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  • using STI and ActiveRecordBase<> with full FindAll

    - by oillio
    Is it possible to use generic support with single table inheritance, and still be able to FindAll of the base class? As a bonus question, will I be able to use ActiveRecordLinqBase< as well? I do love those queries. More detail: Say I have the following classes defined: public interface ICompany { int ID { get; set; } string Name { get; set; } } [ActiveRecord("companies", DiscriminatorColumn="type", DiscriminatorType="String", DiscriminatorValue="NA")] public abstract class Company<T> : ActiveRecordBase<T>, ICompany { [PrimaryKey] private int Id { get; set; } [Property] public String Name { get; set; } } [ActiveRecord(DiscriminatorValue="firm")] public class Firm : Company<Firm> { [Property] public string Description { get; set; } } [ActiveRecord(DiscriminatorValue="client")] public class Client : Company<Client> { [Property] public int ChargeRate { get; set; } } This works fine for most cases. I can do things like: var x = Client.FindAll(); But sometimes I want all of the companies. If I was not using generics I could do: var x = (Company[]) FindAll(Company); Client a = (Client)x[0]; Firm b = (Firm)x[1]; Is there a way to write a FindAll that returns an array of ICompany's that can then be typecast into their respective types? Something like: var x = (ICompany[]) FindAll(Company<ICompany>); Client a = (Client)x[0]; Or maybe I am going about implementing the generic support all wrong?

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  • linear combinations in python/numpy

    - by nmaxwell
    greetings, I'm not sure if this is a dumb question or not. Lets say I have 3 numpy arrays, A1,A2,A3, and 3 floats, c1,c2,c3 and I'd like to evaluate B = A1*c1+ A2*c2+ A3*c3 will numpy compute this as for example, E1 = A1*c1 E2 = A2*c2 E3 = A3*c3 D1 = E1+E2 B = D1+E3 or is it more clever than that? In c++ I had a neat way to abstract this kind of operation. I defined series of general 'LC' template functions, LC for linear combination like: template<class T,class D> void LC( T & R, T & L0,D C0, T & L1,D C1, T & L2,D C2) { R = L0*C0 +L1*C1 +L2*C2; } and then specialized this for various types, so for instance, for an array the code looked like for (int i=0; i<L0.length; i++) R.array[i] = L0.array[i]*C0 + L1.array[i]*C1 + L2.array[i]*C2; thus avoiding having to create new intermediate arrays. This may look messy but it worked really well. I could do something similar in python, but I'm not sure if its nescesary. Thanks in advance for any insight. -nick

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  • Dependency Injection into your Singleton

    - by Langali
    I have a singleton that has a spring injected Dao (simplified below): public class MyService<T> implements Service<T> { private final Map<String, T> objects; private static MyService instance; MyDao myDao; public void set MyDao(MyDao myDao) { this. myDao = myDao; } private MyService() { this.objects = Collections.synchronizedMap(new HashMap<String, T>()); // start a background thread that runs for ever } public static synchronized MyService getInstance() { if(instance == null) { instance = new MyService(); } return instance; } public void doSomething() { myDao.persist(objects); } } My spring config will probably look like this: <bean id="service" class="MyService" factory-method="getInstance"/> But this will instantiate the MyService during startup. Is there a programmatic way to do a dependency injection of MyDao into MyService, but not have spring manage the MyService? Basically I want to be able to do this from my code: MyService.getInstance().doSomething(); while having spring inject the MyDao for me.

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  • .NET MissingMethodException occuring on one of thousands of end-user machines -- any insight?

    - by Yoooder
    This issue has me baffled, it's affecting a single user (to my knowledge) and hasn't been reproduced by us... The user is receiving a MissingMethodException, our trace file indicates it's occuring after we create a new instance of a component, when we're calling an Initialize/Setup method in preparation to have it do work (InitializeWorkerByArgument in the example) The Method specified by the error is an interface method, which a base class implements and classes derived from the base class can override as-needed The user has the latest release of our application All the provided code is shipped within a single assembly Here's a very distilled version of the component: class Widget : UserControl { public void DoSomething(string argument) { InitializeWorkerByArgument(argument); this.Worker.DoWork(); } private void InitializeWorkerByArgument(string argument) { switch (argument) { case "SomeArgument": this.Worker = new SomeWidgetWorker(); break; } // The issue I'm tracking down would have occured during "new SomeWidgetWorker()" // and would have resulted in a missing method exception stating that // method "DoWork" could not be found. this.Worker.DoWorkComplete += new EventHandler(Worker_DoWorkComplete); } private IWidgetWorker Worker { get; set; } void Worker_DoWorkComplete(object sender, EventArgs e) { MessageBox.Show("All done"); } } interface IWidgetWorker { void DoWork(); event EventHandler DoWorkComplete; } abstract class BaseWorker : IWidgetWorker { virtual public void DoWork() { System.Threading.Thread.Sleep(1000); RaiseDoWorkComplete(this, null); } internal void RaiseDoWorkComplete(object sender, EventArgs e) { if (DoWorkComplete != null) { DoWorkComplete(this, null); } } public event EventHandler DoWorkComplete; } class SomeWidgetWorker : BaseWorker { public override void DoWork() { System.Threading.Thread.Sleep(2000); RaiseDoWorkComplete(this, null); } }

