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  • Sparse matrices / arrays in Java

    - by DanM
    I'm working on a project, written in Java, which requires that I build a very large 2-D sparse array. Very sparse, if that makes a difference. Anyway: the most crucial aspect for this application is efficency in terms of time (assume loads of memory, though not nearly so unlimited as to allow me to use a standard 2-D array -- the key range is in the billions in both dimensions). Out of the kajillion cells in the array, there will be several hundred thousand cells which contain an object. I need to be able to modify cell contents VERY quickly. Anyway: Does anyone know a particularly good library for this purpose? It would have to be Berkeley, LGPL or similar license (no GPL, as the product can't be entirely open-sourced). Or if there's just a very simple way to make a homebrew sparse array object, that'd be fine too. I'm considering MTJ, but haven't heard any opinions on its quality. Thanks!! -Dan

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  • How to get the Ansinerator library to work?

    - by konzepz
    I'm trying to get the Ansinerator library to work my on my localhost, but something's amiss. I'm receiving the following errors: Notice: Undefined index: hash in ansi.php on line 23 Notice: Undefined index: aml in ansi.php on line 37 Notice: Undefined variable: PNG_DESTRUCT in ansi.php on line 119 Notice: Undefined offset: -1 in ansi.php on line 362 Notice: Trying to get property of non-object in ansi.php on line 362 Notice: Undefined variable: links in ansi.php on line 459 Notice: Trying to get property of non-object in ansi.php on line 677 Notice: Undefined variable: links in ansi.php on line 459 Notice: Undefined variable: map_link in ansi.php on line 687 Any idea where am I going wrong with this one? I've installed the php-gd library, restarted the server, and while runs perfectly on production server, localhost will refuse. Ideas? Thank you.

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  • RadGrid cannot pass sortExpression to ObjectDataSourceControl

    - by Jeff
    I have a Telerik RadGrid that bound to a datasource object. They are configured to support custom paging, sorting. For paging, only the data of a page is retrieved from the database. Before sorting, it works fine. The select method of the datasource is like public List<xxx> Select(string sortExpression, int maximumRows, int startRowIndex) {} Before sorting the sortExpression is empty, which is expected. But after use click sort, in the OnSortCommand event handler of Radgrid, the SortExpression is correct, indicating RadGrid has caputre user's sorting correctly. protected void OnSort(object source, GridSortCommandEventArgs e) { Console.WriteLine(e.SortExpression); // correct } But what is strange is that the RadGrid does not pass parameter to DataSource correctly this time. sortExpression is still empty, maximumRows became int.Max, and startRowIndex is 0. The the sorting in still render correctly, but grid ask datasource to get all data and do the sorting locally. Is this bug of RadGrid or my configuration is wrong?

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  • Python: Inheritance of a class attribute (list)

    - by Sano98
    Hi everyone, inheriting a class attribute from a super class and later changing the value for the subclass works fine: class Unit(object): value = 10 class Archer(Unit): pass print Unit.value print Archer.value Archer.value = 5 print Unit.value print Archer.value leads to the output: 10 10 10 5 which is just fine: Archer inherits the value from Unit, but when I change Archer's value, Unit's value remains untouched. Now, if the inherited value is a list, the shallow copy effect strikes and the value of the superclass is also affected: class Unit(object): listvalue = [10] class Archer(Unit): pass print Unit.listvalue print Archer.listvalue Archer.listvalue[0] = 5 print Unit.listvalue print Archer.listvalue Output: 10 10 5 5 Is there a way to "deep copy" a list when inheriting it from the super class? Many thanks Sano

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  • How to get SpecFlow working with xUnit.net as the test runner

    - by Mike Scott
    I'm trying to use xUnit.net as the test runner for SpecFlow. The SpecFlow 1.2 binaries from the official download area don't contain an xUnit.net provider but the master branch on GitHub has one, so I build SpecFlow.Core.dll from that. I'm using xUnit.net 1.5. However, when I change the unitTestProvider name in the app.config in my spec project, I get a null reference custom tool error and the generated .feature.cs file is the single line: Object reference not set to an instance of an object. Has anyone succeeded in getting SpecFlow to work with xUnit.net? If so, how?

