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  • how to read in a list of custom configuration objects

    - by Johnny
    hi, I want to implement Craig Andera's custom XML configuration handler in a slightly different scenario. What I want to be able to do is to read in a list of arbitrary length of custom objects defined as: public class TextFileInfo { public string Name { get; set; } public string TextFilePath { get; set; } public string XmlFilePath { get; set; } } I managed to replicate Craig's solution for one custom object but what if I want several? Craig's deserialization code is: public class XmlSerializerSectionHandler : IConfigurationSectionHandler { public object Create(object parent, object configContext, XmlNode section) { XPathNavigator nav = section.CreateNavigator(); string typename = (string)nav.Evaluate("string(@type)"); Type t = Type.GetType(typename); XmlSerializer ser = new XmlSerializer(t); return ser.Deserialize(new XmlNodeReader(section)); } } I think I could do this if I could get Type t = Type.GetType("System.Collections.Generic.List<TextFileInfo>") to work but it throws Could not load type 'System.Collections.Generic.List<Test1.TextFileInfo>' from assembly 'Test1, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null'.

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  • How to not use JavaScript with in the elements events attributes but still load via AJAX

    - by thecoshman
    I am currently loading HTMl content via AJAX. I have code for things on different elements onclick attributes (and other event attributes). It does work, but I am starting to find that the code is getting rather large, and hard to read. I have also read that it is considered bad practice to have the event code 'inline' like this and that I should really do by element.onclick = foobar and have foobar defined somewhere else. I understand how with a static page it is fairly easy to do this, just have a script tag at the bottom of the page and once the page is loaded have it executed. This can then attach any and all events as you need them. But how can I get this sort of affect when loading content via AJAX. There is also the slight case that the content loaded can very depending on what is in the database, some times certain sections of HTML, such as tables of results, will not even be displayed there will be something else entirely. I can post some samples of code if any body needs them, but I have no idea what sort of things would help people with this one. I will point out, that I am using Jquery already so if it has some helpful little functions that would be rather sweet¬

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  • UIActivityIndicatorView in a class without a view

    - by Structurer
    Hi I have defined a class that does a lengthy task and I call it from several other classes. Now I want to show an Activity Indicator while this task is doing it's thing, and then remove it once it's done. Since this is just a boring background task, this class doesn't have a view, and I guess that is where I run into my problem. I can't get this thing to show. This is what I have done in my class: UIActivityIndicatorView *activityIndicator = [[UIActivityIndicatorView alloc] initWithFrame:CGRectMake(0.0f, 0.0f, 32.0f, 32.0f)]; [activityIndicator setCenter:CGPointMake(160.0f, 208.0f)]; activityIndicator.activityIndicatorViewStyle = UIActivityIndicatorViewStyleWhite; UIView *contentView = [[UIView alloc]initWithFrame:[[UIScreen mainScreen] applicationFrame]]; [contentView addSubview:activityIndicator]; [activityIndicator startAnimating]; // Do the class lengthy task that takes several seconds..... [contentView release]; [activityIndicator release]; I guess I do something wrong when I get the contentView, but how should I get it properly? Thanks for any advices...

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  • Silverlight Socket Constantly Returns With Empty Buffer

    - by Benny
    I am using Silverlight to interact with a proxy application that I have developed but, without the proxy sending a message to the Silverlight application, it executes the receive completed handler with an empty buffer ('\0's). Is there something I'm doing wrong? It is causing a major memory leak. this._rawBuffer = new Byte[this.BUFFER_SIZE]; SocketAsyncEventArgs receiveArgs = new SocketAsyncEventArgs(); receiveArgs.SetBuffer(_rawBuffer, 0, _rawBuffer.Length); receiveArgs.Completed += new EventHandler<SocketAsyncEventArgs>(ReceiveComplete); this._client.ReceiveAsync(receiveArgs); if (args.SocketError == SocketError.Success && args.LastOperation == SocketAsyncOperation.Receive) { // Read the current bytes from the stream buffer int bytesRecieved = this._client.ReceiveBufferSize; // If there are bytes to process else the connection is lost if (bytesRecieved > 0) { try { //Find out what we just received string messagePart = UTF8Encoding.UTF8.GetString(_rawBuffer, 0, _rawBuffer.GetLength(0)); //Take out any trailing empty characters from the message messagePart = messagePart.Replace('\0'.ToString(), ""); //Concatenate our current message with any leftovers from previous receipts string fullMessage = _theRest + messagePart; int seperator; //While the index of the seperator (LINE_END defined & initiated as private member) while ((seperator = fullMessage.IndexOf((char)Messages.MessageSeperator.Terminator)) > 0) { //Pull out the first message available (up to the seperator index string message = fullMessage.Substring(0, seperator); //Queue up our new message _messageQueue.Enqueue(message); //Take out our line end character fullMessage = fullMessage.Remove(0, seperator + 1); } //Save whatever was NOT a full message to the private variable used to store the rest _theRest = fullMessage; //Empty the queue of messages if there are any while (this._messageQueue.Count > 0) { ... } } catch (Exception e) { throw e; } // Wait for a new message if (this._isClosing != true) Receive(); } } Thanks in advance.

