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  • A nuts and bolts reference to C# performance and memory use

    - by phil
    I wonder if anyone could point me in the direction where I can read about the nuts and bolts of C#. What I'm interested in learning are method call costs, what it costs to create objects and such. My aim of learning this is to get a better understanding of how increase the performance of an application and get a better understanding of how the C# language works. The reference should preferable be a book, a book that I can read cover to cover.

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  • Are PHP5 objects passed by reference?

    - by morpheous
    I cant seem to get any consistent info on this. Different sources appear to say different things and trhe venerable php.net iteslf (appears) not to explicitly state this - although I must admit, I only had a quick look. In cases where I am passing around 'heavy' objects, I need to pass by reference, but I dont want to keep typing: function foo(TypeName& $obj) if I can get away with simply, function foo(TypeName $obj) So what does the standard say?

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  • by reference in C++

    - by lego69
    I have this snippet of the code Stack& Stack:: operator=(const Stack& stack){ if(this == &stack){ return *this } } here I define operator = but I can't understand, if I receive by reference stack why it should be & in this == &stack and not this == stack and why we return * in return *this and not this thanks in advance for any help

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  • PHP Pass by reference

    - by Salil
    I am calling this function which is modifying an array by reference: function addWord(&$words, $wordIndex, $word) { $words[$wordIndex] = $word; } At the function call, addWord(&$words, $wordsIndex, $word); ($words is used only during the function call) doesn't work. How do I make this or a similar functionality work? I want the addWord to be a separate function.

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  • Multiple reference in SQL

    - by AGarofoli
    Hi! I'm working on a db but i'm kinda new to this so i've bumped into a problem today. I've got some tables: OFFICE, ROOM, EMPLOYEE and DOCUMENT. Document must specify the sender, which can be a single employee, an entire room or an entire office so it must have a reference to the primary keys of those tables. Should I do a "parallel" table for handle it (for example i've done one for handle the multiple recipients documents) or there is another way? Thank you

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  • Getting a null reference exception exporting a slightly complex rdlc report to excel

    - by George Handlin
    Have an issue in exporting a slightly complex report to excel from an rdlc. Exporting a simple tabular report works fine, but getting a null reference exception with a more complex one. As is usually the case, it works on the server in the development environment, but not in the test environment. The server in the development environment has iis, sql and sql reporting services on it and test only has iis (I didn't set them up). I'm guessing there is something that gets installed with SSRS that is not installed with just the report viewer. The report has several parameters going into it and a few generic lists going in for datasources. Some tables for display as well as a list. Working with the 2005 version. Exception follows: [NullReferenceException: Object reference not set to an instance of an object.] Microsoft.ReportingServices.Rendering.ExcelRenderer.ExcelRenderer.RenderPageLayout(PageLayout pageLayout, Int32& currentPageNumber, Stack& stack) +91 Microsoft.ReportingServices.Rendering.ExcelRenderer.ExcelRenderer.RenderPageCollection(PageCollection pageCollection, Int32& currentPageNumber, Stack& stack, PageLayout& lastPageLayout) +607 Microsoft.ReportingServices.Rendering.ExcelRenderer.ExcelRenderer.GenerateWorkSheets() +150 Microsoft.ReportingServices.Rendering.ExcelRenderer.ExcelRenderer.GenerateMainSheet() +358 Microsoft.ReportingServices.Rendering.ExcelRenderer.ExcelRenderer.RenderExcelWorkBook(CreateAndRegisterStream createAndRegisterStream) +158 Microsoft.ReportingServices.Rendering.ExcelRenderer.ExcelRenderer.ProcessReport(CreateAndRegisterStream createAndRegisterStream) +385 Microsoft.ReportingServices.Rendering.ExcelRenderer.ExcelRenderer.Render(Report report, NameValueCollection reportServerParameters, NameValueCollection deviceInfo, NameValueCollection clientCapabilities, EvaluateHeaderFooterExpressions evaluateHeaderFooterExpressions, CreateAndRegisterStream createAndRegisterStream) +230 [ReportRenderingException: An error occurred during rendering of the report.] Microsoft.ReportingServices.Rendering.ExcelRenderer.ExcelRenderer.Render(Report report, NameValueCollection reportServerParameters, NameValueCollection deviceInfo, NameValueCollection clientCapabilities, EvaluateHeaderFooterExpressions evaluateHeaderFooterExpressions, CreateAndRegisterStream createAndRegisterStream) +296 Microsoft.ReportingServices.ReportProcessing.ReportProcessing.RenderSnapshot(IRenderingExtension renderer, CreateReportChunk createChunkCallback, RenderingContext rc, GetResource getResourceCallback) +1124 [WrapperReportRenderingException: An error occurred during rendering of the report.] Microsoft.ReportingServices.ReportProcessing.ReportProcessing.RenderSnapshot(IRenderingExtension renderer, CreateReportChunk createChunkCallback, RenderingContext rc, GetResource getResourceCallback) +1681 Microsoft.Reporting.LocalService.RenderWithDataCache(PreviewItemContext itemContext, ParameterInfoCollection reportParameters, IEnumerable dataSources, DatasourceCredentialsCollection credentials, IRenderingExtension renderer, ReportProcessing repProc, CreateAndRegisterStream createStreamCallback, ReportRuntimeSetup runtimeSetup) +1693 Microsoft.Reporting.LocalService.Render(PreviewItemContext itemContext, Boolean allowInternalRenderers, ParameterInfoCollection reportParameters, IEnumerable dataSources, DatasourceCredentialsCollection credentials, CreateAndRegisterStream createStreamCallback, ReportRuntimeSetup runtimeSetup, ProcessingMessageList& warnings) +227 Microsoft.Reporting.WebForms.LocalReport.InternalRender(String format, Boolean allowInternalRenderers, String deviceInfo, CreateAndRegisterStream createStreamCallback, Warning[]& warnings) +235 [LocalProcessingException: An error occurred during local report processing.] Microsoft.Reporting.WebForms.LocalReport.InternalRender(String format, Boolean allowInternalRenderers, String deviceInfo, CreateAndRegisterStream createStreamCallback, Warning[]& warnings) +276 Microsoft.Reporting.WebForms.LocalReport.InternalRender(String format, Boolean allowInternalRenderers, String deviceInfo, String& mimeType, String& encoding, String& fileNameExtension, String[]& streams, Warning[]& warnings) +189 Microsoft.Reporting.WebForms.LocalReport.Render(String format, String deviceInfo, String& mimeType, String& encoding, String& fileNameExtension, String[]& streams, Warning[]& warnings) +28 Microsoft.Reporting.WebForms.LocalReportControlSource.RenderReport(String format, String deviceInfo, NameValueCollection additionalParams, String& mimeType, String& fileNameExtension) +52 Microsoft.Reporting.WebForms.ExportOperation.PerformOperation(NameValueCollection urlQuery, HttpResponse response) +153 Microsoft.Reporting.WebForms.HttpHandler.ProcessRequest(HttpContext context) +202 System.Web.CallHandlerExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute() +303 System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously) +64

