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  • How to determine which inheriting class is using an abstract class's methods.

    - by Kin
    In my console application have an abstract Factory class "Listener" which contains code for listening and accepting connections, and spawning client classes. This class is inherited by two more classes (WorldListener, and MasterListener) that contain more protocol specific overrides and functions. I also have a helper class (ConsoleWrapper) which encapsulates and extends System.Console, containing methods for writing to console info on what is happening to instances of the WorldListener and MasterListener. I need a way to determine in the abstract ListenerClass which Inheriting class is calling its methods. Any help with this problem would be greatly appreciated! I am stumped :X Simplified example of what I am trying to do. abstract class Listener { public void DoSomething() { if(inheriting class == WorldListener) ConsoleWrapper.WorldWrite("Did something!"); if(inheriting class == MasterListener) ConsoleWrapper.MasterWrite("Did something!"); } } public static ConsoleWrapper { public void WorldWrite(string input) { System.Console.WriteLine("[World] {0}", input); } } public class WorldListener : Listener { public void DoSomethingSpecific() { ConsoleWrapper.WorldWrite("I did something specific!"); } } public void Main() { new WorldListener(); new MasterListener(); } Expected output [World] Did something! [World] I did something specific! [Master] Did something! [World] I did something specific!

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  • How to properly implement the Strategy pattern in a web MVC framework?

    - by jboxer
    In my Django app, I have a model (lets call it Foo) with a field called "type". I'd like to use Foo.type to indicate what type the specific instance of Foo is (possible choices are "Number", "Date", "Single Line of Text", "Multiple Lines of Text", and a few others). There are two things I'd like the "type" field to end up affecting; the way a value is converted from its normal type to text (for example, in "Date", it may be str(the_date.isoformat())), and the way a value is converted from text to the specified type (in "Date", it may be datetime.date.fromtimestamp(the_text)). To me, this seems like the Strategy pattern (I may be completely wrong, and feel free to correct me if I am). My question is, what's the proper way to code this in a web MVC framework? In a client-side app, I'd create a Type class with abstract methods "serialize()" and "unserialize()", override those methods in subclasses of Type (such as NumberType and DateType), and dynamically set the "type" field of a newly-instantiated Foo to the appropriate Type subclass at runtime. In a web framework, it's not quite as straightforward for me. Right now, the way that makes the most sense is to define Foo.type as a Small Integer field and define a limited set of choices (0 = "Number", 1 = "Date", 2 = "Single Line of Text", etc.) in the code. Then, when a Foo object is instantiated, use a Factory method to look at the value of the instance's "type" field and plug in the correct Type subclass (as described in the paragraph above). Foo would also have serialize() and unserialize() methods, which would delegate directly to the plugged-in Type subclass. How does this design sound? I've never run into this issue before, so I'd really like to know if other people have, and how they've solved it.

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  • How do we name test methods where we are checking for more than one condition?

    - by Sandbox
    I follow the technique specified in Roy Osherove's The Art Of Unit Testing book while naming test methods - MethodName_Scenario_Expectation. It suits perfectly well for my 'unit' tests. But,for tests that I write in 'controller' or 'coordinator' class, there isn't necessarily a method which I want to test. For these tests, I generate multiple conditions which make up one scenario and then I verify the expectation. For example, I may set some properties on different instances, generate an event and then verify that my expectation from controller/coordinator is being met. Now, my controller handles events using a private event handler. Here my scenario is that, I set some properties, say 3 condition1,condition2 and condition3 Also, my scenario includes an event is raised I don't have a method name as my event handler is private. How do I name such a test method?

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  • Java - Calling all methods of a class

    - by Thomas Eschemann
    I'm currently working on an application that has to render several Freemarker templates. So far I have a Generator class that handles the rendering. The class looks more or less like this: public class Generator { public static void generate(…) { renderTemplate1(); renderTemplate2(); renderTemplate3(); } private static void render(…) { // renders the template } private static void renderTemplate1() { // Create config object for the rendering // and calls render(); }; private static void renderTemplate1() { // Create config object for the rendering // and calls render(); }; … } This works, but it doesn't really feel right. What I would like to do is create a class that holds all the renderTemplate...() methods and then call them dynamically from my Generator class. This would make it cleaner and easier to extend. I was thinking about using something like reflection, but it doesn't really feel like a good solution either. Any idea on how to implement this properly ?

