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  • Forcing size of a complex Flash object.

    - by John
    As I've found recently, setting width/height properties on a Sprite only forces the Sprite to fit the given dimensions by scaling the actual size, which is calculated by Flash based on the rendered content. This leaves me confused. If I have a custom Sprite subclass which draws using Graphics, how can I do layout before an initial render - the size will be zero until it is first drawn? For a more complex issue, let's say I have a 2D game world with objects spread over a wide area with world coordinates from (0,0) to (5000,5000), where each object has a size of maybe up to 100x100. I want to have a Flash component which is the "game window", and has a fixed size like 400x300, rendering part of the game world. So how do I force the game window size to 400x300 pixels? I can draw a 400x300 rectangle to get the size correct but then if I draw any objects which are partly in-view, they can screw this up. Is the right approach to provide a custom setSize(w,h) method which is used rather than width & height setters? But even so, is there no way to make a Sprite force to the size I want? Do you really have to catch it every render and re-scale it?

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  • Check if NSString exists in custom object in NSArray

    - by Paul Peelen
    I have an NSArray with Store objects. Each Store object has two NSString objects; StoreID and Name. I would like to check quickly if an ID exists in this NSArray with Store objects. Example: Store *s1 = [[Store alloc] init]; s1.name = @"Some Name"; s1.id = @"123ABC"; Store *s2 = [[Store alloc] init]; s2.name = @"Some Other Name"; s2.id = @"ABC123"; NSArray *array = [[NSArray alloc] initWithObjects:s1, s2, nil]; NSString *myIdOne = @"ABCDEF"; NSString *myIdTwo = @"123ABC"; BOOL myIdOneExists = ...? BOOL myIdTwoExists = ...? Its the ...? I need to figure out. I know I can do this using a for loop and break when found... but this seems to me like an nasty approach since the NSArray could contain thousands of objects,... theoretically. So I would like to know about a better solution.

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  • AS3---TypeError: Error #1009: Cannot access a property or method of a null object reference

    - by user571620
    I'm very new to flash and I really have no idea what I'm doing. Thank you in advance. its giving me that error after I click a button to go to another frame. After I get the error, some buttons do not go to its destination and instead it just does nothing. The error is as follows: TypeError: Error #1009: Cannot access a property or method of a null object reference. at wmhssports_fla::MainTimeline/frame39() Here is the code for frame 39: stop(); winter_btn.addEventListener(MouseEvent.CLICK, buttonClick1); function buttonClick1(event:MouseEvent):void{ gotoAndPlay(39); }; spring_btn_boys.addEventListener(MouseEvent.CLICK, buttonClick10); function buttonClick10(event:MouseEvent):void{ gotoAndPlay(114); }; fall_btn_boys.addEventListener(MouseEvent.CLICK, buttonClick11); function buttonClick11(event:MouseEvent):void{ gotoAndPlay(135); }; Edit: I could email the file to someone, if they could look at it for me? Its REALLY sketchy due to my inexperience with flash, but then again its not that big of a clip. email me at: [email protected]

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  • Placing and removing element on array trough object

    - by Chris
    Hello, Lets assume i have 2 methods 1 that places a element on the array and one that removes it. const int Max = 10; int[] table= new int[Max]; I would like to call it up like this: s1.Place(5); // 5 0 0 0 0 0 0 0 0 0 0 s1.Place(9); // 5 9 0 0 0 0 0 0 0 0 0 s1.Remove(9); // 5 0 0 0 0 0 0 0 0 0 0 I would only like to use : using system for this. The result i get right now when i run the program is s1 = "nameofprogram" "name of class object" Normally i should get 0 0 0 0 0 0 0 0 0 0 to begin with. Any ideas how i can exactly add or remove those elements on the array? public void Place(int g) { if (top == Max) { throw new Exception("Stack overflow..."); } else { table[top] = g; top++; } .... Best Regards.