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  • Can't obtain reference to EKReminder array retrieved from fetchRemindersMatchingPredicate

    - by Scionwest
    When I create an NSPredicate via EKEventStore predicateForRemindersInCalendars; and pass it to EKEventStore fetchRemindersMatchingPredicate:completion:^ I can loop through the reminders array provided by the completion code block, but when I try to store a reference to the reminders array, or create a copy of the array into a local variable or instance variable, both array's remain empty. The reminders array is never copied to them. This is the method I am using, in the method, I create a predicate, pass it to the event store and then loop through all of the reminders logging their title via NSLog. I can see the reminder titles during runtime thanks to NSLog, but the local arrayOfReminders object is empty. I also try to add each reminder into an instance variable of NSMutableArray, but once I leave the completion code block, the instance variable remains empty. Am I missing something here? Can someone please tell me why I can't grab a reference to all of the reminders for use through-out the app? I am not having any issues at all accessing and storing EKEvents, but for some reason I can't do it with EKReminders. - (void)findAllReminders { NSPredicate *predicate = [self.eventStore predicateForRemindersInCalendars:nil]; __block NSArray *arrayOfReminders = [[NSArray alloc] init]; [self.eventStore fetchRemindersMatchingPredicate:predicate completion:^(NSArray *reminders) { arrayOfReminders = [reminders copy]; //Does not work. for (EKReminder *reminder in reminders) { [self.remindersForTheDay addObject:reminder]; NSLog(@"%@", reminder.title); } }]; //Always = 0; if ([self.remindersForTheDay count]) { NSLog(@"Instance Variable has reminders!"); } //Always = 0; if ([arrayOfReminders count]) { NSLog(@"Local Variable has reminders!"); } } The eventStore getter is where I perform my instantiation and get access to the event store. - (EKEventStore *)eventStore { if (!_eventStore) { _eventStore = [[EKEventStore alloc] init]; //respondsToSelector indicates iOS 6 support. if ([_eventStore respondsToSelector:@selector(requestAccessToEntityType:completion:)]) { //Request access to user calendar [_eventStore requestAccessToEntityType:EKEntityTypeEvent completion:^(BOOL granted, NSError *error) { if (granted) { NSLog(@"iOS 6+ Access to EventStore calendar granted."); } else { NSLog(@"Access to EventStore calendar denied."); } }]; //Request access to user Reminders [_eventStore requestAccessToEntityType:EKEntityTypeReminder completion:^(BOOL granted, NSError *error) { if (granted) { NSLog(@"iOS 6+ Access to EventStore Reminders granted."); } else { NSLog(@"Access to EventStore Reminders denied."); } }]; } else { //iOS 5.x and lower support if Selector is not supported NSLog(@"iOS 5.x < Access to EventStore calendar granted."); } for (EKCalendar *cal in self.calendars) { NSLog(@"Calendar found: %@", cal.title); } [_eventStore reset]; } return _eventStore; } Lastly, just to show that I am initializing my remindersForTheDay instance variable using lazy instantiation. - (NSMutableArray *)remindersForTheDay { if (!_remindersForTheDay) _remindersForTheDay = [[NSMutableArray alloc] init]; return _remindersForTheDay; } I've read through the Apple documentation and it doesn't provide any explanation that I can find to answer this. I read through the Blocks Programming docs and it states that you can access local and instance variables without issues from within a block, but for some reason, the above code does not work. Any help would be greatly appreciated, I've scoured Google for answers but have yet to get this figured out. Thanks everyone! Johnathon.

