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• Handling deleted users - separate or same table?

  - by Alan Beats

  The scenario is that I've got an expanding set of users, and as time goes by, users will cancel their accounts which we currently mark as 'deleted' (with a flag) in the same table. If users with the same email address (that's how users log in) wish to create a new account, they can signup again, but a NEW account is created. (We have unique ids for every account, so email addresses can be duplicated amongst live and deleted ones). What I've noticed is that all across our system, in the normal course of things we constantly query the users table checking the user is not deleted, whereas what I'm thinking is that we dont need to do that at all...! [Clarification1: by 'constantly querying', I meant that we have queries which are like: '... FROM users WHERE isdeleted="0" AND ...'. For example, we may need to fetch all users registered for all meetings on a particular date, so in THAT query, we also have FROM users WHERE isdeleted="0" - does this make my point clearer?] (1) continue keeping deleted users in the 'main' users table (2) keep deleted users in a separate table (mostly required for historical book-keeping) What are the pros and cons of either approach?

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• Should an object know its own ID?

  - by xenoterracide

  obj.id seems fairly common and also seems to fall within the range of something an object could know about itself. I find myself asking why should my object know its own id? It doesn't seem to have a reason to have it? One of the main reason for it existing is retrieve it, and so my repositories need to know it, and thus use it for database interaction. I also once encountered a problem where I wanted to serialize an object to JSON for a RESTful API where the id did not seem to fit in the payload, but only the URI and including it in the object made that more difficult. Should an object know it's own id? why or why not?

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• Why do most programming languages only support returning a single value from a function?

  - by M4N

  Is there a reason or an explanation why functions in most(?) programming languages are designed to support any number of input parameters but only one return value? In most languages, it is possible to "work around" that limitation, e.g. by using out-parameters, returning pointers or by defining/returning structs/classes. But it seems strange, that programming languages were not designed to support multiple return values in a more "natural" way.

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• Centrally managing 100+ websites without bankrupting a small company

  - by palintropos

  I'm mainly interested in opinions on the trade-offs between having a single central server all the websites connect to as opposed to each website mirroring a subset of the master database with all the products in it. For example, will I run into severe performance issues (or even security issues, or restrictions) making queries to an offsite database? Will we hit scalability issues we can't handle early on from the sheer bandwidth required to maintain this? If we do go with something like a script that keeps smaller databases (each containing a subset of the central master data) in sync, what sorts of issues will we likely encounter there? I would really like the opinions of people far more knowledgeable than I am regarding the pros and cons of both setups and what headaches we are likely to encounter. CLARIFICATION: This should not be viewed as a question about whether we should implement one database vs multiple databases. This question has been answered numerous times. The question is regarding the pros and cons for a deployment like this having the ability to manage all the websites centrally (one server) vs trying to keep them all in sync if they each have their own db (multiple servers). REAL-WORLD EXAMPLE: We are a t-shirt company, and we have individual websites for our different kinds of t-shirts, but we're looking at a central order management integrated with our single shopping cart (which is ColdFusion + MySQL). Now, let's say we have a t-shirt that's on 10 of our websites and we change an image for it. Ideally we would change that in one place and the change would propagate, but how would we set this up?

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• Making a class pseudo-immutable by setting a flag

  - by scott_fakename

  I have a java project that involves building some pretty complex objects. There are quite a lot (dozens) of different ones and some of them have a HUGE number of parameters. They also need to be immutable. So I was thinking the builder pattern would work, but it ends up require a lot of boilerplate. Another potential solution I thought of was to make a mutable class, but give it a "frozen" flag, a-la ruby. Here is a simple example: public class EqualRule extends Rule { private boolean frozen; private int target; public EqualRule() { frozen = false; } public void setTarget(int i) { if (frozen) throw new IllegalStateException( "Can't change frozen rule."); target = i; } public int getTarget() { return target; } public void freeze() { frozen = true; } @Override public boolean checkRule(int i) { return (target == i); } } and "Rule" is just an abstract class that has an abstract "checkRule" method. This cuts way down on the number of objects I need to write, while also giving me an object that becomes immutable for all intents and purposes. This kind of act like the object was its own Builder... But not quite. I'm not too excited, however, about having an immutable being disguised as a bean however. So I had two questions: 1. Before I go too far down this path, are there any huge problems that anyone sees right off the bat? For what it's worth, it is planned that this behavior will be well documented... 2. If so, is there a better solution? Thanks

