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• Method having an abstract class as a parameter

  - by Ferhat

  I have an abstract class A, where I have derived the classes B and C. Class A provides an abstract method DoJOB(), which is implemented by both derived classes. There is a class X which has methods inside, which need to call DoJOB(). The class X may not contain any code like B.DoJOB() or C.DoJOB(). Example: public class X { private A foo; public X(A concrete) { foo = concrete; } public FunnyMethod() { foo.DoJOB(); } } While instantiating class X I want to decide which derived class (B or C) must be used. I thought about passing an instance of B or C using the constructor of X. X kewl = new X(new C()); kewl.FunnyMethod(); //calls C.DoJOB() kewl = new X(new B()); kewl.FunnyMethod(); // calls B.DoJOB() My test showed that declaring a method with a parameter A is not working. Am I missing something? How can I implement this correctly? (A is abstract, it cannot be instantiated)

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• CoreData is saving model without the save: method being called

  - by chris

  I have a list of items with a plus button in the navigation bar that opens up a modal window containing a table of the models attributes, that displays a form when the table items are clicked (pretty standard form style). For some reason if I click the plus button to open the form to create a new model, then immediately click the done button, the person model is saved. The action linked to the done button does nothing but call on a delegate method notifying the personListViewController to close the window. The apple docs do state that the model is not saved after calling the insertNewObjectForEntityName: ... Simply creating a managed object does not cause it to be saved to a persistent store. The managed object context acts as a scratchpad. I am at a lost to why this is happening, but every time I click the done button I have a new blank item in the original tableView. I am using SDK v3.1.3 // PersonListViewController - open modal window - (void)addPerson { // Load the new form PersonNewViewController *newController = [[PersonNewViewController alloc] init]; newController.modalFormDelegate = self; [self presentModalViewController:newController animated:YES]; [newController release]; } // PersonFormViewController - (void)viewDidLoad { [super viewDidLoad]; if ( person == nil ) { MyAppDelegate *appDelegate = [[UIApplication sharedApplication] delegate]; self.person = [NSEntityDescription insertNewObjectForEntityForName:@"Person" inManagedObjectContext:appDelegate.managedObjectContext]; } ... UIBarButtonItem *doneButton = [[UIBarButtonItem alloc] initWithBarButtonSystemItem:UIBarButtonSystemItemDone target:self action:@selector(done)]; self.navigationItem.rightBarButtonItem = doneButton; [doneButton release]; } - (IBAction) done { [self.modalFormDelegate didCancel]; } // delegate method in the original listViewController - (void) didCancel { [self dismissModalViewControllerAnimated:YES]; }

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• Testing ActionMailer's receive method (Rails)

  - by Brian Armstrong

  There is good documentation out there on testing ActionMailer send methods which deliver mail. But I'm unable to figure out how to test a receive method that is used to parse incoming mail. I want to do something like this: require 'test_helper' class ReceiverTest < ActionMailer::TestCase test "parse incoming mail" do email = TMail::Mail.parse(File.open("test/fixtures/emails/example1.txt",'r').read) assert_difference "ProcessedMail.count" do Receiver.receive email end end end But I get the following error on the line which calls Receiver.receive NoMethodError: undefined method `index' for #<TMail::Mail:0x102c4a6f0> /Library/Ruby/Gems/1.8/gems/tmail-1.2.7.1/lib/tmail/stringio.rb:128:in `gets' /Library/Ruby/Gems/1.8/gems/tmail-1.2.7.1/lib/tmail/mail.rb:392:in `parse_header' /Library/Ruby/Gems/1.8/gems/tmail-1.2.7.1/lib/tmail/mail.rb:139:in `initialize' /Library/Ruby/Gems/1.8/gems/tmail-1.2.7.1/lib/tmail/stringio.rb:43:in `open' /Library/Ruby/Gems/1.8/gems/tmail-1.2.7.1/lib/tmail/port.rb:340:in `ropen' /Library/Ruby/Gems/1.8/gems/tmail-1.2.7.1/lib/tmail/mail.rb:138:in `initialize' /Library/Ruby/Gems/1.8/gems/tmail-1.2.7.1/lib/tmail/mail.rb:123:in `new' /Library/Ruby/Gems/1.8/gems/tmail-1.2.7.1/lib/tmail/mail.rb:123:in `parse' /Library/Ruby/Gems/1.8/gems/actionmailer-2.3.4/lib/action_mailer/base.rb:417:in `receive' Tmail is parsing the test file I have correctly. So that's not it. Thanks!

