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• Executes a function until it returns a nil, collecting its values into a list

  - by Baldur

  I got this idea from XKCD's Hofstadter comic; what's the best way to create a conditional loop in (any) Lisp dialect that executes a function until it returns NIL at which time it collects the returned values into a list. For those who haven't seen the joke, it's goes that Douglas Hofstadter's “eight-word” autobiography consists of only six words: “I'm So Meta, Even This Acronym” containing continuation of the joke: (some odd meta-paraprosdokian?) “Is Meta” — the joke being that the autobiography is actually “I'm So Meta, Even This Acronym Is Meta”. But why not go deeper? Assume the acronymizing function META that creates an acronym from a string and splits it into words, returns NIL if the string contains but one word: (meta "I'm So Meta, Even This Acronym") ? "Is Meta" (meta (meta "I'm So Meta, Even This Acronym")) ? "Im" (meta (meta (meta "I'm So Meta, Even This Acronym"))) ? NIL (meta "GNU is Not UNIX") ? "GNU" (meta (meta "GNU is Not UNIX")) ? NIL Now I'm looking for how to implement a function so that: (so-function #'meta "I'm So Meta, Even This Acronym") ? ("I'm So Meta, Even This Acronym" "Is Meta" "Im") (so-function #'meta "GNU is Not Unix") ? ("GNU is Not Unix" "GNU") What's the best way of doing this?

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• MVC Form and Dictionary Type

  - by Brian Schmitt

  I am attempting to use a property on my model that is of type Dictionary<string, string>. This dictionary is one of several other properties on the model, and I am using the dictionary as a key/value store to produce a 'dynamic' form. E.G.: User Name Settings A B I want to be able to submit and save any changes to settings A and B. I can submit the form and get my posted values in all my other fields, however the dictionary gets set to null. <%=Html.LabelFor(m => m.Name)%> <%=Html.DisplayFor(m => m.Name)%> <%=Html.LabelFor(m => m.Settings["A"])%> <%=Html.TextBoxFor(m => m.Settings["A"])%> <%=Html.LabelFor(m => m.Settings["B"])%> <%=Html.TextBoxFor(m => m.Settings["B"])%> Is there a better way to produce the dynamic form with a key/value pair? The actual code will be using partials (there several hundred variations), and the above is only a contrived example.

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• Game login authentication and security.

  - by Charles

  First off I will say I am completely new to security in coding. I am currently helping a friend develop a small game (in Python) which will have a login server. I don't have much knowledge regarding security, but I know many games do have issues with this. Everything from 3rd party applications (bots) to WPE packet manipulation. Considering how small this game will be and the limited user base, I doubt we will have serious issues, but would like to try our best to limit problems. I am not sure where to start or what methods I should use, or what's worth it. For example, sending data to the server such as login name and password. I was told his information should be encrypted when sending, so in-case someone was viewing it (with whatever means), that they couldn't get into the account. However, if someone is able to capture the encrypted string, wouldn't this string always work since it's decrypted server side? In other words, someone could just capture the packet, reuse it, and still gain access to the account? The main goal I am really looking for is to make sure the players are logging into the game with the client we provide, and to make sure it's 'secure' (broad, I know). I have looked around at different methods such as Public and Private Key encryption, which I am sure any hex editor could eventually find. There are many other methods that seem way over my head at the moment and leave the impression of overkill. I realize nothing is 100% secure. I am just looking for any input or reading material (links) to accomplish the main goal stated above. Would appreciate any help, thanks.

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• Display ñ on a C# .NET application

