Search Results

Search found 44734 results on 1790 pages for 'model based design'.

facebook twitter digg google delicious technorati stumbleupon myspace wordpress linkedin gmail igoogle windows live tumblr viadeo yahoo buzz yahoo mail yahoo bookmarks favorites email print

Page 87/1790 | < Previous Page | 83 84 85 86 87 88 89 90 91 92 93 94  | Next Page >

  • Concrete Types or Interfaces for return types?

    - by SDReyes
    Today I came to a fundamental paradox of the object programming style, concrete types or interfaces. Whats the better election for a method's return type: a concrete type or an interface? In most cases, I tend to use concrete types as the return type for methods. because I believe that an concrete type is more flexible for further use and exposes more functionality. The dark side of this: Coupling. The angelic one: A concrete type contains per-se the interface you would going to return initially, and extra functionality. What's your thumb's rule? Is there any programming principle for this? BONUS: This is an example of what I mean http://stackoverflow.com/questions/491375/readonlycollection-or-ienumerable-for-exposing-member-collections

    Read the article

  • What makes static initialization functions good, bad, or otherwise?

    - by Richard Levasseur
    Suppose you had code like this: _READERS = None _WRITERS = None def Init(num_readers, reader_params, num_writers, writer_params, ...args...): ...logic... _READERS = new ReaderPool(num_readers, reader_params) _WRITERS = new WriterPool(num_writers, writer_params) ...more logic... class Doer: def __init__(...args...): ... def Read(self, ...args...): c = _READERS.get() try: ...work with conn finally: _READERS.put(c) def Writer(...): ...similar to Read()... To me, this is a bad pattern to follow, some cons: Doers can be created without its preconditions being satisfied The code isn't easily testable because ConnPool can't be directly mocked out. Init has to be called right the first time. If its changed so it can be called multiple times, extra logic has to be added to check if variables are already defined, and lots of NULL values have to be passed around to skip re-initializing. In the event of threads, the above becomes more complicated by adding locking Globals aren't being used to communicate state (which isn't strictly bad, but a code smell) On the other hand, some pros: its very convenient to call Init(5, "user/pass", 2, "user/pass") It simple and "clean" Personally, I think the cons outweigh the pros, that is, testability and assured preconditions outweigh simplicity and convenience.

    Read the article

  • Example with Visitor Pattern

    - by devoured elysium
    public class Song { public string Genre { get; protected set; } public string Name { get; protected set; } public string Band { get; protected set; } public Song(string name, string band, string genre) { Name = name; Genre = genre; Band = band; } } public interface IMusicVisistor { void Visit(List<Song> items); } public class MusicLibrary { List<Song> _songs = new List<Song> { ...songs ... }; public void Accept(IMusicVisitor visitor) { visitor.Visit(_songs); } } and now here's one Visitor I made: public class RockMusicVisitor : IMusicVisitor { public List<Song> Songs { get; protected set; } public void Visit(List<Song> items) { Songs = items.Where(x => x.Genre == "Rock").ToList(); } } Why is this any better than just putting a public property Songs and then letting any kind of class do with it anything that it wants to? This example comes from this post.

    Read the article

  • Question regarding factory pattern

    - by eriks
    I have a factory class to build objects of base class B. The object (D) that uses this factory received a list of strings representing the actual types. What is the correct implementation: the factory receives an Enum (and uses switch inside the Create function) and D is responsible to convert the string to Enum. the factory receives a string and checks for a match to a set of valid strings (using ifs') other implementation i didn't think of.

    Read the article

  • Overlay 2d weapon sprite over character sprite ?

