Search Results

Search found 13259 results on 531 pages for 'design'.

Page 175/531 | < Previous Page | 171 172 173 174 175 176 177 178 179 180 181 182  | Next Page >

  • .NET: bool vs enum as a method parameter

    - by Julien Lebosquain
    Each time I'm writing a method that takes a boolean parameter representing an option, I find myself thinking: "should I replace this by an enum which would make reading the method calls much easier?". Consider the following with an object that takes a parameter telling whether the implementation should use its thread-safe version or not (I'm not asking here if this way of doing this is good design or not, only the use of the boolean): public void CreateSomeObject(bool makeThreadSafe); CreateSomeObject(true); When the call is next to the declaration the purpose of the parameter seems of course obvious. When it's in some third party library you barely know, it's harder to immediately see what the code does, compared to: public enum CreationOptions { None, MakeThreadSafe } public void CreateSomeObject(CreationOptions options); CreateSomeObject(CreationOptions.MakeThreadSafe); which describes the intent far better. Things get worse when there's two boolean parameters representing options. See what happened to ObjectContext.SaveChanges(bool) between Framework 3.5 and 4.0. It has been obsoleted because a second option has been introduced and the whole thing has been converted to an enum. While it seems obvious to use an enumeration when there's three elements or more, what's your opinion and experiences about using an enum instead a boolean in these specific cases?

    Read the article

  • When to save a mongoose model

    - by kentcdodds
    This is an architectural question. I have models like this: var foo = new mongoose.Schema({ name: String, bars: [{type: ObjectId, ref: 'Bar'}] }); var FooModel = mongoose.model('Foo', foo); var bar = new mongoose.Schema({ foobar: String }); var BarModel = mongoose.model('Bar', bar); Then I want to implement a convenience method like this: BarModel.methods.addFoo = function(foo) { foo.bars = foo.bars || []; // Side note, is this something I should check here? foo.bars.push(this.id); // Here's the line I'm wondering about... Should I include the line below? foo.save(); } The biggest con I see about this is that if I did include foo.save() then I should pass in a callback to addFoo so I avoid issues with the async operation. I'm thinking this is not preferable. But I also think it would be nice to include because addFoo hasn't really "addedFoo" until it's been saved... Am I breaking any design best practices doing it either way?

    Read the article

  • Is "tip-of-the-day" good?

    - by Jonta
    Many programs (often large ones, like MS Office, The GIMP, Maxthon) have a feature called "tip-of-the-day". It explains a small part of the program, like this one in Maxthon: "You can hide/show the main menu bar by pressing Ctrl+F11" You can usually browse through them by clicking next. And other options provided are "Previous", "Close", "Do not show at startup". I think I like the way Maxthon used to handle this; in the browser's statusbar (down at the bottom usually, together with "Done", the progress-bar etc), there would sometimes be a small hint or tip on what else you could do with it. As Joel Spolsky wrote in his article-series "User Interface Design for Programmers", people don't like reading manuals. But we still want them to use the program, and the features they could benefit from, don't we? Therefore, I think it is useful to have such a feature, without the annoyance of the pop-up on startup. What do you think? Pop-up? Maxthonstyle? No way?

    Read the article

  • Structuring iPhone/iPad application views

    - by Mark
    I have an idea about an application that I want to build and Im new to iPhone/iPad development (but not new to development in other languages/frameworks such as .NET and Java). I want to layout some views on the screen so that they animate (slide in) from different directions into their places. The question is about the strucuture of the application, if I have say 4 rectanglular areas on the screen that contain business data, such as contacts (name, photo, etc...) and they all take up different widths of the screen (say the first contact takes up one row of the screen, but the next 2 take up half the width of the next row each, and so on). Should I create a custom view for the different sized contact views, (i.e. LargeCustomView and SmallCustomView, and any other special type that I make) or should it all be one type, say, CustomerDetailsView which could be stretched to fit at design time? Also, if there were, say, 3 different instances of the same custom view on the one screen, are there 3 instances of the view controller also? Im a little confused about powering the data behind a view, can someone shed some light on this for me? Do I just set the properties (say an instance variable ContactForView) on the view controller for each instance? Thanks for any help you can give Cheers, Mark

    Read the article

  • Multiple Foreign keys to a single table and single key pointing to more than one table

    - by user1216775
    I need some suggestions from the database design experts here. I have around six foreign keys into a single table (defect) which all point to primary key in user table. It is like: defect (.....,assigned_to,created_by,updated_by,closed_by...) If I want to get information about the defect I can make six joins. Do we have any better way to do it? Another one is I have a states table which can store one of the user-defined set of values. I have defect table and task table and I want both of these tables to share the common state table (New, In Progress etc.). So I created: task (.....,state_id,type_id,.....) defect(.....,state_id,type_id,...) state(state_id,state_name,...) importance(imp_id,imp_name,...) There are many such common attributes along with state like importance(normal, urgent etc), priority etc. And for all of them I want to use same table. I am keeping one flag in each of the tables to differentiate task and defect. What is the best solution in such a case? If somebody is using this application in health domain, they would like to assign different types, states, importances for their defect or tasks. Moreover when a user selects any project I want to display all the types,states etc under configuration parameters section.

    Read the article

  • [MVC] logic before dispatcher + controller?

    - by Spoonface
    I believe for a typical MVC web application the router / dispatcher routine is used to decide which controller is loaded based primarily on the area requested in the url by the user. However, in addition to checking the url query string, I also like to use the dispatcher to check whether the user is currently logged in or not to decide which controller is loaded. For example if they are logged in and request the login page, the dispatcher would load their account instead. But is this a fairly non-standard design? Would it violate MVC in any way? I only ask as the examples I've read through this weekend have had no major calculations performed before the dispatcher routine, and commonly check whether the user is logged in or not per controller, and then redirect where necessary. But to me it seems odd to redirect a logged in user from the login area to account area if you could just load the account controller in the first place? I hope I've explained my consternation well enough, but could anyone offer some details on how they handle logged in users, and similar session data?

