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  • Unit of Work Pattern in .Net

    - by Jazza
    Does anyone have any concrete examples of a simple Unit of Work pattern in C# or Visual Basic that would handle the following scenario? I'm writing a WinForms application in which a customer can have multiple addresses associated with it. The user can add, edit and delete addresses belonging to the customer before the customer is saved back to the database. Therefore, at the time of saving, all the original addresses need to be deleted from the database and the new addresses added in a single transaction.

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  • Using ViewModel Pattern with MVC 2 Strongly Typed HTML Helpers

    - by Brettski
    I am working with ASP.NET MVC2 RC and can't figure out how to get the HTML helper, TextBoxfor to work with a ViewModel pattern. When used on an edit page the data is not saved when UpdateModel() is called in the controller. I have taken the following code examples from the NerdDinner application. Edit.aspx <%@ Language="C#" Inherits="System.Web.Mvc.ViewUserControl<NerdDinner.Models.DinnerFormViewModel>" %> ... <p> // This works when saving in controller (MVC 1) <label for="Title">Dinner Title:</label> <%= Html.TextBox("Title", Model.Dinner.Title) %> <%= Html.ValidationMessage("Title", "*") %> </p> <p> // This does not work when saving in the controller (MVC 2) <label for="Title">Dinner Title:</label> <%= Html.TextBoxFor(model => model.Dinner.Title) %> <%= Html.ValidationMessageFor(model=> model.Dinner.Title) %> </p> DinnerController // POST: /Dinners/Edit/5 [HttpPost, Authorize] public ActionResult Edit(int id, FormCollection collection) { Dinner dinner = dinnerRepository.GetDinner(id); if (!dinner.IsHostedBy(User.Identity.Name)) return View("InvalidOwner"); try { UpdateModel(dinner); dinnerRepository.Save(); return RedirectToAction("Details", new { id=dinner.DinnerID }); } catch { ModelState.AddModelErrors(dinner.GetRuleViolations()); return View(new DinnerFormViewModel(dinner)); } } When the original helper style is used (Http.TextBox) the UpdateModel(dinner) call works as expected and the new values are saved. When the new (MVC2) helper style is used (Http.TextBoxFor) the UpdateModel(dinner) call does not update the values. Yes, the current values are loaded into the edit page on load. Is there something else which I need to add to the controller code for it to work? The new helper works fine if I am just using a model and not a ViewModel pattern. Thank you.

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  • Data access pattern, combining push and pull?

    - by andlju
    I need some advice on what kind of pattern(s) I should use for pushing/pulling data into my application. I'm writing a rule-engine that needs to hold quite a large amount of data in-memory in order to be efficient enough. I have some rather conflicting requirements; It is not acceptable for the engine to always have to wait for a full pre-load of all data before it is functional. Only fetching and caching data on-demand will lead to the engine taking too long before it is running quickly enough. An external event can trigger the need for specific parts of the data to be reloaded. Basically, I think I need a combination of pushing and pulling data into the application. A simplified version of my current "pattern" looks like this (in psuedo-C# written in notepad): // This interface is implemented by all classes that needs the data interface IDataSubscriber { void RegisterData(Entity data); } // This interface is implemented by the data access class interface IDataProvider { void EnsureLoaded(Key dataKey); void RegisterSubscriber(IDataSubscriber subscriber); } class MyClassThatNeedsData : IDataSubscriber { IDataProvider _provider; MyClassThatNeedsData(IDataProvider provider) { _provider = provider; _provider.RegisterSubscriber(this); } public void RegisterData(Entity data) { // Save data for later StoreDataInCache(data); } void UseData(Key key) { // Make sure that the data has been stored in cache _provider.EnsureLoaded(key); Entity data = GetDataFromCache(key); } } class MyDataProvider : IDataProvider { List<IDataSubscriber> _subscribers; // Make sure that the data for key has been loaded to all subscribers public void EnsureLoaded(Key key) { if (HasKeyBeenMarkedAsLoaded(key)) return; PublishDataToSubscribers(key); MarkKeyAsLoaded(key); } // Force all subscribers to get a new version of the data for key public void ForceReload(Key key) { PublishDataToSubscribers(key); MarkKeyAsLoaded(key); } void PublishDataToSubscribers(Key key) { Entity data = FetchDataFromStore(key); foreach(var subscriber in _subscribers) { subscriber.RegisterData(data); } } } // This class will be spun off on startup and should make sure that all data is // preloaded as quickly as possible class MyPreloadingThread { IDataProvider _provider; MyPreloadingThread(IDataProvider provider) { _provider = provider; } void RunInBackground() { IEnumerable<Key> allKeys = GetAllKeys(); foreach(var key in allKeys) { _provider.EnsureLoaded(key); } } } I have a feeling though that this is not necessarily the best way of doing this.. Just the fact that explaining it seems to take two pages feels like an indication.. Any ideas? Any patterns out there I should have a look at?

