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  • Java annotations for design patterns?

    - by Greg Mattes
    Is there a project that maintains annotations for patterns? For example, when I write a builder, I want to mark it with @Builder. Annotating in this way immediately provides a clear idea of what the code implements. Also, the Javadoc of the @Builder annotation can reference explanations of the builder pattern. Furthermore, navigating from the Javadoc of a builder implementation to @Builder Javadoc is made easy by annotating @Builder with @Documented. I've being slowing accumulating a small set of such annotations for patterns and idioms that I have in my code, but I'd like to leverage a more complete existing project if it exists. If there is no such project, maybe I can share what I have by spinning it off to a separate pattern/idiom annotation project. Update: I've created the Pattern Notes project in response to this discussion. Contributions welcome! Here is @Builder

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  • using PHP for "Fluid" design(using viewport resolution)

    - by Jreeter
    I need some opinions on using PHP to make completely "scalable" websites.. For instance, using viewport resolution and resizing images, applying dynamic css styles..... In my mind doing this just add's to the complexity and should not be done, it should be fixed or fluid using strictly css and no server-side languages to generate layouts based on the device size.. I need some input and maybe some philosophy on why using this approach is not used at all..

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  • Providing multi-version databases for backward compatibility for production applications/databases.

    - by JavaRocky
    How can I manage multiple versions of a database easily? I have some data (as views as selects for data originating in tables from other schemas), which other database may reference using various means including database synonyms & links. I wish to provide a sort of interface/guarantee in-case future for applications/databases which use this data. All of this is for in the event i need to update the views for correctness or applicability inside my database. How can i achieve this in a maintained, controlled and easy way? I am using Oracle 10g if that matters.

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  • Design a GUI browser to view a tree

    - by iamrohitbanga
    I have a large tree. I want to be able to visualize it using a GUI tool. I want the ability to pan and zoom the tree image so that i can focus on part of the tree. Is there an existing tool to achieve this? If not i would like to write a small tool for myself to be able to do this. what is the simplest way of doing this? what computer language should i use? the image should look something like http://upload.wikimedia.org/wikipedia/commons/d/df/Binary_tree.png I should be able to zoom and pan the image.

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  • How to design this class hierarchy?

    - by devoured elysium
    I have defined an Event class: Event and all the following classes inherit from Event: AEvent BEvent CEvent DEvent Now, with the info I gather from all these Event classes, I will make a chart. With AEvent and BEvent, I will generate points for that chart, while with CEvent and DEvent I will paint certain regions of the chart. Now, how should I signal this in my class hierarchy? Should I make AEvent and BEvent inherit from PointEvent while CEvent and DEvent inherit from RegionEvent, being that both RegionEvent and PointEvent inherit from Event? Should I add a field with an Enum to Event with 2 values, Point and Region, and each of the child classes set their value to it? Should I use some kind of pattern here? Which one? Thanks.

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  • Following Domain Driven Design with MVVM/WPF

    - by msfanboy
    Hello, I have plain POCOs here and as INotifyPropertyChanged is a Interface for the Views need its implemented in the ViewModel not the Model. Now I want to show validation errors in the View beside every textbox the user typed in data. I do not want to implemented the IDataErrorInfo interface in my Models because lets assume I am not allowed to touch them as they come from another Service/Supplier. I do not want to put my IsCustomerFirstNameLenthValid Method into the Model because I could not have access to it or I just dont want to pollute my Models with interface`s having nothing to do there! How can I validate my naked POCO`s in the ViewModel and forward the results to the View by showing validation errors ?

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  • Is factory method proper design for my problem?

    - by metdos
    Hello Everyone, here is my problem and I'm considering to use factory method in C++, what are your opinions ? There are a Base Class and a lot of Subclasses. I need to transfer objects on network via TCP. I will create objects in first side, and using this object I will create a byte array TCP message, and send it to other side. On the other side I will decompose TCP message, I will create object and I will add this object to a polymorphic queue.