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  • LazyInitializationException when adding to a list that is held within a entity class using hibernate

    - by molleman
    Right so i am working with hibernate gilead and gwt to persist my data on users and files of a website. my users have a list of file locations. i am using annotations to map my classes to the database. i am getting a org.hibernate.LazyInitializationException when i try to add file locations to the list that is held in the user class. this is a method below that is overridden from a external file upload servlet class that i am using. when the file uploads it calls this method. the user1 is loaded from the database elsewhere. the exception occurs at user1.getFileLocations().add(fileLocation); . i dont understand it really at all.! any help would be great. the stack trace of the error is below public String executeAction(HttpServletRequest request, List<FileItem> sessionFiles) throws UploadActionException { for (FileItem item : sessionFiles) { if (false == item.isFormField()) { try { YFUser user1 = (YFUser)getSession().getAttribute(SESSION_USER); // This is the location where a file will be stored String fileLocationString = "/Users/Stefano/Desktop/UploadedFiles/" + user1.getUsername(); File fl = new File(fileLocationString); fl.mkdir(); // so here i will create the a file container for my uploaded file File file = File.createTempFile("upload-", ".bin",fl); // this is where the file is written to disk item.write(file); // the FileLocation object is then created FileLocation fileLocation = new FileLocation(); fileLocation.setLocation(fileLocationString); //test System.out.println("file path = "+file.getPath()); user1.getFileLocations().add(fileLocation); //the line above is where the exception occurs } catch (Exception e) { throw new UploadActionException(e.getMessage()); } } removeSessionFileItems(request); } return null; } //This is the class file for a Your Files User @Entity @Table(name = "yf_user_table") public class YFUser implements Serializable,ILightEntity { @Id @GeneratedValue(strategy = GenerationType.AUTO) @Column(name = "user_id",nullable = false) private int userId; @Column(name = "username") private String username; @Column(name = "password") private String password; @Column(name = "email") private String email; @ManyToMany(cascade = CascadeType.ALL) @JoinTable(name = "USER_FILELOCATION", joinColumns = { @JoinColumn(name = "user_id") }, inverseJoinColumns = { @JoinColumn(name = "locationId") }) private List<FileLocation> fileLocations = new ArrayList<FileLocation>() ; public YFUser(){ } public int getUserId() { return userId; } private void setUserId(int userId) { this.userId = userId; } public String getUsername() { return username; } public void setUsername(String username) { this.username = username; } public String getPassword() { return password; } public void setPassword(String password) { this.password = password; } public String getEmail() { return email; } public void setEmail(String email) { this.email = email; } public List<FileLocation> getFileLocations() { if(fileLocations ==null){ fileLocations = new ArrayList<FileLocation>(); } return fileLocations; } public void setFileLocations(List<FileLocation> fileLocations) { this.fileLocations = fileLocations; } /* public void addFileLocation(FileLocation location){ fileLocations.add(location); }*/ @Override public void addProxyInformation(String property, Object proxyInfo) { // TODO Auto-generated method stub } @Override public String getDebugString() { // TODO Auto-generated method stub return null; } @Override public Object getProxyInformation(String property) { // TODO Auto-generated method stub return null; } @Override public boolean isInitialized(String property) { // TODO Auto-generated method stub return false; } @Override public void