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  • [Django] One single page to create a Parent object and its associated child objects

    - by ahmoo
    Hi all, This is my very first post on this awesome site, from which I have been finding answers to a handful of challenging questions. Kudos to the community! I am new to the Django world, so am hoping to find help from some Django experts here. Thanks in advance. Item model: class Item(models.Model): name = models.CharField(max_length=50) ItemImage model: class ItemImage(models.Model): image = models.ImageField(upload_to=get_unique_filename) item = models.ForeignKey(Item, related_name='images') As you can tell from the model definitions above, every Item object can have many ItemImage objects. My requirements are as followings: A single web page that allows users to create a new Item while uploading the images associated with the Item. The Item and the ItemImages objects should be created in the database all together, when the "Save" button on the page is clicked. I have created a variable in a custom config file, called NUMBER_OF_IMAGES_PER_ITEM. It is based on this variable that the system generates the number of image fields per item. Questions: What should the forms and the template be like? Can ModelForm be used to achieve the requirements? For the view function, what do I need to watch out other than making sure to save Item before ItemImage objects?

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  • Nullable object must have a value. VB.NET

    - by Glenn05
    I need help. I'm having problem in my program. This is my code on my Business logic layer. Function Load_ItemDetails(ByVal ItemID As String) As Items Dim objItemEnt As New tblitem Dim objitem As New Items Try Using da = New DataAccess objItemEnt = da.Load_ItemDetails(ItemID) With objitem .ItemCode = objItemEnt.ItemCode .ItemName = objItemEnt.ItemName .Description = objItemEnt.Description .NameofType = objItemEnt.NameofType .TypeofPricing = objItemEnt.TypeofPricing .OnStock = objItemEnt.OnStock .ItemPrice = objItemEnt.ItemPrice .DateModified = objItemEnt.DateModified End With Return objitem End Using Catch ex As Exception Throw End Try End Function This code is for my data access layer. Public Function Load_ItemDetails(ByVal ItemCode As String) Dim objitem As New tblitem Try Using entItem = New DAL.systemdbEntities1 Dim qryUsers = From p In entItem.tblitems Where p.ItemCode = ItemCode Select p Dim luser As List(Of tblitem) = qryUsers.ToList If luser.Count > 0 Then Return luser.First Else Return objitem End If End Using Catch ex As Exception Throw End Try End Function` For my Presentation layer: Private Sub Load_Item_Detail(ByVal ItemCode As String) objItem = New Items Using objLogic = New LogicalLayer objItem = objLogic.Load_ItemDetails(ItemCode) With objItem Me.ItemCodetxt.Text = .ItemCode Me.ItemNametxt.Text = .ItemName Me.ItemDesctxt.Text = .Description Me.ItemTypetxt.Text = .NameofType Me.ItemPricetxt.Text = .TypeofPricing Me.ItemOnstocktxt.Text = CStr(.OnStock) Me.ItemPricetxt.Text = CStr(.ItemPrice) Me.TextBox1.Text = CStr(.DateModified) Me.ItemCodetxt.Tag = .ItemCode End With End Using End Sub` and after I run, I get this error Nullable object must have a value help me. I'm stuck. I don't know what to do guys. I new in n tier architecture.

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  • Efficiently fill resultset in object model

    - by Zeeshan
    Hi, I have an object model whose structure is Dashboard  List of panels     List of containers       List of widgets If i get whole dashboard, with panels + containers + widgets, from Database then multiple I/O requires I want to get it in one I/O .For this i prepared a query which gives me this resultset. DASHBOARDID   PANELID  CONTAINERID  WIDGETID 13                          11                    5              2 13                          11                    5              3 13                          11                    6              4 13                          11                    6              5 13                          12                    7              6 13                          12                    7              7 13                          12                    8              8 13                          12                    8              9 Using list datastructure this model is able to be filled but it takes time i want to efficiently fill this resultset in above object model. is there nay way ?