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• Method in RootViewController not Storing Array

  - by Antonio

  I have an array initialized in my RootViewController and a method that addsObjects to an array. I created a RootViewController object in my SecondViewController. The method runs (outputs a message) but it doesn't add anything to the array, and the array seems empty. Code is below, any suggestions? RootViewController.h #import "RootViewController.h" #import "SecondViewController.h" @implementation RootViewController - (void)viewDidLoad { [super viewDidLoad]; myArray2 = [[NSMutableArray alloc] init]; NSLog(@"View was loaded"); } -(void)addToArray2{ NSLog(@"Array triggered from SecondViewController"); [myArray2 addObject:@"Test"]; [self showArray2]; } -(void)showArray2{ NSLog(@"Array Count: %d", [myArray2 count]); } -(IBAction)switchViews{ SecondViewController *screen = [[SecondViewController alloc] initWithNibName:nil bundle:nil]; screen.modalTransitionStyle = UIModalTransitionStyleCoverVertical; [self presentModalViewController:screen animated:YES]; [screen release]; } SecondViewController.m #import "SecondViewController.h" #import "RootViewController.h" @implementation SecondViewController -(IBAction)addToArray{ RootViewController *object = [[RootViewController alloc] init]; [object addToArray2]; } -(IBAction)switchBack{ [self dismissModalViewControllerAnimated:YES]; } EDIT***** With Matt's code I got the following error: " expected specifier-qualifier-list before 'RootViewController' "

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• Invoking a method overloaded where all arguments implement the same interface

  - by double07

  Hello, My starting point is the following: - I have a method, transform, which I overloaded to behave differently depending on the type of arguments that are passed in (see transform(A a1, A a2) and transform(A a1, B b) in my example below) - All these arguments implement the same interface, X I would like to apply that transform method on various objects all implementing the X interface. What I came up with was to implement transform(X x1, X x2), which checks for the instance of each object before applying the relevant variant of my transform. Though it works, the code seems ugly and I am also concerned of the performance overhead for evaluating these various instanceof and casting. Is that transform the best I can do in Java or is there a more elegant and/or efficient way of achieving the same behavior? Below is a trivial, working example printing out BA. I am looking for examples on how to improve that code. In my real code, I have naturally more implementations of 'transform' and none are trivial like below. public class A implements X { } public class B implements X { } interface X { } public A transform(A a1, A a2) { System.out.print("A"); return a2; } public A transform(A a1, B b) { System.out.print("B"); return a1; } // Isn't there something better than the code below??? public X transform(X x1, X x2) { if ((x1 instanceof A) && (x2 instanceof A)) { return transform((A) x1, (A) x2); } else if ((x1 instanceof A) && (x2 instanceof B)) { return transform((A) x1, (B) x2); } else { throw new RuntimeException("Transform not implemented for " + x1.getClass() + "," + x2.getClass()); } } @Test public void trivial() { X x1 = new A(); X x2 = new B(); X result = transform(x1, x2); transform(x1, result); }

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• Whats wrong with this method?

  - by David

  Here's the method: public static String CPUcolor () { System.out.println ("What color am I?") ; String s = getIns() ; System.out.println ("are you sure I'm "+s+"? (Y/N)") ; String a = getIns() ; while (!((a.equals ("y")) || (a.equals ("Y")) || (a.equals ("n")) || (a.equals ("N")))) { System.out.println ("try again") ; a = getIns () ; } if (a.equals ("n") || a.equals("N")) {CPUcolor() ;} System.out.println ("I am "+s) ; return s ; } here is a possible output of this method (y's and n's are user inputs): What color am I? red are you sure I'm red? (Y/N) N What color am I? blue are you sure I'm blue? (Y/N) N What color am I? Yellow are you sure I'm Yellow? (Y/N) y I am Yellow I am blue I am red Why is it that the line's "I am blue" and "I am Blue" printed? Why are they printed in reverse order with red, the first entered, printed last?