  - by mmr

  I have a localization issue. One of my industrious coworkers has replaced all the strings throughout our application with constants that are contained in a dictionary. That dictionary gets various strings placed in it once the user selects a language (English by default, but target languages are German, Spanish, French, Portuguese, Mandarin, and Thai). For our test of this functionality, we wanted to change a button to include text which has a ñ character, which appears both in Spanish and in the Arial Unicode MS font (which we're using throughout the application). Problem is, the ñ is appearing as a square block, as if the program did not know how to display it. When I debug into that particular string being read from disk, the debugger reports that character as a square block as well. So where is the failure? I think it could be in a few places: 1) Notepad may not be unicode aware, so the ñ displayed there is not the same as what vs2008 expects, and so the program interprets the character as a square (EDIT: notepad shows the same characters as vs; ie, they both show the ñ. In the same place.). 2) vs2008 can't handle ñ. I find that very, very hard to believe. 3) The text is read in properly, but the default font for vs2008 can't display it, which is why the debugger shows a square. 4) The text is not read in properly, and I should use something other than a regular StreamReader to get strings. 5) The text is read in properly, but the default String class in C# doesn't handle ñ well. I find that very, very hard to believe. 6) The version of Arial Unicode MS I have doesn't have ñ, despite it being listed as one of the 50k characters by http://www.fileinfo.info. Anything else I could have left out? Thanks for any help!

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• looking for a license key algorithm.

  - by giulio

  There are a lot of questions relating to license keys asked on stackoverflow. But they don't answer this question. Can anyone provide a simple license key algorithm that is technology independent and doesn't required a diploma in mathematics to understand ? The license key algorithm is similar to public key encryption. I just need something simple that can be implemented in any platform .Net/Java and uses simple data like characters. Preferably no byte translations required. So if a person presents a string, a complementary string can be generated that is the authorisation code. Below is a common scenario that it would be used for. Customer downloads s/w which generates a unique key upon initial startup/installation. S/w runs during trial period. At end of trial period an authorisation key is required. Customer goes to designated web-site, enters their code and get authorisation code to enable s/w, after paying :) Don't be afraid to describe your answer as though you're talking to a 5 yr old as I am not a mathemtician. Just need a decent basic algorithm, we're not launching nukes... NB: Please no philosophy on encryption nor who is Diffie-Hellman. I just need a basic solution.

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• Correct escaping of delimited identifers in SQL Server without using QUOTENAME

  - by Ross Bradbury

  Is there anything else that the code must do to sanitize identifiers (table, view, column) other than to wrap them in double quotation marks and "double up" and double quotation marks present in the identifier name? References would be appreciated. I have inherited a code base that has a custom object-relational mapping (ORM) system. SQL cannot be written in the application but the ORM must still eventually generate the SQL to send to the SQL Server. All identifiers are quoted with double quotation marks. string QuoteName(string identifier) { return "\" + identifier.Replace("\"", "\"\"") + "\""; } If I were building this dynamic SQL in SQL, I would use the built-in SQL Server QUOTENAME function: declare @identifier nvarchar(128); set @identifier = N'Client"; DROP TABLE [dbo].Client; --'; declare @delimitedIdentifier nvarchar(258); set @delimitedIdentifier = QUOTENAME(@identifier, '"'); print @delimitedIdentifier; -- "Client""; DROP TABLE [dbo].Client; --" I have not found any definitive documentation about how to escape quoted identifiers in SQL Server. I have found Delimited Identifiers (Database Engine) and I also saw this stackoverflow question about sanitizing. If it were to have to call the QUOTENAME function just to quote the identifiers that is a lot of traffic to SQL Server that should not be needed. The ORM seems to be pretty well thought out with regards to SQL Injection. It is in C# and predates the nHibernate port and Entity Framework etc. All user input is sent using ADO.NET SqlParameter objects, it is just the identifier names that I am concerned about in this question. This needs to work on SQL Server 2005 and 2008.

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• Custom Validation Attribute with Custom Model Binder in MVC 2

  - by griegs

  I apologise for the amount of code I have included. I've tried to keep it to a minimum. I'm trying to have a Custom Validator Attribute on my model as well as a Custom Model binder. The Attribute and the Binder work great seperately but if I have both, then the Validation Attribute no longer works. Here is my code snipped for readability. If I leave out the code in global.asax the custom validation fires but not if I have the custom binder enabled. Validation Attribute; public class IsPhoneNumberAttribute : ValidationAttribute { public override bool IsValid(object value) { //do some checking on 'value' here return true; } } Useage of the attribute in my model; [Required(ErrorMessage = "Please provide a contact number")] [IsPhoneNumberAttribute(ErrorMessage = "Not a valid phone number")] public string Phone { get; set; } Custom Model Binder; public class CustomContactUsBinder : DefaultModelBinder { protected override void OnModelUpdated(ControllerContext controllerContext, ModelBindingContext bindingContext) { ContactFormViewModel contactFormViewModel = bindingContext.Model as ContactFormViewModel; if (!String.IsNullOrEmpty(contactFormViewModel.Phone)) if (contactFormViewModel.Phone.Length > 10) bindingContext.ModelState.AddModelError("Phone", "Phone is too long."); } } Global asax; System.Web.Mvc.ModelBinders.Binders[typeof(ContactFormViewModel)] = new CustomContactUsBinder();