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  • Setting default values for object properties in AS3

    - by Paul T
    I'm an actionscript newbie so please bear with me. Below is a function, and I am curious how to set default property values for objects that are being created in a loop. In the example below, these propeties are the same for each object created in the loop: titleTextField.selectable, titleTextField.wordWrap, titleTextField.x If you pull these properties out of the loop, they are null because the TextField objects have not been created, but it seems silly to have to set them each time. What is the correct way to do this. Thanks! var titleTextFormat:TextFormat = new TextFormat(); titleTextFormat.size = 10; titleTextFormat.font = "Arial"; titleTextFormat.color = 0xfff200; for (var i=0; i<arrThumbPicList.length; i++) { var yPos = 55 * i var titleTextField:TextField = new TextField(); titleTextField.selectable = false; titleTextField.wordWrap = true; titleTextField.text = arrThumbTitles[i]; titleTextField.x = 106; titleTextField.y = 331 + yPos; container.addChild(titleTextField); titleTextField.setTextFormat(titleTextFormat); }

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  • C++11 decltype requires instantiated object

    - by snipes83
    I was experimenting a little with the C++11 standard and came up with this problem: In C++11 you can use auto and decltype to automatically get return type for a function as, for example the begin() and end() functions below: #include <vector> template <typename T> class Container { private: std::vector<T> v; public: auto begin() -> decltype(v.begin()) { return v.begin(); }; auto end() -> decltype(v.end()) { return v.end(); }; }; My problem here is that I have to declare the private vector<T> v before the public declarations which is against my coding style. I would like to declare all my private members after my public members. You have to declare the vector before the function declaration because the expression in decltype is a call to vector member function begin() and requires an instance of the object. Is there a way around this?

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  • Call to a member function find() on a non-object simpleHTMLDOM PHP

    - by wandersolo
    I am trying to read a link from one page, print the url, go to that page, and read the link on the next page in the same location, print the url, go to that page (and so on...) All I'm doing is reading the url and passing it as an argument to the get_links() method until there are no more links. This is my code but it throws a Fatal error: Call to a member function find() on a non-object. Anyone know what's wrong? <?php $mainPage = 'https://www.bu.edu/link/bin/uiscgi_studentlink.pl/1346752597?ModuleName=univschr.pl&SearchOptionDesc=Class+Subject&SearchOptionCd=C&KeySem=20133&ViewSem=Fall+2012&Subject=&MtgDay=&MtgTime='; get_links($mainPage); function get_links($url) { $data = new simple_html_dom(); $data = file_get_html($url); $nodes = $data->find("input[type=hidden]"); $fURL=$data->find("/html/body/form"); $firstPart = $fURL[0]->action . '<br>'; foreach ($nodes as $node) { $val = $node->value; $name = $node->name; $name . '<br />'; $val . "<br />"; $str1 = $str1. "&" . $name . "=" . $val; } $fixStr1 = str_replace('&College', '?College', $str1); $fixStr2 = str_replace('Fall 2012', 'Fall+2012', $fixStr1); $fixStr3 = str_replace('Class Subject', 'Class+Subject', $fixStr2); $fixStr4 = $firstPart . $fixStr3; echo $nextPageURL = chop($fixStr4); get_links($nextPageURL); } ?>

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  • How to Link VS2010 Database Project and LINQ to SQL

    - by Jason
    As I am working with the new database projects in VS2010, and as I am learning LINQ to SQL, I am curious as to the best way to link the two groups of information so that when I update one, the other updates along with it. From my research here at SO, as well as in Google, it appears the general rule of thumb is: "Build the database, and then create your LINQ to SQL classes." Of course, if I make a change in my database, the LINQ to SQL doesn't update automatically and I have to do it by hand. This is fairly simple right now as my database is small, but I am curious if there is an easier way for this to happen. In addition, the LINQ to SQL tool is pretty nice. The ability to create tables, add associations, and even create inheritance is very simple. As my second question, I am curious as to whether or not VS2010 can work the other way - I design the database in the DBLM file and then link it back to my database project. I appreciate any help with either of these two questions. I'm really interested in making this as easy as possible to reduce errors during development and improve the speed at which changes can be made.

