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  • Tableview not drilling down

    - by JoshD
    I have a Tableview which is loaded with a dummy list of exercises. I need to drill to a different page. My didSelectRow is being called, but not implementing the method. The app is a tab bar navigation app that loads a UITableView. #import <UIKit/UIKit.h> @interface Schedule : UIViewController <UITableViewDelegate, UITableViewDataSource> { NSArray *mySchedule; } @end #import "Schedule.h" #import "AnotherViewController.h" @implementation Schedule - (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section{ return mySchedule.count; } - (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath{ //create a cell UITableViewCell *cell = [[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:@"cell"]; //fill it with contents cell.textLabel.text = [mySchedule objectAtIndex:indexPath.row]; //return it return cell; } - (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath{ AnotherViewController *anotherViewController = [[AnotherViewController alloc] initWithNibName:@"AnotherViewController" bundle:nil]; [self.navigationController pushViewController:anotherViewController animated:YES]; [anotherViewController release]; } /* // The designated initializer. Override if you create the controller programmatically and want to perform customization that is not appropriate for viewDidLoad. - (id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil { if (self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil]) { // Custom initialization } return self; } */ // Implement viewDidLoad to do additional setup after loading the view, typically from a nib. - (void)viewDidLoad { NSString *myFile = [[NSBundle mainBundle] pathForResource:@"exercise" ofType:@"plist"]; mySchedule = [[NSArray alloc] initWithContentsOfFile:myFile]; [super viewDidLoad]; }

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  • Objective C: Function returning correct data for the first time of call and null for other times

    - by Kooshal Bhungy
    Hi all, Am a beginner in objective C, i am implementing a function that would query a web server and display the returning string in console. I am calling the function (getDatafromServer) repeatedly in a loop. The problem is that the first time am getting the value whereas the other times, it returns me a (null) in console... I've searched about memory management and check out on the forums but none have worked. Can you please guys tell me where am wrong in the codes below? Thanks in advance.... @implementation RequestThread +(void)startthread:(id)param{ while (true) { //NSLog(@"Test threads"); sleep(5); NSLog(@"%@",[self getDatafromServer]); } } +(NSString *) getDatafromServer{ NSAutoreleasePool *pool = [[NSAutoreleasePool alloc] init]; NSString *myRequestString = @"name=Hello%20&[email protected]"; NSData *myRequestData = [NSData dataWithBytes:[myRequestString UTF8String] length:[myRequestString length]]; NSMutableURLRequest *request = [[NSMutableURLRequest alloc] initWithURL: [NSURL URLWithString:@"http://192.168.1.32/gs/includes/widget/getcalls.php?user=asdasd&passw=asdasdasd"]]; [request setHTTPMethod:@"POST"]; [request setHTTPBody: myRequestData]; [request setValue:@"application/x-www-form-urlencoded" forHTTPHeaderField:@"content-type"]; NSData *returnData = [NSURLConnection sendSynchronousRequest:request returningResponse:nil error:nil]; NSString *myString = [NSString stringWithUTF8String:[returnData bytes]]; [myRequestString release]; [request release]; [returnData release]; return myString; [pool release]; } @end

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  • C As Principal Class For Mac App

    - by CodaFi
    So, I've got a c file raring to go and be the main class behind an all-C mac-app, however, a combination of limiting factors are preventing the application from being launched. As it currently stands, the project is just a main.m and a class called AppDelegate.c, so I entered "AppDelegate" as the name of the principal class in the info.plist, and to my complete surprise, the log printed: Unable to find class: AppDelegate, exiting This would work perfectly well in iOS, because the main function accepts the name of a delegate class, and handles it automatically, but NSApplicationMain() takes no such argument. Now, I know this stems from the fact that there are no @interface/@implementation directives in C, and that's really what the OS seems to be looking for, so I wrote a simple NSApplication subclass and provided it as the Principal Class to the plist, and it launched perfectly well. My question is, how could one go about setting a c file as the principal class in a mac application and have it launch correctly? PS, don't ask what or why I'm doing this for, the foundation must be dug. For @millimoose's amusement, here be the AppDelegate.c file: #include <objc/runtime.h> #include <objc/message.h> struct AppDel { Class isa; id window; }; // This is a strong reference to the class of the AppDelegate // (same as [AppDelegate class]) Class AppDelClass; BOOL AppDel_didFinishLaunching(struct AppDel *self, SEL _cmd, void *application, void *options) { self->window = objc_msgSend(objc_getClass("NSWindow"), sel_getUid("alloc")); self->window = objc_msgSend(self->window, sel_getUid("init")); objc_msgSend(self->window, sel_getUid("makeKeyAndOrderFront:"), self); return YES; }

