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  • C# Lack of Static Inheritance - What Should I Do?

    - by yellowblood
    Alright, so as you probably know, static inheritance is impossible in C#. I understand that, however I'm stuck with the development of my program. I will try to make it as simple as possible. Lets say our code needs to manage objects that are presenting aircrafts in some airport. The requirements are as follows: There are members and methods that are shared for all aircrafts There are many types of aircrafts, each type may have its own extra methods and members. There can be many instances for each aircraft type. Every aircraft type must have a friendly name for this type, and more details about this type. For example a class named F16 will have a static member FriendlyName with the value of "Lockheed Martin F-16 Fighting Falcon". Other programmers should be able to add more aircrafts, although they must be enforced to create the same static details about the types of the aircrafts. In some GUI, there should be a way to let the user see the list of available types (with the details such as FriendlyName) and add or remove instances of the aircrafts, saved, lets say, to some XML file. So, basically, if I could enforce inherited classes to implement static members and methods, I would enforce the aircraft types to have static members such as FriendlyName. Sadly I cannot do that. So, what would be the best design for this scenario?

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  • How do you keep your business rules DRY?

    - by Mario
    I periodically ponder how to best design an application whose every business rule exists in just a single location. (While I know there is no proverbial “best way” and that designs are situational, people must have a leaning toward one practice or another.) I work for a shop where they prefer to house as much of the business rules as possible in the database. This requires developers in many cases to perform identical front-end validations to avoid sending data to the database that will result in an exception—not very DRY. It grates me anytime I find myself duplicating any kind of logic—even lowly validation logic. I am a single-point-of-truth purist to an anal degree. On the other end of the spectrum, I know of shops that create dumb databases (the Rails community leans in this direction) and handle all of the business logic in a separate tier (in Rails the models would house “most” of this). Note the word “most” which implies that some business logic does end up spilling into other places (in Rails it might spill over into the controllers). In way, a clean separation of concerns where all business logic exists in a single core location is a Utopian fantasy that’s hard to uphold (n-tiered architecture or not). Furthermore, is see the “Database as a fortress” and would agree that it should be built on constraints that cause it to reject bad data. As such, I hold principles that cause a degree of angst as I attempt to balance them. How do you balance the database-as-a-fortress view with the desire to have a single-point-of-truth?

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  • AntFarm anti-pattern -- strategies to avoid, antidotes to help heal from

    - by alchemical
    I'm working on a 10 page web site with a database back-end. There are 500+ objects in use, trying to implement the MVP pattern in ASP.Net. I'm tracing the code-execution from a single-page, my finger has been on F-11 in Visual Studio for about 40 minutes, there seems to be no end, possibly 1000+ method calls for one web page! If it was just 50 objects that would be one thing, however, code execution snakes through all these objects just like millions of ants frantically woring in their giant dirt mound house, riddled with object tunnels. Hence, a new anti-pattern is born : AntFarm. AntFarm is also known as "OO-Madnes", "OO-Fever", OO-ADD, or simply design-pattern junkie. This is not the first time I've seen this, nor my associates at other companies. It seems that this style is being actively propogated, or in any case is a misunderstanding of the numerous OO/DP gospels going around... I'd like to introduce an anti-pattern to the anti-pattern: GST or "Get Stuff Done" AKA "Get Sh** done" AKA GRD (GetRDone). This pattern focused on just what it says, getting stuff done, in a simple way. I may try to outline it more in a later post, or please share your ideas on this antidote pattern. Anyway, I'm in the midst of a great example of AntFarm anti-pattern as I write (as a bonus, there is no documentation or comments). Please share you thoughts on how this anti-pattern has become so prevelant, how we can avoid it, and how can one undo or deal with this pattern in a live system one must work with!

