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  • Help naming a class that has a single public method called Execute()

    - by devoured elysium
    I have designed the following class that should work kind of like a method (usually the user will just run Execute()): public abstract class ??? { protected bool hasFailed = false; protected bool hasRun = false; public bool HasFailed { get { return hasFailed; } } public bool HasRun { get { return hasRun; } } private void Restart() { hasFailed = false; hasRun = false; } public bool Execute() { ExecuteImplementation(); bool returnValue = hasFailed; Restart(); return returnValue; } protected abstract void ExecuteImplementation(); } My question is: how should I name this class? Runnable? Method(sounds awkward)?

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  • how can i use switch statement on type-safe enum pattern

    - by Fer
    I found a goodlooking example about implementation enums in a different way. That is called type-safe enum pattern i think. I started using it but i realized that i can not use it in a switch statement. My implementation looks like the following: public sealed class MyState { private readonly string m_Name; private readonly int m_Value; public static readonly MyState PASSED= new MyState(1, "OK"); public static readonly MyState FAILED= new MyState(2, "ERROR"); private MyState(int value, string name) { m_Name = name; m_Value = value; } public override string ToString() { return m_Name; } public int GetIntValue() { return m_Value; } } What can i add to my class in order to be able to use this pattern in switch statements in C#? Thanks.

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  • Should I use IDisposable for purely managed resources?

    - by John Gietzen
    Here is the scenario: I have an object called a Transaction that needs to make sure that only one entity has permission to edit it at any given time. In order to facilitate a long-lived lock, I have the class generating a token object that can be used to make the edits. You would use it like this: var transaction = new Transaction(); using (var tlock = transaction.Lock()) { transaction.Update(data, tlock); } Now, I want the TransactionLock class to implement IDisposable so that its usage can be clear. But, I don't have any unmanaged resources to dispose. however, the TransctionLock object itself is a sort of "unmanaged resource" in the sense that the CLR doesn't know how to properly finalize it. All of this would be fine and dandy, I would just use IDisposable and be done with it. However, my issue comes when I try to do this in the finalizer: ~TransactionLock() { this.Dispose(false); } I want the finalizer to release the transaction from the lock, if possible. How, in the finalizer, do I detect if the parent transaction (this.transaction) has already been finalized? Is there a better pattern I should be using? The Transaction class looks something like this: public sealed class Transaction { private readonly object lockMutex = new object(); private TransactionLock currentLock; public TransactionLock Lock() { lock (this.lockMutex) { if (this.currentLock != null) throw new InvalidOperationException(/* ... */); this.currentLock = new TransactionLock(this); return this.currentLock; } } public void Update(object data, TransactionLock tlock) { lock (this.lockMutex) { this.ValidateLock(tlock); // ... } } internal void ValidateLock(TransactionLock tlock) { if (this.currentLock == null) throw new InvalidOperationException(/* ... */); if (this.currentLock != tlock) throw new InvalidOperationException(/* ... */); } internal void Unlock(TransactionLock tlock) { lock (this.lockMutex) { this.ValidateLock(tlock); this.currentLock = null; } } }

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  • Search for a pattern in a list of strings - Python

    - by Holtz
    I have a list of strings containing filenames such as, file_names = ['filei.txt','filej.txt','filek.txt','file2i.txt','file2j.txt','file2k.txt','file3i.txt','file3j.txt','file3k.txt'] I then remove the .txt extension using: extension = os.path.commonprefix([n[::-1] for n in file_names])[::-1] file_names_strip = [n[:-len(extension)] for n in file_names] And then return the last character of each string in the list file_names_strip: h = [n[-1:] for n in file_names_strip] Which gives h = ['i', 'j', 'k', 'i', 'j', 'k', 'i', 'j', 'k'] How can i test for a pattern of strings in h? So if i,j,k occur sequentially it would return True and False if not. I need to know this because not all file names are formatted like they are in file_names. So: test_ijk_pattern(h) = True no_pattern = ['1','2','3','1','2','3','1','2','3'] test_ijk_pattern(no_pattern) = False

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  • Designing different Factory classes (and what to use as argument to the factories!)

