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• How to refactor to cleaner version of maintaing states of the widget

  - by George

  Backstory I inherited a bunch of code that I'd like to refactor. It is a UI application written in javascript. Current state: We have main application which consist of several UI components. And each component has entry fields, textboxes, menus, etc), like "ticket", "customer information", etc. Based on input, where the application was called from, who is the user, we enable/disable, hide, show, change titles. Unfortunately, the app grew to the point where it is really hard to scale, add new features. Main the driver (application code) calls set/unset functions of the respective components. So a lot of the stuff look like this Main app unit function1() { **call_function2()** component1.setX(true); component1.setY(true); component2.setX(false); } call_function2() { // it may repeat some of the code function1 called } and we have a lot of this in the main union. I am cleaning this mess. What is the best way to maintain the state of widgets? Please let me know if you need me to clarify.

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• How to implement Restricted access to application features

  - by DroidUser

  I'm currently developing a web application, that provides some 'service' to the user. The user will have to select a 'plan' according to which she/he will be allowed to perform application specific actions but up to a limit defined by the plan. A Plan will also limit access to certain features, which will not be available at all for some plans. As an example : say there are 3 plans, 2 actions throughout the application users in plan-1 can perform action-1 3 times, and they can't perform action-2 at all users in plan-2 can perform action-1 10 times, action-2 5 times users in plan-3 can perform action-1 20 times, action-2 10 times So i'm looking for the best way to get this done, and my main concerns besides implementing it, are the following(in no particular order) maintainability/changeability : the number of plans, and type of features/actions will change in the final product industry standard/best practice : for future readiness!! efficiency : ofcourse, i want fast code!! I have never done anything like this before, so i have no clue about how do i go about implementing these functionalities. Any tips/guides/patterns/resources/examples? I did read a little about ACL, RBAC, are they the patterns that i need to follow? Really any sort of feedback will help.

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• Why avoid Java Inheritance "Extends"

  - by newbie

  Good day! Jame Gosling said “You should avoid implementation inheritance whenever possible.” and instead, use interface inheritance. But why? How can we avoid inheriting the structure of an object using the keyword "extends", and at the same time make our code Object Oriented? Could someone please give an Object Oriented example illustrating this concept in a scenario like "ordering a book in a bookstore?" Thank you in advance.

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• Create many similar classes, or just one

  - by soandos

  The goal is to create an application that has objects that can represent some operations (add, subtract, etc). All of those objects will have common functions and members, and thus will either implement an interface or inherit from an abstract class (Which would be better practice, this will be in C# if that matters?). As far as I can see, there are two different ways of organizing all of these classes. I could create an addition class, a subtraction class, etc. This has the upside of being highly modular but the difference between classes is so minimal. I could create one class, and have a member that will say what type of operation is being represented. This means lots of switch statements, and losing some modularity, in addition to being harder to maintain. Which is is better practice? Is there a better way of doing that is not listed above? If it matters, the list of functions that should be supported is long.

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• When is a glue or management class doing too much?

  - by jprete

  I'm prone to building centralized classes that manage the other classes in my designs. It doesn't store everything itself, but most data requests would go to the "manager" first. While looking at an answer to this question I noticed the term "God Object". Wikipedia lists it as an antipattern, understandably. Where is the line between a legitimate glue class, or module, that passes data and messages from place to place, and a class that is doing too much?

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• Where we should put validation for domain model

  - by adisembiring

  I still looking best practice for domain model validation. Is that good to put the validation in constructor of domain model ? my domain model validation example as follows: public class Order { private readonly List<OrderLine> _lineItems; public virtual Customer Customer { get; private set; } public virtual DateTime OrderDate { get; private set; } public virtual decimal OrderTotal { get; private set; } public Order (Customer customer) { if (customer == null) throw new ArgumentException("Customer name must be defined"); Customer = customer; OrderDate = DateTime.Now; _lineItems = new List<LineItem>(); } public void AddOderLine //.... public IEnumerable<OrderLine> AddOderLine { get {return _lineItems;} } } public class OrderLine { public virtual Order Order { get; set; } public virtual Product Product { get; set; } public virtual int Quantity { get; set; } public virtual decimal UnitPrice { get; set; } public OrderLine(Order order, int quantity, Product product) { if (order == null) throw new ArgumentException("Order name must be defined"); if (quantity <= 0) throw new ArgumentException("Quantity must be greater than zero"); if (product == null) throw new ArgumentException("Product name must be defined"); Order = order; Quantity = quantity; Product = product; } } Thanks for all of your suggestion.

