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• how to delete the pluginassembly after AppDomain.Unload(domain)

  - by Ase

  hello, i have a weird problem. i would like to delete an assembly(plugin.dll on harddisk) which is already loaded, but the assembly is locked by the operating system (vista), even if i have unloaded it. f.e. AppDomainSetup setup = new AppDomainSetup(); setup.ShadowCopyFiles = "true"; AppDomain appDomain = AppDomain.CreateDomain(assemblyName + "_AppDomain", AppDomain.CurrentDomain.Evidence, setup); IPlugin plugin = (IPlugin)appDomain.CreateInstanceFromAndUnwrap(assemblyName, "Plugin.MyPlugins"); I also need the assemblyinfos, because I don't know which classes in the pluginassembly implements the IPlugin Interface. It should be possible to have more than one Plugin in one Pluginassembly. Assembly assembly = appDomain.Load(assemblyName); if (assembly != null) { Type[] assemblyTypes = assembly.GetTypes(); foreach (Type assemblyTyp in assemblyTypes) { if (typeof(IPlugin).IsAssignableFrom(assemblyTyp)) { IPlugin plugin = (IPlugin)Activator.CreateInstance(assemblyTyp); plugin.AssemblyName = assemblyNameWithEx; plugin.Host = this; } } } AppDomain.Unload(appDomain); How is it possible to get the assemblyinfos from the appDomain without locking the assembly? best regards

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• Why is my SAX handler returning an object with no values? I am setting it just fine

  - by Blankman

  I'm writing a SAX parser for an xml, and the object it returns doesn't have the values that I am setting in the events. My classes structure is like this: public class ProductSAXHandler extends DefaultHandler { private Product product; public ProductSAXHandler() { product = new Product(); } public Product ParseXmlFile(String xml) { SAXParserFactory spf = new ... XMLReader parser = .... parser.parse(xml); return product; } public void StartElement(....) { for(int ...) { // looping through attributes if(qName == "description" && name == "sku") { product.setSKU(value); } } } } When I am in debug mode, the value of product does get set, and I can see that the product's sku field has the correct value. But for some reason the product object returned is just a new Product object with no values set during the parsing. What am I doing wrong here? It must be me not understanding how these events are fired etc.

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• Suggestions on Working with this Inherited Generic Method

  - by blu

  We have inherited a project that is a wrapper around a section of the core business model. There is one method that takes a generic, finds items matching that type from a member and then returns a list of that type. public List<T> GetFoos<T>() { List<IFoo> matches = Foos.FindAll( f => f.GetType() == typeof(T) ); List<T> resultList = new List<T>(); foreach (var match in matches) { resultList.Add((T)obj); } } Foos can hold the same object cast into various classes in inheritance hierarchy to aggregate totals differently for different UI presentations. There are 20+ different types of descendants that can be returned by GetFoos. The existing code basically has a big switch statement copied and pasted throughout the code. The code in each section calls GetFoos with its corresponding type. We are currently refactoring that into one consolidated area, but as we are doing that we are looking at other ways to work with this method. One thought was to use reflection to pass in the type, and that worked great until we realized the Invoke returned an object, and that it needed to be cast somehow to the List <T>. Another was to just use the switch statement until 4.0 and then use the dynamic language options. We welcome any alternate thoughts on how we can work with this method. I have left the code pretty brief, but if you'd like to know any additional details please just ask.

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• An issue on object orientation in php

  - by rabidmachine9

  Hello people, I have come up to issues while I'm trying to write some classes, here is an example: I have this class called TwitterGrub and I cant call it like that: $c = new TwitterGrub(); $c->twitterDisplay(); here is the class itself: <?php class TwitterGrub{ function twitterCapture($user = 'username',$password = 'pass') { $ch = curl_init("https://twitter.com/statuses/user_timeline.xml"); curl_setopt($ch, CURLOPT_HEADER, 1); curl_setopt($ch,CURLOPT_TIMEOUT, 30); curl_setopt($ch,CURLOPT_USERPWD,$user . ":" . $password); curl_setopt($ch,CURLOPT_RETURNTRANSFER,1); curl_setopt ($ch, CURLOPT_SSL_VERIFYPEER, 0); curl_setopt ($ch, CURLOPT_SSL_VERIFYHOST, 0); $result=curl_exec ($ch); $data = strstr($result, '<?'); $xml = new SimpleXMLElement($data); return $xml; } function twitterDisplay($twitNum = 2){ $xml = $this::twitterCapture(); for($i= 0; $i<$twitNum; $i++){ echo "<div class= 'curvebox'>".$xml->status[$i]->text."</div>"; } } } ?> The problem is that everytime I want to change the username or password I have to jump back to class definition and that makes things not modular... and in many ways it feels wrong. So the question is what would be the proper way to chance my username and password through the objects interface and then call twitterDisplay() method with the new data?Hope that makes sense. Thanks in advance

