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  • How to implement an abstract class in ruby?

    - by Chirantan
    I know there is no concept of abstract class in ruby. But if at all it needs to be implemented, how to go about it? I tried something like... class A def self.new raise 'Doh! You are trying to instantiate an abstract class!' end end class B < A ... ... end But when I try to instantiate B, it is internally going to call A.new which is going to raise the exception. Also, modules cannot be instantiated but they cannot be inherited too. making the new method private will also not work. Any pointers?

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  • 2 or more Controls only 1 is considered Active

    - by Don
    I have 2 controls (MyCtrl) next to each other called ctrlLeft and ctrlRight. Whenever one receives interaction it is considered active (by default the left one). I override OnDraw and customize the look of the active one a bit. Currently I have a property Active and an event that I subscribe to from all MyCtrl in there I store a reference to the active one like this: if (sender is MyCtrl) { ctrlActive = (sender as MyCtrl); ctrlLeft.Active = !(ctrlRight.Active = (ctrlActive == ctrlRight)); } Either way I need to have ctrlActive as I use it for other things but what I am wondering is if this is the best way make them aware of each other? Another option I thought of was to store references to every possible MyCtrl and then loop through em all and activate / deactivate the one that match sender just in case I in the future add a ctrlMiddle. Are my thoughts wrong, is there better options to do this. For example, how does radiobuttons accomplish their similar functionality?

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  • .NET C# MouseEnter listener on a Control WITH Scrollbar

    - by Run CMD
    As long as the mouse is over a specific control, we show some form. When the mouse leaves the control, we hide the control after a small timeout. This is standard hover behavior. However, when a control (for example a Treeview) has a scrollbar, and the mouse is ON or OVER the scrollbar, the events don't fire ... If we could get a reference to the scrollbar control, this would solve our problem, as we would add the same listener events to the scrollbar. However, the scrollbar isn't accessible as far as I know ... How can we solve this problem ?

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  • Inheriting database connection in PHP OOP

    - by vrode
    My abstract class Database is made for database interaction and any child of this class (UserDatabase, ActionDatabase, EventDatabase) inherits its database connection which is defined as static. `abstract class Database { static $connection = mysql_connect( ); } class UserDatabase extends Database { ... public function __construct( ) { $connection ? "connected" : "not connected"; $this-table = "users"; mysql_query( "FROM " . $this-table . " SELECT *" ); } } ` Does that mean, that my database connection is only set up and stored in memory once and passed on to subclasses as reference without being replicated for each instance? Is this how you would implement you OOP-correct database interface?

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  • how to copy char * into a string and vice-versa

    - by user295030
    If i pass a char * into a function. I want to then take that char * convert it to a std::string and once I get my result convert it back to char * from a std::string to show the result. I don't know how to do this for conversion ( I am not talking const char * but just char *) I am not sure how to manipulate the value of the pointer I send in. so steps i need to do take in a char * convert it into a string. take the result of that string and put it back in the form of a char * return the result such that the value should be available outside the function and not get destroyed. If possible can i see how it could be done via reference vs a pointer (whose address I pass in by value however I can still modify the value that pointer is pointing to. so even though the copy of the pointer address in the function gets destroyed i still see the changed value outside. thanks!

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  • Reuse C++ Header files

    - by Amrish
    Guys, I have a Visual C++ solution with 2 projects AlgorithmA & AlgorithmB and both share a common header file RunAlgo.h with the class declaration. Each project in the solution has its own unique implementation for the header file. I am trying to compile a DLL out of the common header file RunAlgo.h and add reference to this DLL in the projects AlgorithmA & AlgorithmB. I have then included separate RunAlgo.cpp definition file in both my projects. The problem is that I am getting linker errors while compiling the new DLL project which has only the header file. So, the question is Can a header file with only class declaration be compiled into a DLL (Similar to class library containing an Interface in C#)? For the above scenario, is there a better approach to reuse the common Header file among projects? Should the above method work (re-check my code?)