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• How to layer if statements when order of logic is irrelevant?

  - by jimmyjimmy

  Basically I have a series of logic in my website that can lead to 5 total outcomes. Basically two different if tests and then a catch all else statement. For example: if cond1: if mod1: #do things elif mod2: #do things elif cond2: if mod1: #do things elif mod2 #do things else: #do things I was thinking about rewriting it like this: if cond1 and mod1: #do things elif cond1 and mod2: #do things elif cond2 and mod1: #do things elif cond2 and mod2: #do things else: #do things Is there any real difference in these two coding options/a better choice for this kind of logic testing?

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• Visitor-pattern vs inheritance for rendering

  - by akaltar

  I have a game engine that currently uses inheritance to provide a generic interface to do rendering: class renderable { public: void render(); }; Each class calls the gl_* functions itself, this makes the code hard to optimize and hard to implement something like setting the quality of rendering: class sphere : public renderable { public: void render() { glDrawElements(...); } }; I was thinking about implementing a system where I would create a Renderer class that would render my objects: class sphere { void render( renderer* r ) { r->renderme( *this ); } }; class renderer { renderme( sphere& sphere ) { // magically get render resources here // magically render a sphere here } }; My main problem is where should I store the VBOs and where should I Create them when using this method? Should I even use this approach or stick to the current one, perhaps something else? PS: I already asked this question on SO but got no proper answers.

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• Interfaces on an abstract class

  - by insta

  My coworker and I have different opinions on the relationship between base classes and interfaces. I'm of the belief that a class should not implement an interface unless that class can be used when an implementation of the interface is required. In other words, I like to see code like this: interface IFooWorker { void Work(); } abstract class BaseWorker { ... base class behaviors ... public abstract void Work() { } protected string CleanData(string data) { ... } } class DbWorker : BaseWorker, IFooWorker { public void Work() { Repository.AddCleanData(base.CleanData(UI.GetDirtyData())); } } The DbWorker is what gets the IFooWorker interface, because it is an instantiatable implementation of the interface. It completely fulfills the contract. My coworker prefers the nearly identical: interface IFooWorker { void Work(); } abstract class BaseWorker : IFooWorker { ... base class behaviors ... public abstract void Work() { } protected string CleanData(string data) { ... } } class DbWorker : BaseWorker { public void Work() { Repository.AddCleanData(base.CleanData(UI.GetDirtyData())); } } Where the base class gets the interface, and by virtue of this all inheritors of the base class are of that interface as well. This bugs me but I can't come up with concrete reasons why, outside of "the base class cannot stand on its own as an implementation of the interface". What are the pros & cons of his method vs. mine, and why should one be used over another?

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• Should this code/logic be included in Business Objects class or a separate class?

  - by aspdotnetuser

  I have created a small application which has a three tier architecture and I have business object classes to represent entities such as User, Orders, UserType etc. In these classes I have methods that are executed when the Constuctor method of, for example, User is called. These methods perform calculations and generate details that setup data for attributes that are part of each User object. Here is the structure for the project in Visual Studio: Here is some code from the business object class User.cs: Public Class User { public string Name { get; set; } public int RandomNumber { get; set; } etc public User { Name = GetName(); RandomNumber = GetRandomNumber(); } public string GetName() { .... return name; } public int GetRandomNumber() { ... return randomNumber; } } Should this logic be included in the Business Object classes or should it be included in a Utilities class of some kind? Or in the business rules?