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  • DB Design Question

    - by hazimdikenli
    I am designing an Org Chart, model is almost ready and simplified a bit for clarity here. OrgUnit (OrgUnitId, Name, ReportsToOrgUnitId, ...) OrgUnitJobs (OrgUnitJobId, OrgUnitId, JobName, ReportsToOrgUnitJobId, ... ,IsJobGroup) Employee (EmployeeId, ........) OrgUnitJobEmployee (OrgUnitJobId, EmployeeId, AssignedDate, .....,) so I want to know every OrgUnit's ManagerEmployee (should have one), and Employees can have more than one job, but one of them has to be the main job, so I know whats his manager and other stuff. This is going to support a little workflow behind the scnese, so that is why it is not a very simple Org chart Model. so what would you do, would you add properties like (IsManager property to OrgUnitJobs model) or add ManagerOrgUnitJobId to OrgUnitModel. and why? Likewise, for employees would you add IsPrimaryJob property to OrgUnitJobEmployee model, or add PrimaryJobId to Employee Model.

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  • quantity of measurable units design pattern

    - by Berryl
    Hello I am thinking through a nice pattern to be useful across domains of measurable units (ie, Length, Time) and came up with the following use case and initial classes, and of course, questions! 1) Does a Composite pattern help or complicate? 2) Should the Convert method(s) in the ComposityNode be a separate converter class? All comments appreciated. Cheers, Berryl Example Use Case: var inch = new ConvertableUnit("inch", 1) var foot = new ConvertableUnit("foot", 12) var imperialUnits = new CompositeConvertableUnit("imperial units", .024) imperialUnits.AddChild(inch) imperialUnits.AddChild(foot) var meter = new ConvertableUnit("meter", 1) var millimeter = new ConvertableUnit("millimeter ", .001) var imperialUnits = new CompositeConvertableUnit("metric units", 1) imperialUnits.AddChild(meter) imperialUnits.AddChild(millimeter) var oneInch = new Quantity(1, inch); var oneFoot = new Quantity(1, foot); oneFoot.ToBase() // "12 inches" var oneMeter = new Quantity(1, meter); oneInch.ToBase() // .024 meters Possible Solution ConvertableUnit : Node double Rate string Name Quantity ConvertableUnit Unit double Amount CompositeConvertableUnit : Node ISet<ConvertableUnit> _children ConvertableUnit BaseUnit {get{ return _children.Where(c=>c.Rate == 1).First() } } Quantity ConvertTo(Quantity from, Quantity to) Quantity ToBase(Quantity from);

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  • Facebook database design?

    - by Marin
    I have always wondered how Facebook designed the friend <- user relation. I figure the user table is something like this: user_email PK user_id PK password I figure the table with user's data (sex, age etc connected via user email I would assume). How does it connect all the friends to this user? Something like this? user_id friend_id_1 friend_id_2 friend_id_3 friend_id_N Probably not. Because the number of users is unknown and will expand.

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  • MongoDB Schema Design - Real-time Chat

    - by Nick
    I'm starting a project which I think will be particularly suited to MongoDB due to the speed and scalability it affords. The module I'm currently interested in is to do with real-time chat. If I was to do this in a traditional RDBMS I'd split it out into: Channel (A channel has many users) User (A user has one channel but many messages) Message (A message has a user) The the purpose of this use case, I'd like to assume that there will be typically 5 channels active at one time, each handling at most 5 messages per second. Specific queries that need to be fast: Fetch new messages (based on an bookmark, time stamp maybe, or an incrementing counter?) Post a message to a channel Verify that a user can post in a channel Bearing in mind that the document limit with MongoDB is 4mb, how would you go about designing the schema? What would yours look like? Are there any gotchas I should watch out for?

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  • Design Patterns: What's the antithesis of Front Controller?

    - by Brian Lacy
    I'm familiar with the Front Controller pattern, in which all events/requests are processed through a single centralized controller. But what would you call it when you wish to keep the various parts of an application separate at the presentation layer as well? My first thought was "Facade" but it turns out that's something entirely different. In my particular case, I'm converting an application from a sprawling procedural mess to a clean MVC architecture, but it's a long-term process -- we need to keep things separated as much as possible to facilitate a slow integration with the rest of the system. Our application is web-based, built in PHP, so for instance, we have an "index.php" and an IndexController, a "account.php" and an AccountController, a "dashboard.php" and DashboardController, and so on.