    - by devoured elysium
    Let's say we have the following piece of code: public class Event { } public class SportEvent1 : Event { } public class SportEvent2 : Event { } public class MedicalEvent1 : Event { } public class MedicalEvent2 : Event { } public interface IEventFactory { bool AcceptsInputString(string inputString); Event CreateEvent(string inputString); } public class EventFactory { private List<IEventFactory> factories = new List<IEventFactory>(); public void AddFactory(IEventFactory factory) { factories.Add(factory); } //I don't see a point in defining a RemoveFactory() so I won't. public Event CreateEvent(string inputString) { try { //iterate through all factories. If one and only one of them accepts //the string, generate the event. Otherwise, throw an exception. return factories.Single(factory => factory.AcceptsInputString(inputString)).CreateEvent(inputString); } catch (InvalidOperationException e) { throw new InvalidOperationException("No valid factory found to generate this kind of Event!", e); } } } public class SportEvent1Factory : IEventFactory { public bool AcceptsInputString(string inputString) { return inputString.StartsWith("SportEvent1"); } public Event CreateEvent(string inputString) { return new SportEvent1(); } } public class MedicalEvent1Factory : IEventFactory { public bool AcceptsInputString(string inputString) { return inputString.StartsWith("MedicalEvent1"); } public Event CreateEvent(string inputString) { return new MedicalEvent1(); } } And here is the code that runs it: static void Main(string[] args) { EventFactory medicalEventFactory = new EventFactory(); medicalEventFactory.AddFactory(new MedicalEvent1Factory()); medicalEventFactory.AddFactory(new MedicalEvent2Factory()); EventFactory sportsEventFactory = new EventFactory(); sportsEventFactory.AddFactory(new SportEvent1Factory()); sportsEventFactory.AddFactory(new SportEvent2Factory()); } I have a couple of questions: Instead of having to add factories here in the main method of my application, should I try to redesign my EventFactory class so it is an abstract factory? It'd be better if I had a way of not having to manually add EventFactories every time I want to use them. So I could just instantiate MedicalFactory and SportsFactory. Should I make a Factory of factories? Maybe that'd be over-engineering? As you have probably noticed, I am using a inputString string as argument to feed the factories. I have an application that lets the user create his own events but also to load/save them from text files. Later, I might want to add other kinds of files, XML, sql connections, whatever. The only way I can think of that would allow me to make this work is having an internal format (I choose a string, as it's easy to understand). How would you make this? I assume this is a recurrent situation, probably most of you know of any other more intelligent approach to this. I am then only looping in the EventFactory for all the factories in its list to check if any of them accepts the input string. If one does, then it asks it to generate the Event. If you find there is something wrong or awkward with the method I'm using to make this happen, I'd be happy to hear about different implementations. Thanks! PS: Although I don't show it in here, all the different kind of events have different properties, so I have to generate them with different arguments (SportEvent1 might have SportName and Duration properties, that have to be put in the inputString as argument).

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  • distributing R package with optional S4 syntax sugar

    - by mariotomo
    I've written a small package for logging, I'm distributing it through r-forge, recently I received some very interesting feedback on how to make it easier to use, but this functionality is based on stuff (setRefClass) that was added to R in 2.12. I'd like to keep distributing the package also for R-2.9, so I'm looking for a way to include or exclude the S4 syntactical sugar automatically, and include it when the library is loaded on a R = 2.12 system. one other option I see, that is to write a small S4 package that needs 2.12, imports the simpler logging package and exports the syntactically sugared interface... I don't like it too much, as I'd need to choose a different name for the S4 package.

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  • SQL Server 2008 Optimization

    - by hgulyan
    I've learned today, if you append to your query OPTION (MAXDOP 0) your query will run on multiple processors and if it's huge query, query will perform faster. I know general guidelines on query optimizations (using indexes, selecting only needed fields etc.), my question is about SQL Server optimization. Maybe changing some options in configurations or anything else. What guidelines are there for SQL Server Optimization? Thank you.

