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  • Alternatives to static methods on interfaces for enforcing consistency

    - by jayshao
    In Java, I'd like to be able to define marker interfaces, that forced implementations to provide static methods. For example, for simple text-serialization/deserialization I'd like to be able to define an interface that looked something like this: public interface TextTransformable<T>{ public static T fromText(String text); public String toText(); Since interfaces in Java can't contain static methods though (as noted in a number of other posts/threads: here, here, and here this code doesn't work. What I'm looking for however is some reasonable paradigm to express the same intent, namely symmetric methods, one of which is static, and enforced by the compiler. Right now the best we can come up with is some kind of static factory object or generic factory, neither of which is really satisfactory. Note: in our case our primary use-case is we have many, many "value-object" types - enums, or other objects that have a limited number of values, typically carry no state beyond their value, and which we parse/de-parse thousands of time a second, so actually do care about reusing instances (like Float, Integer, etc.) and its impact on memory consumption/g.c. Any thoughts?

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  • WCF Async callback setup for polled device

    - by Mark Pim
    I have a WCF service setup to control a USB fingerprint reader from our .Net applications. This works fine and I can ask it to enroll users and so on. The reader allows identification (it tells you that a particular user has presented their finger, as opposed to asking it to verify that a particular user's finger is present), but the device must be constantly polled while in identification mode for its status - when a user is detected the status changes. What I want is for an interested application to notify the service that it wants to know when a user is identified, and provide a callback that gets triggered when this happens. The WCF service will return immediately and spawn a thread in the background to continuously poll the device. This polling could go on for hours at a time if no one tries to log in. What's the best way to acheive this? My service contract is currently defined as follows: [ServiceContract (CallbackContract=typeof(IBiometricCallback))] public interface IBiometricWcfService { ... [OperationContract (IsOneWay = true)] void BeginIdentification(); ... } public interface IBiometricCallback { ... [OperationContract(IsOneWay = true)] void IdentificationFinished(int aUserId, string aMessage, bool aSuccess); ... } In my BeginIdentification() method can I easily spawn a worker thread to poll the device, or is it easier to make the WCF service asynchronous?

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  • What's a good way to provide additional decoration/metadata for Python function parameters?

    - by Will Dean
    We're considering using Python (IronPython, but I don't think that's relevant) to provide a sort of 'macro' support for another application, which controls a piece of equipment. We'd like to write fairly simple functions in Python, which take a few arguments - these would be things like times and temperatures and positions. Different functions would take different arguments, and the main application would contain user interface (something like a property grid) which allows the users to provide values for the Python function arguments. So, for example function1 might take a time and a temperature, and function2 might take a position and a couple of times. We'd like to be able to dynamically build the user interface from the Python code. Things which are easy to do are to find a list of functions in a module, and (using inspect.getargspec) to get a list of arguments to each function. However, just a list of argument names is not really enough - ideally we'd like to be able to include some more information about each argument - for instance, it's 'type' (high-level type - time, temperature, etc, not language-level type), and perhaps a 'friendly name' or description. So, the question is, what are good 'pythonic' ways of adding this sort of information to a function. The two possibilities I have thought of are: Use a strict naming convention for arguments, and then infer stuff about them from their names (fetched using getargspec) Invent our own docstring meta-language (could be little more than CSV) and use the docstring for our metadata. Because Python seems pretty popular for building scripting into large apps, I imagine this is a solved problem with some common conventions, but I haven't been able to find them.

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  • Run-time error 459 when using WithEvents with a class that implements another

    - by Ken Keenan
    I am developing a VBA project in Word and have encountered a problem with handling events when using a class that implements another. I define an empty class, IMyInterface: Public Sub Xyz() End Sub Public Event SomeEvent() And a class, MyClass that implements the above: Implements IMyInterface Public Event SomeEvent() Public Sub Xyz() ' ... code ... RaiseEvent SomeEvent End Sub Private Sub IMyInterface_Xyz() Xyz End Sub If I create a third class, OtherClass, that declares a member variable with the type of the interface class: Private WithEvents mMy As IMyInterface and try to initialize this variable with an instance of the implementing class: Set mMy = New MyClass I get a run-time error '459': This component doesn't support this set of events. The MSDN page for this error message states: "You tried to use a WithEvents variable with a component that can't work as an event source for the specified set of events. For example, you may be sinking events of an object, then create another object that Implements the first object. Although you might think you could sink the events from the implemented object, that isn't automatically the case. Implements only implements an interface for methods and properties." The above pretty much sums up what I'm trying to do. The wording, "that isn't automatically the case", rather than "this is flat-out impossible", seems to suggest that there is some bit of manual work I need to do to get it to work, but it doesn't tell me what! Does anybody know if this is possible in VBA?