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• How to pass value in url using web request GET method asp.net

  - by Narasi

  Am new to .Net and web service..i like to pass id through url..how to do that?whether it was done post or get method?guide me string url = "http://XXXXX//"+id=22; WebRequest request = WebRequest.Create(url); request.Proxy.Credentials = new NetworkCredential(xxxxx); request.Credentials = CredentialCache.DefaultCredentials; //add properties request.Method = "GET"; request.ContentType = "application/json"; //convert byte[] byteArray = Encoding.UTF8.GetBytes(data); request.ContentLength = byteArray.Length; //post data Stream streamdata = request.GetRequestStream(); streamdata.Write(byteArray, 0, byteArray.Length); streamdata.Close(); //response WebResponse response = request.GetResponse(); // Get the stream containing content returned by the server. Stream dataStream = response.GetResponseStream(); // Open the stream using a StreamReader for easy access. StreamReader reader = new StreamReader(dataStream); // Read the content. string responseFromServer = reader.ReadToEnd(); // Clean up the streams and the response. reader.Close(); response.Close(); Thanks in advance

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• How to reload a tableView i.e call the viewDidLoad method if a condition is met

  - by Kquane Ingram

  The problem is this i need a way to basically erase all the entry data a user placed into my arrays if a condition is met. Im new to Objective-C and iOS programming, but i believed the solution might be in calling the viewDidLoad method, thus it would virtually refresh the applications with the values of the array reset to default. If there is any other logical way of doing this i would appreciate the help. In short i need to refresh the arrays as they were when the application first launched and the user did not select anything. This is the part where i need it to refresh. if ([gradeRecieved objectAtIndex:i]==nil) { break; // if this condition is met the program must begin anew. Edit* I need to recall the - (void)viewDidLoad method here is more of the code. -(IBAction)button:(id)sender{ int i = 0; int sum = 0; int gradeEarned; int creditHours = 3; for ( i=0;i<8 ; i++) { if ([[points objectAtIndex:i] tag]==GradeA.intValue) { [gradeRecieved replaceObjectAtIndex:i withObject:GradeA]; } if ([[points objectAtIndex:i]tag]==GradeB.intValue) { [gradeRecieved replaceObjectAtIndex:i withObject:GradeB]; } if ([[points objectAtIndex:i]tag]==GradeC.intValue){ [gradeRecieved replaceObjectAtIndex:i withObject:GradeC]; } if ([gradeRecieved objectAtIndex:i]==nil) { break; // if this condition is met the program must restart. } } while ( i<[gradeRecieved count]) { if ([gradeRecieved objectAtIndex:i] == GradeA ) { [finArray replaceObjectAtIndex:i withObject:GradeA]; i++; continue; } if ([gradeRecieved objectAtIndex:i] == GradeB ) { [gradeRecieved replaceObjectAtIndex:i withObject:GradeB]; i++; continue; } if ([gradeRecieved objectAtIndex:i] == GradeC ) { [gradeRecieved replaceObjectAtIndex:i withObject:GradeC]; i++; continue; } }

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• What might be causing this Rails method error?