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• Extension objects pattern

  - by voroninp

  In this MSDN Magazine article Peter Vogel describes Extension Objects partten. What is not clear is whether extensions can be later implemented by client code residing in a separate assembly. And if so how in this case can extension get acces to private members of the objet being extended? I quite often need to set different access levels for different classes. Sometimes I really need that descendants does not have access to the mebmer but separate class does. (good old friend classes) Now I solve this in C# by exposing callback properties in interface of the external class and setting them with private methods. This also alows to adjust access: read only or read|write depending on the desired interface. class Parent { private int foo; public void AcceptExternal(IFoo external) { external.GetFooCallback = () => this.foo; } } interface IFoo { Func<int> GetFooCallback {get;set;} } Other way is to explicitly implement particular interface. But I suspect more aspproaches exist.

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• python factory function best practices

  - by Jason S

  Suppose I have a file foo.py containing a class Foo: class Foo(object): def __init__(self, data): ... Now I want to add a function that creates a Foo object in a certain way from raw source data. Should I put it as a static method in Foo or as another separate function? class Foo(object): def __init__(self, data): ... # option 1: @staticmethod def fromSourceData(sourceData): return Foo(processData(sourceData)) # option 2: def makeFoo(sourceData): return Foo(processData(sourceData)) I don't know whether it's more important to be convenient for users: foo1 = foo.makeFoo(sourceData) or whether it's more important to maintain clear coupling between the method and the class: foo1 = foo.Foo.fromSourceData(sourceData)

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• Creating a Application in Winrt that requires Internet

  - by wtsang02

  I am making a paid App for Windows 8, c#. I am wondering which is better? If my application doesn't need internet connection normally but does requires internet connection for the first time to download content data. --Makes my life easier Load the default data when installing. Then ask the user if he wants to update in app. -- Making the default data will be pain. Now my big question is, is it safe to assume user has access to internet now-a-days when using application that shouldn't require internet?

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• User input and Automated input seperation

  - by tpaksu

  I have a mysql db and I have an automation script which modifies the data inside once a day. And, these columns may have changed by an user manually. What is the best approach to make the system only update the automated data, not the manually edited ones? I mean yes, flagging the cell which is manually edited is one way to do it, but I want to know if there's another way to accomplish this? Just curiosity.

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• Structuring cascading properties - parent only or parent + entire child graph?

  - by SB2055

  I have a Folder entity that can be Moderated by users. Folders can contain other folders. So I may have a structure like this: Folder 1 Folder 2 Folder 3 Folder 4 I have to decide how to implement Moderation for this entity. I've come up with two options: Option 1 When the user is given moderation privileges to Folder 1, define a moderator relationship between Folder 1 and User 1. No other relationships are added to the db. To determine if the user can moderate Folder 3, I check and see if User 1 is the moderator of any parent folders. This seems to alleviate some of the complexity of handling updates / moved entities / additions under Folder 1 after the relationship has been defined, and reverting the relationship means I only have to deal with one entity. Option 2 When the user is given moderation privileges to Folder 1, define a new relationship between User 1 and Folder 1, and all child entities down to the grandest of grandchildren when the relationship is created, and if it's ever removed, iterate back down the graph to remove the relationship. If I add something under Folder 2 after this relationship has been made, I just copy all Moderators into the new Entity. But when I need to show only the top-level Folders that a user is Moderating, I need to query all folders that have a parent folder that the user does not moderate, as opposed to option 1, where I just query any items that the user is moderating. I think it comes down to determining if users will be querying for all parent items more than they'll be querying child items... if so, then option 1 seems better. But I'm not sure. Is either approach better than the other? Why? Or is there another approach that's better than both? I'm using Entity Framework in case it matters.