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  • Pros and cons of making database IDs consistent and "readable"

    - by gmale
    Question Is it a good rule of thumb for database IDs to be "meaningless?" Conversely, are there significant benefits from having IDs structured in a way where they can be recognized at a glance? What are the pros and cons? Background I just had a debate with my coworkers about the consistency of the IDs in our database. We have a data-driven application that leverages spring so that we rarely ever have to change code. That means, if there's a problem, a data change is usually the solution. My argument was that by making IDs consistent and readable, we save ourselves significant time and headaches, long term. Once the IDs are set, they don't have to change often and if done right, future changes won't be difficult. My coworkers position was that IDs should never matter. Encoding information into the ID violates DB design policies and keeping them orderly requires extra work that, "we don't have time for." I can't find anything online to support either position. So I'm turning to all the gurus here at SA! Example Imagine this simplified list of database records representing food in a grocery store, the first set represents data that has meaning encoded in the IDs, while the second does not: ID's with meaning: Type 1 Fruit 2 Veggie Product 101 Apple 102 Banana 103 Orange 201 Lettuce 202 Onion 203 Carrot Location 41 Aisle four top shelf 42 Aisle four bottom shelf 51 Aisle five top shelf 52 Aisle five bottom shelf ProductLocation 10141 Apple on aisle four top shelf 10241 Banana on aisle four top shelf //just by reading the ids, it's easy to recongnize that these are both Fruit on Aisle 4 ID's without meaning: Type 1 Fruit 2 Veggie Product 1 Apple 2 Banana 3 Orange 4 Lettuce 5 Onion 6 Carrot Location 1 Aisle four top shelf 2 Aisle four bottom shelf 3 Aisle five top shelf 4 Aisle five bottom shelf ProductLocation 1 Apple on aisle four top shelf 2 Banana on aisle four top shelf //given the IDs, it's harder to see that these are both fruit on aisle 4 Summary What are the pros and cons of keeping IDs readable and consistent? Which approach do you generally prefer and why? Is there an accepted industry best-practice?

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  • Pattern for UI configuration

    - by TERACytE
    I have a Win32 C++ program that validates user input and updates the UI with status information and options. Currently it is written like this: void ShowError() { SetIcon(kError); SetMessageString("There was an error"); HideButton(kButton1); HideButton(kButton2); ShowButton(kButton3); } void ShowSuccess() { SetIcon(kError); std::String statusText (GetStatusText()); SetMessageString(statusText); HideButton(kButton1); HideButton(kButton2); ShowButton(kButton3); } // plus several more methods to update the UI using similar mechanisms I do not likes this because it duplicates code and causes me to update several methods if something changes in the UI. I am wondering if there is a design pattern or best practice to remove the duplication and make the functionality easier to understand and update. I could consolidate the code inside a config function and pass in flags to enable/disable UI items, but I am not convinced this is the best approach. Any suggestions and ideas?

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  • Using an ORM with a database that has no defined relationships?

    - by Ahmad
    Consider a database(MSSQL 2005) that consists of 100+ tables which have primary keys defined to a certain degree. There are 'relationships' between tables, however these are not enforced with foreign key constraints. Consider the following simplified example of typical types of tables I am dealing with. The are clear relations between the User and City and Province tables. However, they key issues is the inconsistent data types in the tables and naming conventions. User: UserRowId [int] PK Name [varchar(50)] CityId [smallint] ProvinceRowId [bigint] City: CityRowId [bigint] PK CityDescription [varchar(100)] Province: ProvinceId [int] PK ProvinceDesc [varchar(50)] I am considering a rewrite of the application (in ASP.net MVC) that uses this data source as is similar in design to MVC storefront. However I am going through a proof of concept phase and this is one of the stumbling blocks I have come across. What are my options in terms of ORM choice that can be easily used and why? Should I even be considering an ORM? (The reason I ask this is that most explanations and tutorials all work with relatively cleanly designed existing databases, or newly created ones when compared to mine. I am thus having a very hard time trying to find a way forward with this problem) There is a huge amount of existing SQL queries, would a datamappper(eg IBatis.net) be more suitable since we could easily modify them to work and reuse the investment already made? I have found this question on SO which indicates to me that an ORM can be used - however I get the impression that this a question of mapping? Note: at the moment, the object model is not clearly defined as it was non-existent. The existing system pretty much did almost everything in SQL or consisted of overly complicated, and numerous queries to complete fucntionality. I am pretty much a noob and have zero experience around ORMs and MVC - so this an awesome learning curve I am on.

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  • When is factory method better than simple factory and vice versa?