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• Flash Builder 4 "includeIn" property causing design view error

  - by Chris

  I am creating a custom TextInput component that will define an "error" state. I have extended the TextInput class to change the state to "error" if the errorString property's length is greater than 0. In the skin class, I have defined an "error" state, and added some logic to detect the size and position of the error icon. However, if I have this code at the same time I use the "includeIn" property in the bitmap image tag, I get a design view error. If I either A) Only include that code with no "includeIn" property set, it works or B) dont include the code to set the icon size and position and only use the "includeIn" property, it works. Any ideas what could be causing the design view problem when I use both the "includeIn" property and the icon size/position code at the same time? TextInput Class: package classes { import spark.components.TextInput; public class TextInput extends spark.components.TextInput { [SkinState("error")]; public function TextInput() { super(); } override public function set errorString( value:String ):void { super.errorString = value; invalidateSkinState(); } override protected function getCurrentSkinState():String { if (errorString.length>0) { return "error"; } return super.getCurrentSkinState(); } } } TextInput Skin File: override protected function updateDisplayList(unscaledWidth:Number, unscaledHeight:Number):void { //THIS IS THE CODE THAT SEEMS TO BE CAUSING THE PROBLEM if(getStyle("iconSize") == "large") { errorIcon.right = -12; errorIcon.source = new errorIconLg(); } else { errorIcon.right = -5; errorIcon.source = new errorIconSm(); } super.updateDisplayList(unscaledWidth, unscaledHeight); } </fx:Script> <s:states> <s:State name="normal"/> <s:State name="disabled"/> <s:State name="error"/> </s:states> //If I remove the problem code above or if I take out the includeIn //property here, it works <s:BitmapImage id="errorIcon" verticalCenter="0" includeIn="error" /> </s:SparkSkin>

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• How do I code a tree of objects in Haskell with pointers to parent and children?

  - by axilmar

  I've got the following problem: I have a tree of objects of different classes where an action in the child class invalidates the parent. In imperative languages, it is trivial to do. For example, in Java: public class A { private List<B> m_children = new LinkedList<B>(); private boolean m_valid = true; public void invalidate() { m_valid = false; } public void addChild(B child) { m_children.add(child); child.m_parent = this; } } public class B { public A m_parent = null; private int m_data = 0; public void setData(int data) { m_data = 0; m_parent.invalidate(); } } public class Main { public static void main(String[] args) { A a = new A(); B b = new B(); b.setData(0); //invalidates A } } How do I do the above in Haskell? I cannot wrap my mind around this, since once I construct an object in Haskell, it cannot be changed. I would be much obliged if the relevant Haskell code is posted.

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• How to increase my "advanced" knowledge of PHP further? (quickly)

  - by Kerry

  I have been working with PHP for years and gotten a very good grasp of the language, created many advanced and not-so-advanced systems that are working very well. The problem I'm running into is that I only learn when I find a need for something that I haven't learned before. This causes me to look up solutions and other code that handles the problem, and so I will learn about a new function or structure that I hadn't seen before. It is in this way that I have learned many of my better techniques (such as studying classes put out by Amazon, Google or other major companies). The main problem with this is the concept of not being able to learn something if you don't know it exists. For instance, it took me several months of programming to learn about the empty() function, and I simply would check the string length using strlen() to check for empty values. I'm now getting into building bigger and bigger systems, and I've started to read blogs like highscalability.com and been researching MySQL replication and server data for scaling. I know that structure of your code is very important to make full systems work. After reading a recent blog about reddit's structure, it made me question if there is some standard or "accepted systems" out there. I have looked into frameworks (I've used Kohana, which I regretted, but decided that PHP frameworks were not for me) and I prefer my own library of functions rather than having a framework. My current structure is a mix between WordPress, Kohana and my own knowledge. The ways I can see as being potentially beneficial are: Read blogs Read tutorials Work with someone else Read a book What would be the best way(s) to "get to the next level" the level of being a very good system developer?