    Read the article

  • Social Networking & Network Affiliations

    - by Code Sherpa
    Hi. I am in the process of planning a database for a social networking project and stumbled upon this url which is a (crude) reverse engineered guess at facebook's schema: http://www.flickr.com/photos/ikhnaton2/533233247/ What is of interest to me is the notion of "Affiliations" and I am trying to fully understand how they work, technically speaking. Where I am somewhat confused is the NetworkID column in the FacebookGroups", "FacebookEvent", and "Affiliations" tables (NID in Affiliations). How are these network affiliations interconnected? In my own project, I have a simple profile table: CREATE TABLE [dbo].[Profiles]( [profileid] [int] IDENTITY(1,1) NOT NULL, [userid] [uniqueidentifier] NOT NULL, [username] [varchar](255) COLLATE Latin1_General_CI_AI NOT NULL, [applicationname] [varchar](255) COLLATE Latin1_General_CI_AI NOT NULL, [isanonymous] [bit] NULL, [lastactivity] [datetime] NULL, [lastupdated] [datetime] NULL, CONSTRAINT [PK__Profiles__1DB06A4F] PRIMARY KEY CLUSTERED ( [profileid] ASC )WITH (IGNORE_DUP_KEY = OFF) ON [PRIMARY], CONSTRAINT [PKProfiles] UNIQUE NONCLUSTERED ( [username] ASC, [applicationname] ASC )WITH (IGNORE_DUP_KEY = OFF) ON [PRIMARY] ) ON [PRIMARY] One profile can have many affiliations. And one affiliation can have many profiles. And I would like to design it in such a way that relationships between affiliations tells me something about the associated profiles. In fact, based on the affiliations that users select, I would like to know how to infer as many things as possible about that person. My question is, how should I be designing my network affiliation tables and how do they operate per my above requirements? A rough SQL schema would be appreciated in your response. Thanks in advance...

    Read the article

  • How security of the systems might be improved using database procedures?

    - by Centurion
    The usage of Oracle PL/SQL procedures for controlling access to data often emphasized in PL/SQL books and other sources as being more secure approach. I'v seen several systems where all business logic related with data is performed through packages, procedures and functions, so application code becomes quite "dumb" and is only responsible for visualization part. I even heard some devs call such approaches and driving architects as database nazi :) because all logic code resides in database. I do know about DB procedure performance benefits, but now I'm interested in a "better security" when using thick client model. I assume such design mostly used when Oracle (and maybe MS SQL Server) databases are used. I do agree such approach improves security but only if there are not much users and every system user has a database account, so we might control and monitor data access through standard database user security. However, how such approach could increase the security for an average web system where thick clients are used: for example one database user with DML grants on all tables, and other users are handled using "users" and"user_rights" tables? We could use DB procedures, save usernames into context use that for filtering but vulnerability resides at the root - if the main database account is compromised than nothing will help. Of course in a real system we might consider at least several main users (for example frontend_db_user, backend_db_user).

    Read the article

  • Designing a database for a user/points system? (in Django)

    - by AP257
    First of all, sorry if this isn't an appropriate question for StackOverflow. I've tried to make it as generalisable as possible. I want to create a database (MySQL, site running Django) that has users, who can be allocated a certain number of points for various types of action - it's a collaborative game. My requirements are to obtain: the number of points a user has the user's ranking compared to all other users and the overall leaderboard (i.e. all users ranked in order of points) This is what I have so far, in my Django models.py file: class SiteUser(models.Model): name = models.CharField(max_length=250 ) email = models.EmailField(max_length=250 ) date_added = models.DateTimeField(auto_now_add=True) def points_total(self): points_added = PointsAdded.objects.filter(user=self) points_total = 0 for point in points_added: points_total += point.points return points_total class PointsAdded(models.Model): user = models.ForeignKey('SiteUser') action = models.ForeignKey('Action') date_added = models.DateTimeField(auto_now_add=True) def points(self): points = Action.objects.filter(action=self.action) return points class Action(models.Model): points = models.IntegerField() action = models.CharField(max_length=36) However it's rapidly becoming clear to me that it's actually quite complex (in Django query terms at least) to figure out the user's ranking and return the leaderboard of users. At least, I'm finding it tough. Is there a more elegant way to do something like this? This question seems to suggest that I shouldn't even have a separate points table - what do people think? It feels more robust to have separate tables, but I don't have much experience of database design.

    Read the article

  • Common Properties: Consolidating Loan, Purchase, Inventory and Sale tables into one Transaction tabl

    - by Frank Computer
    Pawnshop Application: I have separate tables for Loan, Purchase, Inventory & Sales transactions. Each tables rows are joined to their respective customer rows by: customer.pk [serial] = loan.fk [integer]; = purchase.fk [integer]; = inventory.fk [integer]; = sale.fk [integer]; Since there are so many common properties within the four tables, I consolidated the four tables into one table called "transaction", where a column: transaction.trx_type char(1) {L=Loan, P=Purchase, I=Inventory, S=Sale} Scenario: A customer initially pawns merchandise, makes a couple of interest payments, then decides he wants to sell the merchandise to the pawnshop, who then places merchandise in Inventory and eventually sells it to another customer. I designed a generic transaction table where for example: transaction.main_amount DECIMAL(7,2) in a loan transaction holds the pawn amount, in a purchase holds the purchase price, in inventory and sale holds sale price. This is clearly a denormalized design, but has made programming alot easier and improved performance. Any type of transaction can now be performed from within one screen, without the need to change to different tables.

    Read the article

  • Unnecessary Redundancy with Tables.