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  • Need help understanding the MVC design pattern

    - by Doron Sinai
    Hi, I am trying to find a ood example of MVC design pattern in java. This is what i understood from reading about it, please correct me if I am wrong: I have the Model part which is the logic behind the program, let's say if we have a phonebook, so adding and removing contact from the Array will be the model. The Gui is the view and it contains buttons that upon clicking them, the model is changing. What I am trying to undersand what is the controller part, is it the ActionListeners? how to you seperate those modules in practice. thank you

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  • Writing a custom iterator -- what to do if you're at the end of the array?

    - by Goose Bumper
    I'm writing a custom iterator for a Matrix class, and I want to implement the increment method, which gets called when the iterator is incremented: void MatrixIterator::increment() { // go to the next element } Suppose the iterator has been incremented too many times and now points to past the end of the matrix (i.e. past the one-past-the-end point). What is the best practice for this situation? Should I catch this with an assert, or should I just say it's the user's responsibility to keep track of where the iterator is pointing and it's none of my business?

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  • A better UPDATE method in LINQ to SQL

    - by Refracted Paladin
    The below is a typical, for me, Update method in L2S. I am still fairly new to a lot of this(L2S & business app development) but this just FEELs wrong. Like there MUST be a smarter way of doing this. Unfortunately, I am having trouble visualizing it and am hoping someone can provide an example or point me in the right direction. To take a stab in the dark, would I have a Person Object that has all these fields as Properties? Then what, though? Is that redundant since L2S already mapped my Person Table to a Class? Is this just 'how it goes', that you eventually end up passing 30 parameters(or MORE) to an UPDATE statement at some point? For reference, this is a business app using C#, WinForms, .Net 3.5, and L2S over SQL 2005 Standard. Here is a typical Update Call for me. This is in a file(BLLConnect.cs) with other CRUD methods. Connect is the name of the DB that holds tblPerson When a user clicks save() this is what is eventually called with all of these fields having, potentially, been updated-- public static void UpdatePerson(int personID, string userID, string titleID, string firstName, string middleName, string lastName, string suffixID, string ssn, char gender, DateTime? birthDate, DateTime? deathDate, string driversLicenseNumber, string driversLicenseStateID, string primaryRaceID, string secondaryRaceID, bool hispanicOrigin, bool citizenFlag, bool veteranFlag, short ? residencyCountyID, short? responsibilityCountyID, string emailAddress, string maritalStatusID) { using (var context = ConnectDataContext.Create()) { var personToUpdate = (from person in context.tblPersons where person.PersonID == personID select person).Single(); personToUpdate.TitleID = titleID; personToUpdate.FirstName = firstName; personToUpdate.MiddleName = middleName; personToUpdate.LastName = lastName; personToUpdate.SuffixID = suffixID; personToUpdate.SSN = ssn; personToUpdate.Gender = gender; personToUpdate.BirthDate = birthDate; personToUpdate.DeathDate = deathDate; personToUpdate.DriversLicenseNumber = driversLicenseNumber; personToUpdate.DriversLicenseStateID = driversLicenseStateID; personToUpdate.PrimaryRaceID = primaryRaceID; personToUpdate.SecondaryRaceID = secondaryRaceID; personToUpdate.HispanicOriginFlag = hispanicOrigin; personToUpdate.CitizenFlag = citizenFlag; personToUpdate.VeteranFlag = veteranFlag; personToUpdate.ResidencyCountyID = residencyCountyID; personToUpdate.ResponsibilityCountyID = responsibilityCountyID; personToUpdate.EmailAddress = emailAddress; personToUpdate.MaritalStatusID = maritalStatusID; personToUpdate.UpdateUserID = userID; personToUpdate.UpdateDateTime = DateTime.Now; context.SubmitChanges(); } }

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  • What's the best way to unit test code that generates random output?