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• jQuery date calculator - show/hide IMG

  - by utopicam

  I have a problem with the following code. I tried changing many things (symbols, classes, imgs in the code) but this is killing me and I have no idea how to fix it. Sorry it's so specific, when solved I'll change the title to something more useful. I have two images. My jquery has to calculate the day and show one image or the other depending on that (using a class with display:none). My month has 24 days (it's a xmas thing). This is what I have so far: <script type="text/javascript"> $(document).ready(function(){ var currentTime = new Date() var day = currentTime.getDate(); if (day > 24){ day = 1; } $(".calDate").each(function(){ var curDate = $(this).attr("date"); if (curDate < day){ $(this).addClass("xMasPast"); } else if(curDate==day){ $(this).addClass("xMasActive"); } else { $(this).addClass("xMasInactive"); } }); $(".calDate2").each(function(){ var curDate = $(this).attr("date"); if (curDate > day){ $(this).addClass("xMasInactive"); } else if(curDate==day){ $(this).addClass("xMasActive"); } else { $(this).addClass("xMasActive"); } }); }); </script> But it's showing all the images. What am I missing? (any ideas on making the code simpler are more than welcomed). Thanks for your help! Update: simplified HTML <div><img src="day21.png" which="21"/></a></div> <img id="bola21" class="calDate2" src="day21.png"/>

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• Select form children when multiple forms are present jQuery

  - by afreeland

  I am dealing with a webpage that has multiple forms..some basic HTML forms and some AJAX forms. I have a created validation for inputs, let me give an example...if an input has a class="required" whenever a submit button is pressed if any required classes are empty then the form doesnt submit. Which works great...until you have multiple forms with required fields that dont apply to the section your submitting. I am able to find the closest form $(this).closest("form") and it gets me the form element properly, I then need to be able to loop only through the children of that form. I have tried: .children(':input'), .find('input') and honestly to many to list. Here is the code for when a button is selected $('#formSubmit').click(function (e) { var submit = true; var form = $(this).closest("form"); var formID = $(form).attr("id"); e.preventDefault(); $(form).children(":input").each(function () { if ($('#ERROR').length > 0) { submit = false; alert("Please fix errors to continue"); } $('.required').each(function () { if ($(this).val() == "" || $(this).val() == undefined) { submit = false; $(this).css({ 'background-color': '#fef236' }); } }); }); if (submit == true) { this.form.submit(); } }); //End of #formSubmit Also of interest I have started creating forms with ids that are GUID's so they will be unique and allow me to target things without any issues, just wanted to throw that out there if it can help lead to a solution I appreciate any help =)

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• How is this function being made use of?

  - by Kay

  Hello all, I am just studying a few classes given to me by my lecturer and I can't understand how the function heapRebuild is being made used of! It doesn't change any global variables and it doesn't print out anything ad it doesn't return anything - so should this even work? It shouldn't, should it? If you were told to make use of heapRebuild to make a new function removeMac would you edit heapRebuild? public class MaxHeap<T extends Comparable<T>> implements Heap<T>{ private T[] heap; private int lastIndex; public T removeMax(){ T rootItem = heap[0]; heap[0] = heap[lastIndex-1]; lastIndex--; heapRebuild(heap, 0, lastIndex); return rootItem; } protected void heapRebuild(T[ ] items, int root, int size){ int child = 2*root+1; if( child < size){ int rightChild = child+1; if ((rightChild < size) && (items[rightChild].compareTo(items[child]) > 0)){ child = rightChild; } if (items[root].compareTo(items[child]) < 0){ T temp = items[root]; items[root] = items[child]; items[child] = temp; heapRebuild(items, child, size);} } } }

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• How to determine if a C++ usertype has been registered with tolua