    - by Stacey
    My items are listed as follows; This is just a summary of course. But I'm using a method shown for the "Detail" table to represent a type of 'inheritence', so to speak - since "Item" and "Downloadable" are going to be identical except that each will have a few additional fields relevant only to them. My question is in this design pattern. This sort of thing appears many, many times in our projects - is there a more intelligent way to handle it? I basically need to normalize the tables as much as possible. I'm extremely new to databases and so this is all very confusing to me. There are 5 items. Awards, Items, Purchases, Tokens, and Downloads. They are all very, very similar, except each has a few pieces of data relevant only to itself. I've tried to use a declaration field (like an enumerator 'Type' field) in conjunction with nullable columns, but I was told that is a bad approach. What I have done is take everything similar and place it in a single table, and then each type has its own table that references a column in the 'base' table. The problem occurs with relationships, or junctions. Linking all of these back to a customer. Each type takes around 2 additional tables to properly junction all of the data together- and as such, my database is growing very, very large. Is there a smarter practice for this kind of behavior? Item ID | GUID Name | varchar(64) Product ID | GUID Name | varchar(64) Store | GUID [ FK ] Details | GUID [FK] Downloadable ID | GUID Name | varchar(64) Url | nvarchar(2048) Details | GUID [FK] Details ID | GUID Price | decimal Description | text Peripherals [ JUNCTION ] ID | GUID Detail | GUID [FK] Store ID | GUID Addresses | GUID Addresses ID | GUID Name | nvarchar(64) State | int [FK] ZipCode | int Address | nvarchar(64) State ID | int Name | varchar(32)

    Read the article

  • How to get java singleton object manager to return any type of object?

    - by Robert
    I'm writing an interactive fiction game in java from scratch. I'm currently storing all of my game object references in a hashmap in a singleton called ObjectManager. ObjectManager has a function called get which takes an integer ID and returns the appropriate reference. The problem is that it returns a BaseObject when I need to return subclasses of BaseObject with more functionality. So, what I've done so far is I've added a getEntity function which returns BaseEntity (which is a subclass of BaseObject). However, when I need the function to return to an object that is a subclass of BaseEntity that has added, required functionality, I will need to make another function. I know there is a better way, but I don't know what it is. I know very little of design patterns, and I'm not sure which one to use here. I tried passing 'class' as a parameter, but that didn't get me anywhere. public BaseObject get(int ID){ return (BaseObject)refMap.get(ID); } public BaseEntity getEntity(int ID){ return (BaseEntity)refMap.get(ID); } Thanks, java ninjas!