    - by Flynn1179
    Specifically, I've got a method picks n items from a list in such a way that a% of them meet one criterion, and b% meet a second, and so on. A simplified example would be to pick 5 items where 50% have a given property with the value 'true', and 50% 'false'; 50% of the time the method would return 2 true/3 false, and the other 50%, 3 true/2 false. Statistically speaking, this means that over 100 runs, I should get about 250 true/250 false, but because of the randomness, 240/260 is entirely possible. What's the best way to unit test this? I'm assuming that even though technically 300/200 is possible, it should probably fail the test if this happens. Is there a generally accepted tolerance for cases like this, and if so, how do you determine what that is?

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  • JavaScript-library-based Project Organization

    - by Laith J
    Hello, I'm very new to the JavaScript library world. I have used JS by itself before to create a mini social network but this is the first time I use a JS library and I really don't know how to go about this. I'm planning to use Google Closure and I'm really not sure how I should go about organizing the code. Should I put everything in one file since it's a web app and should have one screen? Should I separate the code to many chunks and put them in different files? Or should I put different dialogs (like settings) in a separate page and thus a separate file? Like all programmers I'm a perfectionist so please help me out with this one, thanks.

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  • Why is there so much poorly indented code out there?

    - by dsimcha
    The more I browse the code to open source projects in languages that aren't Python, the more I realize that it seems a lot of programmers don't believe in proper indentation. (I won't mention any projects specifically to avoid having anyone take this question too personally.) Usually code is indented, but in a way just different enough from the standard style that it drives me crazy, especially in old/crufty code. I've noticed that when I write in C-like languages, I tend to indent correctly as religiously as when I'm writing in Python, with the exception of debugging code that I actually want to stick out like a sore thumb. Given how easy it is with a modern IDE to fix incorrect indentation, what are some rationales for not religiously keeping indentation in sync with braces?

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  • Exposing a service to external systems - How should I design the contract?

    - by Larsi
    Hi! I know this question is been asked before here but still I'm not sure what to select. My service will be called from many 3 party system in the enterprise. I'm almost sure the information the service will collect (MyBigClassWithAllInfo) will change during the products lifetime. Is it still a good idea to expose objects? This is basically what my two alternatives: [ServiceContract] public interface ICollectStuffService { [OperationContract] SetDataResponseMsg SetData(SetDataRequestMsg dataRequestMsg); } // Alternative 1: Put all data inside a xml file [DataContract] public class SetDataRequestMsg { [DataMember] public string Body { get; set; } [DataMember] public string OtherPropertiesThatMightBeHandy { get; set; } // ?? } // Alternative 2: Expose the objects [DataContract] public class SetDataRequestMsg { [DataMember] public Header Header { get; set; } [DataMember] public MyBigClassWithAllInfo ExposedObject { get; set; } } public class SetDataResponseMsg { [DataMember] public ServiceError Error { get; set; } } The xml file would look like this: <?xml version="1.0" encoding="utf-8"?> <Message>   <Header>     <InfoAboutTheSender>...</InfoAboutTheSender>   </Header>   <StuffToCollectWithAllTheInfo>   <stuff1>...</stuff1> </StuffToCollectWithAllTheInfo> </Message> Any thought on how this service should be implemented? Thanks Larsi

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  • Is it against best practice to throw Exception on most JUnit tests?

    - by Chris Knight
    Almost all of my JUnit tests are written with the following signature: public void testSomething() throws Exception My reasoning is that I can focus on what I'm testing rather than exception handling which JUnit appears to give me for free. But am I missing anything by doing this? Is it against best practice? Would I gain anything by explicitly catching specific exceptions in my test and then fail()'ing on them?

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  • De-normalization for the sake of reports - Good or Bad?

    - by Travis
    What are the pros/cons of de-normalizing an enterprise application database because it will make writing reports easier? Pro - designing reports in SSRS will probably be "easier" since no joins will be necessary. Con - developing/maintaining the app to handle de-normalized data will become more difficult due to duplication of data and synchronization. Others?

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  • When should I write my own Look and Feel for Java Swing instead of customizing one?