removeProxyInformation(String property) { // TODO Auto-generated method stub } @Override public void setInitialized(String property, boolean initialised) { // TODO Auto-generated method stub } @Override public Object getValue() { // TODO Auto-generated method stub return null; } } @Entity @Table(name = "fileLocationTable") public class FileLocation implements Serializable { @Id @GeneratedValue(strategy = GenerationType.AUTO) @Column(name = "locationId", updatable = false, nullable = false) private int ieId; @Column (name = "location") private String location; public FileLocation(){ } public int getIeId() { return ieId; } private void setIeId(int ieId) { this.ieId = ieId; } public String getLocation() { return location; } public void setLocation(String location) { this.location = location; } } Apr 2, 2010 11:33:12 PM org.hibernate.LazyInitializationException <init> SEVERE: failed to lazily initialize a collection of role: com.example.client.YFUser.fileLocations, no session or session was closed org.hibernate.LazyInitializationException: failed to lazily initialize a collection of role: com.example.client.YFUser.fileLocations, no session or session was closed at org.hibernate.collection.AbstractPersistentCollection.throwLazyInitializationException(AbstractPersistentCollection.java:380) at org.hibernate.collection.AbstractPersistentCollection.throwLazyInitializationExceptionIfNotConnected(AbstractPersistentCollection.java:372) at org.hibernate.collection.AbstractPersistentCollection.initialize(AbstractPersistentCollection.java:365) at org.hibernate.collection.AbstractPersistentCollection.write(AbstractPersistentCollection.java:205) at org.hibernate.collection.PersistentBag.add(PersistentBag.java:297) at com.example.server.TestServiceImpl.saveFileLocation(TestServiceImpl.java:132) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25) at java.lang.reflect.Method.invoke(Method.java:597) at net.sf.gilead.gwt.PersistentRemoteService.processCall(PersistentRemoteService.java:174) at com.google.gwt.user.server.rpc.RemoteServiceServlet.processPost(RemoteServiceServlet.java:224) at com.google.gwt.user.server.rpc.AbstractRemoteServiceServlet.doPost(AbstractRemoteServiceServlet.java:62) at javax.servlet.http.HttpServlet.service(HttpServlet.java:713) at javax.servlet.http.HttpServlet.service(HttpServlet.java:806) at org.mortbay.jetty.servlet.ServletHolder.handle(ServletHolder.java:487) at org.mortbay.jetty.servlet.ServletHandler.handle(ServletHandler.java:362) at org.mortbay.jetty.security.SecurityHandler.handle(SecurityHandler.java:216) at org.mortbay.jetty.servlet.SessionHandler.handle(SessionHandler.java:181) at org.mortbay.jetty.handler.ContextHandler.handle(ContextHandler.java:729) at org.mortbay.jetty.webapp.WebAppContext.handle(WebAppContext.java:405) at org.mortbay.jetty.handler.HandlerWrapper.handle(HandlerWrapper.java:152) at org.mortbay.jetty.handler.RequestLogHandler.handle(RequestLogHandler.java:49) at org.mortbay.jetty.handler.HandlerWrapper.handle(HandlerWrapper.java:152) at org.mortbay.jetty.Server.handle(Server.java:324) at org.mortbay.jetty.HttpConnection.handleRequest(HttpConnection.java:505) at org.mortbay.jetty.HttpConnection$RequestHandler.content(HttpConnection.java:843) at org.mortbay.jetty.HttpParser.parseNext(HttpParser.java:647) at org.mortbay.jetty.HttpParser.parseAvailable(HttpParser.java:211) at org.mortbay.jetty.HttpConnection.handle(HttpConnection.java:380) at org.mortbay.io.nio.SelectChannelEndPoint.run(SelectChannelEndPoint.java:396) at org.mortbay.thread.QueuedThreadPool$PoolThread.run(QueuedThreadPool.java:488) Apr 2, 2010 11:33:12 PM net.sf.gilead.core.PersistentBeanManager clonePojo INFO: Third party instance, not cloned : org.hibernate.LazyInitializationException: failed to lazily initialize a collection of role: com.example.client.YFUser.fileLocations, no session or session was closed