    Read the article

  • CodePlex Daily Summary for Wednesday, March 17, 2010

    CodePlex Daily Summary for Wednesday, March 17, 2010New Projectschaosreader: A simple RSS reader.CRM 4.0 Customization GUID Update: The CRM 4.0 customization GUID update is an open source C# console application that automatically replaces GUID values in your exported workflow cu...DotNetNuke® Skin Bright: A DotNetNuke Design Challenge skin package submitted to the "Modern Business" category by Noel Jerke of SiteToolset. This simple and clean business...DotNetNuke® Skin Go: A DotNetNuke Design Challenge skin package submitted to the "Modern Business" category by DnnGo Corporation. The skin uses web standard DIV+CSS tec...DotNetNuke® Skin J10blend: A DotNetNuke Design Challenge skin package submitted to the "Out of the box" category by Timthy Maler of 2M Studio Design. J10-Black v01.00.00 inc...DotNetNuke® Skin Recipe: A DotNetNuke Design Challenge skin package submitted to the "Standards" category by dnnprofis.at. For mobile devices the skin changes to a mobile...DotNetNuke® Skin SpaceSmurfs: A DotNetNuke Design Challenge skin package submitted to the "Personal" category by Eric Johnson of Personify Design. This fun personal skin was ins...ERDOS6 - Web: A Web Project about ERDOS 6Flickrlight: Flickrlight is a personal fun project out of love of Flickr and Silverlight. You can experience it here: http://www.flickrlight.net.GsGrid: Extracting data from Gaussian grid file and grid file calculationiLocator: iLocator is a collaborative educational mapping game for children developed on Microsoft Surface. This game encourages players to collaborate with ...Javascript CallObject SOAP AJAX Helper: CallObject is a Javascript based AJAX helper, it facilitates wrapping of basic soap calls (as long as simple data types are used), asynchronous ret...kbTrainer: kbTrainer is a simple to use HTML application for typing speed training. A lot of features completed in basic. 2 learning keywords layouts -- engli...Laboratório de Engenharia de Software - Projeto: Criado para estudar e aplicar novas tecnologias web.Maxilds Powershell Scripts: Repo of my powershell scriptsNamespacifier: Namespacifier is a C#.NET library and console application to fix XML documents containing multiple default namespaces. It gives prefixes to defaul...OData SDK for Objective-C: This is a CTP of the OData SDK for Objective-C. The library targets iPhone devices and Mac OS X and it is designed to facilitate the connection wit...Open Data App Framework (ODAF): The Open Data Application Framework (ODAF) is a framework that allows cities to easily map existing civic Open Data landmarks, and allow users to r...QuickieB2B: QuickieB2B is web application which main target is to provide quick info about products. It's designed for small companies who have a big number of...RayView: Rayview is an easy-to-use Raytracing-Framework based on Microsoft XNA.Robotics Studio application to navigate Lego Mindstorms robot through labyrinth: A project for Software Systems Analysis and Design Tools subject at the Kaunas University of Technology. The main point of the project is to code L...SharePoint Icon Integration: SharePoint Icon Integration makes it easier for SharePoint Administrators / Developers to add a icon (pdf) to the SharePoint farm. You will no long...TestVersion: Testing VersionieringTimecard: SoftSource Timecard project.T-shirt Cannon: So the Coding4Fun team had two weeks to build two robots able to drive, aim, and shoot t-shirts with a Windows Phone during a MIX10 Keynote demo of...USTF: This project is a bit secretive right now.Windows Azure Command-line Tools for PHP Developers: The “Windows Azure Command-line tools for PHP” provide a command-line experience to developers who wish to develop, package, and deploy PHP applic...New ReleasesCaramel Engine: CaramelEngine Alpha Build 0.0.0.1a: This is an early alpha release of the Engine and it's functionality. Be sure to have the using CaramelEngine statement. This release is for people...Coot: Preview: Basic preview On the first use you have to click Create New Session and Login. After this you can just click Screen Saver each time. Settings sho...CycleMania Starter Kit EAP - ASP.NET 4.0 Problem - Design - Solution: Cyclemania 0.08.32: The latest alpha release.DeepZoomContainer, Expanded DeepZoom for Silverlight & Windows Phone 7 Series: Release ver. 1.20 for Windows Phone 7 Series: SolutionMerge PathAnimation solution into one MouseWheel elimination PathAnimationWP7 Port DeepZoomContainerProject rebuilt for WP7 support De...Desktop Google Reader: 1.3 (the social release): NewsSharing Liking Mail item Labels / Tags Send to Twitter Read It Later http://readitlaterlist.com/ Instapaper http://www.instapaper.com/ Favicons...DotNetNuke® Blog: 04.00.00 RC 2: PLEASE NOTE: Please do not upgrade previous version of the Beta releases - please start from 03.05.01 This is a RELEASE CANDIDATE, and as such ...DotNetNuke® Community Edition: 05.03.00: New FeaturesTemplated User Profiles - User profile pages are now publicly viewable Photo field in User Profile - Users can upload a photo to thei...DotNetNuke® Skin Bright: Bright Package 1.0.0: A DotNetNuke Design Challenge skin package submitted to the "Modern Business" category by Noel Jerke of SiteToolset. This simple and clean business...DotNetNuke® Skin Go: Go Package 1.0.0: A DotNetNuke Design Challenge skin package submitted to the "Modern Business" category by DnnGo Corporation. The skin uses web standard DIV+CSS tec...DotNetNuke® Skin J10blend: J10 Blend Package 1.0.0: A DotNetNuke Design Challenge skin package submitted to the "Out of the box" category by Timthy Maler of 2M Studio Design. J10-Black v01.00.00 incl...DotNetNuke® Skin Recipe: Recipe Package 1.0.0: A DotNetNuke Design Challenge skin package submitted to the "Standards" category by dnnprofis.at. For mobile devices the skin changes to a mobile f...DotNetNuke® Skin SpaceSmurfs: Space Smurfs Package 1.0.0: A DotNetNuke Design Challenge skin package submitted to the "Personal" category by Eric Johnson of Personify Design. This fun personal skin was ins...Dynamo: Dynamo v0.1 Beta: The following is included: Dynamo dlls Antlr dlls Hello world Simple Plugin example Application Dependency injection Singleton Managment ...ExtremeML: ExtremeML v1.0 Beta 1: Timed to accompany the RTM release of the OpenXML SDK v2.0, this is the first Beta release of ExtremeML (it was previously classified as a preview ...Family Tree Analyzer: Version 1.1.1.1: Version 1.1.1.1 Lots of Gedcom parsing fixes it should crash a whole lot less often and tolerate more "interesting" or "quirky" Gedcom entries. Add...Family Tree Analyzer: Version 1.2.0.1: Version 1.2.0.1 Added option to treat residence facts as Census Facts IGI Search now permits default country selection ie: what to use if it doesn...Flickrlight: Flickrlight: Current release is for idea sharing. There are not many design patterns being used. Please bare with the mess. :-) In order to run the applicat...Gherkin editor: Alpha 0.1: Most of the code at this point is the same as the Avalon.Sample from code project, just changed the name, removed extra languages and added syntax ...GsGrid: gsgrid1.6.4: gsgrid1.6.4GsGrid: gsgrid1.6.4-src: gsgrid1.6.4-srcHTML Template Repeater Module: Version 01.00.02: GeneralThe HTML Template Repeater Module is a direct replacement for the Core DotNetNuke Text/HTML module. Use it where you need to repeat the form...Images Compiler: Release 0.1: Last alpha buildJavascript CallObject SOAP AJAX Helper: Beta Release, 0.2.1: Beta Release, 0.2.1 Contains only core objectskbTrainer: kbtrainer 1.25u: kbTrainer is a simple to use speed typing training HTML application. A lot of features. All ither info availiable on http://code.google.com/p/kbtr...MapWindow6: MapWindow 6.0 msi (March 16): This version fixes a bug where selected points were not drawing correctly.Mesopotamia Experiment: Mesopotamia 1.2.43: Release Notes New Features - Scenario Name on title bar - Show organisms in Scnearios with simple stats Bug Fixes - Removed app domain recyling an...MFCMAPI: March 2010 Release: If you just want to run the tool, get the executable. If you want to debug it, get the symbol file and the source. Build: 6.0.0.1018 The 64 bit bu...MVVM Light Toolkit: MVVM Light Toolkit V3: Download the Zip file and extract it to a local folder. Then, follow the instructions on the Installation page http://www.galasoft.ch/mvvm/installi...NETXPF: 1.0.2: Changes: - Added a class "IOUtils" with methods for reading streams and GZip-compressing HTTP responses - Fixed a bug in the size formatter (excep...OData SDK for Objective-C: OData SDK for Objective-C CTP: The current release supports read-only operations only and it has been tested on a limited set of scenarios. The download include a sample iPhone a...Open Data App Framework (ODAF): ODAF 1.0: Initial beta release.Selection Maker: Selection Maker 1.1: New FeaturesContext Menu for ListView added Bug FixesFixed: If the users press Copy/Cut Button when no item is selected in ListView the ListView cl...Selection Maker: Selection Maker 1.2: Bug Fixes:a minor bug fixedSimple.NET: Simple.Mocking 1.0.0.5: Initial version of a new mocking framework for .NET Revision 1: Expect.AnyInocationOn<T>(T target) changed to Expect.AnyInocationOn(object target...SQL Server Extended Properties Quick Editor: New release 1.5.4: Whats new: Move preferences to application settings and add a form to edit preferences. Support to add, modify and delete operations could be made ...SuperModel - A Dynamic View-Model Generator: 1.0.0.0 - Tyra: The final 1.0 release, now less intrusive! If you don't want to implement ISuperModel, simply implement INotifyPropertyChanged.Timecard: Timecard Initial Release: The zipped version of the Initial Checkin.Transparent Persistence.Net: TP.Net 0.1.0: This is the initial alpha release. It's working for small set of use-cases (basic access to Cassandra).VCC: Latest build, v2.1.30316.0: Automatic drop of latest buildVFPnfe: Projeto Ajuda PAF-ECF: Este projeto visa ajudar aos desenvolvedores para homologação do PAF-ECF , sob licença publica GNU/GPL para ver mais detalhes do mesmo assista o vi...Visual Studio DSite: Gif Animator: This program will make an animate gif. (Program written in Vb.Net 2008)Most Popular ProjectsMetaSharpLiveUpload to FacebookSkype Voice ChangerLiveUpload to YouTubeSIPSorceryChartPart for SharePointTFS Branching Guide 2.0TouchFlo DetacherNPandaySnippet EditorMost Active ProjectsLINQ to TwitterRawrOData SDK for PHPDirectQpatterns & practices – Enterprise LibraryBlogEngine.NETN2 CMSOpen Data App Framework (ODAF)NB_Store - Free DotNetNuke Ecommerce Catalog ModuleMapWindow6