    - by Jonas
    I have used a few different Look and Feels for Java Swing, but I don't really like anyone to 100% so I often end up with customizing it a lot. Sometimes I am thinking about if it is a better idea to write my own LaF (by extending an existing one), but I don't really know. For the moment, I mostly use Nimbus, but I change all colors (to darker ones) and rewrite the appearance of some components, like sliders and scrollbars. I also mostly customize all tables and I am thinking about to change the look of a few other components. When is it recommended to create a new Look-and-Feel instead of customizing one? What are the pros and cons? I.e. customize Nimbus or create a new one by extending Nimbus? Related article: Creating a Custom Look and Feel (old)

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  • Is it bad practice to use an enum that maps to some seed data in a Database?

    - by skb
    I have a table in my database called "OrderItemType" which has about 5 records for the different OrderItemTypes in my system. Each OrderItem contains an OrderItemType, and this gives me referential integrity. In my middletier code, I also have an enum which matches the values in this table so that I can have business logic for the different types. My dev manager says he hates it when people do this, and I am not exactly sure why. Is there a better practice I should be following?

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  • ASP Dot Net : How to repeat HTML parts with minor differences on a page?

    - by tinky05
    It's a really simple problem. I've got HTML code like this : <div> <img src="image1.jpg" alt="test1" /> </div> <div> <img src="image2.jpg" alt="test2" /> </div> <div> <img src="image3.jpg" alt="test3" /> </div> etc... The data is comming from a DB (image name, alt text). In JAVA, I would do something like : save the info in array in the back end. For the presentation I would loop through it with JSTL : <c:foeach items="${data}" var="${item}> <div> <img src="${item.image}" alt="${item.alt}" /> </div> </c:foreach> What's the best practice in ASP.net I just don't want to create a string with HTML code in it in the "code behind", it's ugly IMO.

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  • Migrating a simple application from Application Delegate to ViewController Class

    - by eco_bach
    Hi Frst of all wanted to send out a huge thanks for the great feedback and support. I have a simple application working, right now simply loads a sequence of images and alows the user to step thru the images by clicking a button. All of my logic is in my Application Delegate class, with the image loading, initialization of UIImage Views etc happening in my applicationDidFinishLaunching method. My next step is to migrate as much as possible all of the logic from this class to a ViewController, to take advantage of the extra functionality etc in viewcontrollers. All my images and imageViews are initialized like the following in my applicationDidFinishLaunching. img = [UIImage imageWithContentsOfFile:[[NSBundle mainBundle] pathForResource:@image1.jpg" ofType:nil]]; imgView = [[UIImageView alloc] initWithImage:img]; How would I migrate this to a ViewController based application? Where would I put all of the logic currently in my applicationDidFinishLaunching method, or for loading of images, is it necessary to only load them here? Any feedback, tips, suggestions appreciated.

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  • Would ViewModels fit in the Model View Presenter pattern?

    - by Jonn
    Having used ViewModels in MVC, I was wondering if applying the same to the MVP pattern is practical. I only have a few considerations, one being that MVP is already fairly hard to implement (with all the additional coding, not much on the seeming complexity) or that ViewModels already have a slightly similar way of modeling data or entities. Would adding another layer in the form of ViewModels be redundant or is it a logical abstraction that I, as one implementing the MVP pattern, should adhere to?

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  • Communication between layers in an application

    - by Petar Minchev
    Hi guys! Let's assume we have the following method in the business layer. What's the best practice to tell the UI layer that something went wrong and give also the error message? Should the method return an empty String when it was OK, otherwise the error message, or should it throw another exception in the catch code wrapping the caught exception? If we choose the second variant then the UI should have another try,catch which is too much try,catch maybe. Here is a pseudocode for the first variant. public String updateSomething() { try { //Begin transaction here dataLayer.do1(); dataLayer.do2(); dataLayer.doN(); } catch(Exception exc) { //Rollback transaction code here return exc.message; } return ""; } Is this a good practice or should I throw another exception in the catch(then the method will be void)?

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