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  • Specification Pattern vs Spec in BDD

    - by cadmium
    I'm trying to explore Behavior Driven Design and Domain Driven Design. I'm getting that written specifications drive the tests in BDD, but also that business logic can be encapsulated using the specification pattern for re-use in domain objects and repositories, etc. Are these basically the same concept just used in different ways, used in conjunction together, or am I completely confusing the concepts? Please shed some light, if possible.

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  • Unit of Work pattern and persistence

    - by Mosh
    Hello, I have been reading about Unit of Work pattern but I am confused about how the UoW actually persists data. When we commit the changes, UoW should iterate through the list of Added, Updated and Deleted objects and somehow find a class responsible to Add, Update, Delete objects of a certain type. I couldn't find an example showing this technique. Any advice on this would be greatly appreciated. Mosh

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  • Decorator pattern in C++

    - by AlgoMan
    Can someone give me an example of Decorator pattern in C++ ? I have come across the Java version of it. But C++ i have found it difficult to understand the examples that are given.

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  • decorator pattern

    - by vbNewbie
    I have a program that converts currency using a specific design pattern. I now need to take my converted result and using the decorator pattern allow the result to be converted to 3 different formats: 1 - exponential notation, rounded to 2 decimal points. using System; using System.Collections.Generic; using System.ComponentModel; using System.Data; using System.Drawing; using System.Text; using System.Windows.Forms; namespace Converter { public partial class Form1 : Form { // Setup Chain of Responsibility Handler h1 = new USDHandler(); Handler h2 = new CADHandler(); Handler h3 = new AUDHandler(); public string reqCurName; public int reqAmt; public string results; public string requestID; public Form1() { InitializeComponent(); h1.SetSuccessor(h2); h2.SetSuccessor(h3); } // "Handler" private void button1_Click_1(object sender, EventArgs e) { reqCurName = txtInput.Text; reqAmt = Convert.ToInt32(txtAmt.Text.ToString()); results = h1.HandleRequest(reqCurName, reqAmt); if (results != "") { lblResult.Text = results; lblResult.Visible = true; } } abstract class Handler { protected Handler successor; public string retrn; public void SetSuccessor(Handler successor) { this.successor = successor; } public abstract string HandleRequest(string requestID, int reqAmt); } // "USD Handler" class USDHandler : Handler { public override string HandleRequest(string requestID, int reqAmt) { if (requestID == "USD") { retrn = "Request handled by " + this.GetType().Name + " \nConversion from Euro to USD is " + reqAmt/0.630479; return (retrn); } else if (successor != null) { retrn = successor.HandleRequest(requestID, reqAmt); } return (retrn); } } // "CAD Handler" class CADHandler : Handler { public override string HandleRequest(string requestID, int reqAmt) { if (requestID == "CAD") { retrn = "Request handled by " + this.GetType().Name + " \nConversion from Euro to CAD is " + reqAmt /0.617971; return (retrn); } else if (successor != null) { retrn = successor.HandleRequest(requestID, reqAmt); } return (retrn); } } // "AUD Handler" class AUDHandler : Handler { public override string HandleRequest(string requestID, int reqAmt) { if (requestID == "AUD") { requestID = "Request handled by " + this.GetType().Name + " \nConversion from Euro to AUD is " + reqAmt / 0.585386; return (requestID); } else if (successor != null) { retrn = successor.HandleRequest(requestID, reqAmt); } return (requestID); } } } }

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  • preg_replace Pattern

    - by codeworxx
    Hey Guys, i'm not very firm with preg_replace - in other Words i do not really understand - so i hope you can help me. I have a string in a Text like this one: [demo category=1] and want to replace with the Content of Category (id=1) e.g. "This is the Content of my first Category" This is my startpoint Pattern - that's all i have: '/[demo\s*.*?]/i'; Hope you can help? Thanks, Sascha

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  • Is this a dangerous locking pattern?

    - by Martin
    I have an enumerator written in C#, which looks something like this: try { ReadWriteLock.EnterReadLock(); yield foo; yield bar; yield bash; } finally { ReadWriteLock.ExitReadLock(); } I believe this may be a dangerous locking pattern, as the ReadWriteLock will only be released if the enumeration is complete, otherwise the lock is left hanging and is never released, am I correct? If so, what's the best way to combat this?