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• iOS + cocos2d: how to account for sprite's position for the different device dimensions in an universal app?

  - by fuzzlog

  All the questions I've seen regarding iOS universal apps (with or without cocos2d) deal with the "how to add graphics to a universal app". My question is, how does the code need to be written to ensure that the sprites appear appropriately on the screen (given that an iPhone 5's resolution is not proportional to an iPad's resolution)? Is it just a bunch of "if" statements and duplicate code or do iOS/cocos2d provide common function calls that will place the sprites at an appropriate position?

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• Why is facebook cache buggy?

  - by IAdapter

  I just started using facebook and I see that many times when I add something to my profile and visit it later its not there. I bet the reason is that the page is cached and not updated very often. Is this on purpose or is it a bug? P.S. For example I added the music I like and later I see that I did not add it, but next day when I visit again its there. I saw it in two web-browsers, so its a facebook bug. Does it has something to do with scalability?

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• Creating a new variable versus assigning an existing one

  - by rwallace

  Which is more common, creating a new variable versus assigning an existing variable (field, array element etc - anything that syntactically uses the assignment operator)? The reason I ask is that I'm designing a new language, and wondering which of these two operations should get the shorter syntax. It's not intended to be a pure functional language, or the question wouldn't arise, so I'd ideally like to count usage across large existing code bases in procedural and object-oriented languages like C, C++ and Java, though as far as I can see there isn't an easy way to do this automatically, and going by memory and eyeball, neither is obviously more common than the other.

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• Character coding / programming

  - by Jery

  Lately I tryed a few times to create characters for some games, but at some certain point (especially when collision detection came in) everything became messy and the interaction between chars, the world and certain items had a lot of bugs. So here is my question, how do you ussualy keep track of actions that your character is allowed to do, or more in general do you have some links / advices how to set up a char efficiantly? I´m working on a char right now, who should at least be able to run, jump, pick items up and use different fighting animations. Most ideas I came up with until now use some kind of action.priority / action.duration system to determain whats possible and what not, or a "action-manager" which defines for every action what is possible from that action on but it all doesnt work that well together.

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• EAV - is it really bad in all scenarios?

  - by Giedrius

  I'm thinking to use EAV for some of the stuff in one of the projects, but all questions about it in stackoverflow end up to answers calling EAV an anti pattern. But I'm wondering, if is it that wrong in all cases? Let's say shop product entity, it has common features, like name, description, image, price, etc., that take part in logic many places and has (semi)unique features, like watch and beach ball would be described by completely different aspects. So I think EAV would fit for storing those (semi)unique features? All this is assuming, that for showing product list, it is enough info in product table (that means no EAV is involved) and just when showing one product/comparing up to 5 products/etc. data saved using EAV is used. I've seen such approach in Magento commerce and it is quite popular, so may be there are cases, when EAV is reasonable?

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• Service Layer - how broad should it be, and should it also be used from the local application?

  - by BornToCode

  The background: I need to build a desktop application with some operations (CRUD and more) (=winforms), I need to make another application which will re-use some of the functions of the main application (=webforms). I'm using service layer for reusing my functions. The service is calling the functions on the BL layer (correct me if I'm doing this wrong). so my desktop has 4 projects - DAL, BL, UI, WEBSERVICES. The dilemma (simple but I still need some more experienced opinions): In my main winform UI - should I call the functions from the BL - bl.getcustomers(), or do it similar to how I call it in the webform, and call the functions from the service - webservices.getcustomers? Should I create a service for every single function on the BL even if I need some of the functions only in one UI? for example - should I create services for all the CRUD operations, even though I need to re-use only update operation in the webform? YOUR HELP IS MUCH APPRECIATED

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• doing a full permutation search and replace on a string

  - by user73307

  I'm writing an app that does something like a custom number (licence) place generator tool where if I ask for the plate "robin" it will suggest I try: r0bin rob1n r0b1n Are there any published algorithms which can do this? It has to be able to handle replacing single letters with multiples, e.g. m with rn and vise-versa and not fall over if it replaces an i with an l then comes to check the l and replaces it back to an i. The list of what gets swapped with what is going to be user input but I'm not expecting a huge list, possibly 10 pairs at most. I'll be implementing this in Ruby or Python but I should be able to convert code from any other language.