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  • Qt/C++ - confused about caller/callee, object ownership

    - by Isabel
    I am creating a GUI to manipulate a robot arm. The location of the arm can be described by 6 floats (describing the positions of the various arm joints. The interface consists of a QGraphicsView with a diagram of the arm (which can be clicked to change the arm position - adjusting the 6 floats). The interface also has 6 lineEdit boxes, to also adjust those values separately. When the graphics view is clicked, and when the line edit boxes are changed, I'd like the line edit boxes / graphics view to stay in synchronisation. This brings me to confusion about how to store the 6 floats, and trigger events when they're updated. My current idea is this: The robot arm's location should be represented by a class, RobotArmLocation. Objects of this class then have methods such as obj.ShoulderRotation() and obj.SetShoulderRotation(). The MainWindow has a single instance of RobotArmLocation. Next is the bit I'm more confused about, how to join everything up. I am thinking: The MainWindow has a ArmLocationChanged slot. This is signalled whenever the location object is changed. The diagram class will have a SetRobotArmLocation(RobotArmLocation &loc). When the diagram is changed, it's free to change the location object, and fire a signal to the ArmLocationChanged slot. Likewise, changing any of the text boxes will fire a signal to that ArmLocationChanged slot. The slot then has code to synchronise all the elements. This kind of seems like a mess to me, does anyone have any other suggestions? I've also thought of the following, does it have any merrit? The RobotArmLocation class has a ValueChanged slot, the diagram and textboxes can use that directly, and bypass the MainWindow directly (seems cleaner?) thanks for any wisdom!

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  • Two pass JSP page rendering

    - by dotsid
    Suppose an example. I have following interface: public interface DataSource<T> { Future<T> fetch(); } This datasource can do asynchronous data fetching. And we have following tag for using datasource in JSP: <html> <d:fetch from="${orderDS}" var="orders"> <c:foreach in="${orders}" var="order"> <div class="order"> <c:out value="${order.title}" /> </div> </c:foreach> </d:fetch> </html> So, what I want? I want JSP rendering engine to call my custom tag (FetchTag in this example) twice. On first call FetchTag will do DataSource.fetch() call and save Future locally as a object field. On second call FetchTag do Future.get() call and will be blocked until data becomes available. Is there any way to do such a thing?

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  • Passing NULL value

    - by FFXIII
    Hi. I use an instance of NSXMLParser. I store found chars in NSMutableStrings that are stored in an NSMutableDictionary and these Dicts are then added to an NSMutableArray. When I test this everything seems normal: I count 1 array, x dictionnaries and x strings. In a detailview controller file I want to show my parsed results. I call the class where everthing is stored but I get (null) returned. This is what I do (wrong): XMLParser.h @interface XMLParser : NSObject { NSMutableArray *array; NSMUtableDictionary *dictionary; NSSMutabletring *element; } @property (nonatomic, retain) NSMutableArray *array; @property (nonatomic, retain) NSMutableDictionary *dictionary; @property (nonatomic, retain) NSMutableString *element; XMLParser.m @synthesize array, dictionary, element; //parsing goes on here & works fine //so 'element' is filled with content and stored in a dict in an array //and released at the end of the file In my controller file I do this: controller.h @class XMLParser; @interface controller : UIViewController { XMLParser *aXMLParser; } @property (nonatomic, retain) XMLParser *aXMLParser; controller.m #import "XMLParser.h" @synthesize aXMLParser; - (void)viewDidLoad { NSLog(@"test array: %@", aXMLParser.array); NSLog(@"test dict: %@", aXMLParser.dictionary); NSLog(@"test element: %@", aXMLParser.element); } When I test the value of my array, a dict or an element in the XMLParser.h file I get my result. What am I doing wrong so I can't call my results in my controller file? Any help is welcome, because I'm pretty stuck right now :/

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  • Java abstract visitor - guarantueed to succeed? If so, why?

