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• DataGridView Selected Row Move UP and DOWN

  - by Silly Rabbit

  How can I allow selected rows in a DataGridView (DGV) to be moved up or down. I have done this before with a ListView. Unfortunetly, for me, replacing the DGV is not an option (curses). By the way, the DGV datasource is a Generic Collection. The DGV has two buttons on the side, yes, UP & Down. Can anyone help point me in the right direction. I do have the code that I used for the ListView if it'll help (it did not help me).

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• Silverlight: DataContractSerializer cannot handle read only collection properties

  - by moonground.de

  Hey Stackoverflowers :) For our Silverlight Project (SL4) I'm using a Model which might contain Lists (IList<AnotherModel>). According to good practice and rule CA2227:CollectionPropertiesShouldBeReadOnly the IList properties don't have a public setter. We serialize the Model using the DataContractSerializer which is working. But when I try to deserialize, a SecurityException is thrown by DataContractSerializer's ReadObject(Stream) Method, complaining that the target property (pointing to the IList property) cannot be set due to a missing public setter. Since the DataContractSerializer is sealed and neither extendable nor flexible so I currently see no chance to add some kind of additional rules which allow to deserialize the ILists using a foreach-loop on Add() method or some other method of transferring the collection items. I've also tried to dig into DataContractSerializer source (using Reflector) to create a little fork but it looks like i'd have to dig very deep and replicating whole serialization classes doesn't seem to be a viable solution. Do you see another chance to serialize a List with no public setter using the DataContractSerializer? Thank you very much in advance for your ideas! Thomas

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• How can I dynamically access user control properties?

  - by rahkim

  Im trying to create a "user control menu" where links to a page's usercontrols are placed at the top of the page. This will allow me to put several usercontrols on a page and allow the user to jump to that section of the page without scrolling so much. In order to do this, I put each usercontrol in a folder (usercontrols) and gave each control a Description property (<%@ Control Language="C#" Description = "Vehicles" .... %>). My question is how can I access this description dynamically? I want to use this description as the link in my menu. So far, I have a foreach on my page that looks in the ControlCollection for a control that is of the ASP.usercontrols type. If it is I would assume that I could access its attributes and grab that description property. How can I do this? (Im also open to a better way to achieve my "user control menu", but maybe thats another question.) Should I use ((System.Web.UI.UserControl)mydynamiccontrol).Attributes.Keys?

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• Duplicate a collection of entities and persist in Hibernate/JPA

  - by Michael Bavin

  Hi, I want to duplicate a collection of entities in my database. I retreive the collection with: CategoryHistory chNew = new CategoryHistory(); CategoryHistory chLast = (CategoryHistory)em.createQuery("SELECT ch from CategoryHistory ch WHERE ch.date = MAX(date)").getSingleResult; List<Category> categories = chLast.getCategories(); chNew.addCategories(categories)// Should be a copy of the categories: OneToMany Now i want to duplicate a list of 'categories' and persist it with EntityManager. I'm using JPA/Hibernate. UPDATE After knowing how to detach my entities, i need to know what to detach: current code: CategoryHistory chLast = (CategoryHistory)em.createQuery("SELECT ch from CategoryHistory ch WHERE ch.date=(SELECT MAX(date) from CategoryHistory)").getSingleResult(); Set<Category> categories =chLast.getCategories(); //detach org.hibernate.Session session = ((org.hibernate.ejb.EntityManagerImpl) em.getDelegate()).getSession(); session.evict(chLast);//detaches also its child-entities? //set the realations chNew.setCategories(categories); for (Category category : categories) { category.setCategoryHistory(chNew); } //set now create date chNew.setDate(Calendar.getInstance().getTime()); //persist em.persist(chNew); This throws a failed to lazily initialize a collection of role: entities.CategoryHistory.categories, no session or session was closed exception. I think he wants to lazy load the categories again, as i have them detached. What should i do now?

