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  • Message sent to deallocated instance which has never been released

    - by Jakub
    Hello, I started dealing with NSOperations and (as usual with concurrency) I'm observing strange behaviour. In my class I've got an instance variable: NSMutableArray *postResultsArray; when one button in the UI is pressed I initialize the array: postResultsArray = [NSMutableArray array]; and setup the operations (together with dependencies). In the operations I create a custom object and try to add to the array: PostResult *result = [[PostResult alloc] initWithServiceName:@"Sth" andResult:someResult]; [self.postResultsArray addObject:result]; and while adding I get: -[CFArray retain]: message sent to deallocated instance 0x3b40c30 which is strange as I don't release the array anywhere in my code (I did, but when the problem started to appear I commented all the release operations to be sure that they are not the case). I also used to have @synchronized section like below: PostResult *result = [[PostResult alloc] initWithServiceName:@"Sth" andResult:someResult]; @synchronized (self.postResultsArray) { [self.postResultsArray addObject:result]; } but the problem was the same (however, the error was for the synchronized operation). Any ideas what I may be doing wrong?

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  • MySQL - Calculating fields on the fly vs storing calculated data

    - by Christian Varga
    Hi Everyone, I apologise if this has been asked before, but I can't seem to find an answer to a question that I have about calculating on the fly vs storing fields in a database. I read a few articles that suggested it was preferable to calculate when you can, but I would just like to know if that still applies to the following 2 examples. Example 1. Say you are storing data relating to a car. You store the fuel tank size in litres, and how many litres it uses per 100km. You also want to know how many KMs it can travel, which can be calculated from the tank size and economy. I see 2 ways of doing this: When a car is added or updated, calculate the amount of KMs and store this as a static field in the database. Every time a car is accessed, calculate the amount of KMs on the fly. Because the cars economy/tank size doesn't change (although it could be edited), the KMs is a pretty static value. I don't see why we would calculate it every single time the car is accessed. Wouldn't this waste cpu time as opposed to simply storing it in a separate field in the database and calculating only when a car is added or updated? My next example, which is almost an entirely different question (but on the same topic), relates to counting children. Let's say we have a app which has categories and items. We have a view where we display all the categories, and a count of all the items inside each category. Again, I'm wondering what's better. To perform a MySQL query to count all the items in each category every single time the page is accessed? Or store the count in a field in the categories table and update when an item is added / deleted? I know it is redundant to store anything that can be calculated, but I worry that calculating fields or counting records might be slow as opposed to storing the data in a field. If it's not then please let me know, I just want to learn about when to use either method. On a small scale I guess it wouldn't matter either way, but apps like Facebook, would they really count the amount of friends you have every time someone views your profile or would they just store it as a field? I'd appreciate any responses to both of these scenarios, and any resource that might explain the benefits of calculating vs storing. Thanks in advance, Christian

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  • Howto see if form fields are identical in Zend framework

    - by atjepatatje
    Hi there, In Zend Framework (1.10) i want to check if two input fields are identical I have the following code in my form: $this->addElement('password', 'password', array( 'label' => 'Wachtwoord:', 'required' => true ) ); $this->addElement('password', 'verifypassword', array( 'label' => 'Bevestig wachtwoord:', 'required' => true, ) ); I already tryed the "identical" validator, but I did'nt got it to work.

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  • Drupal show / hide fields in view

    - by SteD
    I would like to show / hide certain fields in my Drupal view accordingly to the user role. Provided I can only have this view to work with, how can I achieve this programmatically or there's some settings that I am not aware of in Drupal. P/S: I am aware of the access settings under basic settings in View but that would restrict access to the whole view, not field level.

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  • Binding of JText fields value to Info Class

    - by Faizan Ahmed
    Is there any way to automatic binding of Swing JTextFields to Info Class. e.g private JTextField receiptId; private JTextField Id; public class Info { private string receiptId; private String id; // Getters and Setters } Is there any way when I entered values from Swing page then automatically values bind with my Info class? After that I can pass my Info object to other classes instead of sending all Text Fields.

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  • Adding fields to user registration in Mediawiki

    - by boogie
    Hi, I've been Googling a lot, but I just can't figure out how to add a couple fields to user registration. By default Mediawiki only asks for username, password and real name. I noticed that form is a template under /includes/templates/UserLogin.php, but I don't want to modify that file to make the changes. What is the correct way to do that?

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  • Working with fields which can mutate or be new instances altogether

    - by dotnetdev
    Structs are usually used for immutable data, eg a phone number, which does not mutate, but instead you get a new one (eg the number 000 becoming 0001 would mean two seperate numbers). However, pieces of information like Name, a string, can either mutate (company abc changing its name to abcdef, or being given a new name like def). For fields like this, I assume they should reside in the mutable class and not an immutable structure? My way of structuring code is to have an immutable concept, like Address (any change is a new address completely), in a struct and then reference it from a class like Customer, since Customer always has an address. So I would put CompanyName, or Employer, in the class as it is mutable. But a name can either mutate and so be the same 1 instance, or a new name setup and while the company still owning the first name too. Would the correct pattern for assigning a new instance (eg a new company name but the old name still owned by the company) be?: string name = ""; string newName = new string(); newName = "new"; name = newName; And a mutation just the standard assignment pattern? Thanks

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  • "Finding" an object instance of a known class?

