Search Results

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

Page 29/91 | < Previous Page | 25 26 27 28 29 30 31 32 33 34 35 36  | Next Page >

  • Cassandra or MySQL/PostgreSQL?

    - by Ivri
    Hi! I have huge database (kinda wordnet). And want to know if it's easier to use Cassandra instead of MySQL|PostrgreSQL All my life I was using MySQL and PostrgreSQL and I could easily think in terms of relational algebra, but several weeks ago I learned about cassandra and that it's used in facebook and twitter. Is it more convenient? What DBMS are usually used nowadays to store social net's data, relationships between objects, wordnet?

    Read the article

  • What would be the use of accepting itself as type arguments in generics

    - by Newtopian
    I saw some code on an unrelated question but it got me curious as I never saw such construct with Java Generics. What would be the use of creating a generic class that can take as type argument itself or descendants of itself. Here is example : abstract class A<E extends A> { abstract void foo(E x); } the first thing that came to mind would be a list that takes a list as parameter. Using this code feels strange, how do you declare a variable of type A ? Recursive declaration !? Does this even work ? If so did any of you see that in code ? How was it used ?

    Read the article

  • A way to avoid deriving from the provider classes in mvc authentication

    - by Shymep
    Looking for the best practice for authentication in MVC I unfortunately didn't find the clear answer to my question. Thinking of the problem I tried to imagine some priciples that could be useful in my design. Well, I would like to use a base AccountController class I want to place all the tables such as "Users", Roles, Rights etc into my own database. But I wouldn't like to implement the standard aspnetdb design (which can be easy got by using aspnet_regsql) So the main question is can I do this without deriving abstract classes like MembershipProvider, RoleProvider etc? What I would prefer not to do is implement all the abstract methods from these classes. The second question is still about the best practice for authentication e.g. for the small projects, for the large ones?

    Read the article

  • How do I compete the transformation matrix needed to transform a rectangle into a trapezium?

    - by Rich Bradshaw
    I'm playing around with css transforms and the equivalent filters in IE, and want to simulate perspective by transforming a 2d rectangle into a trapezium. Specifically, I want the right hand side of the rectangle to stay the same height, and the left hand side to be say 80% of the height, so that the mid points of both sides are horizontally in line with each other. I'm familiar with matrix algebra, but can't think how to determine what matrix will do that.

    Read the article

  • How to generate Doctrine models/classes that extend a custom record class

    - by Shane O'Grady
    When I use Doctrine to generate classes from Yaml/db each Base class (which includes the table definition) extends the Doctrine_Record class. Since my app uses a master and (multiple) slave db servers I need to be able to make the Base classes extend my custom record class to force writes to go to the master db server (as described here). However if I change the base class manually I lose it again when I regenerate my classes from Yaml/db using Doctrine. I need to find a way of telling Doctrine to extend my own Base class, or find a different solution to a master/slave db setup using Doctrine. Example generated model: abstract class My_Base_User extends Doctrine_Record { However I need it to be automatically generated as: abstract class My_Base_User extends My_Record { I am using Doctrine 1.2.1 in a new Zend Framework 1.9.6 application if it makes any difference.

    Read the article

  • feeling insufficient while looking for a programming job ...

    - by user325661
    Hello everybody It's really dream to be programmer for me.So i always wanted to be .I had so small knowledges from commodore basic which i couldn't figure out anything in it .Then i tried to learn Visual basic 6 by myself and result wasn't good as i expected because i even didn't understand classes.Then i left to learning programming and to dream to be programmer. But challenge hadn't finished yet . After all of these i started to learn c# and i did chess engine which i hadn't believe that i can create one.I sometimes feel that i understand many thing about programming like knowing classes ,inheritance,abstract class and methods why exist , interfaces ,extension methods ,static classes ,threads. but i am not expert all in it . i just know that as i need . i don't know still i will learn many thing about these.i have also learned html, css2 , php and database concepts a little sql ,tables relations between primary keys etc but i haven't used them in praticaly . i just did some samples so i feel i am lack of knowledges. As a result still i can't evaluate my skills and can't decide what is my level.I just feel myself one step ahead of junior sometimes :) . Still can't decide that it is time to job seeking. While searching job on web i have never seen a junior advertisement. All looking for a good experiencing one.Nobody care about juniors. When found job advertisement which i feel sufficient myself a little then i start to feel that i think i can't do what they want from me and loosing job after have it in short time would leave many crap feelings into my low self-confidence. Please advise me something ... Also i want to ask some of concentrate questions. 1) If i enter a job which i can't provide their expectations should be in employers responsibility to test me while apply the job ? 2) If i answer "yes , i can " questions which is abstract(for example: can u do something like this) would be my responsibility ? Because such abstract questions is not clear and can't know before start it what i really can or not . 3) i have no professional experiences in this job so i even don't know how teams working on projects but a friend of me said that programmers only write method bodies while seniors create all project.So it looks what i can do really easy but i feel that small companies doesn't work like this so it is better work in a big company for starting who has seniors? 4)last applied job was looking for c# . net developer but then i learn that they need .net web developer.Does it take long time to learn specific sides of web programming while knowing c# desktop programming ? Thanks for all answers since now.