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  • UI Design, incase of numerous situations

    - by The King
    Hi... I'm creating a web form, where in there are around 12-15 Input Fields... You can have a look at the screen and The request is such that depending on the data the user selects in the Gridview and the DropDown list, the appropriate Textboxes and CheckBoxes needs to be displayed. Some times the conditions are very direct, like when the DDL value is "ABC", get only paid amount from the user. Sometime they are so complex like... IF DDL is "DEF" and Selected GPMS value is between 1000-2000, calculate the values of allowed, paid etc (using some formula) and the focus should be directed to Page No Field, leaving the other fields open incase user wants to edit... There are around 10-15 conditions like this. As this was done through agile, conditions were being added as and when, and wherever it feels appropriate (DDL on change Event, GridView on selecting change event etc... etc..) After completion, now I see the code has become a big chuck, is growing unmanageably... Now, I'm planning to clear this... From you experience, what you think is the best way to handle this. There is a possibility to add more conditions like this in future... Please let me know, incase you need more information. I'm currently developing this app in C# .Net WindowsForms Edit: Currently there are only three items (The Datagrid, the DDL, the OverrideAmt CheckBox) that change the way other fields behave... Almost all of the conditions will fall between the two situations I mentioned... Mostly they belong to "Enabling/Disabling".. "Setting of Values"... and "Changing Focus" or any combination of these.

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  • Partial Classes - are they bad design?

    - by dferraro
    Hello, I'm wondering why the 'partial class' concept even exists in .NET. I'm working on an application and we are reading a (actually very good) book relavant to the development platform we are implementing at work. In the book he provides a large code base /wrapper around the platform API and explains how he developed it as he teaches different topics about the platform development. Anyway, long story short - he uses partial classes, all over the place, as a way to fake multiple inheritence in C# (IMO). Why he didnt just split the classes up into multiple ones and use composition is beyond me. He will have 3 'partial class' files to make up his base class, each w/ 3-500 lines of code... And does this several times in his API. Do you find this justifiable? If it were me, I'd have followed the S.R.P. and created multiple classes to handle different required behaviors, then create a base class that has instances of these classes as members (e.g. composition). Why did MS even put partial class into the framework?? They removed the ability to expand/collapse all code at each scope level in C# (this was allowed in C++) because it was obviously just allowing bad habits - partial class is IMO the same thing. I guess my quetion is: Can you explain to me when there would be a legitimate reason to ever use a partial class? I do not mean this to be a rant / war thread. I'm honeslty looking to learn something here. Thanks

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  • website design - graphics files

    - by mb08
    Hi Friends, I have a website to be designed and have most of the material ready with me. I have shortlisted a designer who is ready to start. The question I have is, should I hand over the original .psd graphics files of logo etc to the designer. Is it ok to hand over the .psds or is there any risk in doing so that I should be aware of and cover with an agreement... thanks in advance.. mb

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  • C# Design Layout/Patterns

    - by wpfwannabe
    I am still fairly new to C# and I am trying to decide the best way to structure a new program. Here is what I want to do and I would like feed back on my idea. Presentation Layer Business Layer (Separate Class Library) Data Layer (Separate Class Library) Model Layer (Separate Class Library) What I am struggling with is if it is ok to have the classes in the Data Layer and Business Layer inherit from the types I define in Model Layer. This way I can extended the types as needed in my Business Layer with any new properties I see fit. I might not use every property from the Model type in my Business Layer class but is that really a big deal? If this isn't clear enough I can try and put together an example.

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  • What is the "Dispatcher" design pattern?

    - by Ben Farmer
    What is the "dispatcher" pattern and how would I implement it in code? I have a property bag of generic objects and would like to have the retrieval delegated to a generic method. Currently, I have properties looking for a specific key in the bag. For example: private Dictionary<String, Object> Foo { get; set; } private const String WidgetKey = "WIDGETKEY"; public Widget? WidgetItem { get { return Foo.ContainsKey(WidgetKey) ? Foo[WidgetKey] as Widget: null; } set { if (Foo.ContainsKey(WidgetKey)) Foo[WidgetKey] = value; else Foo.Add(WidgetKey, value); } } It was suggested that this could be more generic with the "dispatcher" pattern, but I've been unable to find a good description or example. I'm looking for a more generic way to handle the property bag store/retrieve.