    - by disown
    I was dealing with hibernate, trying to figure out the run-time class behind proxied instances by using the visitor pattern. I then came up with an AbstractVisitable approach, but I wonder if it will always produce correct results. Consider the following code: interface Visitable { public void accept(Visitor v); } interface Visitor { public void visit(Visitable visitorHost); } abstract class AbstractVisitable implements Visitable { @Override public void accept(Visitor v) { v.visit(this); } } class ConcreteVisitable extends AbstractVisitable { public static void main(String[] args) { final Visitable visitable = new ConcreteVisitable(); final Visitable proxyVisitable = (Visitable) Proxy.newProxyInstance( Thread.currentThread().getContextClassLoader(), new Class<?>[] { Visitable.class }, new InvocationHandler() { @Override public Object invoke(Object proxy, Method method, Object[] args) throws Throwable { return method.invoke(visitable, args); } }); proxyVisitable.accept(new Visitor() { @Override public void visit(Visitable visitorHost) { System.out.println(visitorHost.getClass()); } }); } } This makes a ConcreteVisitable which inherits the accept method from AbstractVisitable. In c++, I would consider this risky, since this in AbstractVisitable could be referencing to AbstractVisitable::this, and not ConcreteVisitable::this. I was worried that the code under certain circumstances would print class AbstractVisible. Yet the code above outputs class ConcreteVisitable, even though I hid the real type behind a dynamic proxy (the most difficult case I could come up with). Is the abstract visitor approach above guaranteed to work, or are there some pitfalls with this approach? What guarantees are given in Java with respect to the this pointer?

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  • Trying to make a plugin system in C++

    - by Pirate for Profit
    I'm making a task-based program that needs to have plugins. Tasks need to have properties which can be easily edited, I think this can be done with Qt's Meta-Object Compiler reflection capabilities (I could be wrong, but I should be able to stick this in a QtPropertyBrowser?) So here's the base: class Task : public QObject { Q_OBJECT public: explicit Task(QObject *parent = 0) : QObject(parent){} virtual void run() = 0; signals: void taskFinished(bool success = true); } Then a plugin might have this task: class PrinterTask : public Task { Q_OBJECT public: explicit PrinterTask(QObject *parent = 0) : Task(parent) {} void run() { Printer::getInstance()->Print(this->getData()); // fictional emit taskFinished(true); } inline const QString &getData() const; inline void setData(QString data); Q_PROPERTY(QString data READ getData WRITE setData) // for reflection } In a nutshell, here's what I want to do: // load plugin // find all the Tasks interface implementations in it // have user able to choose a Task and edit its specific Q_PROPERTY's // run the TASK It's important that one .dll has multiple tasks, because I want them to be associated by their module. For instance, "FileTasks.dll" could have tasks for deleting files, making files, etc. The only problem with Qt's plugin setup is I want to store X amount of Tasks in one .dll module. As far as I can tell, you can only load one interface per plugin (I could be wrong?). If so, the only possible way to do accomplish what I want is to create a FactoryInterface with string based keys which return the objects (as in Qt's Plug-And-Paint example), which is a terrible boilerplate that I would like to avoid. Anyone know a cleaner C++ plugin architecture than Qt's to do what I want? Also, am I safely assuming Qt's reflection capabilities will do what I want (i.e. able to edit an unknown dynamically loaded tasks' properties with the QtPropertyBrowser before dispatching)?

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  • Class Generics break completely seperate method

    - by TheLQ
    I found a strange problem when I used class Generics Today: Setting some broke a completely separate method. Here's a small example class that illustrates the problem. This code works just fine public class Sandbox { public interface ListenerManagerTest { public Set<Listener> getListeners(); } public void setListenerManager(ListenerManagerTest listenerManager) { for (Listener curListener : listenerManager.getListeners()) return; } } Now as soon as I use class Generics, the getListeners() method returns Set<Object> instead of Set<Listener> public class Sandbox { public interface ListenerManagerTest<E extends Object> { public Set<Listener> getListeners(); } public void setListenerManager(ListenerManagerTest listenerManager) { for (Listener curListener : listenerManager.getListeners()) //Expected Listener, not Object return; } } What would cause this error? The ##java channel on Freenode said it was because of compile time candy and that I was using a raw type. But how would an raw class type break all generics in the class? And how would of worked before?