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  • Efficient update of SQLite table with many records

    - by blackrim
    I am trying to use sqlite (sqlite3) for a project to store hundreds of thousands of records (would like sqlite so users of the program don't have to run a [my]sql server). I have to update hundreds of thousands of records sometimes to enter left right values (they are hierarchical), but have found the standard update table set left_value = 4, right_value = 5 where id = 12340; to be very slow. I have tried surrounding every thousand or so with begin; .... update... update table set left_value = 4, right_value = 5 where id = 12340; update... .... commit; but again, very slow. Odd, because when I populate it with a few hundred thousand (with inserts), it finishes in seconds. I am currently trying to test the speed in python (the slowness is at the command line and python) before I move it to the C++ implementation, but right now this is way to slow and I need to find a new solution unless I am doing something wrong. Thoughts? (would take open source alternative to SQLite that is portable as well)

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  • Firefox handles xxx.submit(), Safari doesn't ... what can be done?

    - by Prairiedogg
    I'm trying to make a pull down menu post a form when the user selects (releases the mouse) on one of the options from the menu. This code works fine in FF but Safari, for some reason, doesn't submit the form. I re-wrote the code using jquery to see if jquery's .submit() implementation handled the browser quirks better. Same result, works in FF doesn't work in safari. The following snippets are from the same page, which has some django template language mixed in. Here's the vanilla js attempt: function formSubmit(lang) { if (lang != '{{ LANGUAGE_CODE }}') { document.getElementById("setlang_form").submit(); } } Here's the jquery attempt: $(document).ready(function() { $('#lang_submit').hide() $('#setlang_form option').mouseup(function () { if ($(this).attr('value') != '{{ LANGUAGE_CODE }}') { $('#setlang_form').submit() } }); }); and here's the form: <form id="setlang_form" method="post" action="{% url django.views.i18n.set_language %}"> <fieldset> <select name="language"> {% for lang in interface_languages %} <option value="{{ lang.code }}" onmouseup="formSubmit('{{ lang.name }}')" {% ifequal lang.code LANGUAGE_CODE %}selected="selected"{% endifequal %}>{{ lang.name }}</option> {% endfor %} </select> </fieldset> </form> My question is, how can I get this working in Safari?

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  • How do you unit test new code that uses a bunch of classes that cannot be instantiated in a test har

    - by trendl
    I'm writing a messaging layer that should handle communication with a third party API. The API has a bunch of classes that cannot be easily (if at all) instantiated in a test harness. I decided to wrap each class that I need in my unit tests with an adapter/wrapper and expose the members I need through this adapter class. Often I need to expose the wrapped type as well which I do by exposing it as an object. I have also provided an interface for for each or the adapter classes to be able to use them with a mocking framework. This way I can substitute the classes in test for whatever I need. The downside is that I have a bunch of adapter classes that so far server no other reason but testing. For me this is a good reason by itself but others may find this not enough. Possibly, when I write an implementation for another third party vendor's API, I may be able to reuse much of my code and only provide the adapters specific to the vendor's API. However, this is a bit of a long shot and I'm not actually sure it will work. What do you think? Is this approach viable or am I writing unnecessary code that serves no real purpose? Let me say that I do want to write unit tests for my messaging layer and I do now know how to do it otherwise.