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  • Binding sub report in Crystal report

    - by Aijaz Chauhan
    Is it compulsory to bind sub report if we put sub report in main report ? here is my problem : code snippet : DataTable dtExtraDoc = dtDocSub.Select("DocumentId=14").Length == 0 ? null : dtDocSub.Select("DocumentId=14").CopyToDataTable(); if (dtExtraDoc != null && dtExtraDoc.Rows.Count > 0) { if (dtExtraDoc.Rows[0]["ResponceId"].ToString() == "2") { repdoc.Subreports["subRpt-extra-Doc-textile-claim-query-letter.rpt"].SetDataSource(dtExtraDoc); } } If dtExtraDoc is null then it will not bind the sub report and hence it gives me error " Object reference not set to an instance of object" I am totally new to crystal reports please help me.. Thanks in advance.

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  • Have visual studio copy x64 DLL or x86 DLL when building a C# project

    - by MrPurpleStreak
    We're building a C# app that uses an external DLL for Sqlite.NET. This is a .NET dll but it embeds a C dll inside it and so it comes in x86 and x64 flavours. We add a reference to the x86 version in the project so when we build and run on x86 it's fine. Visual studio copies the dll to the bin folder and runs. On x64 it still copies the x86 version of course and then when it runs it fails to load it. We get round this by temporarily setting our project to be x86 only, but ideally we'd like to tell visual studio to copy the correct version depending on which flavour of machine it is. Any ideas how?

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  • wcf service on mobile 5.0

    - by user554271
    hi everyone, I have writed a primitive wcf (vs 2010) service and created proxy files by svcutil. Later I created a mobile project on vs2008 and added proxy files on project but this error occured. Error 1 The type or namespace name 'ServiceContractAttribute' does not exist in the namespace 'System.ServiceModel' (are you missing an assembly reference?) C:\Users\Abb\Documents\Visual Studio 2008\Projects\WCF\MobileService\MobileClient\Sample.cs the proxy files runs well on console application (vs 2008) but there is errors on mobile. System.ServiceModel doesnot support ServiceContractAttribute.

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  • WSAT Security tab error for Custom Role provider

    - by shesb
    I have created custome Membership Role and Profile provider using INGRES db. Now I can see my IngresMembership and IngresRole provider in the Provider tab(Select a different provider for each feature (advanced) ) of WSAT but when I clik on security tab I get this error: "There is a problem with your selected data store. This can be caused by an invalid server name or credentials, or by insufficient permission. It can also be caused by the role manager feature not being enabled. Click the button below to be redirected to a page where you can choose a new data store. The following message may help in diagnosing the problem: Object reference not set to an instance of an object." What am I missing? Do I need to add code for all override methods for Role provider? I have just written code for the Initialize and GetRolesForUser functions. Thanks

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  • iPhone/Obj-C - Archiving object causes lag

    - by Dylan
    Hi I have a table view, and when I delete a cell I am removing an item from an NSMutableArray, archiving that array, and removing the cell. However, when I do this, it is causing the delete button to lag after I click it. Is there any way to fix this? // Override to support editing the table view. - (void)tableView:(UITableView *)tableView commitEditingStyle:(UITableViewCellEditingStyle)editingStyle forRowAtIndexPath:(NSIndexPath *)indexPath { if (editingStyle == UITableViewCellEditingStyleDelete) { int row = [indexPath row]; [savedGames removeObjectAtIndex:row]; [tableView deleteRowsAtIndexPaths:[NSArray arrayWithObject:indexPath] withRowAnimation:UITableViewRowAnimationFade]; //this line causing lag [NSKeyedArchiver archiveRootObject:savedGames toFile:[self dataFilePath]]; } } Thanks

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  • How i call NSObject method in UIViewController class method?