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  • Heap Dump Root Classes

    - by Adnan Memon
    We have production system going into infinite loop of full gc and memory drops form 8 gigs to like 1 MB in just 2 minutes. After taking heap dump it tells me there an is an array of java.lang.Object ([Ljava.lang.Object) with millions of java.lang.String objects having same String taking 99% of heap. But it doesn't tell me which class is referencing to this array so that I can fix it in the code. I took the heap dump using jmap tool on JDK 6 and used JProfiler, NetBeans, SAP Memory Analyzer and IBM Memory Analyzer but none of those tell me what is causing this huge array of objects?? ... like what class is referencing to it or contains it. Do I have to take a different dump with different config in order to get that info? ... Or anything else that can help me find out the culprit class causing this ... it will help a lot.

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  • DataGridView's SelectionChange event firing twice on DataBinding even after removing event binding

    - by Shantanu Gupta
    This Code triggers selection change event twice. how can I prevent it ? Currently i m using a flag or focused property to prevent this. But what is the actual way ? I am using it on winfoms EDIT My Mistake in writing Question, here is the correct code that i wanted to ask private void frmGuestInfo_Load(object sender, EventArgs e) { this.dgvGuestInfo.SelectionChanged -= new System.EventHandler(this.dgvGuestInfo_SelectionChanged); dgvGuestInfo.DataSource=dsFillControls.Tables["tblName"]; this.dgvGuestInfo.SelectionChanged += new System.EventHandler(this.dgvGuestInfo_SelectionChanged); } private void dgvGuestInfo_SelectionChanged(object sender, EventArgs e) { //this function is raised twice, i was expecting that this will not be raised }

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  • Nested attributes in the index view?

    - by user283179
    I seem to be getting error: uninitialized constant Style::Pic when I'm trying to render a nested object in to the index view the show view is fine. class Style < ActiveRecord::Base #belongs_to :users has_many :style_images, :dependent => :destroy accepts_nested_attributes_for :style_images, :reject_if => proc { |a| a.all? { |k, v| v.blank?} } #found this here http://ryandaigle.com/articles/2009/2/1/what-s-new-in-edge-rails-nested-attributes has_one :cover, :class_name => "Pic", :order => "updated_at DESC" accepts_nested_attributes_for :cover end class StyleImage < ActiveRecord::Base belongs_to :style #belongs_to :style_as_cover, :class_name => "Style", :foreign_key => "style_id" has_attached_file :pic, :styles => { :small => "200x0>", :normal => "600x> " } validates_attachment_presence :pic #validates_attachment_size :pic, :less_than => 5.megabytes end <% for style_image in @style.style_images %> <li><%= style_image.caption %></li> <div id="show_photo"> <%= image_tag style_image.pic.url(:normal) %></div> <% end %> As you can see from the above The main model style has many style_images, all these style_images are displayed in the show view but, in the the index view I wish to show one image which has been name and will act as a cover that is displayed for each style. in the index controller I have tried the following: class StylesController < ApplicationController layout "mini" def index @styles = Style.find(:all, :inculde => [:cover,]).reverse respond_to do |format| format.html # index.html.erb format.xml { render :xml => @styles } end end and the index <% @styles.each do |style| %> <%=image_tag style.cover.pic.url(:small) %> <% end %> class StyleImage < ActiveRecord::Base belongs_to :style #belongs_to :style_as_cover, :class_name => "Style", :foreign_key => "style_id" has_attached_file :pic, :styles => { :small => "200x0>", :normal => "600x> " } validates_attachment_presence :pic #validates_attachment_size :pic, :less_than => 5.megabytes end In the style_images table there is an cover_id also. From the about you can see that I have included the cover in the controller and the model. I have know idea where I'm going wrong here! If any one can help please do!

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  • How to serialize and unserialize to/from a C# class?

    - by Earlz
    Hello, I have an object in Javascript that looks like this function MyObject(){ this.name=""; this.id=0; this..... } I then stringify an array of those objects and send it to an ASP.Net web service. Now what I want to do is do some processing on the JSON objects given to the webservice and return a JSON array of the same type of objects(same field names and such) How would I do this easily? I am using Netwonsoft.Json. Is there some way to turn a JSON string into a List or Array of an object?

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  • Performance: use a BinaryReader on a MemoryStream to read a byte array, or read directly?

    - by Virtlink
    I would like to know whether using a BinaryReader on a MemoryStream created from a byte array (byte[]) would reduce performance significantly. There is binary data I want to read, and I get that data as an array of bytes. I am currently deciding between two approaches to read the data, and have to implement many reading methods accordingly. After each reading action, I need the position right after the read data, and therefor I am considering using a BinaryReader. The first, non-BinaryReader approach: object Read(byte[] data, ref int offset); The second approach: object Read(BinaryReader reader); Such Read() methods will be called very often, in succession on the same data until all data has been read. So, using a BinaryReader feels more natural, but has it much impact on the performance?

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  • Anonymous methods/functions: a fundamental feature or a violation of OO principles?