    - by Bruce
    Hi all Working my way through the Head First Design Patterns book. I believe I understand the simple factory and the factory method, but I'm having trouble seeing what advantages factory method brings over simple factory. If an object A uses a simple factory to create its B objects, then clients can create it like this: A a = new A(new BFactory()); whereas if an object uses a factory method, a client can create it like this: A a = new ConcreteA(); // ConcreteA contains a method for instantiating the same Bs that the BFactory above creates, with the method hardwired into the subclass of A, ConcreteA. So in the case of the simple factory, clients compose A with a B factory, whereas with the factory method, the client chooses the appropriate subclass for the types of B it wants. There really doesn't seem to be much to choose between them. Either you have to choose which BFactory you want to compose A with, or you have to choose the right subclass of A to give you the Bs. Under what circumstances is one better than the other? Thanks all!

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  • Why does C# not provide the C++ style 'friend' keyword?

    - by Ash
    The C++ friend keyword allows a class A to designate class B as it's friend. This allows Class B to access the private/protected members of class A. I've never read anything as to why this was left out of C# (and VB.NET). Most answers to this earlier StackOverflow question seem to be saying it is a useful part of C++ and there are good reasons to use it. In my experience I'd have to agree. Another question seems to me to be really asking how to do something similar to friend in a C# application. While the answers generally revolve around nested classes, it doesn't seem quite as elegant as using the friend keyword. The original Design Patterns book uses the friend keyword regularly throughout its examples. So in summary, why is friend missing from C#, and what is the "best practice" way (or ways) of simulating it in C#? (By the way, the "internal" keyword is not the same thing, it allows ALL classes within the entire assembly to access internal members, friend allows you to give access to a class to just one other class.)

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  • DDD: Enum like entities

    - by Chris
    Hi all, I have the following DB model: **Person table** ID | Name | StateId ------------------------------ 1 Joe 1 2 Peter 1 3 John 2 **State table** ID | Desc ------------------------------ 1 Working 2 Vacation and domain model would be (simplified): public class Person { public int Id { get; } public string Name { get; set; } public State State { get; set; } } public class State { private int id; public string Name { get; set; } } The state might be used in the domain logic e.g.: if(person.State == State.Working) // some logic So from my understanding, the State acts like a value object which is used for domain logic checks. But it also needs to be present in the DB model to represent a clean ERM. So state might be extended to: public class State { private int id; public string Name { get; set; } public static State New {get {return new State([hardCodedIdHere?], [hardCodeNameHere?]);}} } But using this approach the name of the state would be hardcoded into the domain. Do you know what I mean? Is there a standard approach for such a thing? From my point of view what I am trying to do is using an object (which is persisted from the ERM design perspective) as a sort of value object within my domain. What do you think? Question update: Probably my question wasn't clear enough. What I need to know is, how I would use an entity (like the State example) that is stored in a database within my domain logic. To avoid things like: if(person.State.Id == State.Working.Id) // some logic or if(person.State.Id == WORKING_ID) // some logic

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  • Announcing the ASP.NET and Web Tools 2012.2 Release Candidate