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  • initialise a var in scala

    - by user unknown
    I have a class where I like to initialize my var by reading a configfile, which produces intermediate objects/vals, which I would like to group and hide in a method. Here is the bare minimum of the problem - I call the ctor with a param i, in reality a File to parse, and the init-method generates the String s, in reality more complicated than here, with a lot of intermediate objects being created: class Foo (val i: Int) { var s : String; def init () { s = "" + i } init () } This will produce the error: class Foo needs to be abstract, since variable s is not defined. In this example it is easy to solve by setting the String to "": var s = "";, but in reality the object is more complex than String, without an apropriate Null-implementation. I know, I can use an Option, which works for more complicated things than String too: var s : Option [String] = None def init () { s = Some ("" + i) } or I can dispense with my methodcall. Using an Option will force me to write Some over and over again, without much benefit, since there is no need for a None else than to initialize it that way I thought I could. Is there another way to achieve my goal?

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  • Mono Develop 2.4.1 + linq error.

    - by Nev_Rahd
    I just started to learn Mono Develop Installed Mono Develop 2.4.1 and trial version of Mono Touch. my Code: using System; using System.Xml.Linq; using System.Collections.Generic; namespace RSSReader { public static class RSSRepository { public static IList<FeedItem> GetFeeds(string url) { XDocument rssFeed = XDocument.Load(url); Console.Write(rssFeed.ToString()); var feeds = new List<FeedItem>(); try { var query = from item in rssFeed.Descendants("item") select new FeedItem { Title = item.Element("title").Value, Published = DateTime.Parse(item.Element("pubDate").Value), Url = item.Element("link").Value }; feeds = query.ToList(); } catch (Exception ex){ Console.WriteLine(ex.Message); } return feeds; } } } This is throwing an error: An implementation of 'select' query expression pattern could not be found. Are you missing 'System.linq' using directive or 'System.Core.dll' assembly reference? I got both references to System.Xml.Linq and System.Core What am i missing ?

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  • c++ templates and inheritance

    - by Armen Ablak
    Hey, I'm experiencing some problems with breaking my code to reusable parts using templates and inheritance. I'd like to achieve that my tree class and avltree class use the same node class and that avltree class inherits some methods from the tree class and adds some specific ones. So I came up with the code below. Compiler throws an error in tree.h as marked below and I don't really know how to overcome this. Any help appreciated! :) node.h: #ifndef NODE_H #define NODE_H #include "tree.h" template <class T> class node { T data; ... node() ... friend class tree<T>; }; #endif tree.h #ifndef DREVO_H #define DREVO_H #include "node.h" template <class T> class tree { public: //signatures tree(); ... void insert(const T&); private: node<T> *root; //missing type specifier - int assumed. Note: C++ does not support default-int }; //implementations #endif avl.h #ifndef AVL_H #define AVL_H #include "tree.h" #include "node.h" template <class T> class avl: public tree<T> { public: //specific int findMin() const; ... protected: void rotateLeft(node<T> *)const; private: node<T> *root; }; #endif avl.cpp (I tried separating headers from implementation, it worked before I started to combine avl code with tree code) #include "drevo" #include "avl.h" #include "vozlisce.h" template class avl<int>; //I know that only avl with int can be used like this, but currently this is doesn't matter :) //implementations ...

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  • How to convert X/Y position to Canvas Left/Top properties when using ItemsControl

    - by kshahar
    I am trying to use a Canvas to display objects that have "world" location (rather than "screen" location). The canvas is defined like this: <Canvas Background="AliceBlue"> <ItemsControl Name="myItemsControl" ItemsSource="{Binding MyItems}"> <ItemsControl.ItemTemplate> <DataTemplate> <Canvas> <TextBlock Canvas.Left="{Binding WorldX}" Canvas.Top="{Binding WorldY}" Text="{Binding Text}" Width="Auto" Height="Auto" Foreground="Red" /> </Canvas> </DataTemplate> </ItemsControl.ItemTemplate> </ItemsControl> </Canvas> MyItem is defined like this: public class MyItem { public MyItem(double worldX, double worldY, string text) { WorldX = worldX; WorldY = worldY; Text = text; } public double WorldX { get; set; } public double WorldY { get; set; } public string Text { get; set; } } In addition, I have a method to convert between world and screen coordinates: Point worldToScreen(double worldX, double worldY) { // return screen coordinates using the canvas properties and an internal MapData object } With the current implementation, the items are positioned in the wrong location, because their location is not converted to screen coordinates. How can I apply the worldToScreen method on the MyItem objects before they are added to the canvas?