  - by Trip

  My error: Notice the undefined method '-@' . This is for a sort by. All sorts on one page break, but all the sorts on other pages use the same helper and do not break. Does it allude to something obvious? Processing OrganizationsController#search (for ::1 at 2010-05-13 15:42:01) [GET] Parameters: {"action"=>"search", "controller"=>"organizations", "direction"=>"desc", "_"=>"1273779721464", "order_by"=>"published_at"} SQL (0.5ms) SHOW TABLES Organization Columns (2.2ms) SHOW FIELDS FROM `organizations` NoMethodError (undefined method `-@' for #<Array:0x2f88cc8>): app/controllers/organizations_controller.rb:190:in `search' sunspot (1.0.5) lib/sunspot/util.rb:84:in `call' sunspot (1.0.5) lib/sunspot/util.rb:84:in `instance_eval_or_call' sunspot (1.0.5) lib/sunspot/search.rb:200:in `build' sunspot (1.0.5) lib/sunspot/session.rb:45:in `new_search' sunspot (1.0.5) lib/sunspot/session.rb:53:in `search' sunspot (1.0.5) lib/sunspot/session_proxy/abstract_session_proxy.rb:11:in `search' sunspot (1.0.5) lib/sunspot.rb:323:in `search' app/controllers/organizations_controller.rb:183:in `search' haml (2.2.2) [v] rails/./lib/sass/plugin/rails.rb:19:in `process' lib/flash_session_cookie_middleware.rb:14:in `call' vendor/gems/hoptoad_notifier-2.2.2/lib/hoptoad_notifier/rack.rb:27:in `call' /usr/local/lib/ruby/1.8/webrick/httpserver.rb:104:in `service' /usr/local/lib/ruby/1.8/webrick/httpserver.rb:65:in `run' /usr/local/lib/ruby/1.8/webrick/server.rb:173:in `start_thread' /usr/local/lib/ruby/1.8/webrick/server.rb:162:in `start' /usr/local/lib/ruby/1.8/webrick/server.rb:162:in `start_thread' /usr/local/lib/ruby/1.8/webrick/server.rb:95:in `start' /usr/local/lib/ruby/1.8/webrick/server.rb:92:in `each' /usr/local/lib/ruby/1.8/webrick/server.rb:92:in `start' /usr/local/lib/ruby/1.8/webrick/server.rb:23:in `start' /usr/local/lib/ruby/1.8/webrick/server.rb:82:in `start' Rendered rescues/_trace (68.5ms) Rendered rescues/_request_and_response (0.6ms) Rendering rescues/layout (internal_server_error)

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• How to call a method from another class that's been instantiated within the current class

  - by Pavan

  my screen has a few views like such __________________ | _____ | | | | | //viewX is a video screen | | | | | viewX | vY | | //viewY is a custom uiview i created. | |____| | //it contains a method which i would like to call that toggles |_________________| //the hidden property of this view. and when it hides, a little | | //button is replaced no the top right corner on top of viewX | viewZ | //the video layer | | |_________________| //viewZ is a view containing many square views - thumbnails. my question is, i dont know how to register for touch events so that it recognises any touch event on no matter which view the user touches the screen.. atm im handling the touch events for each view inside it. so all works well... however what im trying to do is that when the user taps anywhere else on the screen but on viewY, viewY should dissapear by calling that method in the viewY class. this viewY class is instantiated and has no xib file attached to it. the uiview is created progammatically in the viewY class. this whole class for viewY behviour is instantiated in viewX - the video view. my boss says add delegates.. although i have now clue how to do that... any help? is there anyway i can just make it really simple and be able to say REMOVE VIEW no matter which class im calling from? Also ive seen other people achieve this by using these funky arrows - ... <- etc.. although im not sure if thats what i need or how to implement such a thing. ah i think ive made my question quite complicated but i really mean it to be a simple one, and know it can be done in an easy way!

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• Method not being resolved for dynamic generic type

  - by kelloti

  I have these types: public class GenericDao<T> { public T Save(T t) { return t; } } public abstract class DomainObject { // Some properties protected abstract dynamic Dao { get; } public virtual void Save() { var dao = Dao; dao.Save(this); } } public class Attachment : DomainObject { protected dynamic Dao { get { return new GenericDao<Attachment>(); } } } Then when I run this code it fails with RuntimeBinderException: Best overloaded method match for 'GenericDAO<Attachment.Save(Attachment)' has some invalid arguments var obj = new Attachment() { /* set properties */ }; obj.Save(); I've verified that in DomainObject.Save() "this" is definitely Attachment, so the error doesn't really make sense. Can anyone shed some light on why the method isn't resolving? Some more information - It succeeds if I change the contents of DomainObject.Save() to use reflection: public virtual void Save() { var dao = Dao; var type = dao.GetType(); var save = ((Type)type).GetMethod("Save"); save.Invoke(dao, new []{this}); }

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• How to specify generic method type parameters partly