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  • should i advocate migrating from access to (my)sql

    - by HotOil
    Hi: We have a windows MFC app that is written against an access database on a company server. The db is not that big: 19 MB. There are at most 2-3 users accessing it at any one time. It is used in a factory environment where access speed (or lack thereof) over the intranet becomes noticeable as it is part of the manufacturing time for our widgets. The scenario is this: as each widget is completed, it gets a record in the db.. by the end of the year, the db is larger and searching for a record takes longer and longer. The solution so far has been to manually move older records to an archival table about once a year. We are reworking other portions of this app right now, and it would be a good time to move to another db if we are going to do it. It is my understanding that if we were using sql, the search time would not go up as the table gets bigger because the entire .mdb does not have to be sent over the network each time. Is this correct? Does anyone have any insight about whether it could be worth it to go to the trouble (time and money) of migrating to a new db, or should I just add more functionality to the application we have now, and maybe automatically purge the older records from time to time, and add additional facilities to the app to get at the older records when needed? Thanks for any wisdom you can share..

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  • Most "thorough" distribution of points around a circle

    - by hippietrail
    This question is intended to both abstract and focus one approach to my problem expressed at "Find the most colourful image in a collection of images". Imagine we have a set of circles, each has a number of points around its circumference. We want to find a metric that gives a higher rating to a circle with points distributed evenly around the circle. Circles with some points scattered through the full 360° are better but circles with far greater numbers of points in one area compared to a smaller number in another area are less good. The number of points is not limited. Two or more points may coincide. Coincidental points are still relevant. A circle with one point at 0° and one point at 180° is better than a circle with 100 points at 0° and 1000 points at 180°. A circle with one point every degree around the circle is very good. A circle with a point every half degree around the circle is better. In my other (colour based question) it was suggested that standard deviation would be useful but with caveat. Is this a good suggestion and does it cope with the closeness of 359° to 1°?

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  • Setting up Inversion of Control (IoC) in ASP.NET MVC with Castle Windsor

    - by Lirik
    I'm going over Sanderson's Pro ASP.NET MVC Framework and in Chapter 4 he discusses Creating a Custom Controller Factory and it seems that the original method, AddComponentLifeStyle or AddComponentWithLifeStyle, used to register controllers is deprecated now: public class WindsorControllerFactory : DefaultControllerFactory { IWindsorContainer container; public WindsorControllerFactory() { container = new WindsorContainer(new XmlInterpreter(new ConfigResource("castle"))); // register all the controller types as transient var controllerTypes = from t in Assembly.GetExecutingAssembly().GetTypes() where typeof(IController).IsAssignableFrom(t) select t; //[Obsolete("Use Register(Component.For<I>().ImplementedBy<T>().Named(key).Lifestyle.Is(lifestyle)) instead.")] //IWindsorContainer AddComponentLifeStyle<I, T>(string key, LifestyleType lifestyle) where T : class; foreach (Type t in controllerTypes) { container.Register(Component.For<IController>().ImplementedBy<???>().Named(t.FullName).LifeStyle.Is(LifestyleType.Transient)); } } // Constructs the controller instance needed to service each request protected override IController GetControllerInstance(Type controllerType) { return (IController)container.Resolve(controllerType); } } The new suggestion is to use Register(Component.For<I>().ImplementedBy<T>().Named(key).Lifestyle.Is(lifestyle)), but I can't figure out how to present the implementing controller type in the ImplementedBy<???>() method. I tried ImplementedBy<t>() and ImplementedBy<typeof(t)>(), but I can't find the appropriate way to pass int he implementing type. Any ideas?