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  • ReSharper - Possible Null Assignment when using Microsoft.Contracts

    - by HVS
    Is there any way to indicate to ReSharper that a null reference won't occur because of Design-by-Contract Requires checking? For example, the following code will raise the warning (Possible 'null' assignment to entity marked with 'NotNull' attribute) in ReSharper on lines 7 and 8: private Dictionary<string, string> _Lookup = new Dictionary<string, string>(); public void Foo(string s) { Contract.Requires(!String.IsNullOrEmpty(s)); if (_Lookup.ContainsKey(s)) _Lookup.Remove(s); } What is really odd is that if you remove the Contract.Requires(...) line, the ReSharper message goes away. Update I found the solution through ExternalAnnotations which was also mentioned by Mike below. Here's an example of how to do it for a function in Microsoft.Contracts: Create a directory called Microsoft.Contracts under the ExternalAnnotations ReSharper directory. Next, Create a file called Microsoft.Contracts.xml and populate like so: <assembly name="Microsoft.Contracts"> <member name="M:System.Diagnostics.Contracts.Contract.Requires(System.Boolean)"> <attribute ctor="M:JetBrains.Annotations.AssertionMethodAttribute.#ctor"/> <parameter name="condition"> <attribute ctor="M:JetBrains.Annotations.AssertionConditionAttribute.#ctor(JetBrains.Annotations.AssertionConditionType)"> <argument>0</argument> </attribute> </parameter> </member> </assembly> Restart Visual Studio, and the message goes away!

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  • Legit? Two foreign keys referencing the same primary key.

    - by Ryan
    Hi All, I'm a web developer and have recently started a project with a company. Currently, I'm working with their DBA on getting the schema laid out for the site, and we've come to a disagreement regarding the design on a couple tables, and I'd like some opinions on the matter. Basically, we are working on a site that will implement a "friends" network. All users of the site will be contained in a table tblUsers with (PersonID int identity PK, etc). What I am wanting to do is to create a second table, tblNetwork, that will hold all of the relationships between users, with (NetworkID int identity PK, Owners_PersonID int FK, Friends_PersonID int FK, etc). Or conversely, remove the NetworkID, and have both the Owners_PersonID and Friends_PersonID shared as the Primary key. This is where the DBA has his problem. Saying that "he would only implement this kind of architecture in a data warehousing schema, and not for a website, and this is just another example of web developers trying to take the easy way out." Now obviously, his remark was a bit inflammatory, and that have helped motivate me to find an suitable answer, but more so, I'd just like to know how to do it right. I've been developing databases and programming for over 10 years, have worked with some top-notch minds, and have never heard this kind of argument. What the DBA is wanting to do is instead of storing both the Owners_PersonId and Friends_PersonId in the same table, is to create a third table tblFriends to store the Friends_PersonId, and have the tblNetwork have (NetworkID int identity PK, Owner_PersonID int FK, FriendsID int FK(from TBLFriends)). All that tblFriends would house would be (FriendsID int identity PK, Friends_PersonID(related back to Persons)). To me, creating the third table is just excessive in nature, and does nothing but create an alias for the Friends_PersonID, and cause me to have to add (what I view as unneeded) joins to all my queries, not to mention the extra cycles that will be necessary to perform the join on every query. Thanks for reading, appreciate comments. Ryan

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  • Database structure - is mySQL the right choice?

    - by Industrial
    Hi everyone, We are currently planning the database structure of a quite complex e-commerce web app that has flexibility as it's main cornerstone. Our app features a large amount of data (products) and we have run into a slight headache trying to keep performance high without compromizing normalization rules in the database, or leaving our highly beloved flexibility concept behind when integrating product options (also widely known as product attributes or parameters). Based on various references and sources available, we have made up lists on pros and cons of all major and well known database patterns to solve this. After comparing these, we have come up with two final alternatives: EAV (Entity-attribute-value model) : Pros: Database is used for all sorting. Cons: All related queries will include a number of joins between multiple tables in order to complete the collection of data. SLOB (Serialized LOB, also known as Facade?) : Pros: Very flexible. Keeping the number of necessary joins low compared to a EAV design pattern. Easy to update/add/remove data from each product. Cons: All sorting will be done by the application instead of the database. Will use lots of performance (memory?) when big datasets is processed by a large number of users. Our main questions: Which pattern/structure would you use, or maybe even a different solution? Is there better databases besides mySQL available nowadays to accomplish what we want? Thanks a lot! Reference: http://stackoverflow.com/questions/695752/product-table-many-kinds-of-product-each-product-has-many-parameters

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  • Invoice & Invoice lines: How do you store customer address information?

