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  • Do Java or C++ lack any OO features?

    - by tsv
    I am interested in understanding object-oriented programming in a more academic and abstract way than I currently do, and want to know if there are any object-oriented concepts Java and C++ fail to implement. I realise neither of the languages are "pure" OO, but I am interested in what (if anything) they lack, not what they have extra.

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  • Singletons and constants

    - by devoured elysium
    I am making a program which makes use of a couple of constants. At first, each time I needed to use a constant, I'd define it as //C# private static readonly int MyConstant = xxx; //Java private static final int MyConstant = xxx; in the class where I'd need it. After some time, I started to realise that some constants would be needed in more than one class. At this time, I had 3 choises: To define them in the different classes that needed it. This leads to repetition. If by some reason later I need to change one of them, I'd have to check in all classes to replace them everywhere. To define a static class/singleton with all the constants as public. If I needed a constant X in ClassA, ClassB and ClassC, I could just define it in ClassA as public, and then have ClassB and ClassC refer to them. This solution doesn't seem that good to me as it introduces even more dependencies as the classes already have between them. I ended up implementing my code with the second option. Is that the best alternative? I feel I am probably missing some other better alternative. What worries me about using the singleton here is that it is nowhere clear to a user of the class that this class is using the singleton. Maybe I could create a ConstantsClass that held all the constants needed and then I'd pass it in the constructor to the classes that'd need it? Thanks

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  • In what package should a "Settings" class be placed?

    - by Tom
    I'm in the middle of building an application but found myself too easily creating new packages without keeping the project's structure in mind. Now, I'm trying to redo the whole project structure on paper first. I am using a Settings class with public properties, accessed as settings for several other classes around the project. Now, since this Settings class applies for the whole project, I am unsure if it should be packaged and if so, in what kind of package should it exist? Or should it be in the root (the default package) with the main application class? I've been thinking about putting it in my utils package, then again I don't think it really is an utlity. Any strategies on how to decide on such package structure for example for a Settings class?

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  • Need a field / flag / status number for mutliple use ?

    - by Jules
    I want to create a field in my database which will be easy to query. I think if I give a bit of background this will make more sense. My table has listings shown on my website. I run a program which looks at the listings a decides whether to hide them from being shown on the site. I also hide listings manually for various reasons. I want to store these reasons in a field, so more than one reason could be made for hiding. So I need some form of logic to determine which reasons have been used. Can anyone offer me any guidance on what will be future-proof aka new reasons and what will be quick and easy to query upon ?

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  • Correct approach to validate attributes of an instance of class

    - by systempuntoout
    Having a simple Python class like this: class Spam(object): __init__(self, description, value): self.description = description self.value = value Which is the correct approach to check these constraints: "description cannot be empty" "value must be greater than zero" Should i: 1.validate data before creating spam object ? 2.check data on __init__ method ? 3.create an is_valid method on Spam class and call it with spam.isValid() ? 4.create an is_valid static method on Spam class and call it with Spam.isValid(description, value) ? 5.check data on setters declaration ? 6.... Could you recommend a well designed\Pythonic\not verbose (on class with many attributes)\elegant approach?

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  • How to handle request/response propagation up and down a widget hierarchy in a GUI app?

    - by fig-gnuton
    Given a GUI application where widgets can be composed of other widgets: If the user triggers an event resulting in a lower level widget needing data from a model, what's the cleanest way to be able to send that request to a controller (or the datastore itself)? And subsequently get the response back to that widget? Presumably one wouldn't want the controller or datastore to be a singleton directly available to all levels of widgets, or is this an acceptable use of singleton? Or should a top level controller be injected as a dependency through a widget hierarchy, as far down as the lowest level widget that might need that controller? Or a different approach entirely?

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  • Updating access 2000 database through code in VB6

    - by Mark
    I have an application that uses an access 2000 database currently in distribution. I need to update one of the recordsets with additional fields on my customer's computers. My data controls work fine as I have them set to connect in access 2000 format but when I try to open the database in code, I get an unrecognized data format error. What is the best way to replace or add to the database on their machines? Any help is greatly appreciated.

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  • Conditional on WebClient

    - by CarryFlag
    Given: thin client (JS) model services client use services. services use model. Model consists of (for sample): Rect Circle ... Ellipse services: class CanvasProviger { public Canvas getCanvas() { return new Canvas(); } } model: class Canvas ... { private List < Figure > figures = new List < Figure >; ... } class Circle extends Figure { private int x, y, r; } class Rect extends Figure { private x, y, w, h; } client: ... var figure = MyJSRPCImpl.getCanvas().nextFigure(); if(figure == JSLocalModel.Rect) { drawRect(figure); } else if(figure == JSLocalModel.Circle) { drawCircle(figure); } ... How else can do way conditional? In rich client I used pattern Visitor. // my bad english, I know =(

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  • Add list type to association

    - by teucer
    Hi All, I am using the eUML2 (Free version) plugin to draw a UML class diagram. Now, let's assume I have a class Person and a class Car. I want the class Person to have a member cars which is a List<Car>, i.e. private List<Car> cars = null. My question is how do I include this information in the class diagram? To be more precise, how do I include the type information for the List in the eUML2 association? Regards

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  • Need recommendation for a table structure

    - by yapiskan
    I have an entity which has 4 different types of property that could have only one value for each case which are boolean, decimal, string or text. I don't want to define the table with 4 boolean, decimal, nvarchar and ntext columns. What would you recommend to cover this case?

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  • What does ON [PRIMARY] mean?