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  • Tips for Using Multiple Development Systems

    - by Tim Lytle
    When I travel, I don't pack up the desktop I use in the office and take it with me. Maybe I should, but I don't. However, since I'm a contract programmer I like to be able to work wherever I am: I'm mostly thinking of web development here. Version Control goes a long way in keeping sane and working on multiple projects on multiple systems (two or three computers); however, there are the issues of: IDE settings - different display sizes mean the IDE settings can't be completely synced, if at all. Database - if the database is 'external' (even if it's running on the same system, it's not in version control), how do you maintain the needed syncs of structure. Development Stack - Some projects need non-standard extensions, libraries, etc installed. Just an overview of some of the hassle involved with developing on multiple systems. I'll probably end up asking some specific questions, but I thought a CW style tips might reveal some things I would even think to ask about. Update: I guess this would also address tips to make upgrading/replacing your development system easier (something I've just done). So, one tip per answer please, so the 'top' tips are easy to find. How do you make it easier to develop on multiple systems, or to transfer work after upgrading/replaceing a development system?

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  • HTTP POST with URL query parameters -- good idea or not?

    - by Steven Huwig
    I'm designing an API to go over HTTP and I am wondering if using the HTTP POST command, but with URL query parameters only and no request body, is a good way to go. Considerations: "Good Web design" requires non-idempotent actions to be sent via POST. This is a non-idempotent action. It is easier to develop and debug this app when the request parameters are present in the URL. The API is not intended for widespread use. It seems like making a POST request with no body will take a bit more work, e.g. a Content-Length: 0 header must be explicitly added. It also seems to me that a POST with no body is a bit counter to most developer's and HTTP frameworks' expectations. Are there any more pitfalls or advantages to sending parameters on a POST request via the URL query rather than the request body? Edit: The reason this is under consideration is that the operations are not idempotent and have side effects other than retrieval. See the HTTP spec: In particular, the convention has been established that the GET and HEAD methods SHOULD NOT have the significance of taking an action other than retrieval. These methods ought to be considered "safe". This allows user agents to represent other methods, such as POST, PUT and DELETE, in a special way, so that the user is made aware of the fact that a possibly unsafe action is being requested. ... Methods can also have the property of "idempotence" in that (aside from error or expiration issues) the side-effects of N 0 identical requests is the same as for a single request. The methods GET, HEAD, PUT and DELETE share this property. Also, the methods OPTIONS and TRACE SHOULD NOT have side effects, and so are inherently idempotent.

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  • Is there a pattern for this?

    - by Timmy
    i have something that requires a matrix of values, similar to pokemon: i have a class object for each of the types, is there a pattern or a good way to implement this, as a middle layer or in the classes?

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  • Projects with browsable source using dependency injection w/ guice?

    - by André
    I often read about dependency injection and I did research on google and I understand in theory what it can do and how it works, but I'd like to see an actual code base using it (Java/guice would be preferred). Can anyone point me to an open source project, where I can see, how it's really used? I think browsing the code and seeing the whole setup shows me more than the ususal snippets in the introduction articles you find around the web. Thanks in advance!

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  • Reading ResultSet from multiple threads

    - by superdario
    Hello, In the database, I have a definition table that is read from the application once upon starting. This definition table rarely changes, so it makes sense to read it once and restart the application every time it changes. However, after the table is read (put into a ResultSet), it will be read by multiple handlers running in their own threads. How do you suggest to accomplish this? My idea was to populate a CachedRowSet, and then create a copy of this set (through the createCopy() method) for each handler every time a new request comes. Do you think this is wise? Does this offer a good performance? Thanks.