    - by ScottGu
    This week the ASP.NET and Visual Web Developer teams delivered the Release Candidate of the ASP.NET and Web Tools 2012.2 update (formerly ASP.NET Fall 2012 Update BUILD Prerelease). This update extends the existing ASP.NET runtime and adds new web tooling to Visual Studio 2012. Whether you use Web Forms, MVC, Web API, or any other ASP.NET technology, there is something cool in this update for you. You can download and install the RC today: http://www.asp.net/vnext. Great ASP.NET Enhancements This update adds new ASP.NET templates and features, including: New ASP.NET MVC templates. Creating Facebook applications just became easier using the new Facebook Application template. In just a few easy steps you can create a Facebook application that gets data from the logged in user as well as integrates with their friends. A new Single Page Application template allows developers to build interactive client-side web apps using Knockout, jQuery, and ASP.NET Web API. Real-time communication support with ASP.NET SignalR.  This enables you to easily take advantage of the new WebSocket support in .NET 4.5, while also automatically degrading to long-polling and other protocols for older clients.  If you haven’t tried SignalR yet you should – it is awesome. New ASP.NET Web API functionality, including support for OData, integrated tracing, and automatically generating help page documentation for your API. New ASP.NET Friendly URL functionality. This new feature makes it very easy for Web Forms developers to generate cleaner looking URLs (without the .aspx extension). The Friendly URLs feature also makes it easier for developers to add mobile support to their applications with support for mobile .ASPX pages and  supporting switching between desktop and mobile views. It can be used with existing ASP.NET v4.0 applications. Visual Studio 2012 Web publishing enhancements. Web site projects now have the same publish experience as web application projects (including to Windows Azure Web Sites), and you can selectively publish files, see the differences between local and remote files, and update local to remote files or vice versa. Visual Studio 2012 Page Inspector enhancements. JavaScript selection mapping is now supported, and you can CSS updates in real-time. Visual Studio 2012 editor support for Knockout IntelliSense and pasting JSON as a .NET class (which makes it even easier to consume Web APIs from others). Visual Studio 2012 Project Template updates, including the latest versions of jQuery, jQuery UI, jQuery Validation, Modernirz, Knockout and more… How it is delivered You can download and install an integrated setup that contains the above enhancements today from http://www.asp.net/vnext. The new runtime functionality is delivered to ASP.NET via additional NuGet packages. This means that installing this update does not make any changes to the existing ASP.NET binaries, and thus does not cause any compatibility issues with existing projects. New projects will contain the new functionality and existing projects can be updated with the new NuGet packages. Summary Web development is changing, and ASP.NET is rapidly delivering new capabilities to developers that help them take full advantage of new capabilities.  The ASP.NET and Web Tools 2012.2 update installs in minutes without altering the current ASP.NET run time components. For a complete description see the Release Notes. Next week I plan to publish a tutorial showing how to build a cool Facebook application using the new Facebook template. Hope this helps, Scott P.S. In addition to blogging, I am also now using Twitter for quick updates and to share links. Follow me at: twitter.com/scottgu

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  • Question About Example In Robert C Martin's _Clean Code_

    - by Jonah
    This is a question about the concept of a function doing only one thing. It won't make sense without some relevant passages for context, so I'll quote them here. They appear on pgs 37-38: To say this differently, we want to be able to read the program as though it were a set of TO paragraphs, each of which is describing the current level of abstraction and referencing subsequent TO paragraphs at the next level down. To include the setups and teardowns, we include setups, then we include the test page content, and then we include the teardowns. To include the setups, we include the suite setup if this is a suite, then we include the regular setup. It turns out to be very dif?cult for programmers to learn to follow this rule and write functions that stay at a single level of abstraction. But learning this trick is also very important. It is the key to keeping functions short and making sure they do “one thing.” Making the code read like a top-down set of TO paragraphs is an effective technique for keeping the abstraction level consistent. He then gives the following example of poor code: public Money calculatePay(Employee e) throws InvalidEmployeeType { switch (e.type) { case COMMISSIONED: return calculateCommissionedPay(e); case HOURLY: return calculateHourlyPay(e); case SALARIED: return calculateSalariedPay(e); default: throw new InvalidEmployeeType(e.type); } } and explains the problems with it as follows: There are several problems with this function. First, it’s large, and when new employee types are added, it will grow. Second, it very clearly does more than one thing. Third, it violates the Single Responsibility Principle7 (SRP) because there is more than one reason for it to change. Fourth, it violates the Open Closed Principle8 (OCP) because it must change whenever new types are added. Now my questions. To begin, it's clear to me how it violates the OCP, and it's clear to me that this alone makes it poor design. However, I am trying to understand each principle, and it's not clear to me how SRP applies. Specifically, the only reason I can imagine for this method to change is the addition of new employee types. There is only one "axis of change." If details of the calculation needed to change, this would only affect the submethods like "calculateHourlyPay()" Also, while in one sense it is obviously doing 3 things, those three things are all at the same level of abstraction, and can all be put into a TO paragraph no different from the example one: TO calculate pay for an employee, we calculate commissioned pay if the employee is commissioned, hourly pay if he is hourly, etc. So aside from its violation of the OCP, this code seems to conform to Martin's other requirements of clean code, even though he's arguing it does not. Can someone please explain what I am missing? Thanks.