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• Interpolating Large Datasets On the Fly

  - by Karl

  Interpolating Large Datasets I have a large data set of about 0.5million records representing the exchange rate between the USD / GBP over the course of a given day. I have an application that wants to be able to graph this data or maybe a subset. For obvious reasons I do not want to plot 0.5 million points on my graph. What I need is a smaller data set (100 points or so) which accurately (as possible) represents the given data. Does anyone know of any interesting and performant ways this data can be achieved? Cheers, Karl

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• Dictionary returning a default value if the key does not exist

  - by wasatz

  I find myself using the current pattern quite often in my code nowadays var dictionary = new Dictionary<type, IList<othertype>>(); // Add stuff to dictionary var somethingElse = dictionary.ContainsKey(key) ? dictionary[key] : new List<othertype>(); // Do work with the somethingelse variable Or sometimes var dictionary = new Dictionary<type, IList<othertype>>(); // Add stuff to dictionary IList<othertype> somethingElse; if(!dictionary.TryGetValue(key, out somethingElse) { somethingElse = new List<othertype>(); } Both of these ways feel quite roundabout. What I really would like is something like dictionary.GetValueOrDefault(key) Now, I could write an extension method for the dictionary class that does this for me, but I figured that I might be missing something that already exists. SO, is there a way to do this in a way that is more "easy on the eyes" without writing an extension method to dictionary?

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• Android: retrieving all Drawable resources from Resources object

  - by Matt Huggins

  In my Android project, I want to loop through the entire collection of Drawable resources. Normally, you can only retrieve a specific resource via its ID using something like: InputStream is = Resources.getSystem().openRawResource(resourceId) However, I want to get all Drawable resources where I won't know their ID's beforehand. Is there a collection I can loop through or perhaps a way to get the list of resource ID's given the resources in my project? Or, is there a way for me in Java to extract all property values from the R.drawable static class?

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• Hibernate Collection chaining

  - by Anantha Kumaran

  I have two Entities University courses Course students i want to access all the students in a university. I tried the following query select u.courses.students from university u i got the following exception. org.hibernate.QueryException: illegal attempt to dereference collection [university0_.id.courses] with element property reference [students] [ select u.courses.students from com.socialsite.persistence.University u ] at org.hibernate.hql.ast.tree.DotNode$1.buildIllegalCollectionDereferenceException(DotNode.java:46) ..... can anyone explain what is wrong with this?

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• Lists NotifyPropertyChanging