  - by czuger

  We use tolua++ to generate Lua bindings for C++ classes. Assume I have a C++ class: class Foo { //Some methods in Foo, irrelevant to question. }; and a tolua .pkg file with the following contents class Foo { }; Consider the following function: void call_some_lua_function(lua_State* luaState) { Foo* myFoo = new Foo(); tolua_pushusertype(luaState, (void*)myFoo, "Foo"); //More code to actually call Lua, irrelevant to question. } Now, the actual question: tolua_pushusertype causes a segfault in Lua if the 3rd parameter does not correspond to a valid fully qualified string of a C++ class that was registered with a call to tolua_cclass. So, if parameter 3 where "Bar", we get a segfault. What I would like to do is the following: void call_some_lua_function(lua_State* luaState) { //determine if tolua is aware of my type, how to do this? //Something like: //if(!tolua_iscpptype_registered("Foo")) //{ // abort gracefully //} Foo* myFoo = new Foo(); tolua_pushusertype(luaState, (void*)myFoo, "Foo"); //More code to actually call Lua, irrelevant to question. } Is there a way to do this using tolua?

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• Populate array from vector

  - by Zag zag..

  Hi, I would like to populate an 2 dimensional array, from a vector. I think the best way to explain myself is to put some examples (with a array of [3,5] length). When vector is: [1, 0] [ [4, 3, 2, 1, 0], [4, 3, 2, 1, 0], [4, 3, 2, 1, 0] ] When vector is: [-1, 0] [ [0, 1, 2, 3, 4], [0, 1, 2, 3, 4], [0, 1, 2, 3, 4] ] When vector is: [-2, 0] [ [0, 0, 1, 1, 2], [0, 0, 1, 1, 2], [0, 0, 1, 1, 2] ] When vector is: [1, 1] [ [2, 2, 2, 1, 0], [1, 1, 1, 1, 0], [0, 0, 0, 0, 0] ] When vector is: [0, 1] [ [2, 2, 2, 2, 2], [1, 1, 1, 1, 1], [0, 0, 0, 0, 0] ] Have you got any ideas, a good library or a plan? Any comments are welcome. Thanks. Note: I consulted Ruby "Matrix" and "Vector" classes, but I don't see any way to use it in my way... Edit: In fact, each value is the number of cells (from the current cell to the last cell) according to the given vector. If we take the example where the vector is [-2, 0], with the value *1* (at array[2, 3]): array = [ [<0>, <0>, <1>, <1>, <2>], [<0>, <0>, <1>, <1>, <2>], [<0>, <0>, <1>, *1*, <2>] ] ... we could think such as: The vector [-2, 0] means that -2 is for cols and 0 is for rows. So if we are in array[2, 3], we can move 1 time on the left (left because 2 is negative) with 2 length (because -2.abs == 2). And we don't move on the top or bottom, because of 0 for rows.

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• How can I bind the same dependency to many dependents in Ninject?

  - by Mike Bantegui

  Let's I have three interfaces: IFoo, IBar, IBaz. I also have the classes Foo, Bar, and Baz that are the respective implementations. In the implementations, each depends on the interface IContainer. So for the Foo (and similarly for Bar and Baz) the implementation might read: class Foo : IFoo { private readonly IDependency Dependency; public Foo(IDependency dependency) { Dependency = dependency; } public void Execute() { Console.WriteLine("I'm using {0}", Dependency.Name); } } Let's furthermore say I have a class Container which happens to contain instances of the IFoo, IBar and IBaz: class Container : IContainer { private readonly IFoo _Foo; private readonly IBar _Bar; private readonly IBaz _Baz; public Container(IFoo foo, IBar bar, IBaz baz) { _Foo = foo; _Bar = bar; _Baz = baz; } } In this scenario, I would like the implementation class Container to bind against IContainer with the constraint that the IDependency that gets injected into IFoo, IBar, and IBaz be the same for all three. In the manual way, I might implement it as: IDependency dependency = new Dependency(); IFoo foo = new Foo(dependency); IBar bar = new Bar(dependency); IBaz baz = new Baz(dependency); IContainer container = new Container(foo, bar, baz); How can I achieve this within Ninject? Note: I am not asking how to do nested dependencies. My question is how I can guarantee that a given dependency is the same among a collection of objects within a materialized service. To be extremely explicit, I understand that Ninject in it's standard form will generate code that is equivalent to the following: IContainer container = new Container(new Foo(new Dependency()), new Bar(new Dependency()), new Baz(new Dependency())); I would not like that behavior.

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• How to calculate how many business days are between two dates?

