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• Passing information safely between Wicket and Hibernate in long running conversations

  - by Peter Tillemans

  We are using Wicket with Hibernate in the background. As part of out UI we have quite long running conversations spanning multiple requests before the updated information is written back to the database. To avoid getting hibernate errors with detached objects we are now using value objects to transfer info from the service layer to Wicket. However we now end up with an explosion of almost the same objects : e.g. Answer (mapped entity saved in hibernate) AnswerVO (immutable value object) AnswerModel (A mutable bean in the session domain) IModel wrapped Wicket Model and usually this gets wrapped in a CompoundPropertyModel This plumbing becomes exponentially worse when collections to other objects are involved in the objects. There has to be a better way to organize this. Can anyone share tips to make this less onerous? Maybe make the value objects mutable so we can remove the need for a seaprate backing bean in Wicket? Use the entity beans but absolutely make dead-certain they are detached from hibernate. (easier said than done)? Some other tricks or patterns?

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• web ui controls and ASP.NET MVC

  - by ognjenb

  Why will not fill View page of this controller method public ActionResult Person() { testEntities6 testPersons = new testEntities6(); IQueryable<person> persons; DropDownLst.Items.Clear(); DropDownLst.Items.Add("proba"); persons = from i in testPersons.person select i; return View(persons); } and include namespaces: using System; using System.Collections.Generic; using System.Linq; using System.Web; using System.Web.Mvc; using System.Web.Mvc.Ajax; using MvcKVteam.Models; using System.Web.UI; using System.Web.UI.WebControls; using System.Web.UI.WebControls.WebParts; using System.Web.UI.HtmlControls; In view page I put this code: <asp:DropDownList ID="IbekoIngDropDownLst" runat="server"> </asp:DropDownList>

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• How to parse XML to flex Data Grid contents.

  - by Jeeva

  My xml file which is in a webserver is show below. <root> <userdetails> <username>raja</username> <status>offline</status> </userdetails> <userdetails> <username>Test</username> <status>online</status> </userdetails> </root> How can i parse this to flex data grid contents. I tried with below coding < ?xml version="1.0" encoding="utf-8"? < mx:Application xmlns:mx="http://www.adobe.com/2006/mxml" layout="absolute" creationComplete="initApp()" < mx:HTTPService id="userList" result="handleData(event)" resultFormat="object" url="http://apps.facebook.com/ajparkin/user_list.xml" / <mx:Script> <![CDATA[ import mx.collections.ArrayCollection; import mx.rpc.events.ResultEvent; import mx.controls.Alert; public function initApp():void { userList.send(); } [Bindable] var userdetailsArray:ArrayCollection; private function handleData(evt:ResultEvent):void { this.userdetailsArray= evt.result.userdetails; } ]]> </mx:Script> <mx:DataGrid dataProvider="{userdetailsArray}"> <mx:columns> <mx:DataGridColumn dataField="username" headerText="User Name"/> <mx:DataGridColumn dataField="status" headerText="Status" /> </mx:columns> </mx:DataGrid> </mx:Application> I'm getting only the field names not the data.

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• How to close all tabs in Safari using AppleScript?

  - by Form

  I have made a very simple AppleScript to close all tabs in Safari. The problem is, it works, but not completely. Here's the code: tell application "Safari" repeat with aWindow in windows repeat with aTab in tabs of aWindow aTab close end repeat end repeat end tell I've also tried this script: tell application "Safari" repeat with i from 0 to the number of items in windows set aWindow to item i of windows repeat with j from 0 to the number of tabs in aWindow set aTab to item j of tabs of aWindow aTab close end repeat end repeat end tell ... but it does not work either. I tried that on my system (MacBook Pro jan 2008), as well as on a Mac Pro G5 under Tiger and the script fails on both, albeit with a much less descriptive error on Tiger. The problem is that only a couple of tabs are closed. Running the script a few times closes a few tab each time until none is left, but always fails with the same error after closing a few tabs. Under Leopard I get an out of bounds error. Since I am using fast enumeration (not using "repeat from 0 to number of items in windows") I don't see how I can get an out of bounds error with this... My goal is to use the Cocoa Scripting Bridge to close tabs in Safari from my Objective-C Cocoa application but the Scripting Bridge fails in the same manner. The non-deletable tabs show as NULL in the Xcode debugger, while the other tabs are valid objects from which I can get values back (such as their title). In fact I tried with the Scripting Bridge first then told myself why not try this directly in AppleScript and I was surprised to see the same results. I must have a glaring omission or something in there... (seems like a bug in Safari AppleScript support to me... :S) I've used repeat loops and Obj-C 2.0 fast enumeration to iterate through collections before with zero problems, so I really don't see what's wrong here. Anyone can help? Thanks in advance!