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  • What are your recommended tools and frameworks for network development on Linux?

    - by Vivek Sharma
    What are your favourite network-tools, which you use to troubleshoot or design (as in conceptualize) your network-application code. Ethereal/Wireshark Nmap any particular simulators (e.g. ns) any special purpose sniffer any particular frameworks, (e.g. iptables) I am looking at must have, and good/advantage to have tools/framework in ones profile/skill set. I think Wireshark and Nmap are must haves.

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  • Which third party tools/library are available for NoSQL databases?

    - by Horcrux7
    I know that NoSQL databases are very new. I am also new in this point. But exist already tools/libraries to make the life easer like for SQL databases? I think on tools for managing, maintaining, viewing or reporting of the data. There can also be libraries for easer working with the database or an abstract database layer to change the database later. I would prefer Java libraries but also other are interesting.

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  • Patterns for dynamic CMS components (event driven?)

    - by CitrusTree
    Sorry my title is not great, this is my first real punt at moving 100% to OO as I've been procedural for more years than I can remember. I'm finding it hard to understand if what I'm trying to do is possible. Depending on people's thoughts on the 2 following points, I'll go down that route. The CMS I'm putting together is quote small, however focuses very much on different types of content. I could easily use Drupal which I'm very comfortable with, but I want to give myself a really good reasons to move myself into design patterns / OO-PHP 1) I have created a base 'content' class which I wish to be able to extend to handle different types of content. The base class, for example, handles HTML content, and extensions might handle XML or PDF output instead. On the other hand, at some point I may wish to extend the base class for a given project completely. I.e. if class 'content-v2' extended class 'content' for that site, any calls to that class should actually call 'content-v2' instead. Is that possible? If the code instantiates an object of type 'content' - I actually want it to instantiate one of type 'content-v2'... I can see how to do it using inheritance, but that appears to involve referring to the class explicitly, I can't see how to link the class I want it to use instead dynamically. 2) Secondly, the way I'm building this at the moment is horrible, I'm not happy with it. It feels very linear indeed - i.e. get session details get content build navigation theme page publish. To do this all the objects are called 1-by-1 which is all very static. I'd like it to be more dynamic so that I can add to it at a later date (very closely related to first question). Is there a way that instead of my orchestrator class calling all the other classes 1-by-1, then building the whole thing up at the end, that instead each of the other classes can 'listen' for specific events, then at the applicable point jump in and do their but? That way the orchestrator class would not need to know what other classes were required, and call them 1-by-1. Sorry if I've got this all twisted in my head. I'm trying to build this so it's really flexible.

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  • Are there localization tools which spot content strings in xaml/wpf?

    - by Noel Kennedy
    When globalizing a wpf application with static resx classes, it's very easy to miss the odd label or button that has its Content property set to a hard coded string in a particular language, ie English. These should of course be moved off to a {x:Static ...} so they can be localised for each culture. Are there any tools which can spot this and warn you? Built in to VS would be ideal, but I'm thinking that 'style cop' type build tools would do the job as well.

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  • What tools do you use to share knowledge amongst developers in your company?

    - by Chris Ross
    I'm looking for some good tools that help to share tips, best practices, company standards, etc. amongs developers in my company. Two tools I'm currently considering are a wiki (screwturn wiki) or Sharepoint 2010. I'm wondering if there is something better suited to the task, or any input anyone has on this subject. I'd prefer something that's windows based (i.e. runs on IIS, can authenticate users against Active Directory etc) but I am open to anything.

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  • Is this kind of Design by Contract useless?