  - by DNNX

  I have an extension method like below: public static T GetValueAs<T, R>(this IDictionary<string, R> dictionary, string fieldName) where T : R { R value; if (!dictionary.TryGetValue(fieldName, out value)) return default(T); return (T)value; } Currently, I can use it in the following way: var dictionary = new Dictionary<string, object(); //... var list = dictionary.GetValueAs<List<int, object("A"); // this may throw ClassCastException - this is expected behavior; It works pretty fine, but the second type parameter is really annoying. Is it possible in C# 4.0 rewrite GetValueAs is such a way that the method will still be applicable to different types of string-keyed dictionaries AND there will be no need to specify second type parameter in the calling code, i.e. use var list = dictionary.GetValueAs<List<int("A"); or at least something like var list = dictionary.GetValueAs<List<int, ?("A"); instead of var list = dictionary.GetValueAs<List<int, object("A");

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• Error in bisection method code in Matlab

  - by Amanda Collins

  I need to write a proper implementation of the bisection method, which means I must address all possible user input errors. Here is my code: function [x_sol, f_at_x_sol, N_iterations] = bisection(f, xn, xp, eps_f, eps_x) % solving f(x)=0 with bisection method % f is the function handle to the desired function, % xn and xp are borders of search, % f(xn)<0 and f(xp)>0 required, % eps_f defines how close f(x) should be to zero, % eps_x defines uncertainty of solution x if(f(xp) < 0) error('xp must be positive') end; if(f(xn)>0) error('xn must be negative') end; if (xn >= xp) error ('xn must be less than xp') end; xg=(xp+xn)/2; %initial guess fg=f(xg); % initial function evaluation N_iterations=1; while ( (abs(fg) > eps_f) & (abs(xg-xp) > eps_x) ) if (fg>0) xp=xg; else xn=xg; end xg=(xp+xn)/2; %update guess fg=f(xg); %update function evaluation N_iterations=N_iterations+1; end x_sol=xg; %solution is ready f_at_x_sol=fg; if (f_at_x_sol > eps_f) error('No convergence') end and here is the error message I receive when I try to test this in Matlab: >> bisection(x.^2, 2, -1, 1e-8, 1e-10) Attempted to access f(-1); index must be a positive integer or logical. Error in bisection (line 9) if(f(xp)<0) I was attempting to see if my error codes worked, but it doesn't look like they do. I get the same error when I try to test it on a function that should work.

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• getClientRects javascript method supported on iPhone?

  - by genericdan

  Trying to find the top-most visible element in a UIWebView. I am using a JS method to do this, which works great in Safari, but never executes past the getClientRects method when executed from a UIWebView. The elements I'm interested are all of class="h". Here's the javascript which is called from [webView stringByEvaluatingJavaScriptFromString:@"findTopElement()"]; Javascript: function findTopElement() { var pars = document.getElementsByClassName("h"); alert("findingTopElement: num pars:" + pars.length); for (var i = 0; i < pars.length; i++) { var para = pars[i]; alert("checking par " + para.id); var rects = para.getClientRects(); alert("checking rects " + rects.length); for (var j = 0; j < rects.length; j++) { var r = rects[j]; if (r.top > 0 && r.bottom > 0) { alert("success: " + para.id); return para.id; } } } return -1; } Is it possible element getClientRects function is not supported in a UIWebView?

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• Method not found: 'Void Google.Apis.Util.Store.FileDataStore..ctor(System.String)'