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  • VSDBCMD returns "An unexpected failure occurred: Object reference not set to an instance of an objec

    - by Matt Wrock
    I have been succesfully using the command line database deployment tool VSDBCMD on my dev and test environments but the tool fails in our integration environmrnt. I am using the VS 2010 version of the tool. The servers have all of the prerequisites including: .net 4.0 sql server compact edition 3.5 sp1 (as well as the full edition of 2008) sql server 2008 server management objects sql server 2008 native client sql server system clr types msxml 6 all of the dependent DLLs included in: C:\Program Files\Microsoft SQL Server Compact Edition\v3.5\desktop*.dll C:\Program Files\Microsoft SQL Server Compact Edition\v3.5*.dll C:\Program Files (x86)\Microsoft Visual Studio 10.0\VSTSDB\Deploy**. The only reference to this error that I have been able to find has to do with a bug in the VS 2008 edition when the HKEY_CURRENT_USER\Software\Microsoft\VisualStudio\9.0 key is missing. In my case the 10.0 version of the key exists. Has anyone else encountered this?

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  • Objective C ASIHTTPRequest nested GCD block in complete block

    - by T.Leavy
    I was wondering if this is the correct way to have nested blocks working on the same variable in Objective C without causing any memory problems or crashes with ARC. It starts with a ASIHttpRequest complete block. MyObject *object = [dataSet objectAtIndex:i]; ASIHTTPRequest *request = [[ASIHTTPRequest alloc]initWithURL:@"FOO"]; __block MyObject *mutableObject = object; [request setCompleteBlock:^{ mutableObject.data = request.responseData; __block MyObject *gcdMutableObject = mutableObject; dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT,0),^{ [gcdMutableObject doLongComputation]; dispatch_async(dispatch_get_main_queue(),^{ [self updateGUIWithObject:gcdMutableObject]; }); }); [request startAsynchronous]; My main concern is nesting the dispatch queues and using the __block version of the previous queue to access data. Is what I am doing safe?

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  • WPF parent-child window: binding reference problem

    - by LukePet
    I have a WPF Window that open a modal child window to load some data. Both window have a own viewmodel, now I have this problem: after I close the child window it seems still running in background! To close the child window I set DialogResult from viewmodel command; now, if I create a new data and then I edit it from parent window (with the child window closed before), the child window still capture the property changed event for the properties previously bind. How can avoid this? I would clear every reference with data when I close modal window. Which is the best practise to do it?

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  • C# - Pass by value & Pass by Reference

    - by Lijo
    Hi Team, Could you please explain the following behavior of C# Class. I expect the classResult as "Class Lijo"; but actual value is “Changed”. We’re making a copy of the reference. Though the copy is pointing to the same address, the method receiving the argument cannot change original. Still why the value gets changed ? public partial class _Default : System.Web.UI.Page { protected void Page_Load(object sender, EventArgs e) { Person p = new Person(); p.Name = "Class Lijo"; Utilityclass.TestMethod(p); string classResult = p.Name; Response.Write(classResult); } } public class Utilityclass { public static void TestMethod(Person k) { k.Name = "Changed"; } } public class Person { private string name; public string Name { get { return name; } set { name = value; } } } Thanks Lijo

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  • EXC_BAD_ACCESS error on a UITableView with ARC?