    - by Sean C
    My first post here (anywhere for that matter!), re. Cocoa/Obj-C (I'm NOT up to speed on either, please be patient!). I hope I haven't missed the answer already, I did try to find it. I'm an old-school procedural dog (haven't done any programming since the mid 80's, so I probably just can't even learn new tricks), but OOP has my head spinning! My question is: is there any means at all to "discover/find/identify" an instance of an object of a known class, given that some OTHER unknown process instantiated it? eg. somthing that would accomplish this scenario: (id) anObj = [someTarget getMostRecentInstanceOf:[aKnownClass class]]; for that matter, "getAnyInstance" or "getAllInstances" might do the trick too. Background: I'm trying to write a plugin for a commercial application, so much of the heavy lifting is being done by the app, behind the scenes. I have the SDK & header files, I know what class the object is, and what method I need to call (it has only instance methods), I just can't identify the object for targetting. I've spent untold hours and days going over Apples documentation, tutorials and lots of example/sample code on the web (including here at Stack Overflow), and come up empty. Seems that everything requires a known target object to work, and I just don't have one. Since I may not be expressing my problem as clearly as needed, I've put up a web page, with diagram & working sample pages to illustrate: http://www.nulltime.com/svtest/index.html Any help or guidance will be appreciated! Thanks.

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  • Javascript Instance Variable Syntax (AJAX page refresh)

    - by Rosarch
    I'm having difficulty with Javascript instance variables. I'm trying to make an easy way to refresh the chat page, looking for new messages. The AJAX call supplies a mid, or the lowest message id to be returned. This allows the call to only ask for the most recent messages, instead of all of them. MessageRefresher.prototype._latest_mid; function MessageRefresher(latest_mid) { this._latest_mid = latest_mid; // it thinks `this` refers to the MessageRefresher object } MessageRefresher.prototype.refresh = function () { refreshMessages(this._latest_mid); // it thinks `this` refers to the window this._latest_mid++; } function refreshMessages(latest_mid) { $.getJSON('API/read_messages', { room_id: $.getUrlVar('key'), mid: latest_mid }, function (messages) { for (var i = 0; i < messages[0].length; i++) { var newChild = sprintf("<li>%s: %s</li>", messages[1][i], messages[0][i]); $("#messages").append(newChild); } }); var messageRefresher = new MessageRefresher(0); setInterval(messageRefresher.refresh, 1000); This results in all the messages being printed out, over and over again. I know it has other bugs, but the main issue I'm trying to work out right now is the use of the instance variable. Or is there another way I should be going about doing this?

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  • How can I order fields in Django ModelForm?

    - by joozek
    I have an 'order' Model: class Order(models.Model): date_time=models.DateTimeField() # other stuff And I'm using Django ModelForm class to render a form, but I want to display date and time widgets separately. I've came up with this: class Form(forms.ModelForm): class Meta: model = Order exclude = ('date_time',) date = forms.DateField() time = forms.TimeField() The problem is that I want to put these fields somewhere between 'other stuff'

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  • Submit pdf form fields to a HTTP POST request

    - by Josjojo
    I've made a pdf form in Adobe Acrobat. Now I want to make a button that submits the form to a HTTP POST request. I have searched for about 4 hours, but I have not found an example to do this. Here I read that it is possible to send the pdf form fields with a HTTP submission, but there's also no example given: http://acrobatusers.com/tutorials/form-submit-e-mail-demystified I'm looking for a JavaScript example that I can link to the submit button.

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  • multiple search fields

    - by user234194
    What will be the best approach if I have search fields for 20 or more and any combination should be valid. Is there any special way to do it in openJPA or native SQL is better. Any idea would be helpful.Thanks.

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  • multiple search fields

    - by user234194
    What will be the best approach if I have search fields for 20 or more and any combination should be valid. Is there any special way to do it in openJPA or native SQL is better. Any idea would be helpful.Thanks.

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  • text fields and PHP

    - by moustafa
    Does anyone know if it's possible to have several text fields that place the data into different spots in the same web page. If needed I could just use two pages, it doesn't really matter. I've heard this requires a PHP script, but I'm not sure how to set this up.

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  • some fields of "content//sms/"

    - by soclose
    Hi, I query "content//sms/" and don't know what some fields are. They are - Thread ID Protocol Status Reply_Path_Present Service_Center I check them in LogCat. I find them like below Thread ID : 1 to 6 etc.. Protocol : null / 0 Status : -1 Reply_Path_Present : null / 0 Service_Center : null Please tell me what they are.

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  • drupal rules module - add fields to email

    - by bert
    I am looking for the syntax to add node fields to the body of an email. Examples I looked at indicate the the format is: [content_type:content_type_title] However my email arrives with just the string : [content_type:content_type_title] Even better would be a PHP snippet that loads the node and dumps filed title and filed value into the body of the message.

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  • MemoryStream instance timing help

    - by rod
    Hi All, Is it ok to instance a MemoryStream at the top of my method, do a bunch of stuff to it, and then use it? For instance: public static byte[] TestCode() { MemoryStream m = new MemoryStream(); ... ... whole bunch of stuff in between ... ... //finally using(m) { return m.ToArray(); } } Updated code public static byte[] GetSamplePDF() { using (MemoryStream m = new MemoryStream()) { Document document = new Document(); PdfWriter.GetInstance(document, m); document.Open(); PopulateTheDocument(document); document.Close(); return m.ToArray(); } } private static void PopulateTheDocument(Document document) { Table aTable = new Table(2, 2); aTable.AddCell("0.0"); aTable.AddCell("0.1"); aTable.AddCell("1.0"); aTable.AddCell("1.1"); document.Add(aTable); for (int i = 0; i < 20; i++) { document.Add(new Phrase("Hello World, Hello Sun, Hello Moon, Hello Stars, Hello Sea, Hello Land, Hello People. ")); } } My point was to try to reuse building the byte code. In other words, build up any kind of document and then send it to TestCode() method.

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