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  • Spawning a thread in python

    - by morpheous
    I have a series of 'tasks' that I would like to run in separate threads. The tasks are to be performed by separate modules. Each containing the business logic for processing their tasks. Given a tuple of tasks, I would like to be able to spawn a new thread for each module as follows. from foobar import alice, bob charles data = getWorkData() # these are enums (which I just found Python doesn't support natively) :( tasks = (alice, bob, charles) for task in tasks # Ok, just found out Python doesn't have a switch - @#$%! # yet another thing I'll need help with then ... switch case alice: #spawn thread here - how ? alice.spawnWorker(data) No prizes for guessing I am still thinking in C++. How can I write this in a Pythonic way using Pythonic 'enums' and 'switch'es, and be able to run a module in a new thread. Obviously, the modules will all have a class that is derived from a ABC (abstract base class) called Plugin. The spawnWorker() method will be declared on the Plugin interface and defined in the classes implemented in the various modules. Maybe, there is a better (i.e. Pythonic) way of doing all this?. I'd be interested in knowing

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  • DBTransactions between stateless calls using GUIDs

    - by Marty Trenouth
    I'm looking to add transactional support to my DB engine and providing to Abstract Transaction Handling down to passing in Guids with the DB Action Command. The DB engine would run similar to: private static Database DB; public static Dictionary<Guid,DBTransaction> Transactions = new ...() public static void DoDBAction(string cmdstring,List<Parameter> parameters,Guid TransactionGuid) { DBCommand cmd = BuildCommand(cmdstring,parameters); if(Transactions.ContainsKey(TransactionGuid)) cmd.Transaction = Transactions[TransactionGuid]; DB.ExecuteScalar(cmd); } public static BuildCommand(string cmd, List<Parameter> parameters) { // Create DB command from EntLib Database and assign parameters } public static Guid BeginTransaction() { // creates new Transaction adding it to "Transactions" and opens a new connection } public static Guid Commit(Guid g) { // Commits Transaction and removes it from "Transactions" and closes connection } public static Guid Rollback(Guid g) { // Rolls back Transaction and removes it from "Transactions" and closes connection } The Calling system would run similar to: Guid g try { g = DBEngine.BeginTransaction() DBEngine.DoDBAction(cmdstring1, parameters,g) // do some other stuff DBEngine.DoDBAction(cmdstring2, parameters2,g) // sit here and wait for a response from other item DBEngine.DoDBAction(cmdstring3, parameters3,g) DBEngine.Commit(g) } catch(Exception){ DBEngine.Rollback(g);} Does this interfere with .NET connection pooling (other than a connection be accidently left open)? Will EntLib keep the connection open until the commit or rollback?

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  • What is the proper way to use a Logger in a Serializable Java class?

    - by Tim Visher
    I have the following (doctored) class in a system I'm working on and Findbugs is generating a SE_BAD_FIELD warning and I'm trying to understand why it would say that before I fix it in the way that I thought I would. The reason I'm confused is because the description would seem to indicate that I had used no other non-serializable instance fields in the class but bar.model.Foo is also not serializable and used in the exact same way (as far as I can tell) but Findbugs generates no warning for it. import bar.model.Foo; import java.io.File; import java.io.Serializable; import java.util.List; import org.slf4j.Logger; import org.slf4j.LoggerFactory; public class Demo implements Serializable { private final Logger logger = LoggerFactory.getLogger(this.getClass()); private final File file; private final List<Foo> originalFoos; private Integer count; private int primitive = 0; public Demo() { for (Foo foo : originalFoos) { this.logger.debug(...); } } ... } My initial blush at a solution is to get a logger reference from the factory right as I use it: public DispositionFile() { Logger logger = LoggerFactory.getLogger(this.getClass()); for (Foo foo : originalFoos) { this.logger.debug(...); } } That doesn't seem particularly efficient, though. Thoughts?

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  • Cannot connect Nexus One Phone to Android adb

    - by appbee
    I am running Android SDK 2.2 and am trying to get the adb to connect to the Google Nexus One phone. Its a new phone, shipped straight from Google - haven't installed any apps on it yet. (I have Windows XP) Here is what I have done so far: Followed the instructions on setting up the device for development as given on the Android Developer's site: http://developer.android.com/guide/developing/device.html added android:debuggable="true" to my application manifest USB debuggable is checked on the phone downloaded the Device Drivers For Windows Revision 3 (this supports Nexus One phones) Went through the Hardware Installation wizard to install the device - the device shows up as "Android Composite ADB Interface". When I run adb devices on the shell, the device appears for a moment, then disappears. On the Eclipse console, I get the following message: [2010-11-13 11:54:42 - DeviceMonitor]Failed to start monitoring I have rebooted the pc several times, uninstalled and reinstalled the drivers several times, but I get the same error each time. As I was researching this problem, someone had recommended rebooting the phone. I am a bit confused by that - is that a soft or hard reboot? Do I just power the phone off/on and is there something more complex involved? Do I have to hard reboot it to reset to factory version - even though its brand new? Has anyone run into a similar problem? Any help on this would be great. I can't test my application on the device if the adb cannot view the device. Thanks so much in advance.