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• JavaScript and JQuery - Encoding HTML

  - by user70192

  Hello, I have a web page that has a textarea defined on it like so: <textarea id="myTextArea" rows="6" cols="75"></textarea> There is a chance that a user may enter single and double quotes in this field. For instance, I have been testing with the following string: Just testin' using single and double "quotes". I'm hoping the end of this task is comin'. Additionally, the user may enter HTML code, which I would prefer to prevent. Regardless, I am passing the contents of this textarea onto web service. I must encode the contents of the textarea in JavaScript before I can send it on. Currently, I'm trying the following: var contents $('<div/>').text($("#myTextArea).val()).html(); alert(contents); I was expecting contents to display Just testin&#39; using single and double &#34;quotes&#34;. I&#39;m hoping the end of this task is comin&#39;. Instead, the original string is printed out. Beyond just double-and-single quotes, there are a variety of entities to consider. Because of this, I was assuming there would be a way to encode HTML before passing it on. Can someone please tell me how to do this? Thank you,

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• Does the COM server have to call SysFreeString() for an [out] parameter?

  - by sharptooth

  We have the following interface: [object, uuid("uuidhere"), dual ] interface IInterface : IDispatch { [id(1), propget] HRESULT CoolProperty( [out, retval] BSTR* result ); } Now there's a minor problem. On one hand the parameter is "out" and so any value can be passed as input, the parameter will become valid only upon the successful return. On the other hand, there's this MSDN article which is linked to from many pages that basically says (the last paragraph) that if any function is passed a BSTR* it must free the string before assigning a new string. That's horrifying. If that article is right it means that all the callers must surely pass valid BSTRs (maybe null BSTRs), otherwise BSTR passed can be leaked. If the caller passed a random value and the callee tries to call SysFreeString() it runs into undefined behavior, so the convention is critical. Then what's the point in the [out] attribute? What will be the difference between the [in, out] and [out] in this situation? Is that article right? Do I need to free the passed BSTR [out] parameter before assigning a new one?

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• Detecting Xml namespace fast

  - by Anna Tjsoken

  Hello there, This may be a very trivial problem I'm trying to solve, but I'm sure there's a better way of doing it. So please go easy on me. I have a bunch of XSD files that are internal to our application, we have about 20-30 Xml files that implement datasets based off those XSDs. Some Xml files are small (<100Kb), others are about 3-4Mb with a few being over 10Mb. I need to find a way of working out what namespace these Xml files are in order to provide (something like) intellisense based off the XSD. The implementation of this is not an issue - another developer has written the code for this. But I'm not sure the best (and fastest!) way of detecting the namespace is without the use of XmlDocument (which does a full parse). I'm using C# 3.5 and the documents come through as a Stream (some are remote files). All the files are *.xml (I can detect if it was extension based) but unfortunately the Xml namespace is the only way. Right now I've tried XmlDocument but I've found it to be innefficient and slow as the larger documents are awaiting to be parsed (even the 100Kb docs). public string GetNamespaceForDocument(Stream document); Something like the above is my method signature - overloads include string for "content". Would a RegEx (compiled) pattern be good? How does Visual Studio manage this so efficiently? Another college has told me to find a fast Xml parser in C/C++, parse the content and have a stub that gives back the namespace as its slower in .NET, is this a good idea?