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  • Observer pattern and violation of Single Responsibility Principle

    - by Devil Jin
    I have an applet which repaints itself once the text has changed Design 1: //MyApplet.java public class MyApplet extends Applet implements Listener{ private DynamicText text = null; public void init(){ text = new DynamicText("Welcome"); } public void paint(Graphics g){ g.drawString(text.getText(), 50, 30); } //implement Listener update() method public void update(){ repaint(); } } //DynamicText.java public class DynamicText implements Publisher{ // implements Publisher interface methods //notify listeners whenever text changes } Isn't this a violation of Single Responsibility Principle where my Applet not only acts as Applet but also has to do Listener job. Same way DynamicText class not only generates the dynamic text but updates the registered listeners. Design 2: //MyApplet.java public class MyApplet extends Applet{ private AppletListener appLstnr = null; public void init(){ appLstnr = new AppletListener(this); // applet stuff } } // AppletListener.java public class AppletListener implements Listener{ private Applet applet = null; public AppletListener(Applet applet){ this.applet = applet; } public void update(){ this.applet.repaint(); } } // DynamicText public class DynamicText{ private TextPublisher textPblshr = null; public DynamicText(TextPublisher txtPblshr){ this.textPblshr = txtPblshr; } // call textPblshr.notifyListeners whenever text changes } public class TextPublisher implments Publisher{ // implements publisher interface methods } Q1. Is design 1 a SPR violation? Q2. Is composition a better choice here to remove SPR violation as in design 2.

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  • Invoking public method on a class in a different package via reflection

    - by KARASZI István
    I ran into the following problem. I have two different packages in package a I would like to call the implemented method of an interface in a package b but the implementing class has package visibility. So a simplifed code looks like this: package b; public final class Factory { public static B createB() { return new ImplB(); } public interface B { void method(); } static class ImplB implements B { public void method() { System.out.println("Called"); } } } and the Invoker: package a; import java.lang.reflect.Method; import b.Factory; import b.Factory.B; public final class Invoker { private static final Class<?>[] EMPTY_CLASS_ARRAY = new Class<?>[] {}; private static final Object[] EMPTY_OBJECT_ARRAY = new Object[] {}; public static void main(String... args) throws Exception { final B b = Factory.createB(); b.method(); final Method method = b.getClass().getDeclaredMethod("method", EMPTY_CLASS_ARRAY); method.invoke(b, EMPTY_OBJECT_ARRAY); } } When I start the program it prints out Called as expected and throws an Exception because the package visibility prohibits the calling of the discovered method. So my question is any way to solve this problem? Am I missing something in Java documentation or this is simply not possible although simply calling an implemented method is possible without reflection.

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  • iptables : how to allow incoming ftp traffic?

    - by logansama
    Hi, Still fighting my way through the jungle that is called iptables. I have managed to allow FTP access outside of our LAN: both these would work. NOTE: eth0 is the LAN interface and eth1 is the WAN interface. iptables -t filter -A FORWARD -i eth0 -p tcp --dport 20:21 -j ACCEPT or iptables -A FORWARD -i eth0 -o eth1 -p tcp --sport 20:21 --dport 1024:65535 -j ACCEPT But when i connect to a external FTP server i manage to log in and all is fine until it wishes to List the directory content. Then nothing happens as the data is blocked, due to the fact that i do not have a rule set up to allow it! (my last rule on the FORWARD chain is to block all traffic) I have tried a gazillion rules (many of which i did not understand) to try and allow the FTP traffic back through my server. One such rule for example was: iptables -A FORWARD -i eth1 -o eth0 -p tcp --sport 20:21 --dport 1024:65535 -j ACCEPT But i cannot get the List to work. It just times out after a while. Would anyone perhaps know how to build a rule which would allow FTP to List / allow such traffic back? Or have a link to sources i could work through? Thank you,

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  • Can someone explain the declaration of these java generic methods?