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  • C lang. -- Error: Segmentation fault

    - by user233542
    I don't understand why this would give me a seg fault. Any ideas? This is the function that returns the signal to stop the program (plus the other function that is called within this): double bisect(double A0,double A1,double Sol[N],double tol,double c) { double Amid,shot; while (A1-A0 > tol) { Amid = 0.5*(A0+A1); shot = shoot(Sol, Amid, c); if (shot==2.*Pi) { return Amid; } if (shot > 2.*Pi){ A1 = Amid; } else if (shot < 2.*Pi){ A0 = Amid; } } return 0.5*(A1+A0); } double shoot(double Sol[N],double A,double c) { int i,j; /*Initial Conditions*/ for (i=0;i<buff;i++) { Sol[i] = 0.; } for (i=buff+l;i<N;i++) { Sol[i] = 2.*Pi; } Sol[buff]= 0; Sol[buff+1]= A*exp(sqrt(1+3*c)*dx); for (i=buff+2;i<buff+l;i++) { Sol[i] = (dx*dx)*( sin(Sol[i-1]) + c*sin(3.*(Sol[i-1])) ) - Sol[i-2] + 2.*Sol[i-1]; } return Sol[i-1]; } The values buff, l, N are defined using a #define statement. l = 401, buff = 50, N = 2000

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  • Using Cucumber With Modular Sinatra Apps

    - by Rob Conery
    I'm building out a medium-sized application using Sinatra and all was well when I had a single app.rb file and I followed Aslak's guidance up on Github: http://wiki.github.com/aslakhellesoy/cucumber/sinatra As the app grew a bit larger and the app.rb file started to bulge, I refactored out a lot of of the bits into "middleware" style modules using Sinatra::Base, mapping things using a rack-up file (config.ru) etc. The app works nicely - but my specs blew up as there was no more app.rb file for webrat to run against (as defined in the link above). I've tried to find examples on how to work this - and I think I'm just not used to the internal guts of Cuke just yet as I can't find a single way to have it cover all the apps. I tried just pointing to "config.ru" instead of app.rb - but that doesn't work. What I ended up doing - which is completely hackish - is to have a separate app.rb file in my support directory, which has all the requires stuff so I can at least test the model stuff. I can also specify routes in there - but that's not at all what I want to do. So - the question is: how can I get Cucumber to properly work with the modular app approach?

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  • What's the most efficient way to setup a multi-lingual website

    - by Jasper De Bruijn
    Hi, I'm developing a website that will be available in different languages. It is a LAMP (Linux, Apache, MySQL, PHP) setup, and it makes use of Smarty, mostly for the template engine. The way we currently translate is by a self-written smarty plugin, which will recognize certain tags in the HTML files, and will find the corresponding tag in an earlier defined language file. The HTML could look as follows: <p>Hi, welcome to $#gamedesc;!</p> And the language file could look like this: gamedesc:Poing 2009$; welcome:this is another tag$; Which would then output <p>Hi, welcome to Poing 2009!</p> This system is very basic, but it is pretty hard to control, if I f.e. would like to keep track of what has been translated so far, or give certain users the rights to translate only certain tags. I've been looking at some alternative ways to approach this, by either replacing the text-file with XML files which could store some extra meta-data, or by perhaps storing all the texts in the database, and retrieving it there. My question is, what would be the best way to make this system both maintainable and perform well with high user-traffic? Are there perhaps any (lightweight) plugins I could take a look at?