    - by elviejo
    Hi I'm developing an invoicing application. So the general idea is to have two tables: Invoice (ID, Date, CustomerAddress, CustomerState, CustomerCountry, VAT, Total); InvoiceLine (Invoice_ID, ID, Concept, Units, PricePerUnit, Total); As you can see this basic design leads to a lot of repetiton of records where the client will have the same addrres, state and country. So the alternative is to have an address table and then make a relationship Address<-Invoice. However I think that an invoice is immutable document and should be stored just the way it was first made. Sometimes customers change their addresses, or states and if it was coming from an Address catalog that will change all the previously made invoices. So What is your experience? How is the customer address stored in an invoice? In the Invoice table? an Address Table? or something else? Can you provide pointers to a book, article or document where this is discussed in further detail?

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  • DDD: Aggregate Roots

    - by Mosh
    Hello, I need help with finding my aggregate root and boundary. I have 3 Entities: Plan, PlannedRole and PlannedTraining. Each Plan can include many PlannedRoles and PlannedTrainings. Solution 1: At first I thought Plan is the aggregate root because PlannedRole and PlannedTraining do not make sense out of the context of a Plan. They are always within a plan. Also, we have a business rule that says each Plan can have a maximum of 3 PlannedRoles and 5 PlannedTrainings. So I thought by nominating the Plan as the aggregate root, I can enforce this invariant. However, we have a Search page where the user searches for Plans. The results shows a few properties of the Plan itself (and none of its PlannedRoles or PlannedTrainings). I thought if I have to load the entire aggregate, it would have a lot of overhead. There are nearly 3000 plans and each may have a few children. Loading all these objects together and then ignoring PlannedRoles and PlannedTrainings in the search page doesn't make sense to me. Solution 2: I just realized the user wants 2 more search pages where they can search for Planned Roles or Planned Trainings. That made me realize they are trying to access these objects independently and "out of" the context of Plan. So I thought I was wrong about my initial design and that is how I came up with this solution. So, I thought to have 3 aggregates here, 1 for each Entity. This approach enables me to search for each Entity independently and also resolves the performance issue in solution 1. However, using this approach I cannot enforce the invariant I mentioned earlier. There is also another invariant that states a Plan can be changed only if it is of a certain status. So, I shouldn't be able to add any PlannedRoles or PlannedTrainings to a Plan that is not in that status. Again, I can't enforce this invariant with the second approach. Any advice would be greatly appreciated. Cheers, Mosh

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  • .NET Membership with Repository Pattern

    - by Zac
    My team is in the process of designing a domain model which will hide various different data sources behind a unified repository abstraction. One of the main drivers for this approach is the very high probability that these data sources will undergo significant change in the near future and we don't want to be re-writing business logic when this happens. One data source will be our membership database which was originally implemented using the default ASP.Net Membership Provider. The membership provider is tied to the System.Web.Security namespace but we have a design guideline requiring that our domain model layer is not dependent upon System.Web (or any other implementation/environment dependency) as it will be consumed in different environments - nor do we want our websites directly communicating with databases. I am considering what would be a good approach to reconciling the MembershipProvider approach with our abstracted n-tier architecture. My initial feeling is that we could create a "DomainMembershipProvider" which interacts with the domain model and then implement objects in the model which deal with the repository and handle validation/business logic. The repository would then implement data access using our (as-yet undecided) ORM/data access tool. Are there are any glaring holes in this approach - I haven't worked closely with the MembershipProvider class so may well be missing something. Alternatively, is there an approach that you think will better serve the requirements I described above? Thanks in advance for your thoughts and advice. Regards, Zac

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  • structured vs. unstructured data in db