    Read the article

  • How much abstraction is too much?

    - by Daniel Bingham
    In an Object Oriented Program: How much abstraction is too much? How much is just right? I have always been a nuts and bolts kind of guy. I understood the concept behind high levels of encapsulation and abstraction, but always felt instinctively that adding too much would just confuse the program. I always tried to shoot for an amount of abstraction that left no empty classes or layers. And where in doubt, instead of adding a new layer to the hierarchy, I would try and fit something into the existing layers. However, recently I've been encountering more highly abstracted systems. Systems where everything that could require a representation later in the hierarchy gets one up front. This leads to a lot of empty layers, which at first seems like bad design. However, on second thought I've come to realize that leaving those empty layers gives you more places to hook into in the future with out much refactoring. It leaves you greater ability to add new functionality on top of the old with out doing nearly as much work to adjust the old. The two risks of this seem to be that you could get the layers you need wrong. In this case one would wind up still needing to do substantial refactoring to extend the code and would still have a ton of never used layers. But depending on how much time you spend coming up with the initial abstractions, the chance of screwing it up, and the time that could be saved later if you get it right - it may still be worth it to try. The other risk I can think of is the risk of over doing it and never needing all the extra layers. But is that really so bad? Are extra class layers really so expensive that it is much of a loss if they are never used? The biggest expense and loss here would be time that is lost up front coming up with the layers. But much of that time still might be saved later when one can work with the abstracted code rather than more low level code. So when is it too much? At what point do the empty layers and extra "might need" abstractions become overkill? How little is too little? Where's the sweet spot? Are there any dependable rules of thumb you've found in the course of your career that help you judge the amount of abstraction needed?

    Read the article

  • redoing object model construction to fit with asynchronous data fetching

    - by Andrew Patterson
    I have a modeled a set of objects that correspond with some real world concepts. TradeDrug, GenericDrug, TradePackage, DrugForm Underlying the simple object model I am trying to provide is a complex medical terminology that uses numeric codes to represent relationships and concepts, all accessible via a REST service - I am trying to hide away some of that complexity with an object wrapper. To give a concrete example I can call TradeDrug d = Searcher.FindTradeDrug("Zoloft") or TradeDrug d = new TradeDrug(34) where 34 might be the code for Zoloft. This will consult a remote server to find out some details about Zoloft. I might then call GenericDrug generic = d.EquivalentGeneric() System.Out.WriteLine(generic.ActiveIngredient().Name) in order to get back the generic drug sertraline as an object (again via a background REST call to the remote server that has all these drug details), and then perhaps find its ingredient. This model works fine and is being used in some applications that involve data processing. Recently however I wanted to do a silverlight application that used and displayed these objects. The silverlight environment only allows asynchronous REST/web service calls. I have no problems with how to make the asychhronous calls - but I am having trouble with what the design should be for my object construction. Currently the constructors for my objects do some REST calls sychronously. public TradeDrug(int code) { form = restclient.FetchForm(code) name = restclient.FetchName(code) etc.. } If I have to use async 'events' or 'actions' in order to use the Silverlight web client (I know silverlight can be forced to be a synchronous client but I am interested in asychronous approaches), does anyone have an guidance or best practice for how to structure my objects. I can pass in an action callback to the constructor public TradeDrug(int code, Action<TradeDrug> constructCompleted) { } but this then allows the user to have a TradeDrug object instance before what I want to construct is actually finished. It also doesn't support an 'event' async pattern because the object doesn't exist to add the event to until it is constructed. Extending that approach might be a factory object that itself has an asynchronous interface to objects factory.GetTradeDrugAsync(code, completedaction) or with a GetTradeDrugCompleted event? Does anyone have any recommendations?

    Read the article

  • Network communication for a turn based board game

    - by randooom
    Hi all, my first question here, so please don't be to harsh if something went wrong :) I'm currently a CS student (from Germany, if this info is of any use ;) ) and we got a, free selectable, programming assignment, which we have to write in a C++/CLI Windows Forms Application. My team, two others and me, decided to go for a network-compatible port of the board game Risk. We divided the work in 3 Parts, namely UI, game logic and network. Now we're on the part where we have to get everything working together and the big question mark is, how to get the clients synchronized with each other? Our approach so far is, that each client has all information necessary to calculate and/or execute all possible actions. Actually the clients have all information available at all, aside from the game-initializing phase (add players, select map, etc.), which needs one "super-client" with some extra stuff to control things. This is the standard scenario of our approach: player performs action, the action is valid and got executed on the players client action is sent over the network action is executed on the other clients The design (i.e. no or code so far) we came up with so far, is something like the following pseudo sequence diagram. Gui, Controller and Network implement all possible actions (i.e. all actions which change data) as methods from an interface. So each part can implement the method in a way to get their job done. Example with Action(): On the player side's Client: Player-->Gui.Action() Gui-->Controller.Action() Controller-->Logic.Action (Logic.Action() == NoError)? Controller-->Network.Action() Network-->Parser.ParseAction() Network.Send(msg) On all other clients: Network.Recv(msg) Network-->Parser.Deparse(msg) Parser-->Logic.Action() Logic-->Gui.Action() The questions: Is this a viable approach to our task? Any better/easier way to this? Recommendations, critique? Our knowledge (so you can better target your answer): We are on the beginner side, in regards to programming on a somewhat larger projects with a small team. All of us have some general programming experience and basic understanding of the .Net Libraries and Windows Forms. If you need any further information, please feel free to ask.