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• What should the name of this class be?

  - by Tim Murphy

  Naming classes is sometimes hard. What do you think name of the class should be? I originally created the class to use as a cache but can see its may have other uses. Example code to use the class. Dim cache = New NamePendingDictionary(Of String, Sample) Dim value = cache("a", Function() New Sample()) And here is the class that needs a name. ''' <summary> ''' Enhancement of <see cref="System.Collections.Generic.Dictionary"/>. See the Item property ''' for more details. ''' </summary> ''' <typeparam name="TKey">The type of the keys in the dictionary.</typeparam> ''' <typeparam name="TValue">The type of the values in the dictionary.</typeparam> Public Class NamePendingDictionary(Of TKey, TValue) Inherits Dictionary(Of TKey, TValue) Delegate Function DefaultValue() As TValue ''' <summary> ''' Gets or sets the value associated with the specified key. If the specified key does not exist ''' then <paramref name="createDefaultValue"/> is invoked and added to the dictionary. The created ''' value is then returned. ''' </summary> ''' <param name="key">The key of the value to get.</param> ''' <param name="createDefaultValue"> ''' The delegate to invoke if <paramref name="key"/> does not exist in the dictionary. ''' </param> ''' <exception cref="T:System.ArgumentNullException"><paramref name="key" /> is null.</exception> Default Public Overloads ReadOnly Property Item(ByVal key As TKey, ByVal createDefaultValue As DefaultValue) As TValue Get Dim value As TValue If createDefaultValue Is Nothing Then Throw New ArgumentNullException("createValue") End If If Not Me.TryGetValue(key, value) Then value = createDefaultValue.Invoke() Me.Add(key, value) End If Return value End Get End Property End Class

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• how to place dropdown list box in jquery grid column

  - by kumar

  Hello friends, I have a jquery grid columns defined like this.. using System; using System.Collections.Generic; using System.Linq; using System.Web; using Trirand.Web.Mvc; using System.Web.UI.WebControls; namespace JQGridMVCExamples.Models { public class OrdersJqGridModel { public OrdersJqGridModel() { OrdersGrid = new JQGrid { Columns = new List<JQGridColumn>() { new JQGridColumn { DataField = "OrderID", Width = 50 }, new JQGridColumn { DataField = "OrderDate", Width = 100, DataFormatString = "{0:d}" }, new JQGridColumn { DataField = "CustomerID", Width = 100 }, new JQGridColumn { DataField = "Freight", Width = 75 }, new JQGridColumn { DataField = "ShipName" } }, Width = Unit.Pixel(640) }; OrdersGrid.ToolBarSettings.ShowRefreshButton = true; } public JQGrid OrdersGrid { get; set; } } } and in the view I am caling like this <div> <%= Html.Trirand().JQGrid(Model.OrdersGrid, "JQGrid1") %> </div> I am getting result perfect.. but for column Freight in the Jquery grid I need to place a dropdown list dynamically for all result rows.. can anyone help me out.. THanks

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• how can i handle calculator buutons in c# window form program

  - by sama

  using System; using System.Collections.Generic; using System.ComponentModel; using System.Data; using System.Drawing; using System.Linq; using System.Text; using System.Windows.Forms; namespace lab8ass1 { public partial class Form1 : Form { public Form1() { InitializeComponent(); } private void button11_Click(object sender, EventArgs e) { textBox1.Text += "."; } private void btnone_Click(object sender, EventArgs e) { textBox1.Text += "1"; } private void btnrwo_Click(object sender, EventArgs e) { textBox1.Text += "2"; } private void btnthree_Click(object sender, EventArgs e) { textBox1.Text += "3"; } private void btnfour_Click(object sender, EventArgs e) { textBox1.Text += "4"; } private void btnfive_Click(object sender, EventArgs e) { textBox1.Text += "5"; } private void btnsix_Click(object sender, EventArgs e) { textBox1.Text += "6"; } private void btnseven_Click(object sender, EventArgs e) { textBox1.Text += "7"; } private void btneight_Click(object sender, EventArgs e) { textBox1.Text += "8"; } private void btnnine_Click(object sender, EventArgs e) { textBox1.Text += "9"; } private void btnzero_Click(object sender, EventArgs e) { textBox1.Text += "0"; } string s1,s; private void btnplus_Click(object sender, EventArgs e) { s1 = textBox1.Text; textBox1.Text = ""; s = textBox1.Text; //textBox1.Text } private void btnequal_Click(object sender, EventArgs e) { } } } here my code how can i handle calculator buutons