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• Developing web sites that imitate desktop apps. How to fight that paradigm? [closed]

  - by user1598390

  Supposse there's a company where web sites/apps are designed to resemble desktop apps. They struggle to add: Splash screens Drop-down menus Tab-pages Pages that don't grow downward with content, context is inside scrollable area so page is of a fixed size, as if resembling the one-screen limitation of desktop apps. Modal windows, pop-ups, etc. Tree views Absolutely no access to content unless you login-first, even with non-sensitive content. After splash screen desapears, you are presented with a login screen. No links - just simulated buttons. Fixed page-size. Cannot open a linked in other tab Print button that prints directly ( not showing printable page so the user can't print via the browser's print command ) Progress bars for loading content even when the browser indicates it with its own animation Fonts and color amulate a desktop app made with Visual Basic, PowerBuilder etc. Every app seems almost as if were made in Visual Basic. They reject this elements: Breadcrumbs Good old underlined links Generated/dynamic navigation, usage-based suggestions Ability to open links in multiple tabs Pagination Printable pages Ability to produce a URL you can save or share that links to an item, like when you send someone the link to an especific StackExchange question. The only URL is the main one. Back button To achieve this, tons of javascript code is needed. Lots and lots of Javascript and Ajax code for things not related with the business but with the necessity to hide/show that button, refresh this listbox, grey-out that label, etc. The coplexity generated by forcing one paradigm into another means most lines of code are dedicated to maintain the illusion of a desktop app. What is the best way to change this mindset, and make them embrace the web, and start producing modern, web apps instead of desktop imitations ? EDIT: These sites are intranet sites. Users hate these apps. They constantly whine about them, but they have to use them to do their daily work. These sites are in-house solutions, the end-users have no choice but to use them. They are a "captive audience". Also, substitution will not happen because of high costs. But at least if that mindset is changed, new developments would be more web-like.

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• Should interface only be used for behavior and not to show logical data grouped together?

  - by jags

  Should an interface only be used to specify certain behavior? Would it be wrong to use interface to group logically related data? To me it looks like we should not use interface to group logically related data as structure seems a better fit. A class may be used but class name should indicate something like DTO so that user gets the impression that class does not have any behavior. Please let me know if my assumption is correct. Also, are there any exceptions where interface can be used to group logically related data?

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• Create Levels using blender

  - by notrodash

  I am creating a game and I have a custom level format for levels in my game. I wanted to know if it is possible to create levels for that kinda format in Blender. My format is XML based and just declares the positions of certain objects. Online I have seen many people use Blender to create levels in their own custom format that blender can understand. How do i get blender to understand my format and use blender to create levels for my game?

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• Avoiding bloated Domain Objects

  - by djcredo

  We're trying to move data from our bloated Service layer into our Domain layer using a DDD approach. We currently have a lot of business logic in our services, which is spread out all over the place and doesn't benefit from inheritance. We have a central Domain class which is the focus of most of our work - a Trade. The Trade object will know how to price itself, how to estimate risk, validate itself, etc. We can then replace conditionals with polymorphism. Eg: SimpleTrade will price itself one way, but ComplexTrade will price itself another. However, we are worried that this will bloat the Trade class(s). It really should be in charge of its own processing but the class size is going to increase exponentially as more features are added. So we have choices: Put processing logic in Trade class. Processing logic is now polymorphic based on the type of the trade, but Trade class is now has multiple responsibilites (pricing, risk, etc) and is large Put processing logic into other class such as TradePricingService. No longer polymorphic with the Trade inheritance tree, but classes are smaller and easier to test. What would be the suggested approach?

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• Learning to program in the modern era?

  - by BBHorus

  At this time, lets say in the modern era, in which order do you organize a programing course for teaching and/or learning, what should be learned first, what should emphasize: Databases Data structures Design patterns Programing paradigms(Procedural, functional, OOP, ...etc ) Operating System Some specific programing language What about English if you are not native speaker or doesn't know English AI Anything else... I ask this because in the university that I went, the programing course was awful it was not focus on what you were going to see out when you work what you were supposed to learn. PS: Again sorry about my English is not my main language. ...Experts and gurus please share

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• How to decide to which class does a method belong

  - by Eleeist

  I have TopicBusiness.class and PostBusiness.class. I have no problem with deciding into which class methods such as addPostToDatabase() or getAllPostsFromDatabase() should go. But what about getAllPostsFromTopic(TopicEntity topic) or getNumberOfPostsInTopic(TopicEntity topic)? Should the parameter be the deciding factor? So when the method takes TopicEntity as parameter it should belong to TopicBusiness.class? I am quite puzzled by this.

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• Random generation of interesting puzzle levels?

