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  • How to update GUI thread/class from worker thread/class?

    - by user315182
    First question here so hello everyone. The requirement I'm working on is a small test application that communicates with an external device over a serial port. The communication can take a long time, and the device can return all sorts of errors. The device is nicely abstracted in its own class that the GUI thread starts to run in its own thread and has the usual open/close/read data/write data basic functions. The GUI is also pretty simple - choose COM port, open, close, show data read or errors from device, allow modification and write back etc. The question is simply how to update the GUI from the device class? There are several distinct types of data the device deals with so I need a relatively generic bridge between the GUI form/thread class and the working device class/thread. In the GUI to device direction everything works fine with [Begin]Invoke calls for open/close/read/write etc. on various GUI generated events. I've read the thread here (How to update GUI from another thread in C#?) where the assumption is made that the GUI and worker thread are in the same class. Google searches throw up how to create a delegate or how to create the classic background worker but that's not at all what I need, although they may be part of the solution. So, is there a simple but generic structure that can be used? My level of C# is moderate and I've been programming all my working life, given a clue I'll figure it out (and post back)... Thanks in advance for any help.

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  • Java: is Exception class thread-safe?

    - by Vilius Normantas
    As I understand, Java's Exception class is certainly not immutable (methods like initCause and setStackTrace give some clues about that). So is it at least thread-safe? Suppose one of my classes has a field like this: private final Exception myException; Can I safely expose this field to multiple threads? I'm not willing to discuss concrete cases where and why this situation could occur. My question is more about the principle: can I tell that a class which exposes field of Exception type is thread-safe? Another example: class CustomException extends Exception { ... } Is this class thread-safe?

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  • Problems with type and ext attribute of artifact

    - by user315228
    Hi, I have following definition in ivy.xml <dependency org="southbeach" name="ego" rev="4.3.1" conf="properties->asterik" > <artifact name="ego" type="conf" ext="conf" conf="properties->asterik"/> </dependency> I have files with either extension conf or properties which i need at runtime, in ivysettings.xml, i have following: <filesystem name="privateFSa"> <artifact pattern="${localRepositoryLocation}/[artifact].[ext]" /> </filesystem> It always tries to look for ego.jar instead of ego.conf. can please somebody shed light on this? am i doing something wrong or ivy just supports tar,zip,gz, jar and not properties or conf files? I did workaround for now in ivysettings.xml <filesystem name="privateFSa"> <artifact pattern="${localRepositoryLocation}/[artifact].conf" /> </filesystem> but this doesnt looks good to hardcode conf there. Thanks, Almas

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  • How to add a reference to my Web Service Proxy from a Custom Class

    - by coffeeaddict
    I'm creating a custom class to abstract out some of the repeated SOAP header work. I want to reference a Web Service Reference I just created in my custom class so I can create an instance of it. How do I reference it? Notice I said I am trying to reference a Web Service "reference" (right click in VS and I added a "Web Service Reference" not a "Web Service"). So I'm trying to create an instance of that Proxy class that was created in MyCustomClass.cs

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  • C#: Problem trying to resolve a class when two namespaces are similar

    - by rally25rs
    I'm running into an issue where I can't make a reference to a class in a different namespace. I have 2 classes: namespace Foo { public class Class1 { ... } } namespace My.App.Foo { public class Class2 { public void SomeMethod() { var x = new Foo.Class1; // compile error! } } } The compile error is: The type or namespace name 'Class1' does not exist in the namespace 'My.App.Foo' In this situation, I can't seem to get Visual Studio to recognize that "Foo.Class1" refers to the first class. If I mouse-over "Foo", it shows that its trying to resolve that to "My.App.Foo.Class1" If I put the line: using Foo; at the top of the .cs file that contains Class2, then it also resolves that to "My.App.Foo". Is there some trick to referencing the right "Foo" namespace without just renaming the namespaces so they don't conflict? Both of these namespaces are in the same assembly.