    - by Mr.Gando
    Hello, I'm working on a game where my character needs to be able to have different weapons. For that I think that somehow overlaying the weapon over the moving sprite would be the correct choice, but I'm not sure about how could I do this. Assuming my Character spritesheet looks like this: And my preliminar weapon spritesheet ( haven't decided on a fixed square size for the weapon yet ), looks like this: How would you make the overlay to set the weapon correctly over the character hand for each of his frames? I know that one way would be just to have a weapon frame the same size as my character sprites, and overlay those too, but I think that if the game has way too much weapons (say 15 different kinds of one hand weaps) this could get pretty insane ( having one weapon sprite sheet the same size as the character sprite sheet for each type of weapon ) Do you guys have any advice on how to implement this? (supporting overlaying the weapon sprites over the character sprites) Thanks!

    Read the article

  • Factory Method Pattern clarification

    - by nettguy
    My understanding of Factory Method Pattern is (Correct me if i am wrong) Factory Method Pattern "Factory Method allow the client to delegates the product creation (Instance Creation) to the subclass". There are two situation in which we can go for creating Factory Method pattern. (i) When the client is restricted to the product (Instance) creation. (ii) There are multiple products available.But a decision to be made which product instance need to be returned. If you want to create Abstract Method pattern You need to have abstract product Concrete Product Factory Method to return the appropriate product. Example : public enum ORMChoice { L2SQL, EFM, LS, Sonic } //Abstract Product public interface IProduct { void ProductTaken(); } //Concrete Product public class LinqtoSql : IProduct { public void ProductTaken() { Console.WriteLine("OR Mapping Taken:LinqtoSql"); } } //concrete product public class Subsonic : IProduct { public void ProductTaken() { Console.WriteLine("OR Mapping Taken:Subsonic"); } } //concrete product public class EntityFramework : IProduct { public void ProductTaken() { Console.WriteLine("OR Mapping Taken:EntityFramework"); } } //concrete product public class LightSpeed : IProduct { public void ProductTaken() { Console.WriteLine("OR Mapping Taken :LightSpeed"); } } public class Creator { //Factory Method public IProduct ReturnORTool(ORMChoice choice) { switch (choice) { case ORMChoice.EFM:return new EntityFramework(); break; case ORMChoice.L2SQL:return new LinqtoSql(); break; case ORMChoice.LS:return new LightSpeed(); break; case ORMChoice.Sonic:return new Subsonic(); break; default: return null; } } } **Client** Button_Click() { Creator c = new Creator(); IProduct p = c.ReturnORTool(ORMChoice.L2SQL); p.ProductTaken(); } Is my understanding of Factory Method is correct?

    Read the article

  • c# Attribute Question

    - by Petoj
    Well i need some help here i don't know how to solve this problem. the function of the attribute is to determine if the function can be run... So what i need is the following: The consumer of the attribute should be able to determine if it can be executed. The owner of the attribute should be able to tell the consumer that now it can/can't be executed (like a event). It must have a simple syntax. This is what i have so far but it only implements point 1, 3. [AttributeUsage(AttributeTargets.Method, AllowMultiple = false)] public class ExecuteMethodAttribute : Attribute { private Func<object, bool> canExecute; public Func<object, bool> CanExecute { get { return canExecute; } } public ExecuteMethodAttribute() { } public ExecuteMethodAttribute(Func<object, bool> canExecute) { this.canExecute = canExecute; } }

    Read the article

  • UML Class Relationships

    - by 01010011
    Hi, I would like to confirm whether I am on the right track when identifying common UML class relationships. For example, is the relationship between: 1 a stackoverflow member and his/her stackoverflow user account categorized as a composition relationship or an aggregation relationship? At first I thought it was an association because this member "has a" account. However on second thought, I am thinking its composition because each "part" (user account) belongs to only one whole (user) at a time, meaning for as long as I am logged into stackoverflow, I have to use this one and only account until I log off. If I log back onto stackoverflow with a different account then its composition again. Do you agree? 2 a database and a person's user account an aggregation relationship? I think so because 1 database (the whole) can store 0...* number of user accounts (the parts) but another database can store the same user accounts. Finally, can anyone recommend a website that specializes in designing code using UML? Thanks in advance

    Read the article

  • Concurency problem with Isolation - read-committed

    - by Ratn Deo--Dev
    I have to write a simple demo for amount withdrawl from a joint Bank amount .Andy and Jen holds a joint bank account with number 123 . Suppose they have 100$ in their account .Jen and Andy are operating their account at the same time and both are trying to withdraw 90$ at the time being .My transaction Isolation is set to read-committed and both are able to withdraw money leaving the balance to -(minus)80$ although I have constraint that balance should never be less than 0. I am using hibernate .Is versioning only way to solve this problem or I should go for another Isolation level ?