  - by user3732193

  I've been stuck at this for days now. I copied the exact codes from google api samples to upload files to Google Drive. Here is the code UserCredential credential = GoogleWebAuthorizationBroker.AuthorizeAsync( new ClientSecrets { ClientId = ClientId, ClientSecret = ClientSecret, }, new[] { DriveService.Scope.Drive, DriveService.Scope.DriveFile }, "user", CancellationToken.None, new FileDataStore("MyStore")).Result; But it would throw an exception at runtime: Method not found: 'Void Google.Apis.Util.Store.FileDataStore..ctor(System.String)'. I already added the necessary Google Api dlls. Or if anyone could suggest a better code for uploading files to Google Drive in a website which implements Server-Side Authorization. Any help would be greatly appreciated. UPDATE: I changed my code to this var token = new TokenResponse { RefreshToken = "1/6hnki1x0xOMU4tr5YXNsLgutzbTcRK1M-QOTEuRVxL4" }; var credentials = new UserCredential(new GoogleAuthorizationCodeFlow(new GoogleAuthorizationCodeFlow.Initializer { ClientSecrets = new ClientSecrets { ClientId = ClientId, ClientSecret = ClientSecret }, Scopes = new[] { DriveService.Scope.Drive, DriveService.Scope.DriveFile } }), "user", token); But it also throws an exception: Method not found: 'Void Google.Apis.Auth.OAuth2.Flows.GoogleAuthorizationCodeFlow..ctor(Initializer). Is the problem with the dlls?

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• Error: undefined method `contact' for nil:NilClass

  - by user275801

  I have a ruby/rails/hobo system that someone wrote a couple years ago, that I need to port to the latest version of ruby/rails/hobo. It seems that ruby doesn't care about backward compatibility, so code that used to work in the old app doesn't work anymore: In the observation.rb model file, the old app has this: belongs_to :survey has_one :site, :through => :survey def create_permitted? acting_user == self.survey.contact or acting_user.administrator? end survey.rb model file has this: belongs_to :contact, :class_name => 'User', :creator => true Unfortunately the code in observation.rb doesn't work under the new ruby/rails/hobo, and it gives me the error: NoMethodError in Observations#index Showing controller: observations; dryml-tag: index-page where line #1 raised: undefined method `contact' for nil:NilClass Extracted source (around line #1): 0 Rails.root: /home/simon/ruby/frogwatch2 Application Trace | Framework Trace | Full Trace app/models/observation.rb:48:in `create_permitted?' How should the "create_permitted" method be changed? I'm finding that the documentation for ruby/rails/hobo is pretty atrocious (which is fair enough as it is free software). Also I don't even know how to begin searching for this on google (i've been trying for days). Please help! :)

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• c# creating a database query METHOD

  - by Sinaesthetic

  I'm not sure if im delluded but what I would like to do is create a method that will return the results of a query, so that i can reuse the connection code. As i understand it, a query returns an object but how do i pass that object back? I want to send the query into the method as a string argument, and have it return the results so that I can use them. Here's what i have which was a stab in the dark, it obviously doesn't work. This example is me trying to populate a listbox with the results of a query; the sheet name is Employees and the field/column is name. The error i get is "Complex DataBinding accepts as a data source either an IList or an IListSource.". any ideas? public Form1() { InitializeComponent(); openFileDialog1.ShowDialog(); openedFile = openFileDialog1.FileName; lbxEmployeeNames.DataSource = Query("Select [name] FROM [Employees$]"); } public object Query(string sql) { System.Data.OleDb.OleDbConnection MyConnection; System.Data.OleDb.OleDbCommand myCommand = new System.Data.OleDb.OleDbCommand(); string connectionPath; //build connection string connectionPath = "provider=Microsoft.Jet.OLEDB.4.0;Data Source='" + openedFile + "';Extended Properties=Excel 8.0;"; MyConnection = new System.Data.OleDb.OleDbConnection(connectionPath); MyConnection.Open(); myCommand.Connection = MyConnection; myCommand.CommandText = sql; return myCommand.ExecuteNonQuery(); }

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• Pass variable by Post method from JQuery UI Autocomplete to PHP page

  - by Shahriar N Khondokar

  I have two JQuery UI autocomplete input fields. When an option is selected in the first one, the value of the selection will be used as condition for a database query that will send the source data for the second autocomplete field. My problem is how do I send the value of the first selection to the PHP page via Post method? The code so far is shown below (this code is from a tutorial which used the GET method; but I want to use Post): <script> $("input#divisions").autocomplete ({ //this is the first input source : [ { value: "81", label: "City1" }, { value: "82", label: "City2" }, { value: "83", label: "City3" } ], minLength : 0, select: function(event, ui) { $('#divisions').val(ui.item.label); return false; }, focus: function(event, ui){ $('#divisions').val(ui.item.label); return false; }, change: function(event, ui){ //the tutorial has this value sent by variables in the URL; I want the selection value sent by POST. How can I change this? c_t_v_choices = "c_t_v_choices.php?filter=" + ui.item.value; $("#c_t_v").autocomplete("option", "source", c_t_v_choices); } }).focus (function (event) { $(this).autocomplete ("search", ""); }); $("#c_t_v").autocomplete({ source: "", minLength: 2, select: function(event,ui){ //$('#city').val(ui.item.city); } }); </script> Can anyone please help? Dont hesitate to let me know if you have any questions.