    Read the article

  • Have problems designing input and output for a calculator app

    - by zoul
    Hello! I am writing a button calculator. I have the code split into model, view and a controller. The model knows nothing about formatting, it is only concerned with numbers. All formatting is done in the view. The model gets its input as keypresses, each keypress is a part of an enum: typedef enum { kButtonUnknown = 0, kButtonMemoryClear = 100, kButtonMemoryPlus = 112, kButtonMemoryMinus = 109, kButtonMemoryRecall = 114, kButtonClear = 99, … }; When the user presses a button (say 1), the model receives a button code (kButtonNum1), adds the corresponding number to a string input buffer ("1") and updates the numeric output value (1.0). The controller then passes the numeric output value to the view that formats it (1). This is all plain, simple and clean, but does not really work. The problem is that when user enters a part of a number (say 0.00, going to enter 0.001), the input does not survive the way through model to view and the display says 0 instead of 0.00. I know why this happens ("0.00"::string parses to 0::double and that gets formatted as 0). What I don’t know is how to design the calculator so that the code stays clean and simple and the numbers will show up on screen exactly as the user types them. I’ve already come with some kind of solution, but that’s essentially a hack and breaks the beautiful and simple flow from the calculator model to the display. Ideas? Current solution keeps track of the calculator state. If the calculator is building a number, I take the calculator input buffer (a string) and directly set the display contents (also a string). Otherwise I take the proper path, ie. take the numeric calculator output, pass it to the view as a double and the view uses its internal formatter to create a string for the display. Example input: input | display | mode ------+---------+------------ 0 | 0 | from string 0. | 0. | from string 0.0 | 0.0 | from string 0.0+ | 0 | from number This is ugly. (1) The calculator has to expose its input buffer and state. (2) The view has to expose its display and allow setting its contents directly using a string. (3) I have to duplicate some of the formatting code to format the string I got from the calculator input buffer. If user enters 12345.000, I have to display 12,345.000 and therefore I’ve got to have a commification code for strings. Yuck.

    Read the article

  • Any simple approaches for managing customer data change requests for global reference files?

    - by Kelly Duke
    For the first time, I am developing in an environment in which there is a central repository for a number of different industry standard reference data tables and many different customers who need to select records from these industry standard reference data tables to fill in foreign key information for their customer specific records. Because these industry standard reference files are utilized by all customers, I want to reserve Create/Update/Delete access to these records for global product administrators. However, I would like to implement a (semi-)automated interface by which specific customers could request record additions, deletions or modifications to any of the industry standard reference files that are shared among all customers. I know I need something like a "data change request" table specifying: user id, user request datetime, request type (insert, modify, delete), a user entered text explanation of the change request, the user request's current status (pending, declined, completed), admin resolution datetime, admin id, an admin entered text description of the resolution, etc. What I can't figure out is how to elegantly handle the fact that these data change requests could apply to dozens of different tables with differing table column definitions. I would like to give the customer users making these data change requests a convenient way to enter their proposed record additions/modifications directly into CRUD screens that look very much like the reference table CRUD screens they don't have write/delete permissions for (with an additional text explanation and perhaps request priority field). I would also like to give the global admins a tool that allows them to view all the outstanding data change requests for the users they oversee sorted by date requested or user/date requested. Upon selecting a data change request record off the list, the admin would be directed to another CRUD screen that would be populated with the fields the customer users requested for the new/modified industry standard reference table record along with customer's text explanation, the request status and the text resolution explanation field. At this point the admin could accept/edit/reject the requested change and if accepted the affected industry standard reference file would be automatically updated with the appropriate fields and the data change request record's status, text resolution explanation and resolution datetime would all also be appropriately updated. However, I want to keep the actual production reference tables as simple as possible and free from these extraneous and typically null customer change request fields. I'd also like the data change request file to aggregate all data change requests across all the reference tables yet somehow "point to" the specific reference table and primary key in question for modification & deletion requests or the specific reference table and associated customer user entered field values in question for record creation requests. Does anybody have any ideas of how to design something like this effectively? Is there a cleaner, simpler way I am missing? Thank you so much for reading.

    Read the article

  • How can I model the data in a multi-language data editor in WPF with MVVM?

    - by Patrick Szalapski
    Are there any good practices to follow when designing a model/ViewModel to represent data in an app that will view/edit that data in multiple languages? Our top-level class--let's call it Course--contains several collection properties, say Books and TopicsCovered, which each might have a collection property among its data. For example, the data needs to represent course1.Books.First().Title in different languages, and course1.TopicsCovered.First().Name in different languages. We want a app that can edit any of the data for one given course in any of the available languages--as well as edit non-language-specific data, perhaps the Author of a Book (i.e. course1.Books.First().Author). We are having trouble figuring out how best to set up the model to enable binding in the XAML view. For example, do we replace (in the single-language model) each String with a collection of LanguageSpecificString instances? So to get the author in the current language: course1.Books.First().Author.Where(Function(a) a.Language = CurrentLanguage).SingleOrDefault If we do that, we cannot easily bind to any value in one given language, only to the collection of language values such as in an ItemsControl. <TextBox Text={Binding Author.???} /> <!-- no way to bind to the current language author --> Do we replace the top-level Course class with a collection of language-specific Courses? So to get the author in the current language: course1.GetLanguage(CurrentLanguage).Books.First.Author If we do that, we can only easily work with one language at a time; we might want a view to show one language and let the user edit the other. <TextBox Text={Binding Author} /> <!-- good --> <TextBlock Text={Binding ??? } /> <!-- no way to bind to the other language author --> Also, that has the disadvantage of not representing language-neutral data as such; every property (such as Author) would seem to be in multiple languages. Even non-string properties would be in multiple languages. Is there an option in between those two? Is there another way that we aren't thinking of? I realize this is somewhat vague, but it would seem to be a somewhat common problem to design for. Note: This is not a question about providing a multilingual UI, but rather about actually editing multi-language data in a flexible way.