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• Optimizing a bin-placement algorithm

  - by user258651

  Alright, I've got two collections, and I need to place elements from collection1 into the bins (elements) of collection2, based on whether their value falls within a given bin's range. For a concrete example, assume I have a sorted collection objects (bins) which have an int range ([1...4], [5..10], etc). I need to determine the range an int falls in, and place it in the appropriate bin. foreach(element n in collection1) { foreach(bin m in collection2) { if (m.inRange(n)) { m.add(n); break; } } } So the obvious NxM complexity algorithm is there, but I really would like to see Nxlog(M). To do this I'd like to use BinarySearch in place of the inner foreach loop. To use BinarySearch, I need to implement an IComparer class to do the searching for me. The problem I'm running into is this approach would require me to make an IComparer.Compare function that compares two different types of objects (an element to its bin), and that doesn't seem possible or correct. So I'm asking, how should I write this algorithm?

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• Some specific questions about object oriented and MVC design.

  - by Samn

  I have two objects, Users and Mail. Users create Mail objects and send them to other users. If I wanted to get all mail for a User, I could create a method like GetMail() that would return an array of Mail objects owned by that User. But if I wanted to get all mail across the system, what "type" of object would be responsible for that? To solve this problem, I usually create a Manager, which is an object responsible for dealing with a collection of a particular type of object. MailManager deals with collections of Mail objects. GetMailForUser() is one method, GetAllMail() is another method. The User objects invokes the MailManager and executes GetMailForUser(me). Is this stupid? When a user executes the controller CreateMail, a new instance of the Mail object is created. The Mail object, seeing it is creating a new Mail of type 'sent', decides to go ahead and create a second Mail object for the recipient, of type 'received'. Creating one Mail object triggers the creation of a second Mail object. Is this stupid? Should the controller have created both Mail objects, or just the first 'sent' one? When two Users are friends, the association is stored in a table of Relationships. I use a simple object for Relationships. A RelationshipManager has a method called GetFriendsForUser(). The User object has a method GetFriends(), which invokes the RelationshipManager. Is this stupid?

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• Populate a tree from Hierarchical data using 1 LINQ statement

  - by Midhat

  Hi. I have set up this programming exercise. using System; using System.Collections.Generic; using System.Linq; using System.Text; namespace ConsoleApplication2 { class DataObject { public int ID { get; set; } public int ParentID { get; set; } public string Data { get; set; } public DataObject(int id, int pid, string data) { this.ID = id; this.ParentID = pid; this.Data = data; } } class TreeNode { public DataObject Data {get;set;} public List<DataObject> Children { get; set; } } class Program { static void Main(string[] args) { List<DataObject> data = new List<DataObject>(); data.Add(new DataObject(1, 0, "Item 1")); data.Add(new DataObject(2, 0, "Item 2")); data.Add(new DataObject(21, 2, "Item 2.1")); data.Add(new DataObject(22, 2, "Item 2.2")); data.Add(new DataObject(221, 22, "Item 2.2.1")); data.Add(new DataObject(3, 0, "Item 3")); } } } The desired output is a List of 3 treenodes, having items 1, 2 and 3. Item 2 will have a list of 2 dataobjects as its children member and so on. I have been trying to populate this tree (or rather a forest) using just 1 SLOC using LINQ. A simple group by gives me the desired data but the challenge is to organize it in TreeNode objects. Can someone give a hint or an impossibility result for this?

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• What language is this???