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  • Refactoring code/consolidating functions (e.g. nested for-loop order)

    - by bmay2
    Just a little background: I'm making a program where a user inputs a skeleton text, two numbers (lower and upper limit), and a list of words. The outputs are a series of modifications on the skeleton text. Sample inputs: text = "Player # likes @." (replace # with inputted integers and @ with words in list) lower = 1 upper = 3 list = "apples, bananas, oranges" The user can choose to iterate over numbers first: Player 1 likes apples. Player 2 likes apples. Player 3 likes apples. Or words first: Player 1 likes apples. Player 1 likes bananas. Player 1 likes oranges. I chose to split these two methods of outputs by creating a different type of dictionary based on either number keys (integers inputted by the user) or word keys (from words in the inputted list) and then later iterating over the values in the dictionary. Here are the two types of dictionary creation: def numkey(dict): # {1: ['Player 1 likes apples', 'Player 1 likes...' ] } text, lower, upper, list = input_sort(dict) d = {} for num in range(lower,upper+1): l = [] for i in list: l.append(text.replace('#', str(num)).replace('@', i)) d[num] = l return d def wordkey(dict): # {'apples': ['Player 1 likes apples', 'Player 2 likes apples'..] } text, lower, upper, list = input_sort(dict) d = {} for i in list: l = [] for num in range(lower,upper+1): l.append(text.replace('#', str(num)).replace('@', i)) d[i] = l return d It's fine that I have two separate functions for creating different types of dictionaries but I see a lot of repetition between the two. Is there any way I could make one dictionary function and pass in different values to it that would change the order of the nested for loops to create the specific {key : value} pairs I'm looking for? I'm not sure how this would be done. Is there anything related to functional programming or other paradigms that might help with this? The question is a little abstract and more stylistic/design-oriented than anything.

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  • How to encapsulate a third party complex object structure?

    - by tangens
    Motivation Currently I'm using the java parser japa to create an abstract syntax tree (AST) of a java file. With this AST I'm doing some code generation (e.g.: if there's an annotation on a method, create some other source files, ...) Problem When my code generation becomes more complex, I've to dive deeper into the structure of the AST (e.g. I have to use visitors to extract some type information of method parameters). But I'm not sure if I want to stay with japa or if I will change the parser library later. Because my code generator uses freemarker (which isn't good at automatic refactoring) I want the interface that it uses to access the AST information to be stable, even if I decide to change the java parser. Question What's the best way to encapsulate complex datastructures of third party libraries? I could create my own datatypes and copy the parts of the AST that I need into these. I could create lots of specialized access methods that work with the AST and create exactly the infos I need (e.g. the fully qualified return type of a method as one string, or the first template parameter of a class). I could create wrapper classes for the japa datastructures I currently need and embed the japa types inside, so that I can delegate requests to the japa types and transform the resulting japa types to my wrapper classes again. Which solution should I take? Are there other (better) solutions to this problem?

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  • android custom dialog imageButton onclicklistener

    - by Asaf Nevo
    this is my custom dialog class: package com.WhosAround.Dialogs; import com.WhosAround.AppVariables; import com.WhosAround.R; import com.WhosAround.AsyncTasks.LoadUserStatus; import com.WhosAround.Facebook.FacebookUser; import android.app.Dialog; import android.content.Context; import android.graphics.drawable.Drawable; import android.view.MotionEvent; import android.view.View; import android.widget.ImageButton; import android.widget.ImageView; import android.widget.TextView; public class MenuFriend extends Dialog{ private FacebookUser friend; private AppVariables app; public MenuFriend(Context context, FacebookUser friend) { super(context, android.R.style.Theme_Translucent_NoTitleBar); this.app = (AppVariables) context.getApplicationContext(); this.friend = friend; } public void setDialog(String userName, Drawable userProfilePicture) { setContentView(R.layout.menu_friend); setCancelable(true); setCanceledOnTouchOutside(true); TextView name = (TextView) findViewById(R.id.menu_user_name); TextView status = (TextView) findViewById(R.id.menu_user_status); ImageView profilePicture = (ImageView) findViewById(R.id.menu_profile_picture); ImageButton closeButton = (ImageButton) findViewById(R.id.menu_close); name.setText(userName); profilePicture.setImageDrawable(userProfilePicture); if (friend.getStatus() != null) status.setText(friend.getStatus()); else new LoadUserStatus(app, friend, status).execute(0); closeButton.setOnClickListener(new OnClickListener() { @Override public void onClick(View v) { dismiss(); } }) } } for some reason eclipse tells me the following errors on closeButton imageButton: The method setOnClickListener(View.OnClickListener) in the type View is not applicable for the arguments (new DialogInterface.OnClickListener(){}) The type new DialogInterface.OnClickListener(){} must implement the inherited abstract method DialogInterface.OnClickListener.onClick(DialogInterface, int) The method onClick(View) of type new DialogInterface.OnClickListener(){} must override or implement a supertype method why is that ?