    Read the article

  • How can i convert this to a factory/abstract factory?

    - by Amitd
    I'm using MigraDoc to create a pdf document. I have business entities similar to the those used in MigraDoc. public class Page{ public List<PageContent> Content { get; set; } } public abstract class PageContent { public int Width { get; set; } public int Height { get; set; } public Margin Margin { get; set; } } public class Paragraph : PageContent{ public string Text { get; set; } } public class Table : PageContent{ public int Rows { get; set; } public int Columns { get; set; } //.... more } In my business logic, there are rendering classes for each type public interface IPdfRenderer<T> { T Render(MigraDoc.DocumentObjectModel.Section s); } class ParagraphRenderer : IPdfRenderer<MigraDoc.DocumentObjectModel.Paragraph> { BusinessEntities.PDF.Paragraph paragraph; public ParagraphRenderer(BusinessEntities.PDF.Paragraph p) { paragraph = p; } public MigraDoc.DocumentObjectModel.Paragraph Render(MigraDoc.DocumentObjectModel.Section s) { var paragraph = s.AddParagraph(); // add text from paragraph etc return paragraph; } } public class TableRenderer : IPdfRenderer<MigraDoc.DocumentObjectModel.Tables.Table> { BusinessEntities.PDF.Table table; public TableRenderer(BusinessEntities.PDF.Table t) { table =t; } public MigraDoc.DocumentObjectModel.Tables.Table Render(Section obj) { var table = obj.AddTable(); //fill table based on table } } I want to create a PDF page as : var document = new Document(); var section = document.AddSection();// section is a page in pdf var page = GetPage(1); // get a page from business classes foreach (var content in page.Content) { //var renderer = createRenderer(content); // // get Renderer based on Business type ?? // renderer.Render(section) } For createRenderer() i can use switch case/dictionary and return type. How can i get/create the renderer generically based on type ? How can I use factory or abstract factory here? Or which design pattern better suits this problem?

    Read the article

  • Discovering a functional algorithm from a mutable one

    - by Garrett Rowe
    This isn't necessarily a Scala question, it's a design question that has to do with avoiding mutable state, functional thinking and that sort. It just happens that I'm using Scala. Given this set of requirements: Input comes from an essentially infinite stream of random numbers between 1 and 10 Final output is either SUCCEED or FAIL There can be multiple objects 'listening' to the stream at any particular time, and they can begin listening at different times so they all may have a different concept of the 'first' number; therefore listeners to the stream need to be decoupled from the stream itself. Pseudocode: if (first number == 1) SUCCEED else if (first number >= 9) FAIL else { first = first number rest = rest of stream for each (n in rest) { if (n == 1) FAIL else if (n == first) SUCCEED else continue } } Here is a possible mutable implementation: sealed trait Result case object Fail extends Result case object Succeed extends Result case object NoResult extends Result class StreamListener { private var target: Option[Int] = None def evaluate(n: Int): Result = target match { case None => if (n == 1) Succeed else if (n >= 9) Fail else { target = Some(n) NoResult } case Some(t) => if (n == t) Succeed else if (n == 1) Fail else NoResult } } This will work but smells to me. StreamListener.evaluate is not referentially transparent. And the use of the NoResult token just doesn't feel right. It does have the advantage though of being clear and easy to use/code. Besides there has to be a functional solution to this right? I've come up with 2 other possible options: Having evaluate return a (possibly new) StreamListener, but this means I would have to make Result a subtype of StreamListener which doesn't feel right. Letting evaluate take a Stream[Int] as a parameter and letting the StreamListener be in charge of consuming as much of the Stream as it needs to determine failure or success. The problem I see with this approach is that the class that registers the listeners should query each listener after each number is generated and take appropriate action immediately upon failure or success. With this approach, I don't see how that could happen since each listener is forcing evaluation of the Stream until it completes evaluation. There is no concept here of a single number generation. Is there any standard scala/fp idiom I'm overlooking here?

    Read the article

  • translating specifications into query predicates

    - by Jeroen
    I'm trying to find a nice and elegant way to query database content based on DDD "specifications". In domain driven design, a specification is used to check if some object, also known as the candidate, is compliant to a (domain specific) requirement. For example, the specification 'IsTaskDone' goes like: class IsTaskDone extends Specification<Task> { boolean isSatisfiedBy(Task candidate) { return candidate.isDone(); } } The above specification can be used for many purposes, e.g. it can be used to validate if a task has been completed, or to filter all completed tasks from a collection. However, I want to re-use this, nice, domain related specification to query on the database. Of course, the easiest solution would be to retrieve all entities of our desired type from the database, and filter that list in-memory by looping and removing non-matching entities. But clearly that would not be optimal for performance, especially when the entity count in our db increases. Proposal So my idea is to create a 'ConversionManager' that translates my specification into a persistence technique specific criteria, think of the JPA predicate class. The services looks as follows: public interface JpaSpecificationConversionManager { <T> Predicate getPredicateFor(Specification<T> specification, Root<T> root, CriteriaQuery<?> cq, CriteriaBuilder cb); JpaSpecificationConversionManager registerConverter(JpaSpecificationConverter<?, ?> converter); } By using our manager, the users can register their own conversion logic, isolating the domain related specification from persistence specific logic. To minimize the configuration of our manager, I want to use annotations on my converter classes, allowing the manager to automatically register those converters. JPA repository implementations could then use my manager, via dependency injection, to offer a find by specification method. Providing a find by specification should drastically reduce the number of methods on our repository interface. In theory, this all sounds decent, but I feel like I'm missing something critical. What do you guys think of my proposal, does it comply to the DDD way of thinking? Or is there already a framework that does something identical to what I just described?