    - by RD1
    Is the recent movement towards anonymous methods/functions by mainstream languages like perl and C# something important, or a weird feature that violates OO principles? Are recent libraries like the most recent version of Intel's Thread Building Blocks and Microsofts PPL and Linq that depend on such things a good thing, or not? Are languages that currently reject anonymous methods/functions, like Java, making wise choices in sticking with a purely OO model, or are they falling behind by lacking a fundamental programming feature?

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  • Encrypt nsdata in iphone and decrypt it in php

    - by Gaurav Arora
    Hi All, I am new to Iphone development , I want to create an application in which I have to upload some data on php server using my Iphone application. For this I have an file on the Iphone whose content I have to upload on php server. For this I have converted the content of the file in NSData and now I want to encrypt this nsdata object and then pass it to the php server and on php server firstly I have to decrypt the nsdata object then I have to upload it on the server. But I am not able to find any way by which I can encrypt some data in Iphone app and then decrypt it in php. And also I want to compress the encrypted data before transferring it to php and then uncompress that data on php. The complete flow of my application is IPhone NSData -- Encrypted NsData -- Compressed Encrypted Data php Compressed Encrypted Data -- uncompressed encrypted data -- decrypted (original) NSData. Can some one help me how can I develop such application? Thanks in advance. Gaurav

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  • jQuery Javascript array 'contains' functionality?

    - by YourMomzThaBomb
    I'm trying to use the jQuery $.inArray function to iterate through an array and if there's an element whose text contains a particular keyword, remove that element. $.inArray is only returning the array index though if the element's text is equal to the keyword. For example given the following array named 'tokens': - tokens {...} Object [0] "Starbucks^25^http://somelink" String [1] "McDonalds^34^" String [2] "BurgerKing^31^https://www.somewhere.com" String And a call to removeElement(tokens, 'McDonalds'); would return the following array: - tokens {...} Object [0] "Starbucks^25^http://somelink" String [1] "BurgerKing^31^https://www.somewhere.com" String I'm guessing this may be possible using the jQuery $.grep or $.each function, or maybe regex. However, I'm not familiar enough with jQuery to accomplish this. Any help would be appreciated!

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  • get local groups and not the primary groups for a domain user

    - by user175084
    i have a code to get the groups a user belongs to. try { DirectoryEntry adRoot = new DirectoryEntry(string.Format("WinNT://{0}", Environment.UserDomainName)); DirectoryEntry user = adRoot.Children.Find(completeUserName, "User"); object obGroups = user.Invoke("Groups"); foreach (object ob in (IEnumerable)obGroups) { // Create object for each group. DirectoryEntry obGpEntry = new DirectoryEntry(ob); listOfMyWindowsGroups.Add(obGpEntry.Name); } return true; } catch (Exception ex) { new GUIUtility().LogMessageToFile("Error in getting User MachineGroups = " + ex); return false; } the above code works fine when i have to find the groups of a local user but for a domain user it returns a value "Domain User" which is kind of wierd as it is a part of 2 local groups. Please can some1 help in solving this mystery. thanks Research I did some finding and got that i am being returned the primary group of the domain user called "Domain User" group but what i actually want is the groups of the local machines the domain user is a part of... i cannot get that.. any suggestions another code using LDAP string domain = Environment.UserDomainName; DirectoryEntry DE = new DirectoryEntry("LDAP://" + domain, null, null, AuthenticationTypes.Secure); DirectorySearcher search = new DirectorySearcher(); search.SearchRoot = DE; search.Filter = "(SAMAccountName=" + completeUserName + ")"; //Searches active directory for the login name search.PropertiesToLoad.Add("displayName"); // Once found, get a list of Groups try { SearchResult result = search.FindOne(); // Grab the records and assign them to result if (result != null) { DirectoryEntry theUser = result.GetDirectoryEntry(); theUser.RefreshCache(new string[] { "tokenGroups" }); foreach (byte[] resultBytes in theUser.Properties["tokenGroups"]) { System.Security.Principal.SecurityIdentifier mySID = new System.Security.Principal.SecurityIdentifier(resultBytes, 0); DirectorySearcher sidSearcher = new DirectorySearcher(); sidSearcher.SearchRoot = DE; sidSearcher.Filter = "(objectSid=" + mySID.Value + ")"; sidSearcher.PropertiesToLoad.Add("distinguishedName"); SearchResult sidResult = sidSearcher.FindOne(); if (sidResult != null) { listOfMyWindowsGroups.Add((string)sidResult.Properties["distinguishedName"][0]); } } } else { new GUIUtility().LogMessageToFile("no user found"); } return true; } catch (Exception ex) { new GUIUtility().LogMessageToFile("Error obtaining group names: " + ex.Message + " Please contact your administrator."); // If an error occurs report it to the user. return false; } this works too but i get the same result "Domain Users" . Please can some1 tell me how to get the local machine groups...????