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• .NET: bool vs enum as a method parameter

  - by Julien Lebosquain

  Each time I'm writing a method that takes a boolean parameter representing an option, I find myself thinking: "should I replace this by an enum which would make reading the method calls much easier?". Consider the following with an object that takes a parameter telling whether the implementation should use its thread-safe version or not (I'm not asking here if this way of doing this is good design or not, only the use of the boolean): public void CreateSomeObject(bool makeThreadSafe); CreateSomeObject(true); When the call is next to the declaration the purpose of the parameter seems of course obvious. When it's in some third party library you barely know, it's harder to immediately see what the code does, compared to: public enum CreationOptions { None, MakeThreadSafe } public void CreateSomeObject(CreationOptions options); CreateSomeObject(CreationOptions.MakeThreadSafe); which describes the intent far better. Things get worse when there's two boolean parameters representing options. See what happened to ObjectContext.SaveChanges(bool) between Framework 3.5 and 4.0. It has been obsoleted because a second option has been introduced and the whole thing has been converted to an enum. While it seems obvious to use an enumeration when there's three elements or more, what's your opinion and experiences about using an enum instead a boolean in these specific cases?

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• Looping through a method without for/foreach/while

  - by RichK

  Is there a way of calling a method/lines of code multiple times not using a for/foreach/while loop? For example, if I were to use to for loop: int numberOfIterations = 6; for(int i = 0; i < numberOfIterations; i++) { DoSomething(); SomeProperty = true; } The lines of code I'm calling don't use 'i' and in my opinion the whole loop declaration hides what I'm trying to do. This is the same for a foreach. I was wondering if there's a looping statement I can use that looks something like: do(6) { DoSomething(); SomeProperty = true; } It's really clear that I just want to execute that code 6 times and there's no noise involving index instantiating and adding 1 to some arbitrary variable. As a learning exercise I have written a static class and method: Do.Multiple(int iterations, Action action) Which works but scores very highly on the pretentious scale and I'm sure my peers wouldn't approve. I'm probably just being picky and a for loop is certainly the most recognisable, but as a learning point I was just wondering if there (cleaner) alternatives. Thanks. (I've had a look at this thread, but it's not quite the same) http://stackoverflow.com/questions/2248985/using-ienumerable-without-foreach-loop

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• Creating a assertClass() method in JUnit

  - by Mike

  Hi, I'm creating a test platform for a protocol project based on Apache MINA. In MINA when you receive packets the messageReceived() method gets an Object. Ideally I'd like to use a JUnit method assertClass(), however it doesn't exist. I'm playing around trying to work out what is the closest I can get. I'm trying to find something similar to instanceof. Currently I have: public void assertClass(String msg, Class expected, Object given) { if(!expected.isInstance(given)) Assert.fail(msg); } To call this: assertClass("Packet type is correct", SomePacket.class, receivedPacket); This works without issue, however in experimenting and playing with this my interest was peaked by the instanceof operator. if (receivedPacket instanceof SomePacket) { .. } How is instanceof able to use SomePacket to reference the object at hand? It's not an instance of an object, its not a class, what is it?! Once establishing what type SomePacket is at that point is it possible to extend my assertClass() to not have to include the SomePacket.class argument, instead favouring SomePacket?