    - by Rajendra Bhole
    Hi,I am the beginner in iphone development. I develop an application in which i calling some GPS related information(method name is getGPSInformation{}) in clsGPS{} is an pure NSObject class.The code is as follows, import "clsGPS.h" -(void)getGPSInformation { locationManager = [[CLLocationManager alloc ] init]; locationManager.delegate = self; locationManager.distanceFilter = 5.0f; locationManager.desiredAccuracy = kCLLocationAccuracyNearestTenMeters; [locationManager startUpdatingLocation]; } I want the above method calling in UIViewController class. How i call this method in UIViewController class from that i automatically call this method at application launching time? should i calling that method in viewDidLoad event or viewWillAppear method?

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  • WPF MVVM - Correct way to consume a web service asynchronously

    - by byte
    I have implemented MVVM in my WPF application. I was wondering what is the correct way to consume a Web Service from WPF MVVM app. So far, I have created a DataAccess interface and a class that implements this interface. This would serve as a facade / proxy to the web service. The ViewModel gets a reference to this class as the constructor parameter so it can make any calls to get/set data, in this case it will be a Web service call. I would appreciate if you can guide me with some hints and / or direct me to some online resource.

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  • How to build website with two speaking language (Arabic and English)?

    - by Alex
    hi, I am beginner in web designing, I using CLASSIC ASP for web development. My client need his website in two languages (Arabic and English). What is the best way for develop website in multiple language? I read some information from website's :- Create website in two lanuages. for example (www.example.com/English/)and (www.example.com/Arabic/) 2.Use transilaters(Google,SpeakFish,etc..) for your default website. Anyone can help me for this which is the suitable way for develop website in multiple languages? Any reference or any links? hoping your help

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  • Finding the right name for an include that is to be executed before HTML output

    - by Pekka
    I am defining naming conventions for a simple plugin framework. For example: index.php - the main plugin file info.php - returns an array with plugin information install.php - self-explanatory can you think of an elegant, short-hand name for a PHP file that contains the code that is to be executed before any HTML is output? Do any examples from other frameworks come to your mind? What I have been thinking of: head.php - misleading, could be mixed up with HTML <head> before_output.php - clumsy, too long init.php - not exactly correct start.php - current favourite

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  • Function declaration in C and C++

    - by Happy Mittal
    I have two C++ files, say file1.cpp and file2.cpp as //file1.cpp #include<cstdio> void fun(int i) { printf("%d\n",i); } //file2.cpp void fun(double); int main() { fun(5); } When I compile them and link them as c++ files, I get an error "undefined reference to fun(double)". But when I do this as C files, I don't get error and 0 is printed instead of 5. Please explain the reason. Moreover I want to ask whether we need to declare a function before defining it because I haven't declared it in file1.cpp but no error comes in compilation.

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  • Why wasn't C# designed with 'const' for variables and methods?

    - by spoulson
    I suspect const was simplified for the C# spec for general language simplicity. Was there a specific reason we can't declare variable references or methods as const like we can with C++? e.g.: const MyObject o = new MyObject(); // Want const cast referenece of MyObject o.SomeMethod(); // Theoretically legal because SomeMethod is const o.ChangeStuff(); // Theoretically illegal because ChangeStuff is not const class MyObject { public int val = 0; public void SomeMethod() const { // Do stuff, but can't mutate due to const declaration. } public void ChangeStuff() { // Code mutates this instance. Can't call with const reference. val++; } }

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  • How does one validate html that's generated from JS running in the browser?

    - by Henry Rose
    The page in question has very skeletal html sent over the wire to facilitate the building of a complicated UI in javascript. I'm now encountering a strange browser compatibility issue that feels very much like I've got a markup problem somewhere on the page. I've validated the page as it comes across the wire using the W3C tool and ensured there are no issues in that html. I've also tried validating the output of running on the browser console: document.getElementsByTagName('html')[0].outerHTML I find that the output of the above introduces lots of new issues, such as removing the trailing '/' in self closing tags. This added noise is distracting, but it also makes me uneasy about validating this method. How do you validate markup that's rendered client side?