    Read the article

  • Getting PDT code completion to recognise runtime return types from base class?

    - by Keith Humm
    Hi guys, I've got an abstract base class: abstract class BaseClass { /** * @return CLASSNAME */ public function fluent() { // do stuff return $this; } } Generally, i would put BaseClass where CLASSNAME is and all would be fine, PDT would pick up the phpdoc return type and happily autocomplete. Until, that is, I subclass BaseClass and add additional methods, and code compete on an instance of the derived class. PDT will only recognise the methods from BaseClass and not those from the derived class. What I need is something like @return self or @return this. Does PDT have such functionality? Or is there an alternate trick without having to declare these methods in every derived class?

    Read the article

  • StructureMap: Wiring (generic) implementations to an implementation of another type

    - by Jeremy Frey
    If I have an interface: public interface IRepository<T> And an abstract class: public abstract class LinqToSqlRepository<T, TContext> : IRepository<T> where T : class where TContext : DataContext And a whole bunch of implementations of IRepository / LinqToSqlRepository (e.g. AccountRepository, ContactRepository, etc.), what's the best way to to use StructureMap (2.5.3) to generically wire them all up? e.g., I want this code to pass: [Test] public void ShouldWireUpAccountRepositories { var accountRepo = ObjectFactory.GetInstance<IRepository<Account>>(); Assert.IsInstanceOf<AccountRepository>(accountRepo); } Without explicitly writing this: ObjectFactory.Configure(x => x.ForRequestedType<IRepository<Account>>() .TheDefaultIsConcreteType<AccountRepository>()); In the past, we've always created a specific interface on each repository that inherited from the generic one, and used the default scanner to automatically wire all of those instances, but I'd like to be able to ask specifically for an IRepository<Account> without cluttering up the project with additional interfaces / configurations.

    Read the article

  • Is it possible to access variable of subclass using object of superclass in polymorphism

    - by fari
    how can i access state varibale of class keyboard with object of class kalaplayer /** * An abstract class representing a player in Kala. Extend this class * to make your own players (e.g. human players entering moves at the keyboard * or computer players with programmed strategies for making moves). */ public abstract class KalaPlayer { /** * Method by which a player selects a move. * @param gs The current game state * @return A side pit number in the range 1-6 * @throws NoMoveAvailableException if all side pits for the player are empty * (i.e. the game is over) */ public abstract int chooseMove(KalaGameState gs) throws NoMoveAvailableException; } public class KeyBoardPlayer extends KalaPlayer { /** * Method by which a player selects a move. * @param gs The current game state * @return A side pit number in the range 1-6 * @throws NoMoveAvailableException if all side pits for the player are empty * (i.e. the game is over) */ public KalaGameState state; public KeyBoardPlayer() { System.out.println("Enter the number of stones to play with: "); try { BufferedReader br = new BufferedReader(new InputStreamReader(System.in)); int key = Integer.parseInt(br.readLine()); state=new KalaGameState(key); //key=player1.state.turn; } catch(IOException e) { System.out.println(e); } } public int chooseMove(KalaGameState gs) throws NoMoveAvailableException{ return 0; } } import java.io.IOException; import java.io.BufferedReader; import java.io.InputStreamReader; public class KalaGame { KalaPlayer player1,player2; public KalaGame(KeyBoardPlayer Player1,KeyBoardPlayer Player2) { //super(0); player1=new KeyBoardPlayer(); player2 = new KeyBoardPlayer(); //player1=Player1; //player2=Player2; //player1.state ****how can i access the stae variable from Keyboard CLass using object from KalaPlayer key=player1.state.turn; } public void play() { System.out.println("Enter the number of stones to play with: "); try { BufferedReader br = new BufferedReader(new InputStreamReader(System.in)); int key = Integer.parseInt(br.readLine()); System.out.println(key); KalaGameState state=new KalaGameState(key); printGame(); } catch(IOException e) { System.out.println(e); } }