    Read the article

  • How can i return abstract class from any factory?

    - by programmerist
    using System; using System.Collections.Generic; using System.Linq; using System.Web; namespace EfTestFactory { public abstract class _Company { public abstract List<Personel> GetPersonel(); public abstract List<Prim> GetPrim(); public abstract List<Finans> GetFinans(); } public abstract class _Radyoloji { public abstract List<string> GetRadyoloji(); } public abstract class _Satis { public abstract List<string> GetSatis(); } public abstract class _Muayene { public abstract List<string> GetMuayene(); } public class Company : _Company { public override List<Personel> GetPersonel() { throw new NotImplementedException(); } public override List<Prim> GetPrim() { throw new NotImplementedException(); } public override List<Finans> GetFinans() { throw new NotImplementedException(); } } public class Radyoloji : _Radyoloji { public override List<string> GetRadyoloji() { throw new NotImplementedException(); } } public class Satis : _Satis { public override List<string> GetSatis() { throw new NotImplementedException(); } } public class Muayene : _Muayene { public override List<string> GetMuayene() { throw new NotImplementedException(); } } public class GenoTipController { public object CreateByEnum(DataModelType modeltype) { string enumText = modeltype.ToString(); // will return for example "Company" Type classType = Type.GetType(enumText); // the Type for Company class object t = Activator.CreateInstance(classType); // create an instance of Company class return t; } } public class AntsController { static Dictionary<DataModelType, Func<object>> s_creators = new Dictionary<DataModelType, Func<object>>() { { DataModelType.Radyoloji, () => new _Radyoloji() }, { DataModelType.Company, () => new _Company() }, { DataModelType.Muayene, () => new _Muayene() }, { DataModelType.Satis, () => new _Satis() }, }; public object CreateByEnum(DataModelType modeltype) { return s_creators[modeltype](); } } public class CompanyView { public static List<Personel> GetPersonel() { GenoTipController controller = new GenoTipController(); _Company company = controller.CreateByEnum(DataModelType.Company) as _Company; return company.GetPersonel(); } } public enum DataModelType { Radyoloji, Satis, Muayene, Company } } if i write above codes i see some error: Cannot create an instance of abstract class or interface 'EfTestFactory_Company'How can i solve it? Look please below pic.

    Read the article

  • Hierarchy / Flyweight / Instancing Problem in Python

    - by Dan
    Here is the problem I am trying to solve, (I have simplified the actual problem, but this should give you all the relevant information). I have a hierarchy like so: 1.A 1.B 1.C 2.A 3.D 4.B 5.F (This is hard to illustrate - each number is the parent, each letter is the child). Creating an instance of the 'letter' objects is expensive (IO, database costs, etc), so should only be done once. The hierarchy needs to be easy to navigate. Children in the hierarchy need to have just one parent. Modifying the contents of the letter objects should be possible directly from the objects in the hierarchy. There needs to be a central store containing all of the 'letter' objects (and only those in the hierarchy). 'letter' and 'number' objects need to be possible to create from a constructor (such as Letter(**kwargs) ). It is perfectably acceptable to expect that when a letter changes from the hierarchy, all other letters will respect the same change. Hope this isn't too abstract to illustrate the problem. What would be the best way of solving this? (Then I'll post my solution) Here's an example script: one = Number('one') a = Letter('a') one.addChild(a) two = Number('two') a = Letter('a') two.addChild(a) for child in one: child.method1() for child in two: print '%s' % child.method2()

    Read the article

  • Object Oriented Database - why most of the companies do not use them

    - by GigaPr
    Hi, I am pretty new to programming(just finished University). I have been thought in the last 4 years about Object Oriented development and the numerous advantages of this approach. My question is Isn't it easier to use a pure Object Oriented database in development applications? Why Object Oriented database are not as much diffuse as relational? From my point of view makes sense to use OO database, the latter will avoid the numerous construction necessary for the mapping of complex objects on the tables.