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  • ICommand.CanExecute being passed null even though CommandParameter is set...

    - by chaiguy
    I have a tricky problem where I am binding a ContextMenu to a set of ICommand-derived objects, and setting the Command and CommandParameter properties on each MenuItem via a style: <ContextMenu ItemsSource="{Binding Source={x:Static OrangeNote:Note.MultiCommands}}"> <ContextMenu.Resources> <Style TargetType="MenuItem"> <Setter Property="Header" Value="{Binding Path=Title}" /> <Setter Property="Command" Value="{Binding}" /> <Setter Property="CommandParameter" Value="{Binding Source={x:Static OrangeNote:App.Screen}, Path=SelectedNotes}" /> ... However, while ICommand.Execute( object ) gets passed the set of selected notes as it should, ICommand.CanExecute( object ) (which is called when the menu is created) is getting passed null. I've checked and the selected notes collection is properly instantiated before the call is made (in fact it's assigned a value in its declaration, so it is never null). I can't figure out why CanEvaluate is getting passed null.

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  • Objective-C (iPhone) Memory Management

    - by Steven
    I'm sorry to ask such a simple question, but it's a specific question I've not been able to find an answer for. I'm not a native objective-c programmer, so I apologise if I use any C# terms! If I define an object in test.h @interface test : something { NSString *_testString; } Then initialise it in test.m -(id)init { _testString = [[NSString alloc] initWithString:@"hello"]; } Then I understand that I would release it in dealloc, as every init should have a release -(void)dealloc { [_testString release]; } However, what I need clarification on is what happens if in init, I use one of the shortcut methods for object creation, do I still release it in dealloc? Doesn't this break the "one release for one init" rule? e.g. -(id)init { _testString = [NSString stringWithString:@"hello"]; } Thanks for your helps, and if this has been answered somewhere else, I apologise!! Steven

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  • How to improve the builder pattern?

    - by tangens
    Motivation Recently I searched for a way to initialize a complex object without passing a lot of parameter to the constructor. I tried it with the builder pattern, but I don't like the fact, that I'm not able to check at compile time if I really set all needed values. Traditional builder pattern When I use the builder pattern to create my Complex object, the creation is more "typesafe", because it's easier to see what an argument is used for: new ComplexBuilder() .setFirst( "first" ) .setSecond( "second" ) .setThird( "third" ) ... .build(); But now I have the problem, that I can easily miss an important parameter. I can check for it inside the build() method, but that is only at runtime. At compile time there is nothing that warns me, if I missed something. Enhanced builder pattern Now my idea was to create a builder, that "reminds" me if I missed a needed parameter. My first try looks like this: public class Complex { private String m_first; private String m_second; private String m_third; private Complex() {} public static class ComplexBuilder { private Complex m_complex; public ComplexBuilder() { m_complex = new Complex(); } public Builder2 setFirst( String first ) { m_complex.m_first = first; return new Builder2(); } public class Builder2 { private Builder2() {} Builder3 setSecond( String second ) { m_complex.m_second = second; return new Builder3(); } } public class Builder3 { private Builder3() {} Builder4 setThird( String third ) { m_complex.m_third = third; return new Builder4(); } } public class Builder4 { private Builder4() {} Complex build() { return m_complex; } } } } As you can see, each setter of the builder class returns a different internal builder class. Each internal builder class provides exactly one setter method and the last one provides only a build() method. Now the construction of an object again looks like this: new ComplexBuilder() .setFirst( "first" ) .setSecond( "second" ) .setThird( "third" ) .build(); ...but there is no way to forget a needed parameter. The compiler wouldn't accept it. Optional parameters If I had optional parameters, I would use the last internal builder class Builder4 to set them like a "traditional" builder does, returning itself. Questions Is this a well known pattern? Does it have a special name? Do you see any pitfalls? Do you have any ideas to improve the implementation - in the sense of fewer lines of code?