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  • Code promotion: Enforcing the rules

    - by jbarker7
    So here is our problem: We have a small team of developers with their own ways of doing things-- I am trying to formalize a process in which we are required to promote our code in the following order: Local sandbox Dev UAT Staging Live Developers develop/test as they go on their own sandbox, Dev is its own box that we would use for continuous integration, UAT is another site in IIS on the dev box, which uses our dev database. We then promote to staging, which is a site in IIS on the Live box and using live data (just like the live, hence staging). Then, finally, we promote to live. Here are a few of my questions: 1.) Does this seem to be best practice? If not, what needs to be done differently? 2.) How do I enforce the rules to the developers? Often developers skip steps in order to save time... this should not be tolerated and would be great if it could be physically enforced. 3.) How do I enforce these rules to the business group? The business group just wants to get features out FAST. Do we promote only on certain days? Thanks! Josh

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  • Should old/legacy/unused code be deleted from source control repository?

    - by Checkers
    I've encountered this in multiple projects. As the code base evolves, some libraries, applications, and components get abandoned and/or deprecated. Most people prefer to keep them in. The usual argument is that the code does not really take any space, it can be left alone until needed again. So a repository slowly turns into a cesspool of legacy code, where it's hard to find anything. Some people delete old code, since it creates clutter, raises more questions for new people, and you can restore any old snapshot of the code base anyway. However you can't always find the old code if you don't know where to look, as none of the (common) VCS I know offer search over the entire repository including all historical revisions, and the only way to search the old files is to check out the revision where the deleted file exists. What would be a good approach to repository management?

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  • Are we using IoC effectively?

    - by Juliet
    So my company uses Castle Windsor IoC container, but in a way that feels "off": All the data types are registered in code, not the config file. All data types are hard-coded to use one interface implementation. In fact, for nearly all given interfaces, there is and will only ever be one implementation. All registered data types have a default constructor, so Windsor doesn't instantiate an object graph for any registered types. The people who designed the system insist the IoC container makes the system better. We have 1200+ public classes, so its a big system, the kind where you'd expect to find a framework like Windsor. But I'm still skeptical. Is my company using IoC effectively? Is there an advantage to new'ing objects with Windsor than new'ing objects with the new keyword?

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  • Win7: Right place to install a program that may be 'shared' with other computers

    - by robsoft
    We have an app that currently installs itself into 'program files\our app', and it puts the internal data files into the common Application Data folder. This means the program is available to any user on that particular PC. Now we want to make a multi-user version of this program, multiple PCs accessing the program at the same time across the network. In the bad old days, under XP, we'd just have the user who installed the app 'share' the app directory and off we'd go. In principle, is this still the 'right' way to do it under Vista/Windows 7? We'd like to do this 'properly' and be as compliant as possible! Is there a recommended 'Microsoft' approach for doing this, or is it largely down to whatever we can get away with and subsequently support (hah!). I've tried researching this on the MS websites but not found anything too helpful at all - it'd be really useful to have a 'if you're trying to install this kind of thing, put it here' type guide for developers!

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  • Visitor Pattern can be replaced with Callback functions?

    - by getit
    Is there any significant benefit to using either technique? In case there are variations, the Visitor Pattern I mean is this: http://en.wikipedia.org/wiki/Visitor_pattern And below is an example of using a delegate to achieve the same effect (at least I think it is the same) Say there is a collection of nested elements: Schools contain Departments which contain Students Instead of using the Visitor pattern to perform something on each collection item, why not use a simple callback (Action delegate in C#) Say something like this class Department { List Students; } class School { List Departments; VisitStudents(Action<Student> actionDelegate) { foreach(var dep in this.Departments) { foreach(var stu in dep.Students) { actionDelegate(stu); } } } } School A = new School(); ...//populate collections A.Visit((student)=> { ...Do Something with student... }); *EDIT Example with delegate accepting multiple params Say I wanted to pass both the student and department, I could modify the Action definition like so: Action class School { List Departments; VisitStudents(Action<Student, Department> actionDelegate, Action<Department> d2) { foreach(var dep in this.Departments) { d2(dep); //This performs a different process. //Using Visitor pattern would avoid having to keep adding new delegates. //This looks like the main benefit so far foreach(var stu in dep.Students) { actionDelegate(stu, dep); } } } }