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• [Need help]: Issue with submit button and html file input control’s Click() method

  - by somesh

  Scenario: On click of a button, we dynamically create html file input (file upload) control on the page and call that file input controls Click() method. User then selects the file from the disk. There is a “Submit” button to upload the selected file. Problem: The problem is, when clicked on “Submit” button first time, the input value from the file input control is cleared. And the request does not go to the server. When clicked second time, the request goes to server with empty file input value. Why the first click on submit button does not send the request to server. And why it clears the file input control value? Note: The issue is observed only when we call Click() method programmatically. If we let user to click browse, then in that case, the "Submit" does not clear the input value and sends request to server on first click itself. Any help would be appreciated. Thanks in advance. By the way, server side code is in asp.net and client side in java script, testing on IE. -Somesh

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• Can't referr to my get method

  - by chility

  I have this amazing and good looking class: public class SayingsHolder extends Application{ ArrayList<String> SayingsList = new ArrayList<String>(){{ SayingsList.add("1"); SayingsList.add("2"); }}; public ArrayList<String> getSayingsList() { return SayingsList; } } Now I'm trying to call the getSayingsList method inside of my activity's FragmentStatePagerAdapter by: private class ScreenSlidePagerAdapter extends FragmentStatePagerAdapter { final SayingsHolder holder = (SayingsHolder).getApplication(); } Everything fine for now, but when I make my code like this: private class ScreenSlidePagerAdapter extends FragmentStatePagerAdapter { final SayingsHolder holder = (SayingsHolder).getApplication(); holder.getSayingsList(); } it says: Syntax error on token "getSayingsList", Identifier expected after this token The problem is that holder is not functional at all. What I mean is that when i type the this holder. the getSayingsList is not showing at all. What am I missing here? I know that it is an extremely small issue, but it seems that I can't spot it. My activity extends FragmentActivity if it's important It seems that I'm missing something here. I can't call my method anywhere in my activity. I'm starting a bounty, because I need an example.

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• convert a repeating code to method

  - by Mr_Green

  In my project, I am adding ComboBox, Text, Link label to my DataGridView dgvMain.I have created different methods for different cell templates as shown below: (The code below is working) gridLnklbl(string headerName) DataGridViewLinkColumn col = new DataGridViewLinkColumn(); col.HeaderText = headerName; // col.Name = "col" + headerName; // same code repeating to all the methods dgvMain.Columns.Add(col); // gridCmb(string headerName) DataGridViewComboBoxColumn col = new DataGridViewComboBoxColumn(); col.HeaderText = headerName; col.Name = "col" + headerName; dgvMain.Columns.Add(col); gridText(string headerName) DataGridViewTextBoxColumn col = new DataGridViewTextBoxColumn(); col.HeaderText = headerName; col.Name = "col" + headerName; dgvMain.Columns.Add(col); As you can see, except the declaration of objects, the code for every method is repeating. Just curious to know, can the repeating code be converted to single method? I dont know how to do that.. Its not about 3 codes of line, I have written many more lines which can be make common to those methods.

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• objectAtIndex:indexPath.row method always causes exception in IOS

  - by kalkin

  Hi I always seem to get exception when I use objectAtInded method to retrieve NSString from an array. I am reading data from a dictionary which is in the "PropertyList.plist" file.My code is - (void)viewDidLoad { [super viewDidLoad]; NSString *path = [[NSBundle mainBundle] pathForResource:@"PropertyList" ofType:@"plist"]; names = [[NSDictionary alloc] initWithContentsOfFile:path]; keys = [[[names allKeys] sortedArrayUsingSelector: @selector(compare:)] retain]; } -(UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath { NSUInteger section = [indexPath section]; NSUInteger row = [indexPath row]; NSString *key = [keys objectAtIndex:section]; NSArray *nameSection = [names objectForKey:key]; static NSString *SectionsTableIdentifier = @"SectionsTableIdentifier"; UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:SectionsTableIdentifier]; if(cell == nil) { cell = [[[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:SectionsTableIdentifier] autorelease]; } cell.textLabel.text = [nameSection objectAtIndex:row]; return cell; } The exception happens on the method "cellForRowAtIndexPath" in the line cell.textLabel.text = [nameSection objectAtIndex:row]; The error message is Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '-[__NSCFDictionary objectAtIndex:]: unrecognized selector sent to instance 0x6832440 Where ever I use "[nameSection objectAtIndex:row];" type of statement it always get exception.

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