    - by Arnaud Drizard
    I am building a simple app with a custom bar tab which loads the content of the ViewController from a UITableView located in another ViewController. However, every time I try to scroll on the tableview, I get an exc_bad_access error. I enabled NSzombies and guard malloc to get more info on the issue. In the console I get: "message sent to deallocated instance 0x19182f20" and after profiling I get: # Address Category Event Type RefCt Timestamp Size Responsible Library Responsible Caller 56 0x19182f20 FirstTabBarViewController Zombie -1 00:16.613.309 0 UIKit -[UIScrollView(UIScrollViewInternal) _scrollViewWillBeginDragging] Here is a bit of the code of the ViewController in which the error occurs: .h file: #import <UIKit/UIKit.h> #import "DataController.h" @interface FirstTabBarViewController : UIViewController <UITableViewDelegate, UITableViewDataSource> { IBOutlet UITableView* tabBarTable; } @property (strong, nonatomic) IBOutlet UIView *mainView; @property (strong, nonatomic) IBOutlet UITableView *tabBarTable; @property (nonatomic, strong) DataController *messageDataController; @end .m file: #import "FirstTabBarViewController.h" #import "DataController.h" @interface FirstTabBarViewController () @end @implementation FirstTabBarViewController @synthesize tabBarTable=_tabBarTable; - (id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil { self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil]; if (self) { // Custom initialization } return self; } - (void)viewDidLoad { [super viewDidLoad]; } - (void)didReceiveMemoryWarning { [super didReceiveMemoryWarning]; // Dispose of any resources that can be recreated. } - (void)awakeFromNib { [super awakeFromNib]; self.messageDataController=[[DataController alloc] init]; } - (NSInteger)numberOfSectionsInTableView:(UITableView *)tableView { return 1; } - (NSInteger) tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section{ return [self.messageDataController countOfList]; } - (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath { static NSString *CellIdentifier = @"mainCell"; UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier]; if (cell == nil){ cell = [[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:CellIdentifier]; }; NSString *expenseAtIndex = [self.messageDataController objectInListAtIndex:indexPath.row]; [[cell textLabel] setText:expenseAtIndex]; return cell; } - (BOOL)tableView:(UITableView *)tableView canEditRowAtIndexPath:(NSIndexPath *)indexPath { // Return NO if you do not want the specified item to be editable. return NO; } @end This FirstTabBarViewController is loaded in the MainViewController with the following custom segue: #import "customTabBarSegue.h" #import "MainViewController.h" @implementation customTabBarSegue -(void) perform { MainViewController *src= (MainViewController *) [self sourceViewController]; UIViewController *dst=(UIViewController *)[self destinationViewController]; for (UIView *view in src.placeholderView.subviews){ [view removeFromSuperview]; } src.currentViewController =dst; [src.placeholderView addSubview:dst.view]; } @end The Datacontroller class is just a simple NSMutableArray containing strings. I am using ARC so I don't understand where the memory management error comes from. Does anybody have a clue? Any help much appreciated ;) Thanks!!

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  • Visual Studio reference x64 GAC

    - by icelava
    How can one get Visual Studio 2005/2008 to reference assemblies in the 64-bit GAC instead of the 32-bit GAC? We are settin the target platfom to x64 and the compiler is throwing the error of Error 2 Warning as Error: Assembly generation -- Referenced assembly 'System.Data.dll' targets a different processor Common Error 3 Warning as Error: Assembly generation -- Referenced assembly 'mscorlib.dll' targets a different processor Common Error 4 Assembly signing failed; output may not be signed -- The system cannot find the file specified. Common Update 29 Dec 08 Been trying out Aaron Stebner's suggestions to place 64-bit assemblies onto an isolated location (e.g. C:\Windows\Microsoft.NET\Framework64\v2.0.50727\GAC_64) and creating additional entries in the registry like HKLM\SOFTWARE\Microsoft.NETFramework\AssemblyFolders\GAC_64 or HKLM\SOFTWARE\Microsoft.NETFramework\v2.0.50727\AssemblyFoldersEx\GAC_64 but Visual Studio 2005 is still not picking it up....

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  • Are there gotchas using varargs with reference parameters

    - by Roddy
    I have this piece of code (summarized)... AnsiString working(AnsiString format,...) { va_list argptr; AnsiString buff; va_start(argptr, format); buff.vprintf(format.c_str(), argptr); va_end(argptr); return buff; } And, on the basis that pass by reference is preferred where possible, I changed it thusly. AnsiString broken(const AnsiString &format,...) { ... the rest, totally identical ... } My calling code is like this:- AnsiString s1, s2; s1 = working("Hello %s", "World"); s2 = broken("Hello %s", "World"); But, s1 contains "Hello World", while s2 has "Hello (null)". I think this is due to the way va_start works, but I'm not exactly sure what's going on.