  - by Misha Koshelev

  Dear All: I thought this was Javascript... but parser is giving me trouble. Any ideas? Thank you! Misha for (;;); {"error":0,"errorSummary":"","errorDescription":"","errorIsWarning":false,"silentError":0,"payload":{"collections": [{"name":"bcm","type":"flp","filter":"flp_662923563701","value":"662923563701","editable":true,"deletable":true,"members": ["1319651388","539562714","710814793","569071038","1553739575","2413243"]}, {"name":"mstp","type":"flp","filter":"flp_715806870131","value":"715806870131","editable":true,"deletable":true,"members": ["1263807225","1159429816","508447486","508005223","1234906348","642723993","552875889","23401888","10701320","8302901","7931988","3007490","1286522890","1128447272","1076062553","775679867","737520202","640799498","224400055","224400048","14211567","7909445","3005965","2404364","218216","660037273","224400089","73306230","9603033","1111694","1034418884","775680513" ,"704526828","518753881","512477182","224400016","24904610","19000876","5403952","3005641","2100348","100000421128298","1445411167","691445174","1020020100","795471177","683724539","682441089","532450522","224400129","224400005","3006522","2246813","1302265","7197","1900494", "100000474978266","2533582","1205125","1384091677","1260996959","710814793","514951289","224400164","224400156","173601800","13304723","7938844","3004783","3001379","302817","716739950 ","706849","1418109424","562676898","82501644","3007569","13173"]}, {"name":"mystery","type":"flp","filter":"flp_687949656211","value":"687949656211","editable":true,"deletable":true,"members": ["100001286464748","508123007","100001161894460","1148567030","1048974191","769992391","831734347","15347","1297180076","756692945","3005266","733396195","34410910","100000940154241"," 748426280","569417581","1318922027","100000164920046","1475269609","1436536592","10000016210 8385","754095305","100000421128298","537833189","100000692471928","7920231","673753496","3006217","1221878","8365333","1128447272","224400133","218216","505457123","1421958541","183829 5926","2349408","1622810085","1201640391","510959992","23429895","542118016","1017385668","586225579","625100539","100000474886633","26404148","1384091677","224400156","806908635","843 187401","400435","768261176","7901808","748496482","1541469473","2511982","25401573","503715 506","1226000844","559195162","41400094","1099436201","409816","1584400985","1577092523","100000349351880","199301581"]},{"name":"SMS Subscriptions","type":"ms","filter":"ms","value":"3","editable":true,"deletable":false,"members":[]}],"current_view":false}}

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• Dependency Injection into your Singleton

  - by Langali

  I have a singleton that has a spring injected Dao (simplified below): public class MyService<T> implements Service<T> { private final Map<String, T> objects; private static MyService instance; MyDao myDao; public void set MyDao(MyDao myDao) { this. myDao = myDao; } private MyService() { this.objects = Collections.synchronizedMap(new HashMap<String, T>()); // start a background thread that runs for ever } public static synchronized MyService getInstance() { if(instance == null) { instance = new MyService(); } return instance; } public void doSomething() { myDao.persist(objects); } } My spring config will probably look like this: <bean id="service" class="MyService" factory-method="getInstance"/> But this will instantiate the MyService during startup. Is there a programmatic way to do a dependency injection of MyDao into MyService, but not have spring manage the MyService? Basically I want to be able to do this from my code: MyService.getInstance().doSomething(); while having spring inject the MyDao for me.

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• Threadsafe way of exposing keySet()

  - by Jake

  This must be a fairly common occurrence where I have a map and wish to thread-safely expose its key set: public MyClass { Map<String,String> map = // ... public final Set<String> keys() { // returns key set } } Now, if my "map" is not thread-safe, this is not safe: public final Set<String> keys() { return map.keySet(); } And neither is: public final Set<String> keys() { return Collections.unmodifiableSet(map.keySet()); } So I need to create a copy, such as: public final Set<String> keys() { return new HashSet(map.keySet()); } However, this doesn't seem safe either because that constructor traverses the elements of the parameter and add()s them. So while this copying is going on, a ConcurrentModificationException can happen. So then: public final Set<String> keys() { synchronized(map) { return new HashSet(map.keySet()); } } seems like the solution. Does this look right?

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• Proper way to scan a range of IP addresses

  - by Josh G

  Given a range of IP addresses entered by a user (through various means), I want to identify which of these machines have software running that I can talk to. Here's the basic process: Ping these addresses to find available machines Connect to a known socket on the available machines Send a message to the successfully established sockets Compare the response to the expected response Steps 2-4 are straight forward for me. What is the best way to implement the first step in .NET? I'm looking at the System.Net.NetworkInformation.Ping class. Should I ping multiple addresses simultaneously to speed up the process? If I ping one address at a time with a long timeout it could take forever. But with a small timeout, I may miss some machines that are available. Sometimes pings appear to be failing even when I know that the address points to an active machine. Do I need to ping twice in the event of the request getting discarded? To top it all off, when I scan large collections of addresses with the network cable unplugged, Ping throws a NullReferenceException in FreeUnmanagedResources(). !? Any pointers on the best approach to scanning a range of IPs like this?