  - by Carlo

  Well BindingList and ObservableCollection work great to keep data updated and to notify when one of it's objects has changed. However, when notifying a property is about to change, I think these options are not very good. What I have to do right now to solve this (and I warn this is not elegant AT ALL), is to implement INotifyPropertyChanging on the list's type object and then tie that to the object that holds the list PropertyChanging event, or something like the following: // this object will be the type of the BindingList public class SomeObject : INotifyPropertyChanging, INotifyPropertyChanged { private int _intProperty = 0; private string _strProperty = String.Empty; public int IntProperty { get { return this._intProperty; } set { if (this._intProperty != value) { NotifyPropertyChanging("IntProperty"); this._intProperty = value; NotifyPropertyChanged("IntProperty"); } } } public string StrProperty { get { return this._strProperty; } set { if (this._strProperty != value) { NotifyPropertyChanging("StrProperty"); this._strProperty = value; NotifyPropertyChanged("StrProperty"); } } } #region INotifyPropertyChanging Members public event PropertyChangingEventHandler PropertyChanging; #endregion #region INotifyPropertyChanged Members public event PropertyChangedEventHandler PropertyChanged; #endregion public void NotifyPropertyChanging(string propertyName) { if (this.PropertyChanging != null) PropertyChanging(this, new PropertyChangingEventArgs(propertyName)); } public void NotifyPropertyChanged(string propertyName) { if (this.PropertyChanged != null) PropertyChanged(this, new PropertyChangedEventArgs(propertyName)); } } public class ObjectThatHoldsTheList : INotifyPropertyChanging, INotifyPropertyChanged { public BindingList<SomeObject> BindingList { get; set; } public ObjectThatHoldsTheList() { this.BindingList = new BindingList<SomeObject>(); } // this helps notifie Changing and Changed on Add private void AddItem(SomeObject someObject) { // this will tie the PropertyChanging and PropertyChanged events of SomeObject to this object // so it gets notifies because the BindingList does not notify PropertyCHANGING someObject.PropertyChanging += new PropertyChangingEventHandler(someObject_PropertyChanging); someObject.PropertyChanged += new PropertyChangedEventHandler(someObject_PropertyChanged); this.NotifyPropertyChanging("BindingList"); this.BindingList.Add(someObject); this.NotifyPropertyChanged("BindingList"); } // this helps notifies Changing and Changed on Delete private void DeleteItem(SomeObject someObject) { if (this.BindingList.IndexOf(someObject) > 0) { // this unlinks the handlers so the garbage collector can clear the objects someObject.PropertyChanging -= new PropertyChangingEventHandler(someObject_PropertyChanging); someObject.PropertyChanged -= new PropertyChangedEventHandler(someObject_PropertyChanged); } this.NotifyPropertyChanging("BindingList"); this.BindingList.Remove(someObject); this.NotifyPropertyChanged("BindingList"); } // this notifies an item in the list is about to change void someObject_PropertyChanging(object sender, PropertyChangingEventArgs e) { NotifyPropertyChanging("BindingList." + e.PropertyName); } // this notifies an item in the list has changed void someObject_PropertyChanged(object sender, PropertyChangedEventArgs e) { NotifyPropertyChanged("BindingList." + e.PropertyName); } #region INotifyPropertyChanging Members public event PropertyChangingEventHandler PropertyChanging; #endregion #region INotifyPropertyChanged Members public event PropertyChangedEventHandler PropertyChanged; #endregion public void NotifyPropertyChanging(string propertyName) { if (this.PropertyChanging != null) PropertyChanging(this, new PropertyChangingEventArgs(propertyName)); } public void NotifyPropertyChanged(string propertyName) { if (this.PropertyChanged != null) PropertyChanged(this, new PropertyChangedEventArgs(propertyName)); } } Sorry, I know this is a lot of code, which takes me back to my main point IT'S A LOT OF CODE to implement this. So my question is, does anyone know a better, shorter, more elegant solution? Thanks for your time and suggestions.

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• Convert Collection to List

  - by Mercer

  Hello, I want to say how to convert a Collection to a List in Java

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• HashSet vs. List performance

  - by Michael Damatov

  It's clear that a search performance of the generic HashSet<T> class is higher than of the generic List<T> class. Just compare the hash-based key with the linear approach in the List<T> class. However calculating a hash key may itself take some CPU cycles, so for a small amount of items the linear search can be a real alternative to the HashSet<T>. My question: where is the break-even? To simplify the scenario (and to be fair) let's assume that the List<T> class uses the element's Equals() method to identify an item.

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• SelectedItem of listbox - BindableCollection is binded on listbox

  - by user572844

  Hi, I bind BindableCollection from caliburn micro on listbox. Also I bind selected listbox item on property in view model. After I select some item on listbox, property SelectedFriedn which is bind on SelectedItem of listbox is still null. Code from view model: private BindableCollection<UserInfo> _friends; //bind on listbox public BindableCollection<UserInfo> Friends { get { return _friends; } set { _friends = value; NotifyOfPropertyChange(() => Friends); } } private UserInfo _selectedFriend = new UserInfo(); //bind on SelectedItem property of listbox public UserInfo SelectedFriend { get { return _selectedFriend; } set { _selectedFriend = value; NotifyOfPropertyChange(() => SelectedFriend); } } In view I have this: <ListBox Name="Friends" SelectedIndex="{Binding Path=SelectedFriendsIndex,Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}" SelectedItem="{Binding Path=SelectedFriend, Mode=OneWay, UpdateSourceTrigger=PropertyChanged}" Style="{DynamicResource friendsListStyle}" IsTextSearchEnabled="True" TextSearch.TextPath="Nick" Grid.Row="2" Margin="4,4,4,4" PreviewMouseRightButtonUp="ListBox_PreviewMouseRightButtonUp" PreviewMouseRightButtonDown="ListBox_PreviewMouseRightButtonDown" MouseRightButtonDown="ListBox_MouseRightButtonDown" Micro:Message.Attach="[MouseDoubleClick]=[Action OpenChatScreen()]" > Where can be problem?