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  • Serializing Configurations for a Dependency Injection / Inversion of Control

    - by Joshua Starner
    I've been researching Dependency Injection and Inversion of Control practices lately in an effort to improve the architecture of our application framework and I can't seem to find a good answer to this question. It's very likely that I have my terminology confused, mixed up, or that I'm just naive to the concept right now, so any links or clarification would be appreciated. Many examples of DI and IoC containers don't illustrate how the container will connect things together when you have a "library" of possible "plugins", or how to "serialize" a given configuration. (From what I've read about MEF, having multiple declarations of [Export] for the same type will not work if your object only requires 1 [Import]). Maybe that's a different pattern or I'm blinded by my current way of thinking. Here's some code for an example reference: public abstract class Engine { } public class FastEngine : Engine { } public class MediumEngine : Engine { } public class SlowEngine : Engine { } public class Car { public Car(Engine e) { engine = e; } private Engine engine; } This post talks about "Fine-grained context" where 2 instances of the same object need different implementations of the "Engine" class: http://stackoverflow.com/questions/2176833/ioc-resolve-vs-constructor-injection Is there a good framework that helps you configure or serialize a configuration to achieve something like this without hard coding it or hand-rolling the code to do this? public class Application { public void Go() { Car c1 = new Car(new FastEngine()); Car c2 = new Car(new SlowEngine()); } } Sample XML: <XML> <Cars> <Car name="c1" engine="FastEngine" /> <Car name="c2" engine="SlowEngine" /> </Cars> </XML>

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  • Weak hashmap with weak references to the values?

    - by Razor Storm
    I am building an android app where each entity has a bitmap that represents its sprite. However, each entity can be be duplicated (there might be 3 copies of entity asdf for example). One approach is to load all the sprites upfront, and then put the correct sprite in the constructors of the entities. However, I want to decode the bitmaps lazily, so that the constructors of the entities will decode the bitmaps. The only problem with this is that duplicated entities will load the same bitmap twice, using 2x the memory (Or n times if the entity is created n times). To fix this, I built a SingularBitmapFactory that will store a decoded Bitmap into a hash, and if the same bitmap is asked for again, will simply return the previously hashed one instead of building a new one. Problem with this, though, is that the factory holds a copy of all bitmaps, and so won't ever get garbage collected. What's the best way to switch the hashmap to one with weakly referenced values? In otherwords, I want a structure where the values won't be GC'd if any other object holds a reference to it, but as long as no other objects refers it, then it can be GC'd.

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  • ASP.NEt MVC 2 application error on IIS7 works fine on local machine