    - by Tony Giaccone
    I'm reading "Generics in the Java Programming Language" by Gilad Bracha and I'm confused about a style of declaration. The following code is found on page 8: interface Collection<E> { public boolean containsAll(Collection<?> c); public boolean addAll(Collection<? extends E> c); } interface Collection<E> { public <T> boolean containsAll(Collection<T> c); public <T extends E> boolean addAll(Collection<T> c); // hey, type variables can have bounds too! } My point of confusion comes from the second declaration. It's not clear to me what the purpose the <T> declaration serves in the following line: public <T> boolean containsAll(Collection<T> c); The method already has a type (boolean) associated with it. Why would you use the <T> and what does it tell the complier? I think my question needs to be a bit more specific. Why would you write: public <T> boolean containsAll(Collection<T> c); vs public boolean containsAll(Collection<T> c); It's not clear to me, what the purpose of <T> is, in the first declaration of containsAll.

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  • Concise description of how .h and .m files interact in objective c?

    - by RJ86
    I have just started learning objective C and am really confused how the .h and .m files interact with each other. This simple program has 3 files: Fraction.h #import <Foundation/NSObject.h> @interface Fraction : NSObject { int numerator; int denominator; } - (void) print; - (void) setNumerator: (int) n; - (void) setDenominator: (int) d; - (int) numerator; - (int) denominator; @end Fraction.m #import "Fraction.h" #import <stdio.h> @implementation Fraction -(void) print { printf( "%i/%i", numerator, denominator ); } -(void) setNumerator: (int) n { numerator = n; } -(void) setDenominator: (int) d { denominator = d; } -(int) denominator { return denominator; } -(int) numerator { return numerator; } @end Main.m #import <stdio.h> #import "Fraction.h" int main(int argc, char *argv[]) { Fraction *frac = [[Fraction alloc] init]; [frac setNumerator: 1]; [frac setDenominator: 3]; printf( "The fraction is: " ); [frac print]; printf( "\n" ); [frac release]; return 0; } From what I understand, the program initially starts running the main.m file. I understand the basic C concepts but this whole "class" and "instance" stuff is really confusing. In the Fraction.h file the @interface is defining numerator and denominator as an integer, but what else is it doing below with the (void)? and what is the purpose of re-defining below? I am also quite confused as to what is happening with the (void) and (int) portions of the Fraction.m and how all of this is brought together in the main.m file. I guess what I am trying to say is that this seems like a fairly easy program to learn how the different portions work with each other - could anyone explain in non-tech jargon?

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  • In M-V-VM where does my code go?

    - by Nate Bross
    So, this is a pretty basic question I hope. I have a web service that I've added through Add Service Reference. It has some methods to get list and get detail of a perticular table in my database. What I'm trying to do is setup a UI as follows: App Load Load service proxy Call the GetList(); method display the results in a ListBox control User Double Clicks item in ListBox, display a modal dialog with a "detail" view I'm extremely new to using MVVM, so any help would be greatly appreciated. Additional information: // Service Interface (simplification): interface IService { IEnumerable<MyObject> GetList(); MyObject GetDetail(int id); } // Data object (simplification) class MyObject { public int ID { get; set; } public string Name { get; set; } } I'm thinking I should have something like this: MainWindow MyObjectViewUserControl Displays list Opens modal window on double click Specific Questions: What would my ViewModel class look like? Where does the code to handle the double click go? Inside the UserControl? Sorry for the long details, but I'm very new to the whole thing and I'm not educated enough to ask the right questions. I checked out the MVVM Sample from wpf.codeplex.com and something isn't quite clicking for me yet, because it seems very confusing.