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  • What is the '^' in Objective-C

    - by Chris Paterson
    What does the '^' mean in the code below? @implementation AppController - (IBAction) loadComposition:(id)sender { void (^handler)(NSInteger); NSOpenPanel *panel = [NSOpenPanel openPanel]; [panel setAllowedFileTypes:[NSArray arrayWithObjects: @"qtz", nil]]; handler = ^(NSInteger result) { if (result == NSFileHandlingPanelOKButton) { NSString *filePath = [[[panel URLs] objectAtIndex:0] path]; if (![qcView loadCompositionFromFile:filePath]) { NSLog(@"Could not load composition"); } } }; [panel beginSheetModalForWindow:qcWindow completionHandler:handler]; } @end === I've searched and searched - is it some sort of particular reference to memory?

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  • Tell me how to use ActiveRecord#afeter_add

    - by Small Wolf
    Hey,Guys! Now I hava a problem,how can I make the callback#after_add receive a reference to the join model in a has_many :through association? my code like this: class Emergency has_many :departments, :through => :eme_references, :source => :email, :after_add => Proc.new { |eme_reference| eme_reference.eme_flag = 1} end the attribute eme_flag is the model EmeReference's attribute! but in the block ,i get the eme_reference.class is Emergency. I want to set the attribute eme_flag of the model EmeReference. That is my question! cheers!

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  • Joomla contact form doesn't pass W3C validation

    - by aramaz
    Hi, I get the following error when I try to validate a contact page on my site: document type does not allow element "script" here The element named above was found in a context where it is not allowed. This could mean that you have incorrectly nested elements -- such as a "style" element in the "body" section instead of inside "head" -- or two elements that overlap (which is not allowed). One common cause for this error is the use of XHTML syntax in HTML documents. Due to HTML's rules of implicitly closed elements, this error can create cascading effects. For instance, using XHTML's "self-closing" tags for "meta" and "link" in the "head" section of a HTML document may cause the parser to infer the end of the "head" section and the beginning of the "body" section (where "link" and "meta" are not allowed; hence the reported error). I am using Joomla 1.5.7, and the doctype is <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> Any idea how to fix this?

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  • Serving images from Amazon S3 in PHP application

    - by luckytaxi
    So it just occurred to me that once I upload profile pics to S3, I have to figure out a way to keep track of the files. For example, if "susan" uploads 3 profile pics, I need to recall those 3 pictures and display it on her profile page if someone views her page. With that said, would the following work? User uploads picture from form Save file information (filename, user info, etc...) into DB and reference URL from S3 Upload photos to S3 When displaying pictures, I'll query the DB for the info and display the images from S3 accordingly.

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  • Fitting maximum amount of shapes on a surface

    - by Fuu
    In industry, there is often a problem where you need to calculate the most efficient use of material, be it fabric, wood, metal etc. So the starting point is X amount of shapes of given dimensions, made out of polygons and/or curved lines, and target is another polygon of given dimensions. I assume many of the current CAM suites implement this, but having no experience using them or of their internals, what kind of computational algorithm is used to find the most efficient use of space? Can someone point me to a book or other reference that discusses this subject?

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  • A question related to UIButton

    - by vikas Savardekar
    I have taken customview in my code for UIButton. UIButton *button= [[UIButton buttonWithType:UIButtonTypeRoundedRect] retain]; //(UIButton *)newCell.accessoryView; [button addTarget:self action:@selector(checkedimage:) forControlEvents:UIControlEventTouchUpInside]; -(IBAction)checkedimage:(id)sender { NSLog(@"checkedimage"); if(checkImage == NO) { newImage = [UIImage imageNamed:@"a.png"]; checkImage=YES; } else if(checkImage==YES) { newImage = [UIImage imageNamed:@"b.png"]; checkImage=NO; } } but when i click on UIButton it is not going to action checkedimage why?

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  • Any way to ask a method for its name?

    - by Andy
    I'm trying to debug an iPhone app I'm working on, and the idea of adding fifty NSLog statements to the various source files gives me the willies. What I'd like to do is write a pair of statements, say NSString *methodName = [self methodName]; NSLog(@"%@", methodName); that I can just paste into each method I need to. Is there a way to do this? Is there some Objective-C construct for asking a method for its name? Or am I gonna have to do this the hard way?

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