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  • Any solution or programming tips for Inner class?

    - by huahsin68
    Hi, I'm having some toubt here. Hope you guys can share out some programming tips. Just curious to know whether is it a good programming practice if I do something like the code below. class Outer { public: class Inner { public: Inner() {} } Outer() {} }; I have been doing this for structure where I only want my structure to be expose to my class instead of global. But the case is different here, I am using a class now? Have you guys facing such a situation before? Very much appreciated on any advice from you ;)

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  • grabbing layer contents in a class

    - by Mike
    I have a custom UIImageView class that creates thumbnails (UIImageView) and each thumbnail has a label. The label is created by another class. The label class creates a UIImageView and a UITextView on top of it. This is the init object class' init method: - (id)initWithFrame:(CGRect)frame { if ([super initWithFrame:frame] == nil) { return nil; } CGRect myFrame = CGRectMake(0, 0, 100, 100); myLabel = [[myLabelClass alloc] initWithFrame: myFrame]; //myLabelClass is a UIImageView based class [myLabel setCenter:CGPointMake(50, 50)]; [self addSubview: myLabel]; return self; } So, I have this MAIN VIEW CONTROLLER | |___ UIImageView WITH LABEL | |____ label background (UIView) |____ UITEXTVIEW (text) Now I want to write the contents of all these 3 components to a quartz context. I need to write using drawInRect, because I need to write the full object to a precise location. I expected object.layer.contents to be the image equivalent to these 3 "layers" flattened, in other words, the object's image, the label background and the label text, as it would if I created these 3 objects in Photoshop and flatten the composition. I also expect object.myLabel.layer.contents to contains the rendered contents of the UITextView over the label background. The problem is that when I use UIImage *myImage = [UIImage imageWithCGImage:objecto.myLabel.layer.contents]; [myImage drawInRect:CGRectMake(0, 0, 100, 100)]; I get nothing. How can I obtain a "flattened" image resultant to the full object (including its subviews)? thanks

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  • Objective-C subclass and base class casting

    - by ryanjm.mp
    I'm going to create a base class that implements very similar functions for all of the subclasses. This was answered in a different question. But what I need to know now is if/how I can cast various functions (in the base class) to return the subclass object. This is both for a given function but also a function call in it. (I'm working with CoreData by the way) As a function within the base class (this is from a class that is going to become my subclass) +(Structure *)fetchStructureByID:(NSNumber *)structureID inContext:(NSManagedObjectContext *)managedObjectContext {...} And as a function call within a given function: Structure *newStructure = [Structure fetchStructureByID:[currentDictionary objectForKey:@"myId"]]; inContext:managedObjectContext]; Structure is one of my subclasses, so I need to rewrite both of these so that they are "generic" and can be applied to other subclasses (whoever is calling the function). How do I do that? Update: I just realized that in the second part there are actually two issues. You can't change [Structure fetch...] to [self fetch...] because it is a class method, not an instance method. How do I get around that too?

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  • PDO using singleton stored as class properity

    - by Misiur
    Hi again. OOP drives me crazy. I can't move PDO to work. Here's my DB class: class DB extends PDO { public function &instance($dsn, $username = null, $password = null, $driver_options = array()) { static $instance = null; if($instance === null) { try { $instance = new self($dsn, $username, $password, $driver_options); } catch(PDOException $e) { throw new DBException($e->getMessage()); } } return $instance; } } It's okay when i do something like this: try { $db = new DB(DB_TYPE.':host='.DB_HOST.';dbname='.DB_NAME, DB_USER, DB_PASS); } catch(DBException $e) { echo $e->getMessage(); } But this: try { $db = DB::instance(DB_TYPE.':host='.DB_HOST.';dbname='.DB_NAME, DB_USER, DB_PASS); } catch(DBException $e) { echo $e->getMessage(); } Does nothing. I mean, even when I use wrong password/username, I don't get any exception. Second thing - I have class which is "heart" of my site: class Core { static private $instance; public $db; public function __construct() { if(!self::$instance) { $this->db = DB::instance(DB_TYPE.':hpost='.DB_HOST.';dbname='.DB_NAME, DB_USER, DB_PASS); } return self::$instance; } private function __clone() { } } I've tried to use "new DB" inside class, but this: $r = $core->db->query("SELECT * FROM me_config"); print_r($r->fetch()); Return nothing. $sql = "SELECT * FROM me_config"; print_r($core->db->query($sql)); I get: PDOStatement Object ( [queryString] => SELECT * FROM me_config ) I'm really confused, what am I doing wrong?