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• Neo4j Reading data / performing shortest path calculations on stored data

  - by paddydub

  I'm using the Batch_Insert example to insert Data into the database How can i read this data back from the database. I can't find any examples of how i do this. public static void CreateData() { // create the batch inserter BatchInserter inserter = new BatchInserterImpl( "var/graphdb", BatchInserterImpl.loadProperties( "var/neo4j.props" ) ); Map<String,Object> properties = new HashMap<String,Object>(); properties.put( "name", "Mr. Andersson" ); properties.put( "age", 29 ); long node1 = inserter.createNode( properties ); properties.put( "name", "Trinity" ); properties.remove( "age" ); long node2 = inserter.createNode( properties ); inserter.createRelationship( node1, node2, DynamicRelationshipType.withName( "KNOWS" ), null ); inserter.shutdown(); } I would like to store graph data in the database, graph.makeEdge( "s", "c", "cost", (double) 7 ); graph.makeEdge( "c", "e", "cost", (double) 7 ); graph.makeEdge( "s", "a", "cost", (double) 2 ); graph.makeEdge( "a", "b", "cost", (double) 7 ); graph.makeEdge( "b", "e", "cost", (double) 2 ); Dijkstra<Double> dijkstra = getDijkstra( graph, 0.0, "s", "e" ); What is the best method to store this kind data with 10000's of edges. Then run the Dijskra algorighm to find shortest path calculations using the stored graph data.

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• Fluent NHibernate auto mapping: map property from another table's column

  - by queen3

  I'm trying to use S#arp architecture... which includes Fluent NHibernate I'm newbie with (and with NHibernate too, frankly speaking). Auto mapping is used. So I have this: public class UserAction : Entity { public UserAction() { } [DomainSignature] [NotNull, NotEmpty] public virtual string Name { get; set; } [NotNull, NotEmpty] public virtual string TypeName { get; private set; } } public class UserActionMap : IAutoMappingOverride<UserAction> { public void Override(AutoMap<UserAction> mapping) { mapping.WithTable("ProgramComponents", m => m.Map(x => x.TypeName)); } } Now, table UserActions references table ProgramComponents (many to one) and I want property UserAction.TypeName to have value from db field ProgramComponents.TypeName. However, the above code fails with NHibernate.MappingException: Duplicate property mapping of TypeName found in OrderEntry3.Core.UserAction As far as I understand the problem is that TypeName is already auto-mapped... but I haven't found a way to remove the automatic mapping. Actually I think that my WithTable/Map mapping has to replace the automatic TypeName mapping, but seems like it does not. I also tried different mapping (names are different but that's all the same): mapping.WithTable("ProgramComponents", m => m.References<ProgramComponent>( x => x.Selector, "ProductSelectorID" ) and still get the same error. I can overcome this with mapping.HasOne<ProgramComponent>(x => x.Selector); but that's not what I exactly wants to do. And I still wonder why the first two methods do not work. I suspect this is because of WithTable.

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• WTK emulator bluetooth connection problem

  - by Gokhan B.

  Hi! I'm developing a J2ME program with eclipse / WTK 2.5.2 and having problem with connecting two emulators using bluetooth. There is one server and one .client running on two different emulators. The problem is client program cannot discover any bluetooth device. Here is the server and client codes: public Server() { try { LocalDevice local = LocalDevice.getLocalDevice(); local.setDiscoverable(DiscoveryAgent.GIAC); server = (StreamConnectionNotifier) Connector.open("btspp://localhost:" + UUID_STRING + ";name=" + SERVICE_NAME); Util.Log("EchoServer() Server connector open!"); } catch (Exception e) {} } after calling Connector.open, I get following warning in console, which i believe is related: Warning: Unregistered device: unspecified and client code that searches for devices: public SearchForDevices(String uuid, String nm) { UUIDStr = uuid; srchServiceName = nm; try { LocalDevice local = LocalDevice.getLocalDevice(); agent = local.getDiscoveryAgent(); deviceList = new Vector(); agent.startInquiry(DiscoveryAgent.GIAC, this); // non-blocking } catch (Exception e) {} } system never calls deviceDiscovered, but calls inquiryCompleted() with INQUIRY_COMPLETED paramter, so I suppose client program runs fine. Bluetooth is enabled at emulator settings.. any ideas ?