    - by Charlie Pigarelli
    I've just started informatics university and I'm attending a programming course about C(++). The programming professor prefers to teach very few things (in 3 month we have just reached the functions topic) and connect every topic with a type of programming design that somehow is similar to the Design by Contract design. Basically what he ask us to do is to write every exercise with comments Pre-conditions, Post-conditions and Invariants that should prove the correctness of each program we write. But this doesn't make any sense to me. I mean, ok: maybe writing down your thoughts prevent you from doing some mistakes, but if this is all an abstract thing, then if your program intuition is wrong you'll write your program wrong and then you'll also write pre and post conditions wrong probably auto convincing your self about its correctness. Most of the time, both me and other students have written programs that seemed ok and that had correct pre and post condition too. But at the moment of testing it was just completely wrong. I had some experience before this course of programming and I had written a lot of line of code before and I found myself comfortably with just writing a program and unit test it. It take less time to accomplish and is less "abstract" than just thinking about what every single piece of your program should do in every case (which is kinda like mentally testing it). Finally, all this pre and post conditions takes me like 80% of the total time of the exercise. It's harder to think about putting down this pre and post correct than to write the program itself. Since we are like the only course of the only university probably in the entire world that makes this things, could someone please tell me how should I manage this thing? Am I right thinking that this doesn't worth anything? Should I change university? (there are like double of the people attending that course and it seems that usually very few people passes the exam the first year). Should I convince myself it's method is right?

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  • The Endeca UI Design Pattern Library Returns

    - by Joe Lamantia
    I'm happy to announce that the Endeca UI Design Pattern Library - now titled the Endeca Discovery Pattern Library - is once again providing guidance and good practices on the design of discovery experiences.  Launched publicly in 2010 following several years of internal development and usage, the Endeca Pattern Library is a unique and valued source of industry-leading perspective on discovery - something I've come to appreciate directly through  fielding the consistent stream of inquiries about the library's status, and requests for its rapid return to public availability. Restoring the library as a public resource is only the first step!  For the next stage of the library's evolution, we plan to increase the scope of the guidance it offers beyond user interface design to the broader topic of discovery.  This could include patterns for architecture at the systems, user experience, and business levels; information and process models; analytical method and activity patterns for conducting discovery; and organizational and resource patterns for provisioning discovery capability in different settings.  We'd like guidance from the community on the kinds of patterns that are most valuable - so make sure to let us know. And we're also considering ways to increase the number of patterns the library offers, possibly by expanding the set of contributors and the authoring mechanisms. If you'd like to contribute, please get in touch. Here's the new address of the library: http://www.oracle.com/goto/EndecaDiscoveryPatterns And I should say 'Many thanks' to the UXDirect team and all the others within the Oracle family who helped - literally - keep the library alive, and restore it as a public resource.

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  • Software design of a browser-based strategic MMO game

    - by Mehran
    I wonder if there are any known tested software designs for Travian-like browser-based strategic MMO games? I mean how would they implement the server of such games or what is stored in database and what is stored in RAM? Is the state of the world stored in one piece or is it distributed among a number of storage? Does anyone know a resource to study the problems and solutions of creating such games? [UPDATE] Suggested in comments, I'm going to give an example how would I design such a project. Even though I'm not sure if I'm proposing the right one. Having stored the world state in a MongoDB, I would implement an event collection in which all the changes to the world will register. Changes that are meant to happen in the future will come with an action date set to the future and those that are to be carried out immediately will be set to now. Having this datastore as the central point of the system, players will issue their actions as events inserted in datastore. At the other end of the system, I'll have a constant-running software taking out events out of the datastore which are due to be carried out and not done yet. Executing an event means apply some update on the world's state and thus the datastore. As scalable as this design sounds, I'm not sure if it will be worth implementing. For one, it is pointless to cache the datastore as most of updates happen once without any follow ups. For instance if you have the growth of resources in your game, you'll be updating the whole world state periodically in which case, having incorporated a cache, you are keeping the whole world in RAM (which most likely is impossible). So can someone come up with a better design?

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  • Good design for a simple site that contains a blog

    - by bporter
    What is a good design for a simple web site with mostly static pages and a blog? I am helping a friend build this for their small business. We are looking for a simple approach that can be implemented fairly quickly. (I am a programmer and can help with coding, hosting, etc.) One option is to use a site like virb, which lets you choose from one of their themes and build a site pretty easily. You can also include a blog. They host the site for a pretty low monthly rate. I recommended this option, but my friend wants a design that is unique and custom. So, I took one of the themes and started modifying the HTML and CSS. This might still be a good option, but... ...If we are going to greatly modify it, why not just create the static pages from scratch and use something like Wordpress for the blog. Is this a good option? It looks fairly easy to integrate Wordpress with a site so that the design and behavior are really cohesive. Is this a good idea? Do you recommend any other approaches?