    Read the article

  • Conventions for the behavior of double or triple "click to select text" features?

    - by John Sullivan
    Almost any mature program that involves text implements "double click to select the word" and, in some cases, "triple click to select additional stuff like an entire line" as a feature. I find these features useful but they are often inconsistent between programs. Example - some programs' double clicks do not select the ending space after a word, but most do. Some recognize the - character as the end of a word, others do not. SO likes to select the entire paragraph as I write this post when I triple click it, VS web developer 2005 has no triple click support, and ultra-edit 32 will select one line upon triple clicking. We could come up with innumerable inconsistencies about how double and triple click pattern matching is implemented across programs. I am concerned about how to implement this behavior in my program if nobody else has achieved a convention about how the pattern matching should work. My question is, does a convention (conventions? maybe an MS or Linux convention?) exist that dictates how these features are supposed to behave to the end user? What, if any, are they?

    Read the article

  • Can a binary tree or tree be always represented in a Database as 1 table and self-referencing?

    - by Jian Lin
    I didn't feel this rule before, but it seems that a binary tree or any tree (each node can have many children but children cannot point back to any parent), then this data structure can be represented as 1 table in a database, with each row having an ID for itself and a parentID that points back to the parent node. That is in fact the classical Employee - Manager diagram: one boss can have many people under him... and each person can have n people under him, etc. This is a tree structure and is represented in database books as a common example as a single table Employee.

    Read the article

  • Passing data structures to different threads

    - by Robb
    I have an application that will be spawning multiple threads. However, I feel there might be an issue with threads accessing data that they shouldn't be. I'm relatively new to threading so bare with me. Here is the structure of the threaded application (sorry for the crudeness): MainThread / \ / \ / \ Thread A Thread B / \ / \ / \ / \ / \ / \ Thread A_1 Thread A_2 Thread B_1 Thread B_2 Under each lettered thread (which could be many), there will only be two threads and they are fired of sequentially. The issue i'm having is I'm not entirely sure how to pass in a datastructure into these threads. So, the datastructure is created in MainThread, will be modified in the lettered thread (Thread A, etc) specific to that thread and then a member variable from that datastructure is sent to Letter_Numbered threads. Currently, the lettered thread class has a member variable and when the class is constructed, the datastructure from mainthread is passed in by reference, invoking the copy constructor so the lettered thread has it's own copy to play with. The lettered_numbered thread simply takes in a string variable from the data structure within the lettered thread. My question is, is this accceptable? Is there a much better way to ensure each lettered thread gets its own data structure to play with? Sorry for the somewhat poor explanation, please leave comments and i'll try to clarify.

    Read the article

  • Simply doing modelType.ToString() isn't sufficient, How can i use it via Activator.CreateInstance?

    - by programmerist
    public class MyController { public object CreateByEnum(DataModelType modeltype) { string enumText = modeltype.ToString(); // will return for example "Company" Type classType = Type.GetType(enumText); // the Type for Company class object t = Activator.CreateInstance(classType); // create an instance of Company class return t; } } public class CompanyView { public static List<Personel> GetPersonel() { MyController controller = new MyController(); _Company company = controller.CreateByEnum(DataModelType.Company) as _Company; return company.GetPersonel(); } } public enum DataModelType { xyz, klm, tucyz, Company } Yes, I agree Activator.CreateInstance() is very useful. Unfortunately, I need to pass in the correct type. That means building the correct string to pass to Type.GetType(). If I trace through the call to Controller.CreatebyEnum() in the code I posted above, simply doing modelType.ToString() isn't sufficient, even for the case of DataModelType.Company. My solution'll be maintenance bottleneck. What would be better is something that takes the results of modelType.ToString() and then recursively searches through all the types found in all the assemblies loaded in the current AppDomain. According to MSDN, Type.GetType() only searches the current calling assembly, and mscorlib.dll. How can i do that? . i need best performance?