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  • Why are my ActiveRecord class instance variables disappearing after the first request in development

    - by Paul C
    I have a class instance variable on one of my AR classes. I set its value at boot with an initializer and, after that, never touch it again except to read from it. In development mode, this value disappears after the first request to the web server. However, when running tests, using the console or running the production server this does not happen. # The AR class class Group < ActiveRecord::Base class << self attr_accessor :path end end # The initializer Group.path = File.join(RAILS_ROOT, "public", "etc") # First request in a view %p= Group.path #=> "/home/rails/app/public/etc" # Second request in a view %p= Group.path #=> nil Is there something about development mode that nukes instance variables from classes with each request? If so, is there a way to disable this for specific variables or classes?

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  • MySQL: Ignore the timestamp attribute

    - by Nique
    I have a timestamp column in my database, and i use it for almost every field, but now, i just want to update the hit counter.. and i do not want to update the timestamp column with it. I use the timestamp field to see the last 'content' update. Not for every hit. Is it possible to let mysql stop updating the timestamp column for just one query?

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  • Sharing common class in wcf project

    - by Saint
    class MyCommonClass { //properties } This class should be accessible in service project wcf-client project the other for which they are references. In this common project I can't generate servicereferences. I think, I could don't generate MyCommonClass in ServiceReferences but how to mark class to be nonserializable? In properties there's IgnoreDataMemberAttribute. I tried also reuse MyCommonClass type located in common project, but it is still generated

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  • Change storyboard UIImageView to own class with backgroundcolor

    - by Thomas
    I want to draw the background image on my own, so I decided to implement a UIImageView class and connect it in the Storyboard. As first task I just want to set the backgroundcolor of the image on my own, but it's never shown. Image just stays blank. That's the class: class FirstBackgroundImage : UIImageView { required init(coder aDecoder: NSCoder) { super.init(coder: aDecoder) self.backgroundColor = UIColor.redColor() } override init() { super.init() self.backgroundColor = UIColor.redColor() } override required init(image: UIImage!) { super.init(image: image) self.backgroundColor = UIColor.redColor() } } That's how i connected it:

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  • derived class as default argument g++

    - by Vincent
    Please take a look at this code: template<class T> class A { class base { }; class derived : public A<T>::base { }; public: int f(typename A<T>::base& arg = typename A<T>::derived()) { return 0; } }; int main() { A<int> a; a.f(); return 0; } Compiling generates the following error message in g++: test.cpp: In function 'int main()': test.cpp:25: error: default argument for parameter of type 'A<int>::base&' has type 'A<int>::derived' The basic idea (using derived class as default value for base-reference-type argument) works in visual studio, but not in g++. I have to publish my code to the university server where they compile it with gcc. What can I do? Is there something I am missing?

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  • C# Pass Generics At Runtime

    - by TheCloudlessSky
    I have a method like the following: public IEnumerable<T> GetControls<T>() : where T : ControlBase { // removed. } I then created a class: public class HandleBase<TOwner> : ControlBase : TOwner { // Removed } I'd like to be able to call GetControls<HandleBase<this.GetType()>>; where it would use the type of THIS class to pass to the HandleBase. This would in essentially get all HandleBase that have an owner of THIS type. How can I achieve this?