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• How to debug anomalous C memory/stack problems

  - by EBM

  Hello, Sorry I can't be specific with code, but the problems I am seeing are anomalous. Character string values seem to be getting changed depending on other, unrelated code. For example, the value of the argument that is passed around below will change merely depending on if I comment out one or two of the fprintf() calls! By the last fprintf() the value is typically completely empty (and no, I have checked to make sure I am not modifying the argument directly... all I have to do is comment out a fprintf() or add another fprintf() and the value of the string will change at certain points!): static process_args(char *arg) { /* debug */ fprintf(stderr, "Function arg is %s\n", arg); ...do a bunch of stuff including call another function that uses alloc()... /* debug */ fprintf(stderr, "Function arg is now %s\n", arg); } int main(int argc, char *argv[]) { char *my_arg; ... do a bunch of stuff ... /* just to show you it's nothing to do with the argv array */ my_string = strdup(argv[1]); /* debug */ fprintf(stderr, "Argument 1 is %s\n", my_string); process_args(my_string); } There's more code all around, so I can't ask for someone to debug my program -- what I want to know is HOW can I debug why character strings like this are getting their memory changed or overwritten based on unrelated code. Is my memory limited? My stack too small? How do I tell? What else can I do to track down the issue? My program isn't huge, it's like a thousand lines of code give or take and a couple dynamically linked external libs, but nothing out of the ordinary. HELP! TIA!

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• How to determine if an item is the last one in a WPF ItemTemplate?

  - by Mike

  Hi everyone, I have some XAML <ItemsControl Name="mItemsControl"> <ItemsControl.ItemTemplate> <DataTemplate> <TextBox Text="{Binding Mode=OneWay}" KeyUp="TextBox_KeyUp"/> </DataTemplate> </ItemsControl.ItemTemplate> </ItemsControl> that's bound to a simple ObservableCollection private ObservableCollection<string> mCollection = new ObservableCollection<string>(); public MainWindow() { InitializeComponent(); this.mCollection.Add("Test1"); this.mCollection.Add("Test2"); this.mItemsControl.ItemsSource = this.mCollection; } Upon hitting the enter key in the last TextBox, I want another TextBox to appear. I have code that does it, but there's a gap: private void TextBox_KeyUp(object sender, KeyEventArgs e) { if (e.Key != Key.Enter) { return; } TextBox textbox = (TextBox)sender; if (IsTextBoxTheLastOneInTheTemplate(textbox)) { this.mCollection.Add("A new textbox appears!"); } } The function IsTextBoxTheLastOneInTheTemplate() is something that I need, but can't figure out how to write. How would I go about writing it? I've considered using ItemsControl.ItemContainerGenerator, but can't put all the pieces together. Thanks! -Mike

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• Get Eclipse to recognize the maps api

  - by NickTFried

  Hi I'm developing an Android app and trying to incorporate maps into one of my sub-activities. Having followed all of the instructions from Android, my java file will not recognize the "MapActivity" or the import statements to include the needed api. Here is my XML manifest and my class file. <?xml version="1.0" encoding="utf-8"?> <uses-permission android:name="android.permissions.INTERNET"/> <uses-permission android:name="android.permissions.ACCESS_FINE_LOCATION"/> <application android:icon="@drawable/icon" android:label="@string/app_name"> <uses-library android:name="com.google.android.maps" /> <activity android:name=".CadetCommand" android:label="@string/app_name"> <intent-filter> <action android:name="android.intent.action.MAIN" /> <category android:name="android.intent.category.LAUNCHER" /> </intent-filter> </activity> <activity android:name="RedLight"></activity> <activity android:name="PTCalculator"></activity> </application> <uses-sdk android:minSdkVersion="7"/> here is my java file: package edu.elon.cs.mobile; import com.google.android.maps.MapActivity; import com.google.android.maps.MapView; import android.os.Bundle; public class LandNav extends MapActivity{ } Any suggestion would help.