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• IEnumerable<T>.Concat -- A replacement that can work without changing the reference?

  - by Earlz

  Hello, I've recently been bitten by the (way too commmon in my opinion) gotcha of Concat returns it's result, rather than appending to the list itself. For instance. List<Control> mylist=new List<Control>; //.... after adding Controls into mylist MyPanel.Controls.Concat(mylist); //This will not affect MyPanel.Controls at all. MyPanel.Controls=MyPanel.Controls.Concat(mylist); //This is what is needed, but the Controls reference can not be reassigned (for good reason) So is there some other way of combining two lists that will work when the collection reference is read-only? Is the only way to do this with a foreach? foreach(var item in mylist){ MyPanel.Controls.Add(item); } Is there a better way without the foreach?

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• document.getElementById('').length = 0 doesn't work under Win7

  - by Syom

  I have a select list: <select id="sel"> <option>text1</option> <option>text2</option> <option>text3</option> <option>text4</option> </select> I want to delete all items, without for loop. I tried: document.getElementById('sel').length = 0; But this doesn't work in some browsers. Any ideas? Thanks

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• performance of linq extension method ElementAt

  - by Fabiano

  Hi The MSDN library entry to Enumerable.ElementAt(TSource) Method says "If the type of source implements IList, that implementation is used to obtain the element at the specified index. Otherwise, this method obtains the specified element." Let's say we have following example: ICollection<int> col = new List<int>() { /* fill with items */ }; IList<int> list = new List<int>() { /* fill with items */ }; col.ElementAt(10000000); list.ElementAt(10000000); Is there any difference in execution? or does ElementAt recognize that col also implements IList< although it's only declared as ICollection<? Thanks

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• Mapping a collection of enums with NHibernate

  - by beaufabry

  Mapping a collection of enums with NHibernate Specifically, using Attributes for the mappings. Currently I have this working mapping the collection as type Int32 and NH seems to take care of it, but it's not exactly ideal. The error I receive is "Unable to determine type" when trying to map the collection as of the type of the enum I am trying to map. I found a post that said to define a class as public class CEnumType : EnumStringType { public CEnumType() : base(MyEnum) { } } and then map the enum as CEnumType, but this gives "CEnumType is not mapped" or something similar. So has anyone got experience doing this? So anyway, just a simple reference code snippet to give an example with [NHibernate.Mapping.Attributes.Class(Table = "OurClass")] public class CClass : CBaseObject { public enum EAction { do_action, do_other_action }; private IList<EAction> m_class_actions = new List<EAction>(); [NHibernate.Mapping.Attributes.Bag(0, Table = "ClassActions", Cascade="all", Fetch = CollectionFetchMode.Select, Lazy = false)] [NHibernate.Mapping.Attributes.Key(1, Column = "Class_ID")] [NHibernate.Mapping.Attributes.Element(2, Column = "EAction", Type = "Int32")] public virtual IList<EAction> Actions { get { return m_class_actions; } set { m_class_actions = value;} } } So, anyone got the correct attributes for me to map this collection of enums as actual enums? It would be really nice if they were stored in the db as strings instead of ints too but it's not completely necessary.

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• C# Winforms: PropertyGrid not updated when item added to Collection

  - by MysticEarth

  I've got a custom class which can be edited through the PropertyGrid. In that class I've got a custom Collection (with custom PropertyDescriptor and TypeConverter). Items can be added to or removed from the Collection with the default Collection Editor. This all works fine. But - after closing the Collection Editor, the PropertyGrid is not updated. When I manual make a call to Refresh() on the PropertyGrid, the changes are reflected in the PropertyGrid. How can I get the PropertyGrid to automatically refresh when the Collection Editor has been closed? I sought for a solution earlier where I should subclass CollectionEditor (which I can't seem to find). Please help.