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• Is my project a web site or a mobile app?

  - by Evik James

  I am a web developer. I have been developing web sites professionally for 15+ years using ColdFusion, SQL Server, and jQuery. I am doing a project for a client that uses the above technologies. The site has a mobile facet too. For that, I am using jQuery Mobile. The site enables retail store personnel to gather a store customer's preferences using any smart phone or tablet. The store personnel just needs to access a special link via a QR code and a login. Anyone can easily access the site from a PC's browser, too. Some sources suggest that mobile apps must be downloaded and installed using a third party, such as from Google, Amazon, or Apple. Others sources suggest that any information designed for use on mobile device is a mobile app. Regarding the site that is specifically designed for use by mobile devices that extensively uses jQuery Mobile, is this a "web site" or a "mobile app"? What is the "proper" description for this type of site? My customer insists that it is one and not the other. I insist that it is the other and not the one. Can you help me clarify this?

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• Upgrading an app to support iOS5, 6 and 7

  - by drekka

  We are looking at an app that needs an upgrade. Currently it runs on iOS4, 5 & 6. The upgrade will move to iOS5, 6 & 7. It will also involve some UI changes and new features. I've been reading stuff on iOS7 and looking at things like auto-layout. What we are trying to figure out is the best way to handle the differences between the various iOS versions. Auto-layout seems like a good idea, but it's not available on iOS 5. There are also API changes to consider between all 3 versions and other new features of iOS7. So the questions: How would you handle auto layout given iOS5 does not have it? Are there any significant differences between the SDKs that you think would cause issues? Would we be better off with separate code bases?

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• Updating and organizing class diagrams in a growing C++ project

  - by vanna

  I am working on a C++ project that is getting bigger and bigger. I do a lot of UML so it is not really hard to explain my work to co-workers. Lately though I implemented a lot of new features and I gave up updating by hand my Dia UML diagrams. I once used the class diagram of Visual Studio, which is my IDE but didn't get clear results. I need to show my work on a regular basis and I would like to be as clear as possible. Is there any tool that could generate a sort of organized map of my work (namespaces, classes, interactions, etc.) ?

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• De-facto standards for customer information record

  - by maasg

  I'm currently evaluating a potential new project that involves creating a DB for typical customer information (userid, pwd, first & last name, email, adress, telfnr ...). At this point, requirements are only roughly defined. The customer DB is expected in the O(millions) of records. In order to calculate some back-of-the-envelope numbers for DB sizing and evaluate potential DB options & architectures, I'm looking for some de-facto standards for these kind of records. In particular, the std size of every field (first name, last name, address,...) or typical avg for a simple customer record would be great info. With so many e-commerce websites out there, there should be some kind of typical config that can be reused and avoid re-inventing the wheel. Any ideas?

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• How can I cleanly and elegantly handle data and dependancies between classes