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  • Asynchronous sockets in C#

    - by IVlad
    I'm confused about the correct way of using asynchronous socket methods in C#. I will refer to these two articles to explain things and ask my questions: MSDN article on asynchronous client sockets and devarticles.com article on socket programming. My question is about the BeginReceive() method. The MSDN article uses these two functions to handle receiving data: private static void Receive(Socket client) { try { // Create the state object. StateObject state = new StateObject(); state.workSocket = client; // Begin receiving the data from the remote device. client.BeginReceive( state.buffer, 0, StateObject.BufferSize, 0, new AsyncCallback(ReceiveCallback), state); } catch (Exception e) { Console.WriteLine(e.ToString()); } } private static void ReceiveCallback( IAsyncResult ar ) { try { // Retrieve the state object and the client socket // from the asynchronous state object. StateObject state = (StateObject) ar.AsyncState; Socket client = state.workSocket; // Read data from the remote device. int bytesRead = client.EndReceive(ar); if (bytesRead > 0) { // There might be more data, so store the data received so far. state.sb.Append(Encoding.ASCII.GetString(state.buffer,0,bytesRead)); // Get the rest of the data. client.BeginReceive(state.buffer,0,StateObject.BufferSize,0, new AsyncCallback(ReceiveCallback), state); } else { // All the data has arrived; put it in response. if (state.sb.Length > 1) { response = state.sb.ToString(); } // Signal that all bytes have been received. receiveDone.Set(); } } catch (Exception e) { Console.WriteLine(e.ToString()); } } While the devarticles.com tutorial passes null for the last parameter of the BeginReceive method, and goes on to explain that the last parameter is useful when we're dealing with multiple sockets. Now my questions are: What is the point of passing a state to the BeginReceive method if we're only working with a single socket? Is it to avoid using a class field? It seems like there's little point in doing it, but maybe I'm missing something. How can the state parameter help when dealing with multiple sockets? If I'm calling client.BeginReceive(...), won't all the data be read from the client socket? The devarticles.com tutorial makes it sound like in this call: m_asynResult = m_socClient.BeginReceive (theSocPkt.dataBuffer,0,theSocPkt.dataBuffer.Length, SocketFlags.None,pfnCallBack,theSocPkt); Data will be read from the theSocPkt.thisSocket socket, instead of from the m_socClient socket. In their example the two are one and the same, but what happens if that is not the case? I just don't really see where that last argument is useful or at least how it helps with multiple sockets. If I have multiple sockets, I still need to call BeginReceive on each of them, right?

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  • What framework for MVVM should I use?

    - by Rangel
    I am developing an application with the MVVM model, but I have reached a point where I need to choose which framework to use. Among the possible options are: MVVM Toolkit MVVM Foundation WPF Application Framework (WAF) Light MVVM Caliburn Cinch Prism In your experience, which is better?

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  • iPhone UIWebView: loadData does not work with certain types (Excel, MSWord, PPT, RTF)