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• NameValueCollection vs Dictionary<string,string>

  - by frankadelic

  Any reason I should use Dictionary<string,string instead of NameValueCollection? (in C# / .NET Framework) Option 1, using NameValueCollection: //enter values: NameValueCollection nvc = new NameValueCollection() { {"key1", "value1"}, {"key2", "value2"}, {"key3", "value3"} }; // retrieve values: foreach(string key in nvc.AllKeys) { string value = nvc[key]; // do something } Option 2, using Dictionary<string,string... //enter values: Dictionary<string, string> dict = new Dictionary<string, string>() { {"key1", "value1"}, {"key2", "value2"}, {"key3", "value3"} }; // retrieve values: foreach (KeyValuePair<string, string> kvp in dict) { string key = kvp.Key; string val = kvp.Value; // do something } For these use cases, is there any advantage to use one versus the other? Any difference in performance, memory use, sort order, etc.?

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• "Collection was modified..." Issue

  - by Tyler Murry

  Hey guys, I've got a function that checks a list of objects to see if they've been clicked and fires the OnClick events accordingly. I believe the function is working correctly, however I'm having an issue: When I hook onto one of the OnClick events and remove and insert the element into a different position in the list (typical functionality for this program), I get the "Collection was modified..." error. I believe I understand what is going on: The function cycles through each object firing OnClick events where necessary An event is fired and the object changes places in the list per the hooked function An exception is thrown for modifying the collection while iterating through it My question is, how to do I allow the function to iterate through all the objects, fire the necessary events at the proper time and still give the user the option of manipulating the object's position in the list? Thanks, Tyler

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• Returning IEnumerable from an indexer, bad practice?

  - by fearofawhackplanet

  If I had a CarsDataStore representing a table something like: Cars -------------- Ford | Fiesta Ford | Escort Ford | Orion Fiat | Uno Fiat | Panda Then I could do IEnumerable<Cars> fords = CarsDataStore["Ford"]; Is this a bad idea? It's iconsistent with the other datastore objects in my api (which all have a single column PK indexer), and I'm guessing most people don't expect an indexer to return a collection in this situation.

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• Bind a Java Collection to xQuery sequence from xQuery

  - by jtzero

  declare function Error:toString($this as javaObject) as xs:string external; the previous binds a return String() to xs:string. is it possible to return a collection and bind it to an xQuery Sequence, say the following declare function Error:toList($this as javaObject) as squenceType external; so that it can be run through a flwr?

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• Language Tricks to Shorten My Java Code?

  - by yar

  I am currently rediscovering Java (working with Ruby a lot recently), and I love the compilation-time checking of everything. It makes refactoring so easy. However, I miss playing fast-and-loose with types to do an each loop. This is my worst code. Is this as short as it can be? I have a collection called looperTracks, which has instances that implement Looper. I don't want to modify that collection, but I want to iterate through its members PLUS the this (which also implements Looper). List<Looper> allLoopers = new ArrayList<Looper>(looperTracks.length + 1); for (LooperTrack track : looperTracks) { allLoopers.add(track); } allLoopers.add(this); for (Looper looper : allLoopers) { // Finally! I have a looper I'm particularly concerned about any features that are new to Java from 1.5 on that I may have missed. For this question I am not asking about JRuby nor Groovy, though I know that they would work for this. Edit: Sorry (too much Ruby!)... looperTracks is of type LooperTrack[] and LooperTrack implements Looper.

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• ASP.NET MVC2: Can you get ModelMetadata.ContainerType from within a collection?