  - by Neophyte

  I'm working on 2d topdown game in SFML 2, and need to find an elegant way in which everything will work and fit together. Allow me to explain. I have a number of classes that inherit from an abstract base that provides a draw method and an update method to all the classes. In the game loop, I call update and then draw on each class, I imagine this is a pretty common approach. I have classes for tiles, collisions, the player and a resource manager that contains all the tiles/images/textures. Due to the way input works in SFML I decided to have each class handle input (if required) in its update call. Up until now I have been passing in dependencies as needed, for example, in the player class when a movement key is pressed, I call a method on the collision class to check if the position the player wants to move to will be a collision, and only move the player if there is no collision. This works fine for the most part, but I believe it can be done better, I'm just not sure how. I now have more complex things I need to implement, eg: a player is able to walk up to an object on the ground, press a key to pick it up/loot it and it will then show up in inventory. This means that a few things need to happen: Check if the player is in range of a lootable item on keypress, else do not proceed. Find the item. Update the sprite texture on the item from its default texture to a "looted" texture. Update the collision for the item: it might have changed shape or been removed completely. Inventory needs to be updated with the added item. How do I make everything communicate? With my current system I will end up with my classes going out of scope, and method calls to each other all over the place. I could tie up all the classes in one big manager and give each one a reference to the parent manager class, but this seems only slightly better. Any help/advice would be greatly appreciated! If anything is unclear, I'm happy to expand on things.

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• correct pattern to handle a lot of entities in a game

  - by lezebulon

  In my game I usually have every NPC / items etc being derived from a base class "entity". Then they all basically have a virtual method called "update" that I would class for each entity in my game at every frame. I am assuming that this is a pattern that has a lot of downsides. What are some other ways to manage different "game objects" throughout the game? Are there other well-known patterns for this? My game is a RPG if that changes anything

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• Single Responsibility Principle: Responsibility unknown

  - by lurkerbelow

  I store sessions in a SessionManager. The session manager has a dependency to ISessionPersister. SessionManager private readonly ISessionPersister sessionPersister; public SessionManager(ISessionPersister sessionPersister) { this.sessionPersister = sessionPersister; } ISessionPersister public interface ISessionPersister : IDisposable { void PersistSessions(Dictionary<string, ISession> sessions); } Q: If my application shuts down how / where do I call PersistSessions? Who is responsible? First Approach: Use Dispose in SessionManager protected virtual void Dispose(bool disposing) { if (disposing) { if (this.sessionPersister != null && this.sessionMap != null && this.sessionMap.Count > 0) { this.sessionPersister.PersistSessions(this.sessionMap); } } } Is that the way to go or are there any better solutions?

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• C#.NET: How to update multiple .NET pages when a particular event occurs in one .Net page? In another words how to use Observer pattern(Publish and subscribe to events)

  Problem: Suppose you have a scenario in which you have to update multiple pages when an event occurs in main page. For example imagine you have a main page where you are dispalying a tab control. This tab control has 3 tab pages where you are loading 3 different user controls. On click of an update button in main page imagine if you have do something in all the 3 tab panels. In other words an event in main page has to be handled in many other pages. An event in main page which contains the tab control has to be handled in all the tab panels(user controls) Answer: Use Observer pattern Define a base page for the page that contains the tab control. Main page which contains the tab: Baseline_Baseline Basepage for the above main page: BaselineBasePage User control that has to be udpated for an event in main page: Baseline_PriorNonDeloitte Source Code: public class BaselineBasePage : System.Web.UI.Page { IList lstControls = new List(); public void Add(IObserver userControl) { lstControls.Add(userControl); } public void Remove(IObserver userControl) { lstControls.Remove(userControl); } public void RemoveAllUserControls() { lstControls.Clear(); } public void Update(SaveEventArgs e) { foreach (IObserver LobjControl in lstControls) { LobjControl.Save(e); } } } public interface IObserver { void Update(SaveEventArgs e); } public partial class Baseline_Baseline : BaselineBasePage { . . . this.Add(_ucPI); this.Add(_ucPI1); protected void abActionBar_saveClicked(object sender, EventArgs e) { SaveEventArgs se = new SaveEventArgs(); se.TabType = (BaselineTabType)tcBaseline.ActiveTabIndex; this.Update(se); } } Public class Baseline_PriorNonDeloitte : System.Web.UI.UserControl,IObserver { public void Update(SaveEventArgs e) { } } More info at: http://www.dofactory.com/Patterns/PatternObserver.aspx span.fullpost {display:none;}

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