  - by monsterfarm

  I'm making a Sokoban-like game i.e. there's a grid that has some crates on it you can push and you have to get the crates on crosses to win the level (although I'm going to add some extra elements to it). Are there any general algorithms or reading material I can look at for how I could go about generating interesting (as in, not trivial to solve) levels for this style of game? I'm aware that random level generators exist for Sokoban but I'm having trouble finding the algorithm descriptions. I'm interested in making a game where the machine can generate lots of levels for me, sorted by difficulty. I'm even willing to constrain the rules of the game to make the level generation easier (e.g. I'll probably limit the grid size to about 7x7). I suspect there are some general ways to do level generation here as I've seen e.g. Traffic Jam-like games (where you have to move blocks around the free some block) with 1000s of levels where each one has a unique solution. One idea I had was to generate a random map in its final state (i.e. where all crates are on top of their crosses) and then the computer would pull (instead of push) these crates around to create a level. The nice property here is that we know the level is solvable. However, I'd need some heuristics to ensure the level was interesting.

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• Is this a violation of the Liskov Substitution Principle?

  - by Paul T Davies

  Say we have a list of Task entities, and a ProjectTask sub type. Tasks can be closed at any time, except ProjectTasks which cannot be closed once they have a status of Started. The UI should ensure the option to close a started ProjectTask is never available, but some safeguards are present in the domain: public class Task { public Status Status { get; set; } public virtual void Close() { Status = Status.Closed; } } public ProjectTask : Task { public override void Close() { if (Status == Status.Started) throw new Exception("Cannot close a started Project Task"); base.Close(); } } Now when calling Close() on a Task, there is a chance the call will fail if it is a ProjectTask with the started status, when it wouldn't if it was a base Task. But this is the business requirements. It should fail. Can this be regarded as a violation?

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• How to separate and maintain customer specific code

  - by WYSIWYG

  I am implementing customer specific code and currently following simple approach like if (cusomterId == 23) do it. I want to separate out all the customer related code in separate place. But I have following problems. In code is in 1. Stored procs 2. Plain old classes. 3. Controllers 4. Views I came up with two solutions. First is to create table CustomerFunctionlity with columns CustomerId, FunctionalityName, method/Proc, inputs/outputs With this table I can simply check if exists, execute given function. Another way is creating a factory which returns customer related object for an interface. I am writting small end to end customer specific functionalities. How can I write maintenable code. Thanks

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• Is it better to return NULL or empty values from functions/methods where the return value is not present?

  - by P B

  I am looking for a recommendation here. I am struggling with whether it is better to return NULL or an empty value from a method when the return value is not present or cannot be determined. Take the following two methods as an examples: string ReverseString(string stringToReverse) // takes a string and reverses it. Person FindPerson(int personID) // finds a Person with a matching personID. In ReverseString(), I would say return an empty string because the return type is string, so the caller is expecting that. Also, this way, the caller would not have to check to see if a NULL was returned. In FindPerson(), returning NULL seems like a better fit. Regardless of whether or not NULL or an empty Person Object (new Person()) is returned the caller is going to have to check to see if the Person Object is NULL or empty before doing anything to it (like calling UpdateName()). So why not just return NULL here and then the caller only has to check for NULL. Does anyone else struggle with this? Any help or insight is appreciated.

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• Does C++ support subtyping?

  - by the_naive

  I know it might be a silly question to ask, but I didn't quite get an a absolute clear answer on this matter, so I thought I'd put it here. Does c++ support the subtyping in the sense that it fulfills Liskov's principle fully? I understand how parametric polymorphism, inclusion polymorphism(subclassing and overriding) work in c++ but I'm not entirely sure or understand if subtyping exists in the context of C++. Could you please explain?

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• is it valid that a state machine can have more than one possible state for some transition?

  - by shankbond

  I have a requirement for a workflow which I am trying to model as a state machine, I see that there is more than one outcome of a given transition(or activity). Is it valid for a state machine to have more than one possible states, but only one state will be true at a given time? Note: This is my first attempt to model a state machine. Eg. might be: s1-t1-s2 s1-t1-s3 s1-t1-s4 where s1, s2, s3, s4 are states and t1 is transition/activity. A fictitious real world example might be: For a human, there can be two states: hungry, not hungry A basket can have only one item from: apple, orange. So, to model it we will have: hungry-pick from basket-apple found hungry-pick from basket-orange found apple found-eat-not hungry orange found-take juice out of it and then drink- not hungry

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• ?Oracle Database ?7??????????????