    - by Thomas Tempelmann
    My task is to display the supported document types on an iPhone with OS 3.x, such as .pdf, .rtf, .doc, .ppt, .png, .tiff etc. Now, I have stored these files only encrypted on disk. For security reasons, I want to avoid storing them unencrypted on disk. Hence, I prefer to use loadData:MIMEType:textEncodingName:baseURL: instead of loadRequest: to display the document because loadData allows me to pass the content in a NSData object, i.e. I can decrypt the file in memory and have no need to store it on disk, as it would be required when using loadRequest. The problem is that loadData does not appear to work with all file types: Testing shows that all picture types seem to work fine, as well as PDFs, while the more complex types don't. I get a errors such as: NSURLErrorDomain Code=100 NSURLErrorDomain Code=102 WebView appears to need a truly working URL for accessing the documents as a file, despite me offering all content via the NSData object already. Here's the code I use to display the content: [webView loadData:data MIMEType:type textEncodingName:@"utf-8" baseURL:nil]; The mime-type is properly set, e.g. to "application/msword" for .doc files. Does anyone know how I could get loadData to work with all types that loadRequest supports? Or, alternatively, is there some way I can tell which types do work for sure (i.e. officially sanctioned by Apple) with loadData? Then I can work twofold, creating a temp unencrypted file only for those cases that loadData won't like. Update Looks like I'm not the first one running into this. See here: http://osdir.com/ml/iPhoneSDKDevelopment/2010-03/msg00216.html So, I guess, that's the status quo, and nothing I can do about it. Someone suggested a work-around which might work, though: http://osdir.com/ml/iPhoneSDKDevelopment/2010-03/msg00219.html Basically, the idea is to provide a tiny http server that serves the file (from memory in my case), and then use loadRequest. This is probably a bit more memory-intensive, though, as both the server and the webview will probably both hold the entire contents in memory as two copies then, as opposed to using loadData, where both would rather share the same data object. (Mind you, I'll have to hold the decrypted data in memory, that's the whole point here).

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  • Running a Java daemon with a GWT front-end served by embedded Jetty

    - by BinaryMuse
    Greetings, coders, Background Info and Code I am trying to create a daemon-type program (e.g., it runs constantly, polling for things to do) that is managed by a GWT application (servlets in a WAR) which is in turn served by an embedded Jetty server (using a WebAppContext). I'm having problems making the GWT application aware of the daemon object. For testing things, I currently have two projects: The daemon and embedded Jetty server in one (EmbJetTest), and the GWT application in another (DefaultApp). This is the current state of the code: First, EmbJetTest creates an embedded Jetty server like so, using a ServletContextListener to inject the daemon object into the web application context: EmbJetTest.server = new Server(8080); // Create and start the daemon Daemon daemon = new Daemon(); Thread thread = new Thread(daemon); thread.start(); // war handler WebAppContext waContext = new WebAppContext(); waContext.setContextPath("/webapp"); waContext.setWar("./apps/DefaultApp.war"); waContext.addEventListener(new DaemonLoader(daemon)); // Add it to the server EmbJetTest.server.setHandler(waContext); EmbJetTest.server.setThreadPool(new QueuedThreadPool(10)); // Start the server; join() blocks until we shut down EmbJetTest.server.start(); EmbJetTest.server.join(); // Stop the daemon thread daemon.stopLoop(); Daemon is a very simple object with a couple properties, at the moment. DaemonLoader is the following ServletContextListener implementation: private Daemon daemon; public DaemonLoader(Daemon daemon) { this.daemon = daemon; } @Override public void contextDestroyed(ServletContextEvent arg0) { } @Override public void contextInitialized(ServletContextEvent arg0) { arg0.getServletContext().setAttribute("daemon", this.daemon); } Then, in one of my servlets in the GWT application, I have the following code: Daemon daemon = (Daemon) this.getServletContext().getAttribute("daemon"); However, when I visit localhost:8080/webapp/* and invoke the servlet, this code throws a ClassCastException, even though the classes are of the same type. This StackOverflow answer indicates that this is because the two classes are loaded with different classloaders. Question My question is twofold. Am I even on the right track here? Am I going about this completely the wrong way? Something tells me I am, but I can't think of another way to make the daemon available to both applications. Is there a better way to communicate with the daemon from the GWT application? Should the GWT app own the daemon and somehow start the daemon itself? The daemon needs to run even if no one visits the one of the GWT app's servlets--how could I do this? If I am on the right track, how can I get around the classloader issue? Thanks in advance.

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  • LINQ2SQL and MS SQL 2000

    - by artvolk
    Good day! I have used LINQ2SQL with MS SQL 2005, but now I need to use it with MS SQL 2000. I have found only article on MSDN that tells about Skip() and Take() oddities on MS SQL 2000 (that's because it lacks ROW_NUMBER(), I suppose) and nothing more. Anyway, does anybody have expirience with LINQ2SQL and MS SQL 2000 combination. P.S. Just wondering: is it possible to model LINQ2SQL class on view, not a real table?

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