  - by mystify

  A friend asked me yesterday if this was possible on the iPhone. I took a look at NSCalendar and all the related Classes but couldn't find a solution to this. So I thought about this approach: If I had two dates dateA and dateB, I would have to make a for-loop and iterate over every single day in this interval. Then I would count the business days monday until friday, and return the result. Then I went to bed, and I woke up with this probably much better idea: I need to know what day is it when I start. Lets say it's thursday. And then I must know how many days are in that interval. The last part is not hard to figure out. For the first part, I have no clue yet, but I believe there's an day of week value in NSCalendar. With that, I could do some simple math to calculate the amount of business days. Did anyone do that already on the iPhone?

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• Calling child constructor by casting (ChildClass)parentObject; to track revisions

  - by FreshCode

  To track revisions of a Page class, I have a PageRevision class which inherits from Page and adds a revision ID (Guid RevisionID;). If possible, how should I cast an existing Page object to a PageRevision and ensure that the PageRevision constructor is called to create a new revision ID? I could could have a PageRevision(Page page) constructor which generates the Guid and copies all the Page attributes, but I want to automate it, especially if a Page class has many attributes (and I later add one, and forget to modify the copy constructor). Desired use Page page = new Page(123, "Page Title", "Page Body"); // where 123 is page ID PageRevision revision = (PageRevision)page; // now revision.RevisionID should be a new Guid. Page, PageRevision classes: public class Page { public int ID { get; set; } public string Title { get; set; } public string Body { get; set; } } public class PageRevision : Page { public Guid RevisionID { get; set; } public PageRevision() { this.RevisionID = Guid.NewGuid(); } }

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• NHibernate / ORM - Child Update over Web Service

  - by tyndall

  What is the correct way to UPDATE a child object with NHibernate but not have to "awake" the parent object. Lets say you would like to try to avoid this because the parent object is large or expensive to initiate. Lets assume classes are called Author(parent) and Book(child). (still, trying to avoid instantiating Author) Book comes back over a web service as XML. It gets deserialized back into a CLR object. Book has an AuthorId property which allows this to happen. But it also has a Author property. Problem, comes when you try to SaveOrUpdate() Book and the author_id in the database gets wiped out because the Author was null when the object gets deserialized. This seems like this would be a common problem. What is the workaround? Also, if you instantiate the Author and it has a Books property. The book you are trying to update is already one of these books (List<Book>). We have also run into the "a different object with the same identifier value was already associated with the session" problems. What is the standard process to update a child over a web service?

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• A self-creator: What pattern is this? php

  - by user151841

  I have several classes that are basically interfaces to database rows. Since the class assumes that a row already exists ( __construct expects a field value ), there is a public static function that allows creation of the row and returns an instance of the class. Here's a pseudo-code example : class fruit { public $id; public function __construct( $id ) { $this->id = $id; $sql = "SELECT * FROM Fruits WHERE id = $id"; ... $this->arrFieldValues[$field] = $row[$value]; } public function __get( $var ) { return $this->arrFieldValues[$var]; } public function __set( $var, $val ) { $sql = "UPDATE fruits SET $var = $val WHERE id = $this->id"; } public static function create( $id ) { $sql = "INSERT INTO Fruits ( fruit_name ) VALUE ( '$fruit' )"; $id = mysql_insert_id(); $fruit = & new fruit($id); return $fruit; } } $obj1 = fruit::create( "apple" ); $obj2 = & new fruit( 12 ); What is this pattern called? Edit: I changed the example to one that has more database-interface functionality. For most of the time, this kind of class would be instantiated normally, through __construct(). But sometimes when you need to create a new row first, you would call create().

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• Overload the behavior of count() when called on certain objects

  - by Tom

  In PHP 5, you can use magic methods, overload some classes, etc. In C++, you can implement functions that exist is STL as long as the argument types are different. Is there a way to do this in PHP? An example of what I'd like to do is this: class a { function a() { $this->list = array("1", "2"); } } $blah = new a(); count($blah); I would like blah to return 2. IE count the values of a specific array in the class. So in C++, the way I would do this might look like this: int count(a varName) { return count(varName->list); } Basically, I am trying to simplify data calls for a large application so I can call do this: count($object); rather than count($object->list); The list is going to be potentially a list of objects so depending on how it's used, it could be really nasty statement if someone has to do it the current way: count($object->list[0]->list[0]->list); So, can I make something similar to this: function count(a $object) { count($object->list); } I know PHP's count accepts a mixed var, so I don't know if I can override an individual type.