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  • Exceptions over remote methods

    - by Andrei Vajna II
    What are the best practices for exceptions over remote methods? I'm sure that you need to handle all exceptions at the level of a remote method implementation, because you need to log it on the server side. But what should you do afterwards? Should you wrap the exception in a RemoteException (java) and throw it to the client? This would mean that the client would have to import all exceptions that could be thrown. Would it be better to throw a new custom exception with fewer details? Because the client won't need to know all the details of what went wrong. What should you log on the client? I've even heard of using return codes(for efficiency maybe?) to tell the caller about what happened. The important thing to keep in mind, is that the client must be informed of what went wrong. A generic answer of "Something failed" or no notification at all is unacceptable. And what about runtime (unchecked) exceptions?

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  • javascript var assignment conversion to target type

    - by pbhd
    searching for a function, which converts rhs to the type of lhs. e.g. var x=false // x is boolean now; x=assign (x, "true"); //should convert "true" to boolean and return that x=assign (x, 1); // dto, convert 1 to true x=0 // x is number x=assign (x, "123"); // should convert "123" to 123; so such a function can be written, thats not the question. But: Is there somewhere a somehow complete implementation of such a thing? I started with something like that: function assign (v, x) { if (typeof v==typeof x) { return x; } switch (typeof v) { case 'boolean' : { return x=='true'?true:false; } case 'number' : { return parseFloat(x); } } return "xxx"; } var v=true; var x='true'; var r1=assign (v, x); console.log (typeof r1+ " "+r1); v=10; x="123"; var r1=assign (v, x); console.log (typeof r1+ " "+r1); which of course is not complete, but maybe shows what I'm goig for.

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  • Multiple plugin instance loading with MEF

    - by Dave
    In my last application, using MEF to load plugins went just fine, but now I'm running into a new issue. I have a solution for it that I explain at the end of this question, but I'm looking for other ways to do it. Let's say I have an interface called ApplianceInterface. I also have two plugins that inherit from ApplianceInterface, let's call them Blender and Processor. Now, I would like to have multiple Blenders and Processors in my application, but I am not sure how to instantiate them properly. Before, I would simply use the ImportMany attribute and upon calling ComposeParts, my application would load Blender and Processor. For example: [ImportMany(typeof(ApplianceInterface))] private IEnumerable<ApplianceInterface> Appliances { get; set; } and my Blender and Processor plugins would be attributed like this: [PartCreationPolicy(CreationPolicy.NonShared)] [Export(typeof(MyInterface)] public class Blender : ApplianceInterface { ... } but what this ends up doing for me is populating Appliances with one Blender and one Processor. I need to be able to create an arbitrary number of Blender and Processor objects. Now, from the documentation I understand that [PartCreationPolicy(CreationPolicy.NonShared)] is what allows MEF to create a new instance each time, but is there a similar "magical" way to create a specific number of instances of something using MEF? Up until now, I've relied on [Import] and [ImportMany] to resolve the assemblies. Is my only option to use a global container, and then resolve the export manually using GetExportedValue<? I have tried GetExportedValue< and that implementation does work fine for me, but I was just curious if there is a better, more accepted way to do it.

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  • A generic C++ library that provides QtConcurrent functionality?