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  • Question about factory classes

    - by devoured elysium
    Currently I have created a ABCFactory class that has a single method creating ABC objects. Now that I think of it, maybe instead of having a factory, I could just make a static method in my ABC Method. What are the pro's and con's on making this change? Will it not lead to the same? I don't foresee having other classes inherit ABC, but one never knows! Thanks

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  • Best Practice: Software Versioning

    - by Sebi
    I couldn't find a similar question here on SO, but if you find one please link. Is there any guideline or standard best practice how to version a software you develop in your spare time for fun, but nevertheless will be used by some people? I think it's necessary to version such software so that you know about with version one is talking about (e.g. for bug fixing, support, and so on). But where do I start the versioning? 0.0.0? or 0.0? And then how to I increment the numbers? major release.minor change? and should'nt any commit to a version control system be another version? or is this only for versions which are used in a productive manner?

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  • Converting ASP.NET MVC to n-Tiered Architecture

    - by Jeff
    I just built an application using ASP.NET MVC. The programmers at my company want to build all future modules using n-Tiered (Presentation Layer, Business Logic Layer, Data Access Layer) architecture. I am not the programmer and need to know why this makes sense? Do I have to completely rewrite the entire code or can it be converted? We are building an HRIS system with Business Intelligence. Somebody please explain why or why not this approach does or does not make sense.

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  • Is there anything bad in declaring static inner class inside interface in java?

    - by Roman
    I have an interface ProductService with method findByCriteria. This method had a long list of nullable parameters, like productName, maxCost, minCost, producer and so on. I refactored this method by introducing Parameter Object. I created class SearchCriteria and now method signature looks like this: findByCriteria (SearchCriteria criteria) I thought that instances of SearchCriteria are only created by method callers and are only used inside findByCriteria method, i.e.: void processRequest() { SearchCriteria criteria = new SearchCriteria () .withMaxCost (maxCost) ....... .withProducer (producer); List<Product> products = productService.findByCriteria (criteria); .... } and List<Product> findByCriteria(SearchCriteria criteria) { return doSmthAndReturnResult(criteria.getMaxCost(), criteria.getProducer()); } So I did not want to create separate public class for SearchCriteria and put it inside ProductServiceInterface: public interface ProductService { List<Product> findByCriteria (SearchCriteria criteria); static class SearchCriteria { ... } } Is there anything bad in this interface? Where whould you place SearchCriteria class?

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  • What Getters and Setters should and shouldn't do.

    - by cyclotis04
    I've run into a lot of differing opinions on Getters and Setters lately, so I figured I should make it into it's own question. A previous question of mine received an immediate comment (later deleted) that stated setters shouldn't have any side effects, and a SetProperty method would be a better choice. Indeed, this seems to be Microsoft's opinion as well. However, their properties often raise events, such as Resized when a form's Width or Height property is set. OwenP also states "you shouldn't let a property throw exceptions, properties shouldn't have side effects, order shouldn't matter, and properties should return relatively quickly." Yet Michael Stum states that exceptions should be thrown while validating data within a setter. If your setter doesn't throw an exception, how could you effectively validate data, as so many of the answers to this question suggest? What about when you need to raise an event, like nearly all of Microsoft's Control's do? Aren't you then at the mercy of whomever subscribed to your event? If their handler performs a massive amount of information, or throws an error itself, what happens to your setter? Finally, what about lazy loading within the getter? This too could violate the previous guidelines. What is acceptable to place in a getter or setter, and what should be kept in only accessor methods?