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  • Understanding Domain Driven Design

    - by Nihilist
    Hi I have been trying to understand DDD for few weeks now. Its very confusing. I dont understand how I organise my projects. I have lot of questions on UnitOfWork, Repository, Associations and the list goes on... Lets take a simple example. Album and Tracks. Album: AlbumId, Name, ListOf Tracks Tracks: TrackId, Name Question1: Should i expose Tracks as a IList/IEnumerabe property on Album ? If that how do i add an album ? OR should i expose a ReadOnlyCollection of Tracks and expose a AddTrack method? Question2: How do i load Tracks for Album [assuming lazy loading]? should the getter check for null and then use a repository to load the tracks if need be? Question3: How do we organise the assemblies. Like what does each assembly have? Model.dll - does it only have the domain entities? Where do the repositories go? Interfaces and implementations both. Can i define IAlbumRepository in Model.dll? Infrastructure.dll : what shold this have? Question4: Where is unit of work defined? How do repository and unit of work communicate? [ or should they ] for example. if i need to add multiple tracks to album, again should this be defined as AddTrack on Album OR should there a method in the repository? Regardless of where the method is, how do I implement unit of work here? Question5: Should the UI use Infrastructure..dll or should there be ServiceLayer? Do my quesitons make sense? Regards

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  • alt-tab sort of web design

    - by sureshgl
    I am thinking of designing a web site having multiple related services. For every action of the user in a service there will be some computation going on in each of the other services. I want to display the service in action (chosen by the user) in the middle of the page in enlarged mode and rest of the services as small sized (shrunk) versions around the enlarged mode. The services which are shown in the shrunk version, should actually show what is happening in that service, at run time as if that was the chosen service. A close match to this sort of behavior I know is in Reliance BigTV, where all the small images of all the channels will be going on, and we can choose the one that we want to watch. After choosing that one image will become big and occupy the screen. Please, let me know if I can do some thing like this using css, html, ajax & php.

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  • SQL Design: representing a default value with overrides?

    - by Mark Harrison
    I need a sparse table which contains a set of "override" values for another table. I also need to specify the default value for the items overridden. For example, if the default value is 17, then foo,bar,baz will have the values 17,21,17: table "things" table "xvalue" name stuff name xval ---- ----- ---- ---- foo ... bar 21 bar ... baz ... If I don't care about a FK from xvalue.name - things.name, I could simply put a "DEFAULT" name: table "xvalue" name xval ---- ---- DEFAULT 17 bar 21 But I like having a FK. I could have a separate default table, but it seems odd to have 2x the number of tables. table "xvalue_default" xval ---- 17 table "xvalue" name xval ---- ---- bar 21 I could have a "defaults table" tablename attributename defaultvalue xvalue xval 17 but then I run into type issues on defaultvalue. My operations guys prefer as compact a representation as possible, so they can most easily see the "diff" or deviations from the default. What's the best way to represent this, including the default value? This will be for Oracle 10.2 if that makes a difference.

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  • Database normalization question

    - by chchrist
    Hi all, I am trying to make a fashion boutique site. In this site each product (t-shirt,jeans etc) belongs to a collection. Each collection has looks (t-shirt,jean,accessories). A product can belong to one collection and to multiple looks. How should I design the database?

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  • Efficient data structure design

    - by Sway
    Hi there, I need to match a series of user inputed words against a large dictionary of words (to ensure the entered value exists). So if the user entered: "orange" it should match an entry "orange' in the dictionary. Now the catch is that the user can also enter a wildcard or series of wildcard characters like say "or__ge" which would also match "orange" The key requirements are: * this should be as fast as possible. * use the smallest amount of memory to achieve it. If the size of the word list was small I could use a string containing all the words and use regular expressions. however given that the word list could contain potentially hundreds of thousands of enteries I'm assuming this wouldn't work. So is some sort of 'tree' be the way to go for this...? Any thoughts or suggestions on this would be totally appreciated! Thanks in advance, Matt

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