    - by aspCoolguy
    My ASP.NET MVC2 application is developed using 1. VS 2010 2. Linq To SQL for Models Here is Call controller code: namespace CallTrackMVC.Controllers { public class CallController : Controller { private CallTrackRepository repository; public CallController():this(new CallTrackRepository()) { } public CallController(CallTrackRepository newRepository) { repository = newRepository; } } } Error on IIS7 when browsing the Call Create page is NullReferenceException: Object reference not set to an instance of an object.] CallTrackMVC.Models.ExecOfficeDataContext..ctor() in C:\ClearCase\rartadi_view\STS_Dev_TEST\CallTrackMVC\Models\ExecOffice.designer.cs:71 CallTrackMVC.Controllers.CallController..ctor() in C:\ClearCase\rartadi_view\STS_Dev_TEST\CallTrackMVC\Controllers\CallController.cs:16 [TargetInvocationException: Exception has been thrown by the target of an invocation.] System.RuntimeTypeHandle.CreateInstance(RuntimeType type, Boolean publicOnly, Boolean noCheck, Boolean& canBeCached, RuntimeMethodHandleInternal& ctor, Boolean& bNeedSecurityCheck) +0 System.RuntimeType.CreateInstanceSlow(Boolean publicOnly, Boolean skipCheckThis, Boolean fillCache) +117 System.RuntimeType.CreateInstanceDefaultCtor(Boolean publicOnly, Boolean skipVisibilityChecks, Boolean skipCheckThis, Boolean fillCache) +247 System.Activator.CreateInstance(Type type, Boolean nonPublic) +106 System.Web.Mvc.DefaultControllerFactory.GetControllerInstance(RequestContext requestContext, Type controllerType) +102 [InvalidOperationException: **An error occurred when trying to create a controller of type 'CallTrackMVC.Controllers.CallController'. Make sure that the controller has a parameterless public constructor.**] System.Web.Mvc.DefaultControllerFactory.GetControllerInstance(RequestContext requestContext, Type controllerType) +541 System.Web.Mvc.DefaultControllerFactory.CreateController(RequestContext requestContext, String controllerName) +85 System.Web.Mvc.MvcHandler.ProcessRequestInit(HttpContextBase httpContext, IController& controller, IControllerFactory& factory) +165 System.Web.Mvc.MvcHandler.BeginProcessRequest(HttpContextBase httpContext, AsyncCallback callback, Object state) +80 System.Web.CallHandlerExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute() +389 System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously) +371 Code in Global.asax is protected void Application_Start() { AreaRegistration.RegisterAllAreas(); RegisterRoutes(RouteTable.Routes); } Any suggestion would be a great help.

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  • Extending the method pool of a concrete class which is derived by an interface

    - by CelGene
    Hello, I had created an interface to abstract a part of the source for a later extension. But what if I want to extend the derived classes with some special methods? So I have the interface here: class virtualFoo { public: virtual ~virtualFoo() { } virtual void create() = 0; virtual void initialize() = 0; }; and one derived class with an extra method: class concreteFoo : public virtualFoo { public: concreteFoo() { } ~concreteFoo() { } virtual void create() { } virtual void initialize() { } void ownMethod() { } }; So I try to create an Instance of concreteFoo and try to call ownMethod like this: void main() { virtualFoo* ptr = new concreteFoo(); concreteFoo* ptr2 = dynamic_cast(ptr); if(NULL != ptr2) ptr2->ownMethod(); } It works but is not really the elegant way. If I would try to use ptr-ownMethod(); directly the compiler complains that this method is not part of virtualFoo. Is there a chance to do this without using dynamic_cast? Thanks in advance!

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  • WCF data services (OData), query with inheritance limitation?

    - by Mathieu Hétu
    Project: WCF Data service using internally EF4 CTP5 Code-First approach. I configured entities with inheritance (TPH). See previous question on this topic: Previous question about multiple entities- same table The mapping works well, and unit test over EF4 confirms that queries runs smoothly. My entities looks like this: ContactBase (abstract) Customer (inherits from ContactBase), this entity has also several Navigation properties toward other entities Resource (inherits from ContactBase) I have configured a discriminator, so both Customer and Resource map to the same table. Again, everythings works fine on the Ef4 point of view (unit tests all greens!) However, when exposing this DBContext over WCF Data services, I get: - CustomerBases sets exposed (Customers and Resources sets seems hidden, is it by design?) - When I query over Odata on Customers, I get this error: Navigation Properties are not supported on derived entity types. Entity Set 'ContactBases' has a instance of type 'CodeFirstNamespace.Customer', which is an derived entity type and has navigation properties. Please remove all the navigation properties from type 'CodeFirstNamespace.Customer'. Stacktrace: at System.Data.Services.Serializers.SyndicationSerializer.WriteObjectProperties(IExpandedResult expanded, Object customObject, ResourceType resourceType, Uri absoluteUri, String relativeUri, SyndicationItem item, DictionaryContent content, EpmSourcePathSegment currentSourceRoot) at System.Data.Services.Serializers.SyndicationSerializer.WriteEntryElement(IExpandedResult expanded, Object element, ResourceType expectedType, Uri absoluteUri, String relativeUri, SyndicationItem target) at System.Data.Services.Serializers.SyndicationSerializer.<DeferredFeedItems>d__b.MoveNext() at System.ServiceModel.Syndication.Atom10FeedFormatter.WriteItems(XmlWriter writer, IEnumerable`1 items, Uri feedBaseUri) at System.ServiceModel.Syndication.Atom10FeedFormatter.WriteFeedTo(XmlWriter writer, SyndicationFeed feed, Boolean isSourceFeed) at System.ServiceModel.Syndication.Atom10FeedFormatter.WriteFeed(XmlWriter writer) at System.ServiceModel.Syndication.Atom10FeedFormatter.WriteTo(XmlWriter writer) at System.Data.Services.Serializers.SyndicationSerializer.WriteTopLevelElements(IExpandedResult expanded, IEnumerator elements, Boolean hasMoved) at System.Data.Services.Serializers.Serializer.WriteRequest(IEnumerator queryResults, Boolean hasMoved) at System.Data.Services.ResponseBodyWriter.Write(Stream stream) Seems like a limitation of WCF Data services... is it? Not much documentation can be found on the web about WCF Data services (OData) and inheritance specifications. How can I overpass this exception? I need these navigation properties on derived entities, and inheritance seems the only way to provide mapping of 2 entites on the same table with Ef4 CTP5... Any thoughts?