    Read the article

  • Factory Method pattern and public constructor

    - by H4mm3rHead
    Hi, Im making a factory method that returns new instances of my objects. I would like to prevent anyone using my code from using a public constructor on my objects. Is there any way of doing this? How is this typically accomplished: public abstract class CarFactory { public abstract ICar CreateSUV(); } public class MercedesFactory : CarFactory { public override ICar CreateSUV() { return new Mercedes4WD(); } } I then would like to limit/prevent the other developers (including me in a few months) from making an instance of Mercedes4WD. But make them call my factory method. How to?

    Read the article

  • Scala class to implement two Java Interfaces - how?

    - by puudeli
    Hi, I have just started learning Scala and I'm now wondering how I could implement two different Java interfaces with one Scala class? Let's say I have the following interfaces written in Java public interface EventRecorder { public void abstract record(Event event); } public interface TransactionCapable { public void abstract commit(); } But a Scala class can extend only one class at a time. How can I have a Scala class that could fulfill both contracts? Do I have to map those interfaces into traits? Note, my Scala classes would be used from Java as I am trying to inject new functionality written in Scala into an existing Java application. And the existing framework expects that both interface contracts are fulfilled.

    Read the article

  • Inheritance in Java

    - by stevebot
    If I have an abstract class in java named Foo and it has an implementor named Bar then I want to know the following. lets say Foo looks something like public abstract class Foo { Service serviceFoo ... } And Bar is public class Bar extends Foo { ... } Also, lets assume I have an instance with Foo, named foo, currently that has serviceFoo instantiated If I then declare: Foo foo = new Bar(); will this create a a new instance of Bar that has serviceFoo instantiated or not? E.g. will that field be inherited and instantiated or just inherited?

    Read the article

  • How to build boost foreach cycle

    - by Ockonal
    Hi guys! I have some abstract class called IClass (has pure virtual function). There are some classes which inherit IClass: CFirst, CSecond. I want to add objects of classes which inherit into boost::ptr_vector: class IClass { virtual void someFunc() = 0; }; class CFirst : public IClass { }; class CSecond : public IClass { }; boost::ptr_vector<IClass> objectsList; objectsList.push_back(new CFirst()); objectsList.push_back(new CSecond()); And now my goal is to call function (which is declarated in IClass) from all objects in objectsList. I'd prefer to use BOOST_FOREACH: foreach(IClass tempObj, objectsList) { tempObj.someFunc(); } The problem is that IClass - abstract class, so I can't make instance of it for the foreach-cycle. What should I do?

    Read the article

  • Alternative to c++ static virtual methods

    - by Jaime Pardos
    In C++ is not possible to declare a static virtual function, neither cast a non-static function to a C style function pointer. Now, I have a plain ol' C SDK that uses function pointers heavily. I have to fill a structure with several function pointers. I was planning to use an abstract class with a bunch of static pure virtual methods, and redefine them in derived classes and fill the structure with them. It wasn't until then that I realized that static virtual are not allowed in C++. Is there any good alternative? The best I can think of is defining some pure virtual methods GetFuncA(), GetFuncB(),... and some static members FuncA()/FuncB() in each derived class, which would be returned by the GetFuncX(). Then a function in the abstract class would call those functions to get the pointers and fill the structure.

    Read the article

  • Have a link that is imported in xml, clickable to execute a function

    - by Benjamin Sterling
    Ok, here's the question, I have an xml doc that is being import into an AS3 file and then with .htmlText, appending it to a movie clip. An example of what this looks like is: <abstract><![CDATA[<p><strong>AEO Times Square</strong> Store Wins Prestigious SEGD Merit Award for Dynamic Environments <a href='event:OpenArticle1'>View Article</a></p>]]></abstract> What I'd like to have happen is when I click that view article link that I can call a function passing in "OpenArticle1". Thanks in advance.