    - by Lucas
    QtConcurrent is awesome. I'll let the Qt docs speak for themselves: QtConcurrent includes functional programming style APIs for parallel list processing, including a MapReduce and FilterReduce implementation for shared-memory (non-distributed) systems, and classes for managing asynchronous computations in GUI applications. For instance, you give QtConcurrent::map() an iterable sequence and a function that accepts items of the type stored in the sequence, and that function is applied to all the items in the collection. This is done in a multi-threaded manner, with a thread pool equal to the number of logical CPU's on the system. There are plenty of other function in QtConcurrent, like filter(), filteredReduced() etc. The standard CompSci map/reduce functions and the like. I'm totally in love with this, but I'm starting work on an OSS project that will not be using the Qt framework. It's a library, and I don't want to force others to depend on such a large framework like Qt. I'm trying to keep external dependencies to a minimum (it's the decent thing to do). I'm looking for a generic C++ framework that provides me with the same/similar high-level primitives that QtConcurrent does. AFAIK boost has nothing like this (I may be wrong though). boost::thread is very low-level compared to what I'm looking for. I know C# has something very similar with their Parallel Extensions so I know this isn't a Qt-only idea. What do you suggest I use?

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  • EF 4.0 Guid or Int as A primary Key

    - by bigb
    I am Implementing custom ASPNetMembership using EF 4.0 Is there any reason why i should use Guid as a primary key in User tables? As far as i know Int as a PK on SQL Server more performanced than strings. And Int is easier to iterate. Also, for security purpose if i need to pass this it id somewhere in url i may encrypt it somehow and pass it like a strings with no probs. But if i want to use auto generated Guid on SQL Server side using EF 4.0 i need to do this trick http://leedumond.com/blog/using-a-guid-as-an-entitykey-in-entity-framework-4/ I can't see any cases why i should use Guid as PK, may be only one if system going to have millions ans millions users, but also, theoretically, Guid could be duplicated sometime isn't so? Anyway Int32 size is 2,147.483.647 it is pretty much even for very-very big system, but if this number is still not enough I may go with Int64, in that cases I may have 9,223.372.036.854.775.807 rows. Pretty much huh? From another hand, M$ using Guids as PK in their ASPNetMembership implementation. [aspnetdb].[aspnet_Users] - PK UserId Type uniqueidentifier, should be some reasons/explanation why the did it?! May be some one has any ideas/experience about that?

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  • Silverlight: Button template with texttrimming cut off

    - by dex3703
    I'm replacing the default Button template's ContentPresenter with a TextBlock, so the text can be trimmed when it's too long. Works fine in WPF. In Silverlight the text gets pushed to one edge and cut off on the left, even when there's space on the right: Template is nothing special, just replaced the ContentPresenter with the TextBlock: <Border x:Name="bdrBackground" BorderBrush="{TemplateBinding BorderBrush}" BorderThickness="{TemplateBinding BorderThickness}" Background="{TemplateBinding Background}" /> <Rectangle x:Name="rectMouseOverVisualElement" Opacity="0"> <Rectangle.Fill> <SolidColorBrush x:Name="rectMouseOverColor" Color="{StaticResource MouseOverItemBgColor}"/> </Rectangle.Fill> </Rectangle> <Rectangle x:Name="rectPressedVisualElement" Opacity="0" Style="{TemplateBinding Tag}"/> <TextBlock x:Name="textblock" Text="{TemplateBinding Content}" TextTrimming="WordEllipsis" TextWrapping="NoWrap" HorizontalAlignment="{TemplateBinding HorizontalContentAlignment}" Margin="{TemplateBinding Padding}" VerticalAlignment="{TemplateBinding VerticalContentAlignment}"/> <Rectangle x:Name="rectDisabledVisualElement" Opacity="0" Style="{StaticResource RectangleDisabledStyle}"/> <Rectangle x:Name="rectFocusVisualElement" Opacity="0" Style="{StaticResource RectangleFocusStyle}"/> </Grid> </ControlTemplate> How do I fix this? More info: With the latest comment about HorizontalAlignment, it's clear that SL's implementation of TextTrimming differs from WPF's. In SL, TextTrimming only really works if the text is aligned left. SL isn't smart enough to align the text the way WPF does. For instance: WPF button: SL button with the textblock horizontalalignment = left: SL button with textblock horizontalalignment = center:

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  • Want to mimic iphone address book search (In terms of interface & interaction)

    - by mr-sk
    Hi, When you do a search in the address book the flow is: 1) Select the search bar 2) The right most transparent a-z index is removed 3) A transparent black window is placed over the current UITableView 4) When you begin typing, a new UITableView is loaded with no data 5) The UITableView is populated with data as you type. 6) If you select an item you are brought to it 7) If you cancel the search you return to the main UITalbeView My first real question is, how do I load a new UITableView when a user begins searching? Is it as easy as popping a new view on the stack? It would then be a seperate .m/.h file with its own implementation? The second question is how do you remove the right most index? Or just that just go away when you render the new (blank) UITableView? I've gotten search working, but mine does it in the same UITableView, which when you start contains like 2K results, is grouped (A results under A Heading, etc) and has a right most index. I'd be happy leaving the results in the table, if I could; 1) Remove the rightmost a-z index 2) Drop the table groupings 3) Tell the view I only have N search results so it will build the scroll bar correctly. Thanks for your input; sk

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  • Datastructure choices for highspeed and memory efficient detection of duplicate of strings

    - by Jonathan Holland
    I have a interesting problem that could be solved in a number of ways: I have a function that takes in a string. If this function has never seen this string before, it needs to perform some processing. If the function has seen the string before, it needs to skip processing. After a specified amount of time, the function should accept duplicate strings. This function may be called thousands of time per second, and the string data may be very large. This is a highly abstracted explanation of the real application, just trying to get down to the core concept for the purpose of the question. The function will need to store state in order to detect duplicates. It also will need to store an associated timestamp in order to expire duplicates. It does NOT need to store the strings, a unique hash of the string would be fine, providing there is no false positives due to collisions (Use a perfect hash?), and the hash function was performant enough. The naive implementation would be simply (in C#): Dictionary<String,DateTime> though in the interest of lowering memory footprint and potentially increasing performance I'm evaluating a custom data structures to handle this instead of a basic hashtable. So, given these constraints, what would you use? EDIT, some additional information that might change proposed implementations: 99% of the strings will not be duplicates. Almost all of the duplicates will arrive back to back, or nearly sequentially. In the real world, the function will be called from multiple worker threads, so state management will need to be synchronized.

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  • paypal_adaptive gem in Rails: Dynamic Receiver "Population" (Chained Payments)

    - by Jmlevick
    Note: I didn't find a better title for this O.o Hello, Humm... Look, what I want to do is to have a Rails app where a visitor can click a button/link to make a "special" chained payment using Paypal; Currently I have a Users registration form that has one field for the user to enter his/her paypal account email, and as I saw here: http://marker.to/XGg9MR it is possible to specify the primary reciever and the secondary ones by adding such info in a controller action when using the paypal_adaptive gem in a rails app. The thing is, I don't want to hard code the secondary reciever as I need to specify a different secondary reciever from time to time, (being specific my primary reciever will always be the same, but depending on what button/link the visitor clicks, the secondary one is going to change) and I want that secondary reciever email to be the paypal e-mail account from one of the registered users when the visitor clicks on their specific button/link... My question is: Is it possible to create such enviroment functionality in my app using the current implementation of the paypal_adaptive gem? Could someone point me in the right direction on how to accomplish such thing? I'm still learning rails and also I'm really new in the paypal handling universe with this framework! XD P.S. Thanks! :)

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  • Limiting object allocation over multiple threads