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• Avoiding instanceof in Java

  - by Mark Lutton

  Having a chain of "instanceof" operations is considered a "code smell". The standard answer is "use polymorphism". How would I do it in this case? There are a number of subclasses of a base class; none of them are under my control. An analogous situation would be with the Java classes Integer, Double, BigDecimal etc. if (obj instanceof Integer) {NumberStuff.handle((Integer)obj);} else if (obj instanceof BigDecimal) {BigDecimalStuff.handle((BigDecimal)obj);} else if (obj instanceof Double) {DoubleStuff.handle((Double)obj);} I do have control over NumberStuff and so on. I don't want to use many lines of code where a few lines would do. (Sometimes I make a HashMap mapping Integer.class to an instance of IntegerStuff, BigDecimal.class to an instance of BigDecimalStuff etc. But today I want something simpler.) I'd like something as simple as this: public static handle(Integer num) { ... } public static handle(BigDecimal num) { ... } But Java just doesn't work that way. I'd like to use static methods when formatting. The things I'm formatting are composite, where a Thing1 can contain an array Thing2s and a Thing2 can contain an array of Thing1s. I had a problem when I implemented my formatters like this: class Thing1Formatter { private static Thing2Formatter thing2Formatter = new Thing2Formatter(); public format(Thing thing) { thing2Formatter.format(thing.innerThing2); } } class Thing2Formatter { private static Thing1Formatter thing1Formatter = new Thing1Formatter(); public format(Thing2 thing) { thing1Formatter.format(thing.innerThing1); } } Yes, I know the HashMap and a bit more code can fix that too. But the "instanceof" seems so readable and maintainable by comparison. Is there anything simple but not smelly?

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• How do you get and set a class property across multiple functions in Objective-C?

  - by editor

  Following up on this question about sharing objects between classes, I now need to figure out how to share the objects across various functions in a class. First, the setup: In my App Delegate I load menu information from JSON into a NSMutableDictionary and message that through to a view controller using a function called initWithData. I need to use this dictionary to populate a new Table View, which has methods like numberOfRowsInSection and cellForRowAtIndexPath. I'd like to use the dictionary count to return numberOfRowsInSection and info in the dictionary to populate each cell. Unfortunately, my code never gets beyond the init stage and the dictionary is empty so numberOfRowsInSection always returns zero. I thought I could create a class property, synthesize it and then set it. But it doesn't seem to want to retain the property's value. What am I doing wrong here? In the header .h: @interface FirstViewController:UIViewController <UITableViewDataSource, UITableViewDelegate, UITabBarControllerDelegate> { NSMutableDictionary *sectorDictionary; NSInteger sectorCount; } @property (nonatomic, retain) NSMutableDictionary *sectorDictionary; - (id)initWithData:(NSMutableDictionary*)data; @end in the implementation .m: - (id) testFunction:(NSMutableDictionary*)dictionary { NSLog(@"Count #1: %d", [dictionary count]); return nil; } - (id)initWithData:(NSMutableDictionary *)data { if (!(self=[super init])) { return nil; } [self testFunction:data]; // this is where I'd like to set a retained property self.sectorDictionary = data; return nil; } - (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section { NSLog(@"Count #2: %d", [self.sectorDictionary count]); return [self.sectorDictionary count]; } Output from NSLog: 2010-05-04 23:00:06.255 JSONApp[15890:207] Count #1: 9 2010-05-04 23:00:06.259 JSONApp[15890:207] Count #2: 0

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• C++ compile time polymorphism doubt ?

  - by user313921

  Below program contains two show() functions in parent and child classes, but first show() function takes FLOAT argument and second show() function takes INT argument. .If I call show(10.1234) function by passing float argument, it should call class A's show(float a) function , but it calls class B's show(int b). #include<iostream> using namespace std; class A{ float a; public: void show(float a) { this->a = a; cout<<"\n A's show() function called : "<<this->a<<endl; } }; class B : public A{ int b; public: void show(int b) { this->b = b; cout<<"\n B's show() function called : "<<this->b<<endl; } }; int main() { float i=10.1234; B Bobject; Bobject.show((float) i); return 0; } Output: B's show() function called : 10 Expected output: A's show() function called : 10.1234 Why g++ compiler chosen wrong show() function i.e class B's show(int b) function ?