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  • Alternatives to checking against the system time

    - by vikp
    Hi, I have an application which license should expire after some period of time. I can check the time in the applicatino against the system time, but system time can be changed by the administrator, therefore it's not a good idea to check against the system time in my opinion. What alternatives do I have? Thank you

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  • [MySQL] Efficiently store last X records per item

    - by Saif Bechan
    I want to store the last X records in an MySQL database in an efficient way. So when the 4th record is stored the first should be deleted. The way I do this not is first run a query getting the items. Than check what I should do then insert/delete. There has to be a better way to do this. Any suggestions? Edit I think I should add that the records stored do not have a unique number. They have a mixed par. For example article_id and user_id. Then I want to make a table with the last X items for user_x. Just selecting the article from the table grouped by user and sorted by time is not an option for me. The table where I do the sort and group on has millions of records and gets hit a lot for no reason. So making a table in between with the last X records is way more effient. PS. I am not using this for articles and users.

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  • wpf command pattern

    - by evan
    I have a wpf gui which displays a list of information in separate window and in a separate thread from the main application. As the user performs actions in the main window the side window is updated. (For example if you clicked page down in the main window a listbox in the side window would page down). Right now the architecture for this application feels very messy and I'm sure there is a cleaner way to do it. It looks like this: Main Window contains a singleton SideWindowControl which communicates with an instance of the SideWindowDisplay using events - so, for example, the pagedown button would work like: 1) the event handler of the button on the main window calls SideWindowControl.PageDown() 2) in the PageDown() function a event is created and thrown. 3) finally the gui, ShowSideWindowDisplay is subscribing to the SideWindowControl.Actions event handles the event and actually scrolls the listbox down - note because it is in a different thread it has to do that by running the command via Dispatcher.Invoke() This just seems like a very messy way to this and there must be a clearer way (The only part that can't change is that the main window and the side window must be on different threads). Perhaps using WPF commands? I'd really appreciate any suggestions!! Thanks

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  • "requiresuniqueemail=true" implementation in asp.net site

    - by domineer
    Hi people I got a social networking site that is running live right now.The first time I launched my site I let requiresuniqueemail=false set-up on my web.config inorder for me to create dummy accounts for testing purposes and to start up the site you know.However the site is kind of stable right now w/ almost 5k members.So I would like to set-up the requiresuniqueemail to true so that users cannot reuse their existing email address and for me to make it sure that there will be unique email ad for each site user.I know the site got like 100 users with the same email address.My question is what could be the problem I'm going to face if I do this right now(requiresuniqueemail="true") and how to do this efficiently(without errors and if possible sitewide say in the global assax)?I tested and I already got an error if I logout an account.Like say a user try to click log-out this code runs: Dim d As DateTime = DateTime.Now.AddMinutes(-1 * Membership.UserIsOnlineTimeWindow) Dim theuser As MembershipUser = Membership.GetUser() theuser.LastActivityDate = d Membership.UpdateUser(theuser) If Not Cache(Page.User.Identity.Name.ToLower() + "currentstatus") Is Nothing Then Cache.Remove(Page.User.Identity.Name.ToLower() + "currentstatus") End If Then an exception occured on updateuser() function saying System.Configuration.Provider.ProviderException: The E-mail supplied is invalid. This is just one instance I know that I encountered a problem. Hoping to hear your ideas guys.....

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  • Good code architecture for this problem?

    - by RCIX
    I am developing a space shooter game with customizable ships. You can increase the strength of any number of properties of the ship via a pair of radar charts*. Internally, i represent each ship as a subclassed SpaceObject class, which holds a ShipInfo that describes various properties of that ship. I want to develop a relatively simple API that lets me feed in a block of relative strengths (from minimum to maximum of what the radar chart allows) for all of the ship properties (some of which are simplifications of the underlying actual set of properties) and get back a ShipInfo class i can give to a PlayerShip class (that is the object that is instantiated to be a player ship). I can develop the code to do the transformations between simplified and actual properties myself, but i would like some recommendations as to what sort of architecture to provide to minimize the pain of interacting with this translator code (i.e. no methods with 5+ arguments or somesuch other nonsense). Does anyone have any ideas? *=not actually implemented yet, but that's the plan.

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