    - by Igor
    the question is one of design. i'm gathering a big chunk of performance data with lots of key-value pairs. pretty much everything in /proc/cpuinfo, /proc/meminfo/, /proc/loadavg, plus a bunch of other stuff, from several hundred hosts. right now, i just need to display the latest chunk of data in my UI. i will probably end up doing some analysis of the data gathered to figure out performance problems down the road, but this is a new application so i'm not sure what exactly i'm looking for performance-wise just yet. i could structure the data in the db -- have a column for each key i'm gathering. the table would end up being O(100) columns wide, it would be a pain to put into the db, i would have to add new columns if i start gathering a new stat. but it would be easy to sort/analyze the data just using SQL. or i could just dump my unstructured data blob into the table. maybe three columns -- host id, timestamp, and a serialized version of my array, probably using JSON in a TEXT field. which should I do? am i going to be sorry if i go with the unstructured approach? when doing analysis, should i just convert the fields i'm interested in and create a new, more structured table? what are the trade-offs i'm missing here?

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  • Database migration pattern for Java?

    - by Eno
    Im working on some database migration code in Java. Im also using a factory pattern so I can use different kinds of databases. And each kind of database im using implements a common interface. What I would like to do is have a migration check that is internal to the class and runs some database schema update code automatically. The actual update is pretty straight forward (I check schema version in a table and compare against a constant in my app to decide whether to migrate or not and between which versions of schema). To make this automatic I was thinking the test should live inside (or be called from) the constructor. OK, fair enough, that's simple enough. My problem is that I dont want the test to run every single time I instantiate a database object (it runs a query so having it run on every construction is not efficient). So maybe this should be a class static method? I guess my question is, what is a good design pattern for this type of problem? There ought to be a clean way to ensure the migration test runs only once OR is super-efficient.

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  • Flexible Decorator Pattern?

    - by Omar Kooheji
    I was looking for a pattern to model something I'm thinking of doing in a personal project and I was wondering if a modified version of the decorator patter would work. Basicly I'm thinking of creating a game where the characters attributes are modified by what items they have equiped. The way that the decorator stacks it's modifications is perfect for this, however I've never seen a decorator that allows you to drop intermediate decorators, which is what would happen when items are unequiped. Does anyone have experience using the decorator pattern in this way? Or am I barking up the wrong tree? Clarification To explain "Intermediate decorators" if for example my base class is coffe which is decorated with milk which is decorated with sugar (using the example in Head first design patterns) milk would be an intermediate decorator as it decorates the base coffee, and is decorated by the sugar. Yet More Clarification :) The idea is that items change stats, I'd agree that I am shoehorning the decorator into this. I'll look into the state bag. essentially I want a single point of call for the statistics and for them to go up/down when items are equiped/unequiped. I could just apply the modifiers to the characters stats on equiping and roll them back when unequiping. Or whenever a stat is asked for iterate through all the items and calculate the stat. I'm just looking for feedback here, I'm aware that I might be using a chainsaw where scissors would be more appropriate...

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  • Can the Diamond Problem be really solved?

    - by Mecki
    A typical problem in OO programming is the diamond problem. I have parent class A with two sub-classes B and C. A has an abstract method, B and C implement it. Now I have a sub-class D, that inherits of B and C. The diamond problem is now, what implementation shall D use, the one of B or the one of C? People claim Java knows no diamond problem. I can only have multiple inheritance with interfaces and since they have no implementation, I have no diamond problem. Is this really true? I don't think so. See below: [removed vehicle example] Is a diamond problem always the cause of bad class design and something neither programmer nor compiler needs to solve, because it shouldn't exist in the first place? Update: Maybe my example was poorly chosen. See this image Of course you can make Person virtual in C++ and thus you will only have one instance of person in memory, but the real problem persists IMHO. How would you implement getDepartment() for GradTeachingFellow? Consider, he might be student in one department and teach in another one. So you can either return one department or the other one; there is no perfect solution to the problem and the fact that no implementation might be inherited (e.g. Student and Teacher could both be interfaces) doesn't seem to solve the problem to me.