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  • multi-line pattern matching in pyhon

    - by Horace Ho
    A periodic computer generated message (simplified): Hello user123, - (604)7080900 - 152 - minutes Regards Using python, how can I extract "(604)7080900", "152", "minutes" (i.e. any text following a leading "- " pattern) between the two empty lines (empty line is the \n\n after "Hello user123" and the \n\n before "Regards"). Even better if the result string list are stored in an array. Thanks!

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  • Are Maybes a good pattern for scala?

    - by Fred Haslam
    For a while I have been struggling to integrate scala with java methods that might return null. I came up with the following utility which helps a lot: // produce an Option, nulls become None object Maybe { def apply[T](t:T) = if (t==null) None else Some(t) } Maybe(javaClass.getResultCouldBeNull()).map( result => doSomeWork(result) ) I have a few questions about this solution: Is there a better or more standard pattern to use? Am I duplicating something that already exists? Does this functionality have hidden gotchas?

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  • VBA regex pattern

    - by KeyMs92
    This is probably a simple problem, but unfortunately I wasn't able to get the results I wanted... Say, I have the following line: "Wouldn't It Be Nice" (B. Wilson/Asher/Love) I would have to look for this pattern: " (<any string>) In order to retrieve: B. Wilson/Asher/Love I tried something like "" (([^))]*)) but it doesn't seem to work. Also, I'd like to use Match.Submatches(0) so that might complicate things a bit because it relies on brackets...

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  • Recursively add files by pattern

    - by Michel Krämer
    How do I recursively add files by a pattern (or glob) located in different directories? For example, I'd like to add A/B/C/foo.java and D/E/F/bar.java (and several other java files) with one command: git add '*.java' Unfortunately, that doesn't work as expected.

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  • [bash] Escape a string for sed search pattern

    - by Alexander Gladysh
    In my bash script I have an external (received from user) string, which I should use in sed pattern. REPLACE="<funny characters here>" sed "s/KEYWORD/$REPLACE/g" How can I escape the $REPLACE string so it would be safely accepted by sed as a literal replacement? NOTE: The KEYWORD is a dumb substring with no matches etc. It is not supplied by user.

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  • Parent child class relationship design pattern

    - by Jeremy
    I have a class which has a list of child items. Is there a design pattern I can copy that I can apply to these classes so that I can access the parent instance from the child, and it enforces rules such as not being able to add the child to multiple parents, etc?

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  • Python singleton pattern

    - by Javier Garcia
    Hi, someone can tell me why this is incorrect as a singleton pattern: class preSingleton(object): def __call__(self): return self singleton = preSingleton() a = singleton() b = singleton() print a==b a.var_in_a = 100 b.var_in_b = 'hello' print a.var_in_b print b.var_in_a Edit: The above code prints: True hello 100 thank you very much

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  • Disposable Registry: good pattern?

    - by illdev
    Imagine a: public class Global : IDisposable { private static readonly List<IDisposable> Disposables = new List<IDisposable>(); public void ApplicationStart() { var heavyLifter = new HeavyLifter(); Disposables.Add(heavyLifter); } public void Dispose() { Disposables.ForEach(d => d.Dispose()); } } I am somewhat inexperienced with IDisposable. Is this a viable pattern?

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  • Makefile generic pattern rule -- xyzzy-en_US.ext2 from xyzzy.ext0

    - by Janne Savukoski
    I can't figure out a way to define a generic pattern rule for the following kind of production with make: require xyzzy-en_US.ext2 from xyzzy.ext0 via xyzzy.ext1. This works: all: xyzzy-en_US.ext2 # to be compiled from xyzzy.ext0 %.ext1 : %.ext0 # produce xyzzy.ext1 %-en_US.ext2 : %.ext1 # produce xyzzy-en_US.ext2 But how to generalize the locale part of the second rule? Or do I need to generate rules for all different locales? Neither of these work: %-??_??.ext2 : %.ext1 # ... %.ext2 : $(@,%-??_??.ext2,%.ext1) # ...

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  • Simple but good pattern for EJB

    - by Sara
    What would you suggest as a good and practical but simple pattern for a soloution with: HTML + JSP (as a view/presentation) SERVLETS (controller, request, session-handling) EJB (persistence, businesslogic) MySQL DB And is it necessary to use an own layer of DAO for persistence? I use JPA to persist objects to my DB. Should I withdraw business logic from my EJB? Sources online all tell me different things and confuses me...

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