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• Why does java.util.concurrent.ArrayBlockingQueue use 'while' loops instead of 'if' around calls to

  - by theFunkyEngineer

  I have been playing with my own version of this, using 'if', and all seems to be working fine. Of course this will break down horribly if signalAll() is used instead of signal(), but if only one thread at a time is notified, how can this go wrong? Their code here - check out the put() and take() methods; a simpler and more-to-the-point implementation can be seen at the top of the JavaDoc for Condition. Relevant portion of my implementation below. public Object get() { lock.lock(); try { if( items.size() < 1 ) hasItems.await(); Object poppedValue = items.getLast(); items.removeLast(); hasSpace.signal(); return poppedValue; } catch (InterruptedException e) { e.printStackTrace(); return null; } finally { lock.unlock(); } } public void put(Object item) { lock.lock(); try { if( items.size() >= capacity ) hasSpace.await(); items.addFirst(item); hasItems.signal(); return; } catch (InterruptedException e) { e.printStackTrace(); } finally { lock.unlock(); } } P.S. I know that generally, particularly in lib classes like this, one should let the exceptions percolate up.

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• Basic Ajax Cache Issue

  - by michaelespinosa

  I have a single page that I need to on occasion asynchronously check the server to see if the status of the page is current (basically, Live or Offline). You will see I have a function with a var live that is set when the page initially loads. I then do an ajax request to the server to retrieve whether the status of live is true or false. I compare the initial live variable with the newly returned data json object. If they're the same I do nothing, but if there different I apply some css classes. I recursively run it with setTimeout (Is there a better way to recursively do this?). My Problem: data.live doesn't change from it's initial time it runs even when it has changed in the db. I know my mysql is working because it returs the right value on the initial load. It seems like a caching issue. Any help is greatly appreciated. function checkLive() { var live = <?=$result["live"]?>; $.ajax({ type: 'get', url: '/live/live.php', dataType: 'json', success: function(data) { console.log('checking for updates... current:' + data.live); if (data.live == live) { return; } else { var elems = $('div.player_meta, object, h3.offline_message'); if (data.live == '1') { elems.removeClass('offline').addClass('live'); } else { elems.addClass('live').addClass('offline'); } } } }); setTimeout(function() { checkLive() } ,15000); } checkLive();

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• Mutate an object into an instance of one its subclasses

  - by Gohu

  Hi, Is it possible to mutate an object into an instance of a derived class of the initial's object class? Something like: class Base(): def __init__(self): self.a = 1 def mutate(self): self = Derived() class Derived(Base): def __init__(self): self.b = 2 But that doesn't work. >>> obj = Base() >>> obj.mutate() >>> obj.a 1 >>> obj.b AttributeError... If this isn't possible, how should I do otherwise? My problem is the following: My Base class is like a "summary", and the Derived class is the "whole thing". Of course getting the "whole thing" is a bit expensive so working on summaries as long as it is possible is the point of having these two classes. But you should be able to get it if you want, and then there's no point in having the summary anymore, so every reference to the summary should now be (or contain, at least) the whole thing. I guess I would have to create a class that can hold both, right? class Thing(): def __init__(self): self.summary = Summary() self.whole = None def get_whole_thing(self): self.whole = Whole()

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• OOP beginner: classB extends classA. classA already object. method in classB needed.. etc.

  - by Yvo

  Hey guys, I'm learning myself to go from function based PHP coding to OOP. And this is the situation: ClassA holds many basic tool methods (functions). it's __construct makes a DB connection. ClassB holds specific methods based on a certain activity (extract widgets). ClassB extends ClassA because it uses some of the basic tools in there e.g. a database call. In a php file I create a $a_class = new ClassA object (thus a new DB connection). Now I need a method in ClassB. I do $b_class = new ClassB; and call a method, which uses a method from it's parent:: ClassA. In this example, i'm having ClassA 'used' twice. Onces as object, and onces via a parent:: call, so ClassA creates another DB connection (or not?). So what is the best setup for this basic classes parent, child (extend) situation? I only want to make one connection of course? I don't like to forward the object to ClassB like this $b_class = new ClassB($a_object); or is that the best way? Thanks for thinking with me, and helping :d

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