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  • Plug-in based software design

    - by gekod
    I'm a software developer who is willing to improve his software design skills. I think software should not only work but have a solid and elegant design too to be reusable and extensive to later purposes. Now I'm in search of some help figuring out good practices for specific problems. Actually, I'm trying to find out how to design a piece of software that would be extensible via plug-ins. The questions I have are the following: Should plug-ins be able to access each others functionality? This would bring dependencies I guess. What should the main application offer to the plug-ins if I want to let's say develop a multimedia software which would play videos and music but which could later on get functionality added over plug-ins that would let's say be able to read video status (time, bps, ...) and display it. Would this mean that the player itself would have to be part of the main program and offer services to plug-ins to get such information or would there be a way to develop the player as a plug-in also but offer in some way the possibility to other plug-ins to interact with it? As you see, my questions are mainly for learning purposes as I strive to improve my software development skills. I hope to find help here and apologize if something is wrong with my question.

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  • Balancing dependency injection with public API design

    - by kolektiv
    I've been contemplating how to balance testable design using dependency injection with providing simple fixed public API. My dilemma is: people would want to do something like var server = new Server(){ ... } and not have to worry about creating the many dependencies and graph of dependencies that a Server(,,,,,,) may have. While developing, I don't worry too much, as I use an IoC/DI framework to handle all that (I'm not using the lifecycle management aspects of any container, which would complicate things further). Now, the dependencies are unlikely to be re-implemented. Componentisation in this case is almost purely for testability (and decent design!) rather than creating seams for extension, etc. People will 99.999% of the time wish to use a default configuration. So. I could hardcode the dependencies. Don't want to do that, we lose our testing! I could provide a default constructor with hard-coded dependencies and one which takes dependencies. That's... messy, and likely to be confusing, but viable. I could make the dependency receiving constructor internal and make my unit tests a friend assembly (assuming C#), which tidies the public API but leaves a nasty hidden trap lurking for maintenance. Having two constructors which are implicitly connected rather than explicitly would be bad design in general in my book. At the moment that's about the least evil I can think of. Opinions? Wisdom?

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  • A fix for the design time error in MVVM Light V4.1

    - by Laurent Bugnion
    For those of you who installed V4.1 of MVVM Light and created a project for Windows Phone 8, you will have noticed an error showing up in the design surface (either in Visual Studio designer, or in Expression Blend). The error says: “Could not load type ‘System.ComponentModel.INotifyPropertyChanging’ from assembly ‘mscorlib.extensions’” with additional information about version numbers. The error is caused by an incompatibility between versions of System.Windows.Interactivity. Because this assembly is strongly named, any version incompatibility is causing the kind of error shown here (for an interesting discussion on the strong naming issue, see this thread on Codeplex). I managed to resolve the issue for Windows Phone 8 and will publish a cleaned up installer next week. In the mean time, in order to allow you to continue development, please follow the steps: Download the new DLLs zip package (MVVMLight_V4_1_25_WP8). Right click on the Zip file and select Properties from the context menu. Press the “Unblock” button (if available) and then OK. Right click again on the zip package and select “Extract all…”. Select a known location for the new DLLs. Open the MVVM Light project with the design time error in Visual Studio 2012. Open the References folder in the Solution Explorer. Select the following DLLs: GalaSoft.MvvmLight.dll, GalaSoft.MvvmLight.Extras.dll, Microsoft.Practices.ServiceLocation.dll and System.Windows.Interactivity.dll. Press “delete” and confirm to remove the DLLs from your project. Right click on References and select Add Reference from the context menu. Browse to the folder with the new DLLs. Select the four new DLLs and press OK. Rebuild your application, and open it again in Blend or in the Visual Studio designer. The error should be gone now. In the next few days, as time allows, I will publish a new MSI containing a fixed version of the DLLs as well as a few other improvements. This quick fix should however allow you to continue working on your Windows Phone 8 projects in design mode too.   Laurent Bugnion (GalaSoft) Subscribe | Twitter | Facebook | Flickr | LinkedIn

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