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  • WCF Multiple contracts with duplicate method names

    - by haxelit
    Hello, I have a service with multiple contracts like so. [ServiceContract] public partial interface IBusinessFunctionDAO { [OperationContract] BusinessFunction GetBusinessFunction(Int32 businessFunctionRefID); [OperationContract] IEnumerable<Project> GetProjects(Int32 businessFunctionRefID); } [ServiceContract] public partial interface IBusinessUnitDAO { [OperationContract] BusinessUnit GetBusinessUnit(Int32 businessUnitRefID); [OperationContract] IEnumerable<Project> GetProjects(Int32 businessUnitRefID); } I then explicitly implemented each one of the interfaces like so. public class TrackingTool : IBusinessFunctionDAO, IBusinessUnitDAO { BusinessFunction IBusinessFunctionDAO.GetBusinessFunction(Int32 businessFunctionRefID) { // implementation } IEnumerable<Project> IBusinessFunctionDAO.GetProjects(Int32 businessFunctionRefID) { // implementation } BusinessUnit IBusinessUnitDAO.GetBusinessUnit(Int32 businessUnitRefID) { // implementation } IEnumerable<Project> IBusinessUnitDAO.GetProjects(Int32 businessUnitRefID) { // implementation } } As you can see I have two GetProjects(int) methods, but each one is implemented explicitly so this compiles just fine and is perfectly valid. The problem arises when I actually start this as a service. It gives me an error staying that TrackingTool already contains a definition GetProject. While it is true, it is part of a different service contract. Does WCF not distinguish between service contracts when generating the method names ? Is there a way to get it to distinguish between the service contracts ? My App.Config looks like this <service name="TrackingTool"> <endpoint address="BusinessUnit" contract="IBusinessUnitDAO" /> <endpoint address="BusinessFunction" contract="IBusinessFunctionDAO" /> </service> Any help would be appreciated. Thanks, Raul

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  • C# Multiple constraints

    - by John
    I have an application with lots of generics and IoC. I have an interface like this: public interface IRepository<TType, TKeyType> : IRepo Then I have a bunch of tests for my different implementations of IRepository. Many of the objects have dependencies on other objects so for the purpose of testing I want to just grab one that is valid. I can define a separate method for each of them: public static EmailType GetEmailType() { return ContainerManager.Container.Resolve<IEmailTypeRepository>().GetList().FirstOrDefault(); } But I want to make this generic so it can by used to get any object from the repository it works with. I defined this: public static R GetItem<T, R>() where T : IRepository<R, int> { return ContainerManager.Container.Resolve<T>().GetList().FirstOrDefault(); } This works fine for the implementations that use an integer for the key. But I also have repositories that use string. So, I do this now: public static R GetItem<T, R, W>() where T : IRepository<R, W> This works fine. But I'd like to restrict 'W' to either int or string. Is there a way to do that? The shortest question is, can I constrain a generic parameter to one of multiple types?

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  • ZendX Jquery Decorator

    - by iJD
    How use partial decorator in Jquery Element I use this code for Form Element: $title = new Zend_Form_Element_Text('title'); $title->setRequired(true) ->setAttrib('class', 'inputbox') ->setLabel('Title'); $title->viewScript = 'RegElement.phtml'; $title->setDecorators( array( array('ViewScript', array('class' => 'RegElement')) ) ); But when i use Jquery Element i dont know how implement it: $datePicker = new ZendX_JQuery_Form_Element_DatePicker( "datePicker1", array("label" => "Date:") ); $datePicker->viewScript = 'RegElement.phtml'; $datePicker->setDecorators( array( array('ViewScript', array('class' => 'RegElement')) ) ); //views/scripts/RegElement.phtml <li class="row <?php echo $this->class ?>"> <div class="cont-error"> <?php echo $this->formErrors($this->element->getMessages()); ?> </div> <div class="rowfields"> <?php echo $this->formLabel($this->element->getName(), $this->element->getLabel()) ?> <?php echo $this->{$this->element->helper}( $this->element->getName(), $this->element->getValue(), $this->element->getAttribs() ) ?> </div> <div class="hint"><?php echo $this->element->getDescription() ?></div> </li> And display this error: Warning: Exception caught by form: Cannot render jQuery form element without at least one decorator implementing the 'ZendX_JQuery_Form_Decorator_UiWidgetElementMarker' interface. I need display datePicker with same format. but idk how implement this interface. thx for your help.

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  • Approaches for animating a C# property over time?