  - by OTN-J Master

  Oracle Database??????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????!!(???????????????????????????????)????????????????????????????????????????OTN?????????????????????????????????????? ?????????????????????????????????????????????????????????????????????????????????????????????!???????????????(?????????????????) ???7????????????????? ?????????????? ???????? ?28??????LOB????????? ?????????????????????????????????????????????????????????????????????????????????????????13?????????????LOB(Large OBject)???????????????????????????????????????????????????????????????????????????????????????????????????? >> ????? ?????????????!DBA??? ???????? ?19? ????????·????????????????????????????MAA????????????????????????????Oracle???????????????????????Oracle Maximum Availability Architecture??????????????????????MAA??Oracle??????????????????????????????????????????MAA??????????????????????????????????????>> ????? OTN?????????????????????? ?????????????????????????????????

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• Is it a good idea to cache data from web services into a database?

  - by Thierry Lam

  Let's assume that Stackoverflow offers web services where you can retrieve all the questions asked by a specific user. A request to get all question from user A can result in the following json output: { { "question": "What is rest?", "date_created": "20/02/2010", "votes": 1, }, { "question": "Which database to use for ...", "date_created": "20/07/2009", "votes": 5, }, } If I want to manipulate and present the data in any ways that I want, will it be wise to dump it in a local database? At some point, I will also want to retrieve all answers for each question and store them in a local database. The workflow that I'm thinking is: User logs in. Web services retrieve all questions asked by the logged in user, dump them in a local database. User wants all answers for a specific question, another web service does the retrieval and dump them in a local database. After user logs out, delete from the local database all questions and answers from that user.

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• User Control as container at design time

  - by Luca

  I'm designing a simple expander control. I've derived from UserControl, drawn inner controls, built, run; all ok. Since an inner Control is a Panel, I'd like to use it as container at design time. Indeed I've used the attributes: [Designer(typeof(ExpanderControlDesigner))] [Designer("System.Windows.Forms.Design.ParentControlDesigner, System.Design", typeof(IDesigner))] Great I say. But it isn't... The result is that I can use it as container at design time but: The added controls go back the inner controls already embedded in the user control Even if I push to top a control added at design time, at runtime it is back again on controls embedded to the user control I cannot restrict the container area at design time into a Panel area What am I missing? Here is the code for completeness... why this snippet of code is not working? [Designer(typeof(ExpanderControlDesigner))] [Designer("System.Windows.Forms.Design.ParentControlDesigner, System.Design", typeof(IDesigner))] public partial class ExpanderControl : UserControl { public ExpanderControl() { InitializeComponent(); .... [System.Security.Permissions.PermissionSet(System.Security.Permissions.SecurityAction.Demand, Name = "FullTrust")] internal class ExpanderControlDesigner : ControlDesigner { private ExpanderControl MyControl; public override void Initialize(IComponent component) { base.Initialize(component); MyControl = (ExpanderControl)component; // Hook up events ISelectionService s = (ISelectionService)GetService(typeof(ISelectionService)); IComponentChangeService c = (IComponentChangeService)GetService(typeof(IComponentChangeService)); s.SelectionChanged += new EventHandler(OnSelectionChanged); c.ComponentRemoving += new ComponentEventHandler(OnComponentRemoving); } private void OnSelectionChanged(object sender, System.EventArgs e) { } private void OnComponentRemoving(object sender, ComponentEventArgs e) { } protected override void Dispose(bool disposing) { ISelectionService s = (ISelectionService)GetService(typeof(ISelectionService)); IComponentChangeService c = (IComponentChangeService)GetService(typeof(IComponentChangeService)); // Unhook events s.SelectionChanged -= new EventHandler(OnSelectionChanged); c.ComponentRemoving -= new ComponentEventHandler(OnComponentRemoving); base.Dispose(disposing); } public override System.ComponentModel.Design.DesignerVerbCollection Verbs { get { DesignerVerbCollection v = new DesignerVerbCollection(); v.Add(new DesignerVerb("&asd", new EventHandler(null))); return v; } } } I've found many resources (Interaction, designed, limited area), but nothing was usefull for being operative... Actually there is a trick, since System.Windows.Forms classes can be designed (as usual) and have a correct behavior at runtime (TabControl, for example).

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