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• Set .aspx page title to that of an Eval

  - by user1860529

  I am trying to use an <%# Eval("name") %> to be the title of my page. I can't seem to figure out any solutions online. I have tried the other StackOverflow question but that did now work either. The page is a bio.aspx and on the site it is displayed as bio.aspx?id=123 so the page title needs to vary depending on the ID. I figured I could just use the Eval("name") but no luck yet. I currently am using JavaScript: window.onload = function() { document.title = '<%# Eval("name") %> | Title Line'; } This works, but it still leaves the title tags empty, and it's kind of spammy. Here is the codebehind: using System; using System.Data; using System.Configuration; using System.Collections; using System.Web; using System.Web.Security; using System.Web.UI; using System.Web.UI.WebControls; using System.Web.UI.WebControls.WebParts; using System.Web.UI.HtmlControls; public partial class DoctorBio : System.Web.UI.Page { protected void Page_Load(object sender, EventArgs e) { Page.Title = "Your Page Title"; HtmlMeta metaDescription = new HtmlMeta(); metaDescription.Name = "description"; metaDescription.Content = "brief description"; Page.Header.Controls.Add(metaDescription); HtmlMeta metaKeywords = new HtmlMeta(); metaKeywords.Name = "keywords"; metaKeywords.Content = "keywords, keywords"; Page.Header.Controls.Add(metaKeywords); } protected void SetPageTitle(object title) { this.Title = title.ToString(); } protected string ReplaceLineBreaks(object text) { string newText = text as string; if (newText == null) { return string.Empty; } return newText.Replace("\r\n", "<br />"); } }

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• how to Solve the "Digg" problem in MongoDB

  - by user193116

  A while back,a Digg developer had posted this blog ,"http://about.digg.com/blog/looking-future-cassandra", where the he described one of the issues that were not optimally solved in MySQL. This was cited as one of the reasons for their move to Cassandra. I have been playing with MongoDB and I would like to understand how to implement the MongoDB collections for this problem From the article, the schema for this information in MySQL : CREATE TABLE Diggs ( id INT(11), itemid INT(11), userid INT(11), digdate DATETIME, PRIMARY KEY (id), KEY user (userid), KEY item (itemid) ) ENGINE=InnoDB DEFAULT CHARSET=utf8; CREATE TABLE Friends ( id INT(10) AUTO_INCREMENT, userid INT(10), username VARCHAR(15), friendid INT(10), friendname VARCHAR(15), mutual TINYINT(1), date_created DATETIME, PRIMARY KEY (id), UNIQUE KEY Friend_unique (userid,friendid), KEY Friend_friend (friendid) ) ENGINE=InnoDB DEFAULT CHARSET=utf8; This problem is ubiquitous in social networking scenario implementation. People befriend a lot of people and they in turn digg a lot of things. Quickly showing a user what his/her friends are up to is very critical. I understand that several blogs have since then provided a pure RDBMs solution with indexes for this issue; however I am curious as to how this could be solved in MongoDB.

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• How to enumerate word document using office interop API?

  - by Shekhar

  Hello everyone, I want to traverse through all the elements of an word document one by one and according to type of element (header, sentence, table,image,textbox, shape, etc.) I want to process that element. I tried to search any enumerator or object which can represent elements of document in office interop API but failed to find any. API offers sentences, paragraphs, shapes collections but doesnt provide generic object which can point to next element. For example : <header of document> <plain text sentences> <table with many rows,columns> <text box> <image> <footer> (Please imagine it as a word document) So, now I want some enumerator which will first give me <header of document>, then on next iteration give me <plain text sentences>, then <table with many rows,columns> and so on. Does anyone knows how we can achieve this? Is it possible? I am using C#, visual studio 2005 and Word 2003. Thanks a lot

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• Object Design: How to Organize/Structure a "Collection Class"

