Search Results

Search found 2258 results on 91 pages for 'abstract algebra'.

Page 60/91 | < Previous Page | 56 57 58 59 60 61 62 63 64 65 66 67  | Next Page >

  • Passing arguments to anonymous inner classes

    - by synic
    I'm trying to make an API library for our web services, and I'm wondering if it's possible to do something like this: abstract class UserRequest(val userId: Int) { def success(message: String) def error(error: ApiError) } api.invokeRequest(new UserRequest(121) { override def success(message: String) = { // handle success } override def error(error: ApiError) = { // handle the error } } I'm talking about passing parameters to the anonymous inner class, and also overriding the two methods. I'm extremely new to Scala, and I realize my syntax might be completely wrong. I'm just trying to come up with a good design for this library before I start coding it. I'm willing to take suggestions for this, if I'm doing it the completely wrong way, or if there's a better way. The idea is that the API will take some sort of request object, use it to make a request in a thread via http, and when the response has been made, somehow signal back to the caller if the request was a success or an error. The request/error functions have to be executed on the main thread.

    Read the article

  • A c# Generics question involving Controllers and Repositories

    - by UpTheCreek
    I have a base repository class which contains all the common repository methods (as generic): public abstract class BaseRepository<T, IdType> : IBaseRepository<T, IdType> My repositories from this base e.g.: public class UserRepository : BaseRepository<User, int>, IUserRepository I also have a base controller class containing common actions, and inherit from this in controllers. The repository is injected into this by DI. E.g. public class UserController : BaseController<User> { private readonly IUserRepository userRepository; public UserController (IUserRepository userRepository) { this.userRepository= userRepository; } My question is this: The base controller needs to be able to access the repository methods that are defined in the base repository. However I'm passing in via DI a different repository type for each controller (even though they all inherrit from the base repository). How can the base controller somehow access the repository that is passed in (regardless of what type it is), so that it can access the common base methods?

    Read the article

  • C# to Java Conversion: What is a [DefaultProperty("value")]?

    - by Shiftbit
    I do not understand how the DefaultProperty Metadata tag work or what it signifies. I've read the MSDN and went through the sample but I find it confusing. DefaultPropertyAttribute Class I've read a few blogs and they seem to refer to the indexers. I'm not sure why you would want metadata for your properties? I am coming from a Java background, perhaps a Java analogy would help. [DefaultProperty("Value")] public abstract class FOO<T> : ANY, IBAR<T> { public FOO() { } public FOO(T value) { this.Value = value; } public virtual T Value { get; set; } }

    Read the article

  • Java cannot find symbol enum

    - by JDelage
    Hi, I'm modeling a chess game on Java, and I'm having some problem. Here's what the code looks like (the relevant parts): Enum class Couleur.java: public enum Couleur {BLANC, NOIR} Piece.java: public abstract class Piece { (...) public Piece(Couleur couleurParam){ this.couleurPiece = couleurParam; } (...) } And finally Tour.java: public class Tour extends Piece { (...) public Tour(Couleur couleurParam){ super(couleurParam); } (...) } All the .java files are in the same folder. Yet at compile I get a "cannot find symbol symbol : variable NOIR location: class Plateau" (Plateau is the class that instantiates Tour.) Can anyone help me figure out what's wrong here? Many thanks, JDelage

    Read the article

  • Type parameterization in Scala

    - by horatius83
    So I'm learning Scala at the moment, and I'm trying to create an abstract vector class with a vector-space of 3 (x,y,z coordinates). I'm trying to add two of these vectors together with the following code: package math class Vector3[T](ax:T,ay:T,az:T) { def x = ax def y = ay def z = az override def toString = "<"+x+", "+y+", "+z+">" def add(that: Vector3[T]) = new Vector3(x+that.x, y+that.y, z+that.z) } The problem is I keep getting this error: error: type mismatch; found : T required: String def add(that: Vector3[T]) = new Vector3(x+that.x, y+that.y, z+that.z) I've tried commenting out the "toString" method above, but that doesn't seem to have any effect. Can anyone tell me what I'm doing wrong?

    Read the article

  • c# Generic overloaded method dispatching ambiguous

    - by sebgod
    Hello, I just hit a situation where a method dispatch was ambiguous and wondered if anyone could explain on what basis the compiler (.NET 4.0.30319) chooses what overload to call interface IfaceA { } interface IfaceB<T> { void Add(IfaceA a); T Add(T t); } class ConcreteA : IfaceA { } class abstract BaseClassB<T> : IfaceB<T> { public virtual T Add(T t) { ... } public virtual void Add(IfaceA a) { ... } } class ConcreteB : BaseClassB<IfaceA> { // does not override one of the relevant methods } void code() { var concreteB = new ConcreteB(); // it will call void Add(IfaceA a) concreteB.Add(new ConcreteA()); } In any case, why does the compiler not warn me or even why does it compile? Thank you very much for any answers.