    - by Mario Fritsch
    I'm currently trying to animate a bunch of public properties on certain objects. Usually they are of type float or vectors of floats (the type is known at compile-time). I want to be able to: assign a static value to them (MyObject.Duration = 10f;) or assign a random value to them by specifying a minimum and maximum value and optionally also a weight (MyObject.Duration = new RandomFloat(5f, 20f, 2f);) or "bind" this property to the property of another object (think of a child object binding some of its properties to its parent object, like its color or size or sth.) or assign sort of a keyframe animation to them, specifying a variable number of keyframes with timecode and the property's value at that specific point in time as well as information about how to interpolate between these frames The keyframes should be able to accept random values for each frame, both for the time and the property's value. What would be a practical approach for this kind of system? Currently I'm thinking about polymorphism: implement a base class or interface with a public Value-property and/or GetValue(float time)-method and then creating different sub classes like StaticValue, RandomValue, BindingValue and AnimatedValue implementing this base class or interface. Doesn't seem very elegant, though, and the initialization of even simple objects becomes a bit tedious. Another idea would be to implement these properties just as regular floats or vectors and create special "Modifier"-types binding to these properties. To retrieve the "real" value of the property, I'd first call any Modifier bound to the property, which would in turn update the actual object's property for me to retrieve later on. That would most likely mean using reflection at some point, which could be quite bad for performance as I'll probably have thousands of properties to update dozens of times per second. Any suggestions on this? Being a novice I'm (hopefully) missing some far more elegant and/or practical solution than I'm already playing around with :( Edit: Probably should have mentioned this earlier, but WPF isn't an option - it's not available on all targetted platforms, so I can't rely on it. I'm aware of its powerful databinding and animation capabilities, but I need to roll my own (or find some other lightweight alternative meeting my needs).

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  • Java Generic Type and Reflection

    - by Tom Tucker
    I have some tricky generic type problem involving reflection. Here's the code. public @interface MyConstraint { Class<? extends MyConstraintValidator<?>> validatedBy(); } public interface MyConstraintValidator<T extends Annotation> { void initialize(T annotation); } /** @param annotation is annotated with MyConstraint. */ public void run(Annotation annotation) { Class<? extends MyConstraintValidator<? extends Annotation>> validatorClass = annotation.annotationType().getAnnotation(MyConstraint.class).validatedBy(); validatorClass.newInstance().initialize(annotation) // will not compile! } The run() method above will not compile because of the following error. The method initialize(capture#10-of ? extends Annotation) in the type MyConstraintValidator<capture#10-of ? extends Annotation> is not applicable for the arguments (Annotation) If I remove the wild cards, then it compiles and works fine. What would be the propert way to declare the type parameter for the vairable validatorClass? Thanks.

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  • Serialization of Entity Framework Models with .NET WCF Rest Service

    - by Chris Phillips
    I'm trying to put together a very simple REST-style interface for communicating with our partners. An example object in the API is a partner, which we'd like to have serialized like this: <partner> <id>ID</id> <name>NAME</name> </partner> This is fairly simply to achieve using the .NET 4.0 WCF REST template if we simply declare a partner class as: public class Partner { public int Id {get; set;} public string Name {get; set;} } But when I use the Entity Framework to define and store Partner objects, the resulting serialization looks something like this: <Partner p1:Id="NCNameString" p1:Ref="NCNameString" xmlns:p1="http://schemas.microsoft.com/2003/10/Serialization/" xmlns="http://schemas.datacontract.org/2004/07/TheTradeDesk.AdPlatform.Provisioning"> <EntityKey p1:Id="NCNameString" p1:Ref="NCNameString" xmlns="http://schemas.datacontract.org/2004/07/System.Data.Objects.DataClasses"> <EntityContainerName xmlns="http://schemas.datacontract.org/2004/07/System.Data">String content</EntityContainerName> <EntityKeyValues xmlns="http://schemas.datacontract.org/2004/07/System.Data"> ... This XML is obviously unacceptable for use as an external API. What are suggested mechanisms for using EF for the data store but maintaining a simple XML serialization interface?

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  • Can I use drawRect to refresh a UIView subclass?