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  • Explaining the need to avoid horizontal scroll

    - by Bradley Herman
    I need help explaining to my boss why her design is poor on a client's website. She has no knowledge of the web, and it can be difficult as a web developer working with a woman who is a graphic designer (not even a web designer really). On a current site she has designed, an image bar "needs" to be ~1200px according to her, though it isn't necessary with the content. A quick sketch to illustrate what's going on: As you see, the banner spills out past the 960px of the content and as wide as 1200px. This creates a horizontal scroll when all the content is viewable within the 960px wide viewport. I need to make this an <img and not a CSS background because it's a jQuery slideshow that fades from image to image. I think this is a big problem because a lot of people are going to get a horizontal scroll bar imposed in their browser when they're still able to see all the relevant content. She thinks no one will notice and it'll be fine; I think it's very bad practice and confusing to the end user. How do I explain the problem to her?

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  • Naming convention for non-virtual and abstract methods

    - by eagle
    I frequently find myself creating classes which use this form (A): abstract class Animal { public void Walk() { // TODO: do something before walking // custom logic implemented by each subclass WalkInternal(); // TODO: do something after walking } protected abstract void WalkInternal(); } class Dog : Animal { protected override void WalkInternal() { // TODO: walk with 4 legs } } class Bird : Animal { protected override void WalkInternal() { // TODO: walk with 2 legs } } Rather than this form (B): abstract class Animal { public abstract void Walk(); } class Dog : Animal { public override void Walk() { // TODO: do something before walking // custom logic implemented by each subclass // TODO: walk with 4 legs // TODO: do something after walking } } class Bird : Animal { public override void Walk() { // TODO: do something before walking // custom logic implemented by each subclass // TODO: walk with 2 legs // TODO: do something after walking } } As you can see, the nice thing about form A is that every time you implement a subclass, you don't need to remember to include the initialization and finalization logic. This is much less error prone than form B. What's a standard convention for naming these methods? I like naming the public method Walk since then I can call Dog.Walk() which looks better than something like Dog.WalkExternal(). However, I don't like my solution of adding the suffix "Internal" for the protected method. I'm looking for a more standardized name. Btw, is there a name for this design pattern?

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  • Users in database server or database tables

    - by Batcat
    Hi all, I came across an interesting issue about client server application design. We have this browser based management application where it has many users using the system. So obvisously within that application we have an user management module within it. I have always thought having an user table in the database to keep all the login details was good enough. However, a senior developer said user management should be done in the database server layer if not then is poorly designed. What he meant was, if a user wants to use the application then a user should be created in the user table AND in the database server as a user account as well. So if I have 50 users using my applications, then I should have 50 database server user logins. I personally think having just one user account in the database server for this database was enough. Just grant this user with the allowed privileges to operate all the necessary operation need by the application. The users that are interacting with the application should have their user accounts created and managed within the database table as they are more related to the application layer. I don't see and agree there is need to create a database server user account for every user created for the application in the user table. A single database server user should be enough to handle all the query sent by the application. Really hope to hear some suggestions / opinions and whether I'm missing something? performance or security issues? Thank you very much.

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  • How can I place validating constraints on my method input parameters?

    - by rcampbell
    Here is the typical way of accomplishing this goal: public void myContractualMethod(final String x, final Set<String> y) { if ((x == null) || (x.isEmpty())) { throw new IllegalArgumentException("x cannot be null or empty"); } if (y == null) { throw new IllegalArgumentException("y cannot be null"); } // Now I can actually start writing purposeful // code to accomplish the goal of this method I think this solution is ugly. Your methods quickly fill up with boilerplate code checking the valid input parameters contract, obscuring the heart of the method. Here's what I'd like to have: public void myContractualMethod(@NotNull @NotEmpty final String x, @NotNull final Set<String> y) { // Now I have a clean method body that isn't obscured by // contract checking If those annotations look like JSR 303/Bean Validation Spec, it's because I borrowed them. Unfortunitely they don't seem to work this way; they are intended for annotating instance variables, then running the object through a validator. Which of the many Java design-by-contract frameworks provide the closest functionality to my "like to have" example? The exceptions that get thrown should be runtime exceptions (like IllegalArgumentExceptions) so encapsulation isn't broken.

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