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  • Why doesn't java.lang.Number implement Comparable?

    - by Julien Chastang
    Does anyone know why java.lang.Number does not implement Comparable? This means that you cannot sort Numbers with Collections.sort which seems to me a little strange. Post discussion update: Thanks for all the helpful responses. I ended up doing some more research about this topic. The simplest explanation for why java.lang.Number does not implement Comparable is rooted in mutability concerns. For a bit of review, java.lang.Number is the abstract super-type of AtomicInteger, AtomicLong, BigDecimal, BigInteger, Byte, Double, Float, Integer, Long and Short. On that list, AtomicInteger and AtomicLong to do not implement Comparable. Digging around, I discovered that it is not a good practice to implement Comparable on mutable types because the objects can change during or after comparison rendering the result of the comparison useless. Both AtomicLong and AtomicInteger are mutable. The API designers had the forethought to not have Number implement Comparable because it would have constrained implementation of future subtypes. Indeed, AtomicLong and AtomicInteger were added in Java 1.5 long after java.lang.Number was initially implemented. Apart from mutability, there are probably other considerations here too. A compareTo implementation in Number would have to promote all numeric values to BigDecimal because it is capable of accommodating all the Number sub-types. The implication of that promotion in terms of mathematics and performance is a bit unclear to me, but my intuition finds that solution kludgy.

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  • How to properly implement the Strategy pattern in a web MVC framework?

    - by jboxer
    In my Django app, I have a model (lets call it Foo) with a field called "type". I'd like to use Foo.type to indicate what type the specific instance of Foo is (possible choices are "Number", "Date", "Single Line of Text", "Multiple Lines of Text", and a few others). There are two things I'd like the "type" field to end up affecting; the way a value is converted from its normal type to text (for example, in "Date", it may be str(the_date.isoformat())), and the way a value is converted from text to the specified type (in "Date", it may be datetime.date.fromtimestamp(the_text)). To me, this seems like the Strategy pattern (I may be completely wrong, and feel free to correct me if I am). My question is, what's the proper way to code this in a web MVC framework? In a client-side app, I'd create a Type class with abstract methods "serialize()" and "unserialize()", override those methods in subclasses of Type (such as NumberType and DateType), and dynamically set the "type" field of a newly-instantiated Foo to the appropriate Type subclass at runtime. In a web framework, it's not quite as straightforward for me. Right now, the way that makes the most sense is to define Foo.type as a Small Integer field and define a limited set of choices (0 = "Number", 1 = "Date", 2 = "Single Line of Text", etc.) in the code. Then, when a Foo object is instantiated, use a Factory method to look at the value of the instance's "type" field and plug in the correct Type subclass (as described in the paragraph above). Foo would also have serialize() and unserialize() methods, which would delegate directly to the plugged-in Type subclass. How does this design sound? I've never run into this issue before, so I'd really like to know if other people have, and how they've solved it.

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  • anti-if campaign

    - by Andrew Siemer
    I recently ran against a very interesting site that expresses a very interesting idea - the anti-if campaign. You can see this here at www.antiifcampaign.com. I have to agree that complex nested IF statements are an absolute pain in the rear. I am currently on a project that up until very recently had some crazy nested IFs that scrolled to the right for quite a ways. We cured our issues in two ways - we used Windows Workflow Foundation to address routing (or workflow) concerns. And we are in the process of implementing all of our business rules utilizing ILOG Rules for .NET (recently purchased by IBM!!). This for the most part has cured our nested IF pains...but I find myself wondering how many people cure their pains in the manner that the good folks at the AntiIfCampaign suggest (see an example here) by creating numerous amounts of abstract classes to represent a given scenario that was originally covered by the nested IF. I wonder if another way to address the removal of this complexity might also be in using an IoC container such as StructureMap to move in and out of different bits of functionality. Either way... Question: Given a scenario where I have a nested complex IF or SWITCH statement that is used to evaluate a given type of thing (say evaluating an Enum) to determine how I want to handle the processing of that thing by enum type - what are some ways to do the same form of processing without using the IF or SWITCH hierarchical structure? public enum WidgetTypes { Type1, Type2, Type3, Type4 } ... WidgetTypes _myType = WidgetTypes.Type1; ... switch(_myType) { case WidgetTypes.Type1: //do something break; case WidgetTypes.Type2: //do something break; //etc... }