    Read the article

  • Zend_Form and Liskov Substitution Principle

    - by blockhead
    A very common pattern I see (I'm picking on Zend Framework, only because I was dealing with it at the moment of this question), is something like this: class My_Form extends Zend_Form { public function init() { $this->addElement(); } } Zend_Form is not an abstract class, but is perfectly usable on its own. This seems to be "recommended" as place to "encapsulate" your forms into a nice class. Does this violate the Liskov Substitution Principle? Each subclass of Zend_Form will have a wildy different behavior than the base class. Would it be better to use composition for this, or am I totally misunderstanding this principle?

    Read the article

  • Magento: Why do controller action predispatch events not fire if the controller is rewritten?

    - by mattalexx
    Why do controller action predispatch events not fire if the controller is rewritten? Here is a snippet of store/app/code/core/Mage/Core/Controller/Varien/Action.php: abstract class Mage_Core_Controller_Varien_Action { // [...] public function preDispatch() { // [...] if ($this->_rewrite()) { return; // [What is the purpose if this?] } // [...] // [This is where my event needs to be firing, but this code never gets // executed because the controller is rewritten] Mage::dispatchEvent( 'controller_action_predispatch_'.$this->getFullActionName(), array('controller_action'=>$this) ); } // [...] } I don't know where to start fixing this problem. Anyone out there ever dealt with this before?

    Read the article

  • C#: why Base class is allowed to implement an interface contract without inheriting from it?

    - by etarassov
    I've stumbled upon this "feature" of C# - the base class that implements interface methods does not have to derive from it. Example: public interface IContract { void Func(); } // Note that Base does **not** derive from IContract public abstract class Base { public void Func() { Console.WriteLine("Base.Func"); } } // Note that Derived does *not* provide implementation for IContract public class Derived : Base, IContract { } What happens is that Derived magically picks-up a public method Base.Func and decides that it will implement IContract.Func. What is the reason behind this magic? IMHO: this "quasi-implementation" feature is very-unintuitive and make code-inspection much harder. What do you think?

    Read the article

  • Using enums or a set of classes when I know I have a finite set of different options?

    - by devoured elysium
    Let's say I have defined the following class: public abstract class Event { public DateTime Time { get; protected set; } protected Event(DateTime time) { Time = time; } } What would you prefer between this: public class AsleepEvent : Event { public AsleepEvent(DateTime time) : base(time) { } } public class AwakeEvent : Event { public AwakeEvent(DateTime time) : base(time) { } } and this: public enum StateEventType { NowAwake, NowAsleep } public class StateEvent : Event { protected StateEventType stateType; public MealEvent(DateTime time, StateEventType stateType) : base(time) { stateType = stateType; } } and why? I am generally more inclined to the first option, but I can't explain why. Is it totally the same or are any advantages in using one instead of the other? Maybe with the first method its easier to add more "states", altough in this case I am 100% sure I will only want two states: now awake, and now asleep (they signal the moments when one awakes and one falls asleep).

    Read the article

  • Connect two daemons in python

    - by Simon
    What is the best way to connect two daemons in Python? I have daemon A and B. I'd like to receive data generated by B in A's module (maybe bidirectional). Both daemons support plugins, so I'd like to shut communication in plugins. What's the best and cross-platform way to do that? I know few mechanisms from low-level solutions - shared memory (C/C++), linux pipe, sockets (TCP/UDP), etc. and few high-level - queue (JMS, Rabbit), RPC. Both daemons should run on the same host, but obviously better approach is to abstract from connection type. What are typical solutions/libraries in python? I'm looking for an elegant and lightweight solution. I don't need external server, just two processes talking with each other. What should I use in python to do that?

    Read the article

  • Custom OData operation / customize EF model to hide join table in many-to-many relationship

    - by AC
    I've got a data model that has two tables with a join table for a many to many relationship & creating an OData service to expose the data for CRUD ops in a Silverlight app. What I'd like to do is abstract the join table from the service. I'm not sure if the best way to do this would be in the model (using EF in .NET3.5SP1) or if I should do it with a custom service operation. If I do it in the EF model (not sure how I'd do this), then the OOTB WCF Data Service stuff would make it easy to say [..]/Courses(1)/Modules ... otherwise I'd have to create a custom operation to do this. Is it possible to do this in the EF model and if so, how does that work?

    Read the article

  • Is it possible to create nested classes in PHP as it is in C#?