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• Run a .java file using ProcessBuilder

  - by David K

  I'm a novice programmer working in Eclipse, and I need to get multiple processes running (this is going to be a simulation of a multi-computer system). My initial hackup used multiple threads to multiple classes, but now I'm trying to replace the threads with processes. From my reading, I've gleaned that ProcessBuilder is the way to go. I have tried many many versions of the input you see below, but cannot for the life of me figure out how to properly use it. I am trying to run the .java files I previously created as classes (which I have modified). I eventually just made a dummy test.java to make sure my process is working properly - its only function is to print that it ran. My code for the two files are below. Am I using ProcessBuilder correctly? Is this the correct way to read the output of my subprocess? Any help would be much appreciated. David primary process package Control; import java.io.*; import java.lang.*; public class runSPARmatch { /** * @param args */ public static void main(String args[]) { try { ProcessBuilder broker = new ProcessBuilder("javac.exe","test.java","src\\Broker\\"); Process runBroker = broker.start(); Reader reader = new InputStreamReader(runBroker.getInputStream()); int ch; while((ch = reader.read())!= -1) System.out.println((char)ch); reader.close(); runBroker.waitFor(); System.out.println("Program complete"); } catch (IOException e) { // TODO Auto-generated catch block e.printStackTrace(); } catch (InterruptedException e) { // TODO Auto-generated catch block e.printStackTrace(); } } } subprocess package Broker; public class test { /** * @param args */ public static void main(String[] args) { // TODO Auto-generated method stub System.out.println("This works"); } }

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• ADO.NET Batch Insert with over 2000 parameters

  - by Liming

  Hello all, I'm using Enterprise library, but the idea is the same. I have a SqlStringCommand and the sql is constructed using StringBuilder in the forms of "insert into table (column1, column2, column3) values (@param1-X, @param2-X, @parm3-X)"+" " where "X" represents a "for loop" about 700 rows StringBuilder sb = new StringBuilder(); for(int i=0; i<700; i++) { sb.Append("insert into table (column1, column2, column3) values (@param1-"+i+", @param2-"+i, +",@parm3-"+i+") " ); } followed by constructing a command object injecting all the parameters w/ values into it. Essentially, 700 rows with 3 parameters, I ended up with 2100 parameters for this "one sql" Statement. It ran fine for about a few days and suddenly I got this error =============================================================== A severe error occurred on the current command. The results, if any, should be discarded. at System.Data.SqlClient.SqlConnection.OnError(SqlException exception, Boolean breakConnection) at System.Data.SqlClient.SqlInternalConnection.OnError(SqlException exception, Boolean breakConnection) at System.Data.SqlClient.TdsParser.ThrowExceptionAndWarning(TdsParserStateObject stateObj) at System.Data.SqlClient.TdsParser.Run(RunBehavior runBehavior, SqlCommand cmdHandler, SqlDataReader dataStream, BulkCopySimpleResultSet bulkCopyHandler, TdsParserStateObject stateObj) at System.Data.SqlClient.SqlCommand.FinishExecuteReader(SqlDataReader ds, RunBehavior runBehavior, String resetOptionsString) at System.Data.SqlClient.SqlCommand.RunExecuteReaderTds(CommandBehavior cmdBehavior, RunBehavior runBehavior, Boolean returnStream, Boolean async) at System.Data.SqlClient.SqlCommand.RunExecuteReader(CommandBehavior cmdBehavior, RunBehavior runBehavior, Boolean returnStream, String method, DbAsyncResult result) at System.Data.SqlClient.SqlCommand.InternalExecuteNon Any pointers are greatly appreciated.

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• Rails: unable to set any attribute of child model

  - by Bryan Roth

  I'm having a problem instantiating a ListItem object with specified attributes. For some reason all attributes are set to nil even if I specify values. However, if I specify attributes for a List, they retain their values. Attributes for a List retain their values: >> list = List.new(:id => 20, :name => "Test List") => #<List id: 20, name: "Test List"> Attributes for a ListItem don't retain their values: >> list_item = ListItem.new(:id => 17, :list_id => 20, :name => "Test Item") => #<ListItem id: nil, list_id: nil, name: nil> UPDATE #1: I thought the id was the only attribute not retaining its value but realized that setting any attribute for a ListItem gets set to nil. list.rb: class List < ActiveRecord::Base has_many :list_items, :dependent => :destroy accepts_nested_attributes_for :list_items, :reject_if => lambda { |a| a[:name].blank? }, :allow_destroy => true end list_item.rb: class ListItem < ActiveRecord::Base belongs_to :list validates_presence_of :name end schema.rb ActiveRecord::Schema.define(:version => 20100506144717) do create_table "list_items", :force => true do |t| t.integer "list_id" t.string "name" t.datetime "created_at" t.datetime "updated_at" end create_table "lists", :force => true do |t| t.string "name" t.datetime "created_at" t.datetime "updated_at" end end