    Read the article

  • what is this 'content_type' mean..

    - by zjm1126
    content_type = ContentType.objects.get_for_model(Map) maps = maps.extra(select=SortedDict([ ('member_count', MEMBER_COUNT_SQL), ('topic_count', TOPIC_COUNT_SQL), ]), select_params=(content_type.id,)) and the ContentType is: class ContentType(models.Model): name = models.CharField(max_length=100) app_label = models.CharField(max_length=100) model = models.CharField(_('python model class name'), max_length=100) objects = ContentTypeManager() class Meta: verbose_name = _('content type') verbose_name_plural = _('content types') db_table = 'django_content_type' ordering = ('name',) unique_together = (('app_label', 'model'),) def __unicode__(self): return self.name def model_class(self): "Returns the Python model class for this type of content." from django.db import models return models.get_model(self.app_label, self.model) def get_object_for_this_type(self, **kwargs): """ Returns an object of this type for the keyword arguments given. Basically, this is a proxy around this object_type's get_object() model method. The ObjectNotExist exception, if thrown, will not be caught, so code that calls this method should catch it. """ return self.model_class()._default_manager.using(self._state.db).get(**kwargs) def natural_key(self): return (self.app_label, self.model) i want to know: what is the 'content_type' used for ??

    Read the article

  • Some basic UML questions

    - by devoured elysium
    What does it mean when you have something as the following picture? Each Customer has none, one or more Orders while each Order has only one Customer? And in relationship to the following one: What does the black diamond mean in this context? How is that black diamond called? Thanks

    Read the article

  • Is it good to subclass a class only to separate some functional parts?

    - by prostynick
    Suppose we have abstract class A (all examples in C#) public abstract class A { private Foo foo; public A() { } public void DoSomethingUsingFoo() { //stuff } public void DoSomethingElseUsingFoo() { //stuff } //a lot of other stuff... } But we are able to split it into two classes A and B: public abstract class A { public A() { } //a lot of stuff... } public abstract class B : A { private Foo foo; public B() : base() { } public void DoSomethingUsingFoo() { //stuff } public void DoSomethingElseUsingFoo() { //stuff } //nothing else or just some overrides of A stuff } That's good, but we are 99.99% sure, that no one will ever subclass A, because functionality in B is very important. Is it still good to have two separate classes only to split some code into two parts and to separate functional elements?

    Read the article

  • Facade controller, is it efficient?

    - by Berlioz
    Using a facade controller pattern in .net. It seems as if though it is not efficient BECAUSE, for every event that happens in a domain object(Sales, Register, Schedule, Car) it has to be subscribed to by the controller(use case controller) and then the controller in turn has to duplicate that same event to make it available for the presentation, so that the presentation can show it to the user. Does this make sense? Please comment!

    Read the article

  • date representation in user interface

    - by Samuel
    Most of the sites capture the date (e.g. birth date) information as either a single entity (i.e via a calendar control) or instead as separate fields (date, month, year). Are there any benefits in showing them as separate fields? Are they represented in the database as DATE data type or as separate fields. I am just trying to understand the pros & cons of representing the date field.

    Read the article

facebook twitter digg google delicious technorati stumbleupon myspace wordpress linkedin gmail igoogle windows live tumblr viadeo yahoo buzz yahoo mail yahoo bookmarks favorites email print

< Previous Page | 83 84 85 86 87 88 89 90 91 92 93 94  | Next Page >