    Read the article

  • Is it ok to dynamic cast "this" as a return value?

    - by Panayiotis Karabassis
    This is more of a design question. I have a template class, and I want to add extra methods to it depending on the template type. To practice the DRY principle, I have come up with this pattern (definitions intentionally omitted): template <class T> class BaseVector: public boost::array<T, 3> { protected: BaseVector<T>(const T x, const T y, const T z); public: bool operator == (const Vector<T> &other) const; Vector<T> operator + (const Vector<T> &other) const; Vector<T> operator - (const Vector<T> &other) const; Vector<T> &operator += (const Vector<T> &other) { (*this)[0] += other[0]; (*this)[1] += other[1]; (*this)[2] += other[2]; return *dynamic_cast<Vector<T> * const>(this); } } template <class T> class Vector : public BaseVector<T> { public: Vector<T>(const T x, const T y, const T z) : BaseVector<T>(x, y, z) { } }; template <> class Vector<double> : public BaseVector<double> { public: Vector<double>(const double x, const double y, const double z); Vector<double>(const Vector<int> &other); double norm() const; }; I intend BaseVector to be nothing more than an implementation detail. This works, but I am concerned about operator+=. My question is: is the dynamic cast of the this pointer a code smell? Is there a better way to achieve what I am trying to do (avoid code duplication, and unnecessary casts in the user code)? Or am I safe since, the BaseVector constructor is private?

    Read the article

  • Foreign key pointing to different tables

    - by Álvaro G. Vicario
    I'm implementing a table per subclass design I discussed in a previous question. It's a product database where products can have very different attributes depending on their type, but attributes are fixed for each type and types are not manageable at all. I have a master table that holds common attributes: product_type ============ product_type_id INT product_type_name VARCHAR E.g.: 1 'Magazine' 2 'Web site' product ======= product_id INT product_name VARCHAR product_type_id INT -> Foreign key to product_type.product_type_id valid_since DATETIME valid_to DATETIME E.g. 1 'Foo Magazine' 1 '1998-12-01' NULL 2 'Bar Weekly Review' 1 '2005-01-01' NULL 3 'E-commerce App' 2 '2009-10-15' NULL 4 'CMS' 2 '2010-02-01' NULL ... and one subtable for each product type: item_magazine ============= item_magazine_id INT title VARCHAR product_id INT -> Foreign key to product.product_id issue_number INT pages INT copies INT close_date DATETIME release_date DATETIME E.g. 1 'Foo Magazine Regular Issue' 1 89 52 150000 '2010-06-25' '2010-06-31' 2 'Foo Magazine Summer Special' 1 90 60 175000 '2010-07-25' '2010-07-31' 3 'Bar Weekly Review Regular Issue' 2 12 16 20000 '2010-06-01' '2010-06-02' item_web_site ============= item_web_site_id INT name VARCHAR product_id INT -> Foreign key to product.product_id bandwidth INT hits INT date_from DATETIME date_to DATETIME E.g. 1 'The Carpet Store' 3 10 90000 '2010-06-01' NULL 2 'Penauts R Us' 3 20 180000 '2010-08-01' NULL 3 'Springfield Cattle Fair' 4 15 150000 '2010-05-01' '2010-10-31' Now I want to add some fees that relate to one specific item. Since there are very little subtypes, it's feasible to do this: fee === fee_id INT fee_description VARCHAR item_magazine_id INT -> Foreign key to item_magazine.item_magazine_id item_web_site_id INT -> Foreign key to item_web_site.item_web_site_id net_price DECIMAL E.g.: 1 'Front cover' 2 NULL 1999.99 2 'Half page' 2 NULL 500.00 3 'Square banner' NULL 3 790.50 4 'Animation' NULL 3 2000.00 I have tight foreign keys to handle cascaded editions and I presume I can add a constraint so only one of the IDs is NOT NULL. However, my intuition suggests that it would be cleaner to get rid of the item_WHATEVER_id columns and keep a separate table: fee_to_item =========== fee_id INT -> Foreign key to fee.fee_id product_id INT -> Foreign key to product.product_id item_id INT -> ??? But I can't figure out how to create foreign keys on item_id since the source table varies depending on product_id. Should I stick to my original idea?

    Read the article

  • Grid sorting with persistent master sort

    - by MikeWyatt
    I have a UI with a grid. Each record in the grid is sorted by a "master" sort column, let's call it a page number. Each record is a story in a magazine. I want the user to be able to drag and drop a record to a new position in the grid and automatically update the page number field to reflect the updated position. Easy enough, right? Now imagine that I also want to have the grid sortable by any other column (story title, section, author name, etc.). How does the drag and drop operation work now? Revert to page number sort during or after the drag and drop operation? This could confuse the user (why did my sort just change?). It would also result in arbitrary row positioning. Would the story now be before the row that was after it when the user dropped it? Or, would it be after the row that was before it? Those rows may now be widely separated after the master order sort. Disable the drag and drop feature if the grid isn't currently sorted by the page number? This would be easy, but the user might wonder why he can't drag and drop at certain times. Knowing to first sort by page number may not be very intuitive. Let the user rearrange his rows, but not make any changes to the page number? Require the user to enter a "Arrange Stories" mode, in which the grid sort is temporarily switched to page number and drag and drop is enabled? They would then exit the mode, and the previous sort would be reapplied. The big difference between this and the second option is that it would be more explicit than simply clicking on a column header. Any other ideas, or reasons why one of the above is the way to go? EDIT I'd like to point out that any of the above is technically possible, and easy to implement. My question is design-related. What is the most intuitive way to solve this problem, from the user's perspective?

    Read the article

< Previous Page | 171 172 173 174 175 176 177 178 179 180 181 182  | Next Page >