    - by John
    I have an application which retrieves and caches the results of a clients query. The client then requests different chunks of data and the application sends the relevant results and removes them from the cache. A new requirement for this application is that there needs to be a run-time configurable maximum number of results which may be cached. I've taken the naive approach and implemented this by using a counter under a lock which is incremented every time a result is cached and decremented whenever a result is removed from the cache. Unfortunately, this has drastically reduced the applications performance when processing a large number of concurrent requests. I have tried both a critical section lock and spin-lock; the performance improves a bit with a spin-lock, but is still unacceptably slow. Is there a better way to solve this problem which may improve performance? Right now I have a thread pool that services requests and each request is tied to a Request object which stores that cached results for that particular request. Here is a simplified pseudo code version of my current implementation: void ResultCallback( Result result, Request *request ) { lock totalResultsCached lock cachedLimit if( totalResultsCached + 1 > cachedLimit ) { unlock cachedLimit unlock totalResultsCached //cancel the request return; } ++totalResultsCached; unlock cachedLimit unlock totalResultsCached request.add(result) } void SendResults( int resultsToSend, Request *request ) { while ( resultsToSend > 0 ) { send(request.remove()) lock totalResultsCached --totalResultsCached unlock totalResultsCached --resultsToSend; } }

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  • GADTs and Scrap your Boilerplate

    - by finnsson
    I'm writing a XML (de)serializer using Text.XML.Light and Scrap your Boilerplate (at http://github.com/finnsson/Text.XML.Generic) and so far I got working code for "normal" ADTs but I'm stuck at deserializing GADTs. I got the GADT data DataBox where DataBox :: (Show d, Eq d, Data d) => d -> DataBox and I'm trying to get this to compile instance Data DataBox where gfoldl k z (DataBox d) = z DataBox `k` d gunfold k z c = k (z DataBox) -- not OK toConstr (DataBox d) = toConstr d dataTypeOf (DataBox d) = dataTypeOf d but I can't figure out how to implement gunfold for DataBox. The error message is Text/XML/Generic.hs:274:23: Ambiguous type variable `b' in the constraints: `Eq b' arising from a use of `DataBox' at Text/XML/Generic.hs:274:23-29 `Show b' arising from a use of `DataBox' at Text/XML/Generic.hs:274:23-29 `Data b' arising from a use of `k' at Text/XML/Generic.hs:274:18-30 Probable fix: add a type signature that fixes these type variable(s) It's complaining about not being able to figure out the data type of b. I'm also trying to implement dataCast1 and dataCast2 but I think I can live without them (i.e. an incorrect implementation). I guess my questions are: Is it possible to combine GADTs with Scrap your Boilerplate? If so: how do you implement gunfold for a GADT?

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  • C++ Beginner - Trouble using structs and constants!

    - by Francisco P.
    Hello everyone! I am currently working on a simple Scrabble implementation for a college project. I can't get a part of it to work, though! Check this out: My board.h: http://pastebin.com/J9t8VvvB The subroutine where the error lies: //Following snippet contained in board.cpp //I believe the function is self-explanatory... //Pos is a struct containing a char, y, a int, x and an orientation, o, which is not //used in this particular case void Board::showBoard() { Pos temp; temp.o = 0; for (temp.y = 'A'; temp.y < (65 + TOTAL_COLUMNS); ++temp.y) { for (temp.x = 1; temp-x < (1 + TOTAL_ROWS); ++temp.x) { cout << _matrix[temp].getContents(); } cout << endl; } } The errors returned on compile time: http://pastebin.com/bZv7fggq How come the error states that I am trying to compare two Pos when I am comparing chars and ints? I also really can't place these other errors... Thanks for your time!

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  • Singleton issue causing a buffer overrun

    - by Rudiger
    Hi everyone, Ive created a singleton to store 2 arrays: @interface Globals : NSObject { NSMutableArray *items; NSMutableArray *extras; } + (Globals *)sharedInstance; @property (nonatomic, assign) NSMutableArray *items; @property (nonatomic, assign) NSMutableArray *extras; @end @implementation Globals @synthesize items, extras; + (Globals *)sharedInstance { static Globals *myInstance = nil; @synchronized(self) { if(!myInstance) { myInstance = [[Globals alloc] init]; } } return myInstance; } -(void)dealloc { [items release]; [extras release]; [super dealloc]; } @end When I set the Arrays in the singleton from the App delegate and then output them to NSLog it displays what is expected. But when I call it from a view controller further into the App it displays the first entry fine, some of the second entry and then garbage which is i assume a buffer overrun, sometimes it also crashes. I set the singleton array in the appDelegate like so: Globals *sharedInstance = [Globals sharedInstance]; [sharedInstance setItems:items]; and retrieve it: [[[sharedInstance items] objectAtIndex:indexPath.row] objectForKey:@"name"]; cell.description.text = [[[sharedInstance items] objectAtIndex:indexPath.row] objectForKey:@"description"]; Name works fine in both cells if there is 2, description works in the first case, never in the second case. Is it because the arrays in my singleton aren't static? If so why is it outputting the first entry fine? Cheers for any help.