  - by CrimsonX

  I'm currently struggling to understand how I should organize/structure a class which I have already created. The class does the following: As its input in the constructor, it takes a collection of logs In the constructor it validates and filters the logs through a series of algorithms implementing my business logic After all filtering and validation is complete, it returns a collection (a List) of the valid and filtered logs which can be presented to the user graphically in a UI. Here is some simplified code describing what I'm doing: class FilteredCollection { public FilteredCollection( SpecialArray<MyLog> myLog) { // validate inputs // filter and validate logs in collection // in end, FilteredLogs is ready for access } Public List<MyLog> FilteredLogs{ get; private set;} } However, in order to access this collection, I have to do the following: var filteredCollection = new FilteredCollection( secialArrayInput ); //Example of accessing data filteredCollection.FilteredLogs[5].MyLogData; Other key pieces of input: I foresee only one of these filtered collections existing in the application (therefore should I make it a static class? Or perhaps a singleton?) Testability and flexibility in creation of the object is important (Perhaps therefore I should keep this an instanced class for testability?) I'd prefer to simplify the dereferencing of the logs if at all possible, as the actual variable names are quite long and it takes some 60-80 characters to just get to the actual data. My attempt in keeping this class simple is that the only purpose of the class is to create this collection of validated data. I know that there may be no "perfect" solution here, but I'm really trying to improve my skills with this design and I would greatly appreciate advice to do that. Thanks in advance.

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• Limit TCP requests per IP

  - by asmo

  Hello! I'm wondering how to limit the TCP requests per client (per specific IP) in Java. For example, I would like to allow a maximum of X requests per Y seconds for each client IP. I thought of using static Timer/TimerTask in combination with a HashSet of temporary restricted IPs. private static final Set<InetAddress> restrictedIPs = Collections.synchronizedSet(new HashSet<InetAddress>()); private static final Timer restrictTimer = new Timer(); So when a user connects to the server, I add his IP to the restricted list, and start a task to unrestrict him in X seconds. restrictedIPs.add(socket.getInetAddress()); restrictTimer.schedule(new TimerTask() { public void run() { restrictedIPs.remove(socket.getInetAddress()); } }, MIN_REQUEST_INTERVAL); My problem is that at the time the task will run, the socket object may be closed, and the remote IP address won't be accessible anymore... Any ideas welcomed! Also, if someone knows a Java-framework-built-in way to achieve this, I'd really like to hear it.

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• When are predicates appropriate and what is the best pattern for usage

  - by Maxim Gershkovich

  When are predicates appropriate and what is the best pattern for usage? What are the advantages of predicates? It seems to me like most cases where a predicate can be employed a tight loop would accomplish the same functionality? I don’t see a reusability argument given you will probably only implement a predicate in one method right? They look and feel nice but besides that they seem like you would only employ them when you need a quick hack on the collection classes? UPDATE But why would you be rewriting the tight loop again and again? In my mind/code when it comes to collections I always end up with something like Class Person End Class Class PersonList Inherits List(Of Person) Function FindByName(Name) as Person tight loop.... End Function End Class @Ani By that same logic I could implement the method as such Class PersonList Inherits List(Of Person) Function FindByName(Name) as PersonList End Function Function FindByAge(Age) as PersonList End Function Function FindBySocialSecurityNumber(SocialSecurityNumber) as PersonList End Function End Class And call it as such Dim res as PersonList = MyList.FindByName("Max").FindByAge(25).FindBySocialSecurityNumber(1234) and the result along with the amount of code and its reusability is largely the same, no? I am not arguing just trying to understand.

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• Why is Func<T> ambiguous with Func<IEnumerable<T>>?

  - by Matt Hamilton

  This one's got me flummoxed, so I thought I'd ask here in the hope that a C# guru can explain it to me. Why does this code generate an error? class Program { static void Main(string[] args) { Foo(X); // the error is on this line } static String X() { return "Test"; } static void Foo(Func<IEnumerable<String>> x) { } static void Foo(Func<String> x) { } } The error in question: Error 1 The call is ambiguous between the following methods or properties: 'ConsoleApplication1.Program.Foo(System.Func<System.Collections.Generic.IEnumerable<string>>)' and 'ConsoleApplication1.Program.Foo(System.Func<string>)' C:\Users\mabster\AppData\Local\Temporary Projects\ConsoleApplication1\Program.cs 12 13 ConsoleApplication1 It doesn't matter what type I use - if you replace the "String" declarations with "int" in that code you'll get the same sort of error. It's like the compiler can't tell the difference between Func<T> and Func<IEnumerable<T>>. Can someone shed some light on this?