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• Using LINQ in generic collections

  - by Hugo S Ferreira

  Hi, Please consider the following snippet from an implementation of the Interpreter pattern: public override object Execute(Interpreter interpreter, object ctx) { var list = ctx as IEnumerable<string>; return (list != null) ? list.FirstOrDefault() : null; } What about if I want to use the same function for integers? public override object Execute(Interpreter interpreter, object ctx) { var list = ctx as IEnumerable<string>; if (list != null) return list.FirstOrDefault(); var list = ctx as IEnumerable<int>; return (list != null) ? list.FirstOrDefault() : null; } What I wanted was something like: public override object Execute(Interpreter interpreter, object ctx) { var list = ctx as IEnumerable; return (list != null) ? list.FirstOrDefault() : null; } But Linq doesn't act on IEnumerables. Instead, to get to this solution, I would be forced to write something like: public override object Execute(Interpreter interpreter, object ctx) { var list = ctx as IEnumerable; if (list != null) foreach(var i in list) { yield return i; return; } return null; } Or use a generic method: public override T Execute<T>(Interpreter interpreter, object ctx) { var list = ctx as IEnumerable<T>; return (list != null) ? list.FirstOrDefault() : null; } Which would break the Interpreter pattern (as it was implemented in this system). Covariance would also fail (at least in C#3), though would it work, it would be the exact behavior I wanted: public override object Execute(Interpreter interpreter, object ctx) { var list = ctx as IEnumerable<object>; return (list != null) ? list.FirstOrDefault() : null; } So, my question is: what's the best way to achieve the intended behavior? Thanks :-)

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• Problem Activating Sharepoint Timer Job

  - by Ben Robinson

  I have created a very simple sharepoint timer job. All i want it to do is iterate through a list and update each list item so that it triggers an existing workflow that works fine. In other words all i am trying to do is work around the limitation that workflows cannot be triggered on a scheduled basis. I have written a class that inherits from SPJobDefinition that does the work and i have a class that inherits from SPFeatureReceiver to install and activate it. I have created the feature using SPVisualdev that my coleagues have used in the past for other SP development. My Job class is below: public class DriverSafetyCheckTrigger : SPJobDefinition { private string pi_SiteUrl; public DriverSafetyCheckTrigger(string SiteURL, SPWebApplication WebApp):base("DriverSafetyCheckTrigger",WebApp,null, SPJobLockType.Job) { this.Title = "DriverSafetyCheckTrigger"; pi_SiteUrl = SiteURL; } public override void Execute(Guid targetInstanceId) { using (SPSite siteCollection = new SPSite(pi_SiteUrl)) { using (SPWeb site = siteCollection.RootWeb) { SPList taskList = site.Lists["Driver Safety Check"]; foreach(SPListItem item in taskList.Items) { item.Update(); } } } } } And the only thing in the feature reciever class is that i have overridden the FeatureActivated method below: public override void FeatureActivated(SPFeatureReceiverProperties Properties) { SPSite site = Properties.Feature.Parent as SPSite; // Make sure the job isn't already registered. foreach (SPJobDefinition job in site.WebApplication.JobDefinitions) { if (job.Name == "DriverSafetyCheckTrigger") job.Delete(); } // Install the job. DriverSafetyCheckTrigger oDriverSafetyCheckTrigger = new DriverSafetyCheckTrigger(site.Url, site.WebApplication); SPDailySchedule oSchedule = new SPDailySchedule(); oSchedule.BeginHour = 1; oDriverSafetyCheckTrigger.Schedule = oSchedule; oDriverSafetyCheckTrigger.Update(); } The problem i have is that when i try to activate the feature it throws a NullReferenceException on the line oDriverSafetyCheckTrigger.Update(). I am not sure what is null in this case, the example i have followed for this is this tutorial. I am not sure what I am doing wrong.