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  • How do you give variables reference in javascript?

    - by Eric
    I want to give variables reference in javascript. For example, I want to do: a=1 b=a a=2 and have b=2, and change accordingly to a. Is this possible in javascript? If it isn't is there a way to do like a.onchange = function () {b=a}? What I wanted to do was make a function like makeobject which make an object and puts it in an array and than returns it like function makeobject() { objects[objects.length] = {blah:'whatever',foo:8}; } so than I could do a=makeobject() b=makeobject() c=makeobject() and later in the code do for (i in objects) { objects[i].blah = 'whatev'; } and also change the values of a,b and c

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  • Assembly reference in Silverlight class library and used only in xaml is not packaged in XAP

    - by Brandon Copeland
    I have a 3rd party library (A). That library is referenced in my Silverlight class library (B). That Silverlight class library is referenced in my Silverlight application (C). The 3rd party library is not explicitly referenced in the Silverlight application. It seems that "A" is added to my XAP if "A" is used in any class in "B" because of a chain in dependencies (C - B - A). This is the behavior I would expect and need. If "A" is never explicitly used in a C# class but only defined in Xaml, the assembly is not packaged to the XAP. Maybe "A" includes a control that is only used declaratively and never referenced otherwise. Is this behavior by design? Am I missing a property somewhere that controls this? I would prefer to not explicitly reference the third party library in my Silverlight application. What's to best practice to ensure all necessary assemblies are packaged in the XAP?

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  • Assinging a GD reference to a new variable fails to copy

    - by Stomped
    This is a contrived example, but it illustrates my problem much more concisely then the code I'm using - and I've tested this and it exhibits the problem: $image = imagecreatefromjpeg('test.jpg'); $copy_of_image = $image; // The important bit imagedestroy($image); header('Content-type: image/jpeg'); imagejpeg($copy_of_image); Now, my expectation is that $copy_of_image is exactly that, but when I run this, it fails, printing out the URL of the script of all things. Comment out the imagedestroy() and it works just fine. a var_dump of $image provides: resource(3) of type (gd) So why can't I copy this? Apparently the assignment $copy_of_image = $image is creating a reference rather then a copy - is there a way to prevent that?

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  • Referencing a control programatically with external source

    - by James
    Forgive me about the title, I have no idea what this is called. I have a MS Access database set up, with a Period field that has either values 1, 2, 3, 4 or 5. I retrieve these values using a database connection and I would like to reference a particular control based on what period was grabbed from the database. Here's example code, pseudo of course. TextBox(dr(3)).Text = dr(0) dr(3) contains the period, and dr(0) contains the content I would like to put into the text box. I have these text boxes on my form: TextBox1, TextBox2, TextBox3, TextBox4 and TextBox5. So if dr(3) contained 2 then I would want to reference TextBox2. I hope I've made myself clear, any help would be greatly appreciated, thanks. :)

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  • weak or strong for IBOutlet and other

    - by Piero
    I have switched my project to ARC, and I don't understand if I have to use strong or weak for IBOutlets. Xcode do this: in interface builder, if a create a UILabel for example and I connect it with assistant editor to my ViewController, it create this: @property (nonatomic, strong) UILabel *aLabel; It uses the strong, instead I read a tutorial on RayWenderlich website that say this: But for these two particular properties I have other plans. Instead of strong, we will declare them as weak. @property (nonatomic, weak) IBOutlet UITableView *tableView; @property (nonatomic, weak) IBOutlet UISearchBar *searchBar; Weak is the recommended relationship for all outlet properties. These view objects are already part of the view controller’s view hierarchy and don’t need to be retained elsewhere. The big advantage of declaring your outlets weak is that it saves you time writing the viewDidUnload method. Currently our viewDidUnload looks like this: - (void)viewDidUnload { [super viewDidUnload]; self.tableView = nil; self.searchBar = nil; soundEffect = nil; } You can now simplify it to the following: - (void)viewDidUnload { [super viewDidUnload]; soundEffect = nil; } So use weak, instead of the strong, and remove the set to nil in the videDidUnload, instead Xcode use the strong, and use the self... = nil in the viewDidUnload. My question is: when do I have to use strong, and when weak? I want also use for deployment target iOS 4, so when do I have to use the unsafe_unretain? Anyone can help to explain me well with a small tutorial, when use strong, weak and unsafe_unretain with ARC?

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