    - by Edward Tanguay
    In C# you can have nested classes like this, which are useful if you have classes which do not have meaning outside the scope of one particular class, e.g. in a factory pattern: public abstract class BankAccount { private BankAccount() {} private sealed class SavingsAccount : BankAccount { ... } private sealed class CheckingAccount : BankAccount { ... } public BankAccount MakeSavingAccount() { ... } public BankAccount MakeCheckingAccount() { ... } } Is this possible in PHP? I've read that it was planned for PHP 5, then cancelled, then planned again, but can't find definitive info. Does anyone know how to create nested classes (classes within the scope of another class) as in the above C# example using PHP 5.3?

    Read the article

  • Creating a computer with pencil and paper [closed]

    - by Justian Meyer
    This concept has been brought to my attention before, but many people might know it from this popular comic here, where he uses stones instead of points on a paper. This concept is so abstract to me. A full-functioning computer that can manage algorithms, input, output, etc. without electricity? Surely, it's difficult to visualize because my definition of a computer is not exactly what the word sounds like COMPUTE-ER. Can someone help me bring the concept to light - the understanding, how to make one, etc? It seems like it'd be an interesting read, although I think I wouldn't be able to make it do anything. Many thanks in advance for responses. I've tried searching Google, but all I got were ways to diagram code and chart ideas. -.Justian.

    Read the article

  • How can one describe a rock-paper-scissors relationship between 3 items?

    - by Madara Uchiha
    Let's say I have the following structure: abstract class Hand {} class Rock extends Hand {} class Paper extends Hand {} class Scissors extends Hand {} The goal is to make a function (or a method) Hand::compareHands(Hand $hand1, Hand $hand2), which would return the winning hand in a rock-paper-scissors match. That would be very easy with a bunch of ifs, but the point is to have a more robust structure, that's relying on polymorphism rather than on procedural code. P.S. this is done in actual production code, if someone is asking. This isn't some sort of challenge or homework. (It's not really rock-paper-scissors, but you get the point).

    Read the article

  • Questions about my program and Polymorphism

    - by Strobe_
    Ok, so basically I'm creating a program which allows the user to select a shape (triangle, square, circle) and then it takes in a int and calculates the boundary length and area. I have no problem doing this and have a program that's working perfectly. (https://gist.github.com/anonymous/c63a03c129560a7b7434 4 classes) But now I have to implement this with polymorphism concepts and I'm honestly struggling as to how to do it. I have a basic idea of what I want to do when it comes to inheritance Main | Shapes / | \ triangle circle square But I don't understand how I'm supposed to override when all the methods within the triangle/square/circle classes are unique, there are no "abstract" methods as such that I could inherit from the "Shapes" class. If somebody could make look quickly at the code I linked and suggest a way to do this it would be much appreciated. Sorry if I was bad at explaining this. Thanks.

    Read the article

  • NHibernate: discriminator without common base class?

    - by joniba
    Is it possible to map two classes to the same property without them sharing a common base class? For example, a situation like this: class Rule { public virtual int SequenceNumber { get; set; } public virtual ICondition Condition { get; set; } } interface ICondition { } class ExpressionCondition : ICondition { public virtual string Expression { get; set; } } class ThresholdCondition : ICondition { public virtual int Threshold { get; set; } } I also cannot add some empty abstract class that both conditions inherit from because the two ICondition implementations exist in different domains that are not allowed to reference each other. (Please no responses telling me that this situation should not occur in the first place - I'm aware of it and it doesn't help me.)

    Read the article

  • How to set order of appearance for fields when using Html.EditorFor in MVC 2?

    - by Anrie
    I have the following classes in my Model: public abstract class Entity : IEntity { [ScaffoldColumn(false)] public int Id { get; set; } [Required,StringLength(500)] public string Name { get; set; } } and public class Model : SortableEntity { [Required] public ModelType Type { get; set; } [ListRequired] public List<Producer> Producers { get; set; } public List<PrintArea> PrintAreas { get; set; } public List<Color> Colors { get; set; } } To display the "Model" class in the view I simply call Html.EditorFor(model=model), but the "Name" property of the base class is rendered last, which is not the desired behaviour. Is it possible to influenece on the order of displayed fields somehow?

    Read the article

  • How Does a Login system generally work with OOP?

    - by fakingfantastic
    Sorry if this is a badly formed question, but I'm trying to make my web applications (using PHP) more OO. *EDIT* I'm developing the Framework myself */EDIT* Everything is great so far, I've made a Front Controller system that taps into a MVC system. The FC figures out what page you want, loads the specific page Controller (*EDIT* which extends an abstract Controller Object */EDIT*), which gets anything it needs from Models, and then calls the appropriate View. Very basic. But now, I need to make an admin section (quasi-CMS). How does a login system fit into the grand scheme of things? Do you set controllers as needing a login? If so, how? What If you only want certain views of a controller requiring login? Thanks in advance.

    Read the article

  • using PIVOT to sql server.