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  • problems getting HTTPRiot working

    - by bwizzy
    I've got an iphone app where I'm trying to use HTTPRiot to make some API calls to a web app. Problem is I can't see that none of the HTTPRiot delegate methods are being called. I've got a log in all the delegate methods, and I'm also looking at the webserver log. I see that the URL is being hit. //API.h #import <Foundation/Foundation.h> #include <HTTPRiot/HTTPRiot.h> @interface API : HRRestModel { } +(void)runTest; @end //API.m #import "API.h" @implementation API + (void)initialize { NSLog(@"api initialize"); [self setDelegate:self]; [self setBaseURL:[NSURL URLWithString:@"http://localhost:3000/api"]]; [self setBasicAuthWithUsername:@"demo" password:@"123456"]; NSDictionary *params = [NSDictionary dictionaryWithObject:@"1234567" forKey:@"api_key"]; [self setDefaultParams:params]; }//end initialize +(void)runTest { NSLog(@"api run test"); // Would send a request to http://localhost:1234/api/people/1?api_key=1234567 [self getPath:@"/save_diet" withOptions:nil object:nil]; } +(void)restConnection:(NSURLConnection *)connection didReturnResource:(id)resource object:(id)object { NSLog(@"didReturnResource"); } +(void)restConnection:(NSURLConnection *)connection didReceiveResponse:(NSHTTPURLResponse *)response object:(id)object { NSLog(@"didReceiveResponse"); } +(void)restConnection:(NSURLConnection *)connection didReceiveParseError:(NSError *)error responseBody:(NSString *)body object:(id)object { NSLog(@"didReceiveParseError"); } +(void)restConnection:(NSURLConnection *)connection didReceiveError:(NSError *)error response:(NSHTTPURLResponse *)response object:(id)object { NSLog(@"didReceiveError"); } +(void)restConnection:(NSURLConnection *)connection didFailWithError:(NSError *)error object:(id)object { NSLog(@"didFailWithError"); } @end //test code [API runTest]; //log output

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  • Java Detect Variable Change Using PropertyChangeSupport and PropertyChangeListener

    - by Sam
    I'm trying to print out debug statements when some third party code changes a variable. For example, consider the following: public final class MysteryClass { private int secretCounter; public synchronized int getCounter() { return secretCounter; } public synchronized void incrementCounter() { secretCounter++; } } public class MyClass { public static void main(String[] args) { MysteryClass mysteryClass = new MysteryClass(); // add code here to detect calls to incrementCounter and print a debug message } I don't have the ability to change the 3rd party MysteryClass, so I thought that I could use PropertyChangeSupport and PropertyChangeListener to detect changes to the secretCounter: public class MyClass implements PropertyChangeListener { private PropertyChangeSupport propertySupport = new PropertyChangeSupport(this); public MyClass() { propertySupport.addPropertyChangeListener(this); } public void propertyChange(PropertyChangeEvent evt) { System.out.println("property changing: " + evt.getPropertyName()); } public static void main(String[] args) { MysteryClass mysteryClass = new MysteryClass(); // do logic which involves increment and getting the value of MysteryClass } } Unfortunately, this did not work and I have no debug messages printed out. Does anyone see what is wrong with my implementation of the PropertyChangeSupport and Listener interfaces? I want to print a debug statement whenever incrementCounter is called or the value of secretCounter changes.

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