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• RTTI Dynamic array TValue Delphi 2010

  - by user558126

  Hello I have a question. I am a newbie with Run Time Type Information from Delphi 2010. I need to set length to a dynamic array into a TValue. You can see the code. Type TMyArray = array of integer; TMyClass = class publihed function Do:TMyArray; end; function TMyClass.Do:TMyArray; begin SetLength(Result,5); for i:=0 to 4 Result[i]=3; end; ....... ....... ...... y:TValue; Param:array of TValue; ......... y=Methods[i].Invoke(Obj,Param);//delphi give me a DynArray type kind, is working, Param works to any functions. if Method[i].ReturnType.TypeKind = tkDynArray then//is working... begin I want to set length for y to 10000//i don't know how to write. end; I don't like Generics Collections.

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• Is there a more elegant way to act on the first and last items in a foreach enumeration than count++

  - by Edward Tanguay

  Is there a more elegant way to act on the first and last items when iterating through a foreach loop than incrementing a separate counter and checking it each time? For instance, the following code outputs: >>> [line1], [line2], [line3], [line4] <<< which requires knowing when you are acting on the first and last item. Is there a more elegant way to do this now in C# 3 / C# 4? It seems like I could use .Last() or .First() or something like that. using System; using System.Collections.Generic; using System.Text; namespace TestForNext29343 { class Program { static void Main(string[] args) { StringBuilder sb = new StringBuilder(); List<string> lines = new List<string> { "line1", "line2", "line3", "line4" }; int index = 0; foreach (var line in lines) { if (index == 0) sb.Append(">>> "); sb.Append("[" + line + "]"); if (index < lines.Count - 1) sb.Append(", "); else sb.Append(" <<<"); index++; } Console.WriteLine(sb.ToString()); Console.ReadLine(); } } }

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• Why doesn't java.lang.Number implement Comparable?

  - by Julien Chastang

  Does anyone know why java.lang.Number does not implement Comparable? This means that you cannot sort Numbers with Collections.sort which seems to me a little strange. Post discussion update: Thanks for all the helpful responses. I ended up doing some more research about this topic. The simplest explanation for why java.lang.Number does not implement Comparable is rooted in mutability concerns. For a bit of review, java.lang.Number is the abstract super-type of AtomicInteger, AtomicLong, BigDecimal, BigInteger, Byte, Double, Float, Integer, Long and Short. On that list, AtomicInteger and AtomicLong to do not implement Comparable. Digging around, I discovered that it is not a good practice to implement Comparable on mutable types because the objects can change during or after comparison rendering the result of the comparison useless. Both AtomicLong and AtomicInteger are mutable. The API designers had the forethought to not have Number implement Comparable because it would have constrained implementation of future subtypes. Indeed, AtomicLong and AtomicInteger were added in Java 1.5 long after java.lang.Number was initially implemented. Apart from mutability, there are probably other considerations here too. A compareTo implementation in Number would have to promote all numeric values to BigDecimal because it is capable of accommodating all the Number sub-types. The implication of that promotion in terms of mathematics and performance is a bit unclear to me, but my intuition finds that solution kludgy.

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• <string xmlns=''> was not expected in c#

  - by Nishant

  Hi all I am trying to serialize value in xml. Every time I am getting <string xmlns=''> was not expected in c# Not able to find root cause plz help me out here. namespace CustomDataType.usercontrols { public partial class CustomDataTypes : System.Web.UI.UserControl, umbraco.editorControls.userControlGrapper.IUsercontrolDataEditor { private Status _umbval; public object value { get { var status = GetStatus(); return SerializationHelper.ValueToXmlString(status); } set { //if (value == null || string.IsNullOrEmpty(value.ToString())) //{ // _umbval = Status.Empty; //} //else //{ _umbval =(Status)SerializationHelper.ValueFromXmlString(value,typeof(Status)); //} } } } } using System; using System.Collections.Generic; using System.Linq; using System.Web; using System.Xml.Serialization; namespace CustomDataType { [Serializable] [XmlRoot("StatuMain")] public class Status { [XmlElement("statusvalue")] public string StatusValue { get; set; } [XmlElement("statusvalue1")] public string StatusValue1 { get; set; } [XmlElement("statusvalue2")] public string StatusValue2 { get; set; } [XmlElement("statusvalue3")] public string StatusValue3 { get; set; } //[XmlElement("isEmailChecked")] //public bool HasEmailChecked { get; set; } //[XmlElement("datetime")] //public DateTime Date { get; set; } public static Status Empty { get { var schedule = new Status(); schedule = null; return schedule; } } } }

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