    - by Timbo
    I've created a subclass of UIView called Status which is designed to display a rectangle of a certain size (within a view) depending on the value of a variable. // Interface #import <Foundation/Foundation.h> #import <QuartzCore/QuartzCore.h> @interface Status: UIView { NSString* name; int someVariable; } @property int someVariable; @property (assign) NSString *name; - (void) createStatus: (NSString*)withName; - (void) drawRect:(CGRect)rect; @end // Implementation #import "Status.h" @implementation Status @synthesize name, someVariable; - (void) createStatus: (NSString*)withName { name = withName; someVariable = 10000; } - (void) drawRect:(CGRect)rect { CGContextRef context = UIGraphicsGetCurrentContext(); //Draw Status CGContextSetRGBFillColor(context, 0.0, 0.0, 1.0, 1); // fill CGContextFillRect(context, CGRectMake(0.0, 0.0, someVariable, 40.0)); } //// myviewcontroller implementation - (void) viewDidAppear:(BOOL)animated { [super viewDidAppear:animated]; myStatus = [[Status alloc] initWithFrame:CGRectMake(8,8,200,56)]; myStatus.backgroundColor = [UIColor grayColor]; [self.view addSubview:myStatus]; } How do I set this up so I can repeatedly call a refresh of the status bar? I'll probably call the refresh 4 times per second using a NSTimer, I'm just not sure what to call or if I should move this rectangle drawing to a separate function or something... Thanks in advance for your help :)

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  • Stuck trying to get Log4Net to work with Dependency Injection

    - by Pure.Krome
    I've got a simple winform test app i'm using to try some Log4Net Dependency Injection stuff. I've made a simple interface in my Services project :- public interface ILogging { void Debug(string message); // snip the other's. } Then my concrete type will be using Log4Net... public class Log4NetLogging : ILogging { private static ILog Log4Net { get { return LogManager.GetLogger( MethodBase.GetCurrentMethod().DeclaringType); } } public void Debug(string message) { if (Log4Net.IsDebugEnabled) { Log4Net.Debug(message); } } } So far so good. Nothing too hard there. Now, in a different project (and therefore namesapce), I try and use this ... public partial class Form1 : Form { public Form1() { FileInfo fileInfo = new FileInfo("Log4Net.config"); log4net.Config.XmlConfigurator.Configure(fileInfo); } private void Foo() { // This would be handled with DI, but i've not set it up // (on the constructor, in this code example). ILogging logging = new Log4NetLogging(); logging.Debug("Test message"); } } Ok .. also pretty simple. I've hardcoded the ILogging instance but that is usually dependency injected via the constructor. Anyways, when i check this line of code... return LogManager.GetLogger(MethodBase.GetCurrentMethod().DeclaringType); the DeclaringType type value is of the Service namespace, not the type of the Form (ie. X.Y.Z.Form1) which actually called the method. Without passing the type INTO method as another argument, is there anyway using reflection to figure out the real method that called it?

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  • OOP design issue: Polymorphism

    - by Graham Phillips
    I'm trying to solve a design issue using inheritance based polymorphism and dynamic binding. I have an abstract superclass and two subclasses. The superclass contains common behaviour. SubClassA and SubClassB define some different methods: SubClassA defines a method performTransform(), but SubClassB does not. So the following example 1 var v:SuperClass; 2 var b:SubClassB = new SubClassB(); 3 v = b; 4 v.performTransform(); would cause a compile error on line 4 as performTransform() is not defined in the superclass. We can get it to compile by casting... (v as SubClassA).performTransform(); however, this will cause a runtime exception to be thrown as v is actually an instance of SubClassB, which also does not define performTransform() So we can get around that by testing the type of an object before casting it: if( typeof v == SubClassA) { (cast v to SubClassA).performTransform(); } That will ensure that we only call performTransform() on v's that are instances of SubClassA. That's a pretty inelegant solution to my eyes, but at least its safe. I have used interface based polymorphism (interface meaning a type that can't be instantiated and defines the API of classes that implement it) in the past, but that also feels clunky. For the above case, if SubClassA and SubClassB implemented ISuperClass that defined performTransform, then they would both have to implement performTransform(). If SubClassB had no real need for a performTransform() you would have to implement an empty function. There must be a design pattern out there that addresses the issue.

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