(IBOutlet)next; -(void)loadDefault; ... @implementation GameView - (IBOutlet)next{ int numElements = [currentGame count]; int r = rand() % numElements; NSString *myString = [currentGame objectAtIndex:(NSUInteger)r]; [label setText: myString]; } - (void)loadDefault { NSDictionary *games; NSString *path = [[NSBundle mainBundle] bundlePath]; NSString *finalPath = [path stringByAppendingPathComponent:@"Games.plist"]; games = [NSDictionary dictionaryWithContentsOfFile:finalPath]; currentGame = [games objectForKey:@"Default"]; } when loadDefault gets called, everything runs perfectly, but when I try to use the currentGame NSArray later in the method call to next, currentGame appears to be nil. I am also aware of the memory management issues with this code. Any help would be appreciated with this problem.

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  • C++/CLI value class constraint won't compile. Why?

    - by Simon
    Hello, a few weeks ago a co-worker of mine spent about two hours finding out why this piece of C++/CLI code won't compile with Visual Studio 2008 (I just tested it with Visual Studio 2010... same story). public ref class Test { generic<class T> where T : value class void MyMethod(Nullable<T> nullable) { } }; The compiler says: Error 1 error C3214: 'T' : invalid type argument for generic parameter 'T' of generic 'System::Nullable', does not meet constraint 'System::ValueType ^' C:\Users\Simon\Desktop\Projektdokumentation\GridLayoutPanel\Generics\Generics.cpp 11 1 Generics Adding ValueType will make the code compile. public ref class Test { generic<class T> where T : value class, ValueType void MyMethod(Nullable<T> nullable) { } }; My question is now. Why? What is the difference between value class and ValueType?

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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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  • how can I pass method Of one class to another class ?

    - by srikanth rongali
    I have a ClassA. in ClassA there is a method(-(void)parseData:). I have a ClassB which have ClassA object. And ClassB *aClassB is member variable of ClassA. In ClassB the code is aClassB = [[ClassB alloc]init]; [aClassB parseData]; I have ClassC. I need to use the method parseData of ClassB in ClassC. I think I can use the object created in ClassB of ClassA. How can I pass the method to ClassC ? Thank You.

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