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  • In what package should a "Settings" class be?

    - by Tom
    I've in the middle of building an application but found myself too easily creating new packages without keeping the project's structure in mind. Now, I'm trying to redo the whole project structure on paper first. I am using a Settings class with public properties, accessed as settings for several other classes around the project. Now, since this Settings class applies for the whole project, I am unsure if it should be packaged and if so, in what kind of package should it exist? Or should it be in the root (the default package) with the main application class? I've been thinking about putting it in my utils package, then again I don't think it really is an utlity. Any strategies on how to decide on such package structure for example for a Settings class?

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  • getting attribute as column headers

    - by edwards
    I have the following XML: <DEVICEMESSAGES> <VERSION xml="1" checksum="" revision="0" envision="33050000" device="" /> <HEADER id1="0001" id2="0001" content="Nasher[&lt;messageid&gt;]: &lt;!payload&gt;" /> <MESSAGE level="7" parse="1" parsedefvalue="1" tableid="15" id1="24682" id2="24682" eventcategory="1003010000" content="Access to &lt;webpage&gt; was blocked due to its category (&lt;info&gt; by &lt;hostname&gt;)" /> </DEVICEMESSAGES> I am using the following XSLT: <xsl:stylesheet version="2.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform"> <xsl:output method="text"/> <xsl:strip-space elements="*"/> <xsl:template match="DEVICEMESSAGES/HEADERS"> <xsl:value-of select="@id2"/>,<xsl:text/> <xsl:value-of select="@content"/>,<xsl:text/> <xsl:text>&#xa;</xsl:text> </xsl:template> </xsl:stylesheet> I get the following output: 0001 , Nasher[<messageid>]: <!payload> whereas I need the column headings, too: id2, content 0001 , Nasher[<messageid>]: <!payload>

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  • Obtaining reference to Class instance by string name - VB.NET

    - by Jeff Williams
    Is it possible using Reflection or some other method to obtain a reference to a specific class instance from the name of that class instance? For example the framework for the applications i develop heavily uses public class instances such as: Public bMyreference as MyReference = new MyReference Then throughout the application bMyReference is used by custom controls and code. One of the properties of the custom controls is the "FieldName" which references a Property in these class instances (bMyReference.MyField) as a string. What i would like to be able to do is analyze this string "bMyReference.MyField" and then refer back to the actual Instance/Property. In VB6 I would use an EVAL or something simular to convert the string to an actual object but this obviously doesn't work in VB.net What I'm picturing is something like this Dim FieldName as String = MyControl.FieldName ' sets FielName to bMyReference.MyField Dim FieldObject() as String = FieldName.Split(".") ' Split into the Object / Property Dim myInstance as Object = ......... ' Obtain a reference to the Instance and set as myInstance Dim myProperty = myInstance.GetType().GetProperty(FieldObject(1))

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  • StructureMap - Injecting a dependency into a base class?

    - by David
    In my domain I have a handful of "processor" classes which hold the bulk of the business logic. Using StructureMap with default conventions, I inject repositories into those classes for their various IO (databases, file system, etc.). For example: public interface IHelloWorldProcessor { string HelloWorld(); } public class HelloWorldProcessor : IHelloWorldProcessor { private IDBRepository _dbRepository; public HelloWorldProcessor(IDBRepository dbRepository) { _dbRepository = dbrepository; } public string HelloWorld(){ return _dbRepository.GetHelloWorld(); } } Now, there are some repositories that I'd like to be available to all processors, so I made a base class like this: public class BaseProcessor { protected ICommonRepository _commonRepository; public BaseProcessor(ICommonRepository commonRepository) { _commonRepository = commonRepository; } } But when my other processors inherit from it, I get a compiler error on each one saying that there's no constructor for BaseProcessor which takes zero arguments. Is there a way to do what I'm trying to do here? That is, to have common dependencies injected into a base class that my other classes can use without having to write the injections into each one?