    - by NoviceToDotNet
    This is the abstract idea which i want to do by my first select of first line, i am presenting here, but i am unable to do that correct. here category[0], category[2]..etc representing the category columns values...i know this kind of syntax not work, but i want to do something like this. SELECT category[0], category[1], category[2], category[3], category[4], category[5] FROM( select Row_number() OVER(ORDER BY (SELECT 1)) AS 'Serial Number', EP.FirstName,Ep.LastName, Ep.SignUpID, [dbo].[GetBookingRoleName](ES.UserId,EP.BookingRole) as RoleName, (select top 1 convert(varchar(10),eventDate,103)from [3rdi_EventDates] where EventId=@ItemId) as EventDate, (CASE [dbo].[GetBookingRoleName](ES.UserId,EP.BookingRole) WHEN 'Employee - Marketing' THEN 'DC' WHEN 'Employee - Accounting' THEN 'DC' WHEN 'Coaches' THEN 'DC' WHEN 'Student Client' THEN 'ST' WHEN 'Guest Doctor' THEN 'GDC' ---....more categories here, i just removed a few END) as Category from [3rdi_EventParticipants] as EP inner join [3rdi_EventSignup] as ES on EP.SignUpId = ES.SignUpId WHERE EP.EventId = @ItemId AND EP.PlaceStatus IN (0,3,4,8) and userid in( select distinct userid from userroles where roleid not in(19,20,21,22) and roleid not in(1,2, 25, 44)) (My Below Query) PIVOT(sum(First_Name+Last_Name)) FOR Category (category[0], category[1], category[2], category[3], category[4], category[5]) Group by (SignUpID)

    Read the article

  • What is the initiating actor for the usecase shown here

    - by Illep
    I am new to drawing use case and writing use case descriptions. I have an Actor called User , an abstract usecase called Work Type and another use case called Manager. The usecase Manager has a generalized relationship with the Work Type use case. I'm now writing the use case description for Manager use case. And what is the initiating Actor for this use case. Is it the Actor User ? or doesn't it have an initiating Actor ? Note: I only want to know the initiating Actor for the use case Manager

    Read the article

  • Java generics question

    - by user247866
    So I have 3 classes. Abstract class A Class B extends class A independent Class C In class D that contains the main method, I create a list of instances of class B List<B> b = methodCall(); // the method returns a list of instances of class B Now in class C I have one method that is common to both A and B, and hence I don't want to duplicate it. I want to have one method that takes as input an instance of class A, as follows: public void someMethod(List<A> a) However, when I do: C c = new C(); c.someMethod(b); I get an error that some-method is not applicable for the argument List<B>, instead it's expecting to get List<A>. Is there a good way to fix this problem? Many thanks!

    Read the article

  • Getting error in integrating Contacts APIs in Android 1.6 and 2.0

    - by dhaiwat
    Hi All, I have seen the BusinessCard example provide in Android examples. I am using ContactAccessor abstract class to seperate out the SDK versions. My code is running fine for 2.0 onwards, but when I am trying to build the code in Adnroid 1.6 I am getting the following errors: Build.VERSION_CODES.ECLAIR is not resolved. Getting errors in the whole class in which I have used Contacts APIs from 2.0 (say in class ContactAccessorSdk5.java). How to resolve these issues? I want to run my App on both the versions. Please help me. Regards, Dhaiwat Bhavsar.

    Read the article

  • Returning a static array without using a class field

    - by Bart Friederichs
    I have the following base and derived (partial, for sake of brevity) classes: class Base { public abstract int[] someArray { get; } } class Derived : Base { private readonly static int[] _someArray = new int[] { 1,2,3,4 }; public override int[] someArray { get { return _someArray; } } } What I would like now, is put the new int[] { 1,2,3,4 } in the return part of the getter. But, that would create a new array every time the getter is called. Is it possible to directly return some kind of object, which stays the same for all objects of class Derived ? Something along the lines of (I know this is invalid C#): get { return (int[]) { 1, 2, 3, 4 }; }

    Read the article

  • How to overload shutdown function?

    - by Michal M
    I am using Kohana (v3) framework but I believe it's not tied to a particular framework. What I have is basically an app with a front-end, where I want to use Kohana's native Kohana::shutdown_handler(), but I also have a part of the - RESTful API - where I don't want colourful and html-encoded exception reporting. I want a plain text reporting. The way I thought it might work is to register another shutdown function in API's controller abstract class constructor, but then I realised register_shutdown_function() works differently to set_exception_handler() and instead of replacing it adds another function to the shutdown procedure. What's worse PHP doesn't allow "unregistering" shutdown functions and that's where my problem lies. What to do, if you want to use another shutdown function instead of one already registered?

    Read the article

< Previous Page | 56 57 58 59 60 61 62 63 64 65 66 67  | Next Page >