    Read the article

  • Ideas for a C/C++ library

    - by Mohit Deshpande
    I thought one of the best ways to familiarise myself with C/C++, is to make a helpful library. I was maybe thinking like a geometry library, like to calculate areas, surface area, etc. It would be useful in game programming. Or maybe an algebra library, like for different formulas like the distance formula, quadratic formula, etc. Or maybe like a standard library for very simple functions, like calculating the number of items in an array.

    Read the article

  • How to allow users to customize a DAL

    - by rsteckly
    Hi, I'm working in ASP.NET in an application where often users want to add fields or change field names. I'd like to be able to have an xml schema in place that is parsed and a dynamic object model created from it that can be accessed throughout the application. My initial reaction is that this is not realistic. I think there is flexibility about the dynamic nature of it. I think the people I'm trying to build this for wouldn't mind recompiling. Even if the app recompiled, I don't know how to abstract away enough in my code access the data to allow for users changing property names, etc. How can you write LINQ when the properties might change? In short, there's two questions here: 1) is there a way to dynamically generate an object model of the database and 2) is there a way to abstract away enough so that code accessing the database doesn't break when properties change?

    Read the article

  • Inheriting the main method

    - by Eric
    I want to define a base class that defines a main method that instantiates the class, and runs a method. There are a couple of problems though. Here is the base class: public abstract class Strategy { abstract void execute(SoccerRobot robot); public static void main(String args) { Strategy s = new /*Not sure what to put here*/(); s.execute(new SoccerRobot()) } } And here is an example derived class: public class UselessStrategy { void execute(SoccerRobot robot) { System.out.println("I'm useless") } } It defines a simple execute method, which should be called in a main method upon usage as a the main application. However, in order to do so, I need to instantiate the derived class from within the base class's main method. Which doesn't seem to be possible. I'd rather not have to repeat the main method for every derived class, as it feels somewhat unnessary. Is there a right way of doing this?

    Read the article

  • Ways to improve Java Generics and dont say get rid of wildcards and reification.

    - by mP
    Sometimes i like to write up template classes and use type parameters to make the abstract methods more type safe. Template<X> { abstract void doStuff( X ); // NOT public } While type safety is great etc, the problem remains that even though X is not visible to outside code, one must still include the type to avoid warnings. My solution in this case would be to make it possible to define a scope for type parameters (now they are always public). Would other original features besides the obvious would you like.

    Read the article

  • Help naming a class that has a single public method called Execute()

    - by devoured elysium
    I have designed the following class that should work kind of like a method (usually the user will just run Execute()): public abstract class ??? { protected bool hasFailed = false; protected bool hasRun = false; public bool HasFailed { get { return hasFailed; } } public bool HasRun { get { return hasRun; } } private void Restart() { hasFailed = false; hasRun = false; } public bool Execute() { ExecuteImplementation(); bool returnValue = hasFailed; Restart(); return returnValue; } protected abstract void ExecuteImplementation(); } My question is: how should I name this class? Runnable? Method(sounds awkward)?

    Read the article

  • Reverse Expression.Like criterion

    - by Joel Potter
    How should I go about writing a backwards like statement using NHibernate criteria? WHERE 'somestring' LIKE [Property] + '%' Sub Question: Can you access the abstract root alias in a SQLCriterion expression? This is somewhat achievable using the SQLCriterion expression Expression.Sql("? like {alias}.[Property] + '.%'", value, NHibernateUtil.String); However, in the case of class inheritance, {alias} is replaced with the incorrect alias for the column. Example (these classes are stored in separate tables): public abstract class Parent { public virtual string Property { get; set; } } public class Child : Parent { } The above query executed with Child as the root type will replace {alias} with the alias to the Child table rather than the Parent table. This results in an invalid column exception. I need to execute a like statement as above where the property exists on the parent table rather than on the root type table.

    Read the article

  • Accessing Session and IPrinciple data in a Master View in Asp.Net MCV

    - by bplus
    I currently have a abstract controller class that I all my controllers inherit from. In my master page I want to be able to access some data that will be in Session and also the currently user (IPrinciple). I read that I could use the contructor of by abstract base controller class, that is I could do something like public BaseController() { ViewData["SomeData"] = Session["SomeData"]; ViewData["UserName"] = this.User.Identity.Name; } I could then access ViewData["UserName"] etc from my master page. My problem is that both Session and User are null at this point. Does anybody know of a different approach? Thanks in advance.