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  • Base class with abstract subclasses in C# ?

    - by Nick Brooks
    public abstract class Request { public class Parameters { //Threre are no members here //But there should be in inherited classes } public Request() { parameters = new Parameters(); } public Parameters parameters; } Two questions: How do I make it so I can add stuff to the constructor but the original constructor will still be executed? How do I make it so the subclasses can add members to the Parameters class?

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  • NSSortDescriptor for NSFetchRequestController causes crash when value of sorted attribute is changed

    - by AJ
    I have an Core Data Entity with a number of attributes, which include amount(float), categoryTotal(float) and category(string) The initial ViewController uses a FethchedResultsController to retrieve the entities, and sorts them based on the category and then the categoryTotal. No problems so far. NSManagedObjectContext *moc = [self managedObjectContext]; NSEntityDescription *entityDescription = [NSEntityDescription entityForName:@"Transaction" inManagedObjectContext:moc]; NSFetchRequest *request = [[[NSFetchRequest alloc] init] autorelease]; [request setEntity:entityDescription]; NSPredicate *predicate = [NSPredicate predicateWithFormat:@"(dateStamp >= %@) AND (dateStamp =< %@)", startDate, endDate]; [request setPredicate:predicate]; NSSortDescriptor *sortByCategory = [[NSSortDescriptor alloc] initWithKey:@"category" ascending:sortOrder]; NSSortDescriptor *sortByTotals = [[NSSortDescriptor alloc] initWithKey:@"categoryTotal" ascending:sortOrder]; NSArray *sortDescriptors = [[NSArray alloc] initWithObjects:sortByTotals, sortByCategory, nil]; [request setSortDescriptors:sortDescriptors]; NSFetchedResultsController *aFetchedResultsController = [[NSFetchedResultsController alloc] initWithFetchRequest:request managedObjectContext:managedObjectContext sectionNameKeyPath:@"category" cacheName:nil]; aFetchedResultsController.delegate = self; self.fetchedResultsController = aFetchedResultsController; On selecting a row (tableView:didSelectRowAtIndexPath), another view controller is loaded that allows editing of the amount field for the selected entity. Before returning to the first view, categoryTotal is updated by the new ‘amount’. The problem comes when returning to the first view controller, the app bombs with *Serious application error. Exception was caught during Core Data change processing: Invalid update: invalid number of rows in section 0. The number of rows contained in an existing section after the update (1) must be equal to the number of rows contained in that section before the update (1), plus or minus the number of rows inserted or deleted from that section (0 inserted, 1 deleted). with userInfo (null) Program received signal: “EXC_BAD_ACCESS”.* This seems to be courtesy of NSSortDescriptor *sortByTotals = [[NSSortDescriptor alloc] initWithKey:@"categoryTotal" ascending:sortOrder]; If I remove this everything works as expected, but obviously without the sorting I want. I'm guessing this is to do with the sorting order changing due to categoryTotal changing (deletion / insertion) but can't find away fix this. I've verified that values are being modified correctly in the second view, so it appears down to the fetchedResultsController being confused. If the categoryAmount is changed to one that does not change the sort order, then no error is generated I'm not physically changing (ie deleting) the number of items the fetchedResultsController is returning ... the only other issue I can find that seem to generate this error Any ideas would be most welcome Thanks, AJ

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  • Java - Could not find the main class?

    - by asmo
    I'm having a hard-time with a Java error. I'm getting this when double-clicking on my compiled project Jar file in order to run it: Could not find the main class: testPackage.testFrame. Program will exit. However, my main class is cleary defined in the project properties. Furthermore, everything works fine when I run the project directly from NetBeans. I'm using the ip2c.jar third-party library to determine countries from IP addresses. If I comment the class that is using the ip2c.jar file, I don't get the error. How can a third-party library be preventing the JVM from finding my main class?

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