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• Opengl-es draw an .obj file, but how?

  - by lacas

  I d like to parse an .obj file. My parser is working good, but my displaying is not good. Obj file is here my code is: public ObjModelParser parse() { long startTime = System.currentTimeMillis(); InputStream fileIn = resources.openRawResource(resourceID); BufferedReader buffer = new BufferedReader(new InputStreamReader(fileIn)); String line=""; Log.e("model loader", "Start parsing object " + resourceID); try { while ((line = buffer.readLine()) != null) { StringTokenizer parts = new StringTokenizer(line, " "); int numTokens = parts.countTokens(); if (numTokens == 0) continue; String part = parts.nextToken(); if (part.equals(VERTEX)) { Log.e("v ", line); vertices.add(Float.parseFloat(parts.nextToken())); vertices.add(Float.parseFloat(parts.nextToken())); vertices.add(Float.parseFloat(parts.nextToken())); .... and my displaying code is: draw that model with TRIANGLE_STRIP and gl.glDrawArrays(rendermode, 0, coords.length/dimension); What is the mistake here? edited: file here to show what is my good coords from my program for a cube, and what is from .obj file, that never show Thanks, Leslie

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• Entity framework entity class mapping with plain .net class

  - by Elan

  I have following in entity framework Table - Country Fields List item Country_ID Dialing_Code ISO_Alpha2 ISO_Alpha3 ISO_Full I would like to map only selected fields from this entity model to my domain class. My domain model class is public class DomainCountry { public int Country_ID { get; set; } public string Dialing_Code { get; set; } public string ISO_3166_1_Alpha_2 { get; set; } } The following will work however insert or update is not possible. In order to get insert or update we need to use ObjectSet< but it will not support in my case. IQueryable<DomainCountry> countries = context.Countries.Select( c => new DomainCountry { Country_ID = c.Country_Id, Dialing_Code = c.Dialing_Code, ISO_3166_1_Alpha_2 = c.ISO_3166_1_Alpha_2 }); It will be really fantastic could someone provide a nice solution for this. Ideally it will be kind of proxy class which will support all the futures however highly customizable i.e. only the columns we want to expose to the outer world

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• XML parsing design using xmlpp and C++

  - by shagv

  I would like to use an xml format similar to the following: <CONFIG> <PROFILE NAME="foobar"> <PARAM ID="0" NAME="Foo" CLASS="BaseParam"/> <PARAM ID="2" NAME="Bar" CLASS="StrIntParam"> <VALUE TYPE="STRING">some String</VALUE> <VALUE TYPE="INT">1234</VALUE> </PARAM> </PROFILE> </CONFIG> CONFIG contains a list of PROFILEs which contain a list of PARAMs which themselves can be any structure (to be defined in the future). The idea was to define classes that parsed each PARAM type and to keep track of which class to use in the PARAM's CLASS attribute. In code I have a config class that manages the list of profiles and a profile class that manages the list of params. I would like the profile class to handle additional param types (that inherit BaseParam) without modification to the profile class (or at the very least with minimal modification). First of all, is this design viable? If so, what are some ways I could use different param classes and have their creation at run-time be automatic (the profile class sees the CLASS attribute and knows which type to create)?

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• Selecting a multi-dimensional array in LINQ

  - by mckhendry

  I have a task where I need to translate a DataTable to a two-dimensional array. That's easy enough to do by just looping over the rows and columns (see example below). private static string[,] ToArray(DataTable table) { var array = new string[table.Rows.Count,table.Columns.Count]; for (int i = 0; i < table.Rows.Count; ++i) for (int j = 0; j < table.Columns.Count; ++j) array[i, j] = table.Rows[i][j].ToString(); return array; } What I'd really like to do is use a select statement in LINQ to generate that 2D array. Unfortunately it looks like there is no way in LINQ to select a multidimensional array. Yes, I'm aware that I can use LINQ to select a jagged array, but that's not what I want. Is my assumption correct, or is there a way to use LINQ to select a multi-dimensional array?

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