    Read the article

  • Does this code describe an Existential Type in C#?

    - by noblethrasher
    Currently watching Bart De Smet's explanation of IQueryable and he mentioned Existential Types (which I've been curious about for some time). After reading the answers to this question I'm just wondering if this is a way to construct it in C#: public abstract class ExistentialType { private ExistentialType() { } public abstract int Foo(); public ExistentialType Create() { return new ConcreateType1(); } private class ConcreateType1 : ExistentialType { public override int Foo() { throw new NotImplementedException(); } } private class ConcreateType2 : ExistentialType { public override int Foo() { throw new NotImplementedException(); } } private class ConcreateType3 : ExistentialType { public override int Foo() { throw new NotImplementedException(); } } }

    Read the article

  • Running a method after the constructor of any derived class

    - by Alexey Romanov
    Let's say I have a Java class abstract class Base { abstract void init(); ... } and I know every derived class will have to call init() after it's constructed. I could, of course, simply call it in the derived classes' constructors: class Derived1 extends Base { Derived1() { ... init(); } } class Derived2 extends Base { Derived2() { ... init(); } } but this breaks "don't repeat yourself" principle rather badly (and there are going to be many subclasses of Base). Of course, the init() call can't go into the Base() constructor, since it would be executed too early. Any ideas how to bypass this problem? I would be quite happy to see a Scala solution, too.

    Read the article

  • help with generating models from database for many to many in doctrine

    - by ajsie
    im using doctrine and i have set up some test tables to be generated into models: I want a many-to-many relationship models (3 tables converted into 3 models) (things are simplified to make the point clear) mysql tables: user: id INT // primary key name VARCHAR group: id INT // primary key name VARCHAR user_group: user_id INT // primary and foreign key to user.id group_id INT // primary and foreign key to group.id i thought that it would generate these models (from the documentation): // User.php class User extends Doctrine_Record { public function setTableDefinition() { $this->hasColumn('id'); $this->hasColumn('name); } public function setUp() { $this->hasMany('Group as Groups', array( 'refClass' => 'UserGroup', 'local' => 'user_id', 'foreign' => 'group_id' ) ); } } // Group.php class Group extends Doctrine_Record { public function setTableDefinition() { $this->hasColumn('id'); $this->hasColumn('name); } public function setUp() { $this->hasMany('User as Users', array( 'refClass' => 'UserGroup', 'local' => 'group_id', 'foreign' => 'user_id' ) ); } } // UserGroup.php class UserGroup extends Doctrine_Record { public function setTableDefinition() { $this->hasColumn('user_id') ); $this->hasColumn('group_id') ); } } but it generated this: // User.php abstract class BaseUser extends Doctrine_Record { public function setTableDefinition() { $this->hasColumn('id'); $this->hasColumn('name'); } public function setUp() { $this->hasMany('UserGroup', array( 'local' => 'id', 'foreign' => 'user_id')); } } // Group.php abstract class BaseGroup extends Doctrine_Record { public function setTableDefinition() { $this->hasColumn('id'); $this->hasColumn('name'); } public function setUp() { $this->hasMany('UserGroup', array( 'local' => 'id', 'foreign' => 'group_id')); } } // UserGroup.php abstract class BaseUserGroup extends Doctrine_Record { public function setTableDefinition() { $this->hasColumn('user_id'); $this->hasColumn('group_id'); } public function setUp() { $this->hasOne('User', array( 'local' => 'user_id', 'foreign' => 'id')); $this->hasOne('Group', array( 'local' => 'group_id', 'foreign' => 'id')); } } as you can see, there is no 'refClass' in the 'User' and 'Group' models pointing to the 'UserGroup'. the 'UserGroup' table in this case is just another table from Doctrine's perspective not a reference table. I've checked my table definitions in mysql. They are correct. user_group has 2 columns (primary keys and foreign keys), each one pointing to the primary key in either User or Group. But i want the standard many-to-many relationship models in Doctrine models. I'd appreciate some help. I have struggled to figure it out for a half day now. What is wrong? Thanks!

    Read the article

< Previous Page | 25 26 27 28 29 30 31 32 33 34 35 36  | Next Page >