  - by CodeSponge

  I'm trying to call DisplayFor and DisplayForModel to iterate an IEnumerable< with various element types from within a view. I have Templates defined for each element/Model type. What I would like to do is check the ViewData.ModelMetadata.ContainerType from within the Template so that Template can determine if it was called as part of a collection. A simple example: Index1.aspx: To render a collection of Foos. <%@ Page Language="C#" MasterPageFile="~/Views/Shared/Site.Master" Inherits="System.Web.Mvc.ViewPage<IEnumerable<Foo>>" %> <asp:Content ContentPlaceHolderID="MainPlaceHolder" runat="server"> <ul><%:Html.DisplayForModel()%></ul> </asp:Content> Index2.aspx: To render a Foo. <%@ Page Language="C#" MasterPageFile="~/Views/Shared/Site.Master" Inherits="System.Web.Mvc.ViewPage<Foo>" %> <asp:Content ContentPlaceHolderID="MainPlaceHolder" runat="server"> <%:Html.DisplayForModel()%> </asp:Content> Shared\DisplayTemplates\Foo.ascx: A context aware Template for Foo. <%@ Control Language="C#" Inherits="System.Web.Mvc.ViewUserControl<Foo>" %> <% var tag = typeof(IEnumerable).IsAssignableFrom(ViewData.ModelMetaData.ContainerType) ? "li" : "div"; %> <<%:tag%>><%:Model.Name%></<%:tag%>> The problem with this example is that ViewData.ModelMetaData.ContainerType is null in the Template when resolved though Index1.aspx. From what I've read on Brad Wilson post and others it has to do with the use of IEnumerable and its being an interface. Is there a way to insure that the ContainerType is set? Perhaps by creating a ModelMetadataProviders? I looked into that breifly but it appears the ContainerType value is determined before and then passed to the Provider. Any suggestions would be appreciated.

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• Hibernate - query caching/second level cache does not work by value object containing subitems

  - by Zoltan Hamori

  Hi! I have been struggling with the following problem: I have a value object containing different panels. Each panel has a list of fields. Mapping: <class name="com.aviseurope.core.application.RACountryPanels" table="CTRY" schema="DBDEV1A" where="PEARL_CTRY='Y'" lazy="join"> <cache usage="read-only"/> <id name="ctryCode"> <column name="CTRY_CD_ID" sql-type="VARCHAR2(2)" not-null="true"/> </id> <bag name="panelPE" table="RA_COUNTRY_MAPPING" fetch="join" where="MANDATORY_FLAG!='N'"> <key column="COUNTRY_LOCATION_ID"/> <many-to-many class="com.aviseurope.core.application.RAFieldVO" column="RA_FIELD_MID" where="PANEL_ID='PE'"/> </bag> </class> I use the following criteria to get the value object: Session m_Session = HibernateUtil.currentSession(); m_Criteria = m_Session.createCriteria(RACountryPanels.class); m_Criteria.add(Expression.eq("ctryCode", p_Country)); m_Criteria.setCacheable(true); As I see the query cache contains only the main select like select * from CTRY where ctry_cd_id=? Both RACountryPanels and RAFieldVO are second level cached. If I check the 2nd level cache content I can see that it cointains the RAFields and the RACountryPanels as well and I can see the select .. from CTRY where ctry_cd_id=... in query cache region as well. When I call the servlet it seems that it is using the cache, but second time not. If I check the content of the cache using JMX, everything seems to be ok, but when I measure the object access time, it seems that it does not always use the cache. Cheers Zoltan

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• Generic Dictionary and generating a hashcode for multi-part key

  - by Andrew

  I have an object that has a multi-part key and I am struggling to find a suitable way override GetHashCode. An example of what the class looks like is. public class wibble{ public int keypart1 {get; set;} public int keypart2 {get; set;} public int keypart3 {get; set;} public int keypart4 {get; set;} public int keypart5 {get; set;} public int keypart6 {get; set;} public int keypart7 {get; set;} public single value {get; set;} } Note in just about every instance of the class no more than 2 or 3 of the keyparts would have a value greater than 0. Any ideas on how best to generate a unique hashcode in this situation? I have also been playing around with creating a key that is not unique, but spreads the objects evenly between the dictionaries buckets and then storing objects with matched hashes in a List< or LinkedList< or SortedList<. Any thoughts on this?

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