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  • What is wrong with locking non-static fields? What is the correct way to lock a particular instance?

    - by smartcaveman
    Why is it considered bad practice to lock non-static fields? And, if I am not locking non-static fields, then how do I lock an instance method without locking the method on all other instances of the same or derived class? I wrote an example to make my question more clear. public abstract class BaseClass { private readonly object NonStaticLockObject = new object(); private static readonly object StaticLockObject = new object(); protected void DoThreadSafeAction<T>(Action<T> action) where T: BaseClass { var derived = this as T; if(derived == null) { throw new Exception(); } lock(NonStaticLockObject) { action(derived); } } } public class DerivedClass :BaseClass { private readonly Queue<object> _queue; public void Enqueue(object obj) { DoThreadSafeAction<DerivedClass>(x=>x._queue.Enqueue(obj)); } } If I make the lock on the StaticLockObject, then the DoThreadSafeAction method will be locked for all instances of all classes that derive from BaseClass and that is not what I want. I want to make sure that no other threads can call a method on a particular instance of an object while it is locked.

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  • Objective C number keypad, custom comma button

    - by rom_j
    I'm trying to add a comma button on a number keypad that has previous, next and done buttons, so that it looks like this : Problem is, that the orange button does not respond to taps. Actually if I moved it above the "7" button and tapped it, the 7 would be tapped. So my orange button may be shown above the keyboard, but it's reacting to taps as if it were below. Here is an abstract of my code : -(void)textFieldDidBeginEditing:(UITextField *)textField{ UIView *inputAccessoryView = [[UIView alloc] initWithFrame:CGRectMake(0, 500, screenWidth, 40.0)]; // 3 buttons on top UIView *topToolbar = [[UIView alloc] initWithFrame:CGRectMake(0, 0.0, screenWidth, 40.0)]; [topToolbar addSubview:self.inputPrevButton]; [topToolbar addSubview:self.inputNextButton]; [topToolbar addSubview:self.inputDoneButton]; [inputAccessoryView addSubview:topToolbar]; // Comma button UIButton *commaButton = [UIButton buttonWithType:UIButtonTypeCustom]; [commaButton setFrame: CGRectMake(0, 204, 105, 52)]; [commaButton setTitle:@"." forState:UIControlStateNormal]; [commaButton addTarget:self action:@selector(addComma) forControlEvents:UIControlEventTouchUpInside]; [commaButton setBackgroundColor:[UIColor orangeColor]]; [inputAccessoryView addSubview:commaButton]; // Useless, but tried anyway [inputAccessoryView bringSubviewToFront:commaButton]; [textField setInputAccessoryView:self.inputAccessoryView]; } All I know is that I should not be doing this (which is actually not working), so what should I do ?

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  • Mapping relationships from multiple databases in NHibernate

    - by mannish
    I have a multi-database application configured with NHibernate. The entities that correspond to tables from each database are in their own separate assemblies (an assembly per database if you will). I have a need/desire to relate an entity from one database to an entity of another database. Everything up to this point works as I want it to (the application handles multiple session factories, etc.). The relationship I want is many-to-one, but in reality my application only cares about one side of the relationship (for reasons that aren't relevant). The relevant entities are Project and PMProject, where a Project HAS A PMProject. When I map the many-to-one, I get the following error: NHibernate.MappingException: An association from the table PROJECTS refers to an unmapped class: SDMS.PPRM.PMProject The Project mapping itself reads (ignore the funky column naming; it's an Oracle db): <many-to-one name="PMProject" class="SDMS.PPRM.PMProject" column="PM_PROJECT_ID" cascade="none" /> In the class attribute, I'm referencing the appropriate assembly, but I get that error which seems to tell me it simply can't find the mapping file for PMProject. But that file exists (it's set as embedded resource), the session factory instantiation works without fail; so I'm at a loss on how to tell the Project mapping how/where to look for the appropriate mapping. Is there something I'm missing? A better way to go about this? Thanks in advance.

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