    - by Icono123
    I'm creating an SQL setup script and I'm using someone else's script as an example. Here's an example of the script: SET ANSI_NULLS ON GO SET QUOTED_IDENTIFIER ON GO CREATE TABLE [dbo].[be_Categories]( [CategoryID] [uniqueidentifier] ROWGUIDCOL NOT NULL CONSTRAINT [DF_be_Categories_CategoryID] DEFAULT (newid()), [CategoryName] [nvarchar](50) NULL, [Description] [nvarchar](200) NULL, [ParentID] [uniqueidentifier] NULL, CONSTRAINT [PK_be_Categories] PRIMARY KEY CLUSTERED ( [CategoryID] ASC )WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY] ) ON [PRIMARY] GO Does anyone know what the ON [PRIMARY] command does? Regards.

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  • User's possibilities on site

    - by Lari13
    I want to build a system on the website, that allows users to do some things depend on their rating. For example I have rule for rating value X: 1 post in 3 days 10 comments in 1 day 20 votes in 2 days for rating value Y, rule may be following: 3 post in 1 day 50 comments in 1 day 30 votes in 1 day Each night I recalculate users' ratings, so I know what each user is able to do. Possibilities don't sum or reset on each rating's recalculation. One more important thing is that admin can fill concrete user's possibilities at any time. What is optimal database (MySQL) structure for desired? I can count what concrete user has done: SELECT COUNT(*) FROM posts WHERE UserID=XXX AND DateOfPost >= 'YYY' SELECT COUNT(*) FROM comments WHERE UserID=XXX AND CommentOfPost >= 'YYY' But how can I do admin filling possibilities in this case?

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  • Three customer addresses in one table or in separate tables?

    - by DR
    In my application I have a Customer class and an Address class. The Customer class has three instances of the Address class: customerAddress, deliveryAddress, invoiceAddress. Whats the best way to reflect this structure in a database? The straightforward way would be a customer table and a separate address table. A more denormalized way would be just a customer table with columns for every address (Example for "street": customer_street, delivery_street, invoice_street) What are your experiences with that? Are there any advantages and disadvantages of these approaches?

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  • Splitting values into groups evenly

    - by Paul Knopf
    Let me try to explain the situation the best I can. Lets say I have 3 values 1, 2, 3 I tell an algorithm to split this values into x columns. Lets say x = 2 for clarification. The algorithm determines that the group of values is best put into two columns the following way. 1st column 2nd column --------------------------- 1 3 2 Each column has an even number (totals, not literals) value. Now lets say I have the following values 7, 8, 3, 1, 4 I tell the algorithm that I want the values split into 3 columns. The algorithm now tells me that the following is the best fit. 1st column 2nd column 3rd column 8 7 3 1 4 Notice how the columns arent quiet even, but it is as close as it can get. A little over and a little under is considered ok, as long as the list is AS CLOSE TO EVEN AS IT CAN BE. Anybody got any suggestions? Know any good methods of doing this?

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  • One database or many?

    - by dsims
    I am developing a website that will manage data for multiple entities. No data is shared between entities, but they may be owned by the same customer. A customer may want to manage all their entities from a single "dashboard". So should I have one database for everything, or keep the data seperated into individual databases? Is there a best-practice? What are the positives/negatives for having a: database for the entire site (entity has a "customerID", data has "entityID") database for each customer (data has "entityID") database for each entity (relation of database to customer is outside of database) Multiple databases seems like it would have better performance (fewer rows and joins) but may eventually become a maintenance nightmare.

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  • Are free and open source templates, themes, self content management systems replacing the need of we

    - by metal-gear-solid
    Are free and open source templates, themes, self content management systems replacing the need of web designers? You can find templates online for pretty much anything these days. There are html and css templates, templates for Wordpress, all sorts of different cms templates, e-ecommerce templates, etc. Many of these are pretty cheap and some are even free, so where do web designers fit into this picture? I’ve had many clients and potential customers ask why they should use my services instead of just buying a cheap template. Are web designers being replaced?

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  • Should Service Depend on Many Repositories, or Break Them Up?

    - by Josh Pollard
    I'm using a repository pattern for my data access. So I basically have a repository per table/class. My UI currently uses service classes to actually get things done, and these service classes wrap, and therefore depend on repositories. In many cases my services are only dependent upon one or two repositories, so things aren't too crazy. Unfortunately, one of my forms in the UI expects the user to enter data that will span five different tables. For this form I made a single service class that depends upon five repositories. Then the methods within the service for saving and loading the data call the appropriate methods on all of the corresponding repositories. As you can imagine, the save and load methods in this service are really big. Also, unit testing this service is getting really difficult because I have to setup so many fake repositories. Would it have been a better choice to break this single service apart into a few smaller services? It would put more code at the UI layer, but would make the services smaller and more testable.

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  • Database tables with dynamic information

    - by Tim Fennis
    I've googled this and found that it's almost impossible to create a database with dynamic collumns. I'll explain my problem first. I am making a webshop for a customer. It has multiple computer products for sale. CPU's HDD's RAM ect. All these products have different properties, a CPU has an FSB, RAM has a CAS latency. But this is very inconvenient because my orders table needs foreign keys to different tables which is impossible. An other option is to store all the product specific information in a varchar or blob field and let PHP figure it out. The problem with this solution is that the website needs a PC builder. A step-by-step guide to building your PC. So for instance if a customer decides he wants a new "i7 920" or whatever i want to be able to sellect all motherboards for socket 1366, which is impossible because all the data is stored in one field. I know it's possible to select all motherboards form the DB and let PHP figure out which ones are for socket 1366 but i was wondering, is there a better solution?

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