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  • Background color remaining when switching views

    - by Guy
    Hi Guys. I have a UIViewController named equationVC who's user interface is being programmatically created from another NSObject class called equationCon. Upon loading equationVC, a method called chooseInterface is called from the equationCon class. I have a global variable (globalVar) that points to a user defined string. chooseInterface finds a method in the equationCon class that matches the string globalVar points to. In this case, let's say that globalVar points to a string that is called "methodThatMatches." In methodThatMatches, another view controller needs to show the results of what methodThatMatches did. methodThatMatches creates a new equationVC that calls upon methodThatMatches2. As a test, each method changes the color of the background. When the application starts up, I get a purple background, but as soon as I hit backwards I get another purple screen, which should be yellow. I do not think that I am release the view properly. Can anyone help? -(void)chooseInterface { NSString* equationTemp = [globalVar stringByReplacingOccurrencesOfString:@" " withString:@""]; equationTemp = [equationTemp stringByReplacingOccurrencesOfString:@"'" withString:@""]; SEL equationName = NSSelectorFromString(equationTemp); NSLog(@"selector! %@",NSStringFromSelector(equationName)); if([self respondsToSelector:equationName]){ [self performSelector:equationName]; } } -(void)methodThatMatches{ self.equationVC.view.backgroundColor = [UIColor yellowColor]; [setGlobalVar:@"methodThatMatches2"]; EquationVC* temp = [[EquationVC alloc] init]; [[self.equationVC navigationController] pushViewController:temp animated:YES ]; [temp release]; } -(void)methodThatmatches2{ self.equationVC.view.backgroundColor = [UIColor purpleColor]; }

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  • How to call functions inside a C dll which take pointers as arguments from C#

    - by AndrejaKo
    Hi people, this is my first post here! I'm trying to make a windows forms program using C# which will use a precompiled C library. It will access a smart card and provide output from it. For the library, I have a .dll, .lib and .h and no source. In the .h file there are several structs defined. Most interesting functions of the .dll expect pointers to allocated structs as arguments. I've been calling functions inside the .dll like this: For example function EID_API int WINAPI EidStartup(int nApiVersion); would be called like this [DllImport("CelikApi.dll")]//the name of the .dll public static extern int EidStartup(int nApiVersion); Now my problem is that I can't find equivalent of C's pointers which point to dynamically allocated structures in memory in C#, so I don't know what to pass as argument to functions which take C pointers. I don't have much experience in C#, but to me its use looked as the easiest way of making the program I need. I tried with C++, but Visual Studio 2010 doesn't have IntelliSense for C++/CLR. If you can point me to something better, feel free to do so.

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  • New projects not built when target platform is set explicitly

    - by stiank81
    I create a new solution with one project, and then change the target platform from "Any CPU" to "x86". After this new projects added doesn't get built by default, and their target platform doesn't follow the global settings. Why?! Looking at the configuration manager new projects added are not checked to "Build", and they get target platform "Any CPU" instead of the globally set x86. Why is this happening? I expect new projects too to get the globally set and defined x86 target platform.. Some things I've tried: Toggle global platform back to Any CPU, and then to x86 again. No change.. Choosing platform explicitly for the new project. x86 is not available in the list, and when I say <New..> and try adding it I'm not allowed as ".. a solution platform with the same name already exists.". On the build properties for the new project I can't change the platform in the Configuration section, but I can set "Platform target" to x86 in the General section. It is however not clear whether this actually makes a difference, and it wouldn't respond if I change the target platform globally later. Initially I thought this was a problem from converting my solution from VS2008 to VS2010, but the problem applies both places. I.e. when I create a solution in VS2008 and just stay in VS2008 I still get the problem.

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  • Use interface between model and view in ASP.NET MVC

    - by Icerman
    Hi, I am using asp.net MVC 2 to develop a site. IUser is used to be the interface between model and view for better separation of concern. However, things turn to a little messy here. In the controller that handles user sign on: I have the following: IUserBll userBll = new UserBll(); IUser newUser = new User(); newUser.Username = answers[0].ToString(); newUser.Email = answers[1].ToString(); userBll.AddUser(newUser); The User class is defined in web project as a concrete class implementing IUser. There is a similar class in DAL implementing the same interface and used to persist data. However, when the userBll.AddUser is called, the newUser of type User can't be casted to the DAL User class even though both Users class implementing the interface (InvalidCastException). Using conversion operators maybe an option, but it will make the dependency between DAL and web which is against the initial goal of using interface. Any suggestions?

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  • Converting Generic Type into reference type after checking its type using GetType(). How ?

    - by Shantanu Gupta
    i am trying to call a function that is defined in a class RFIDeas_Wrapper(dll being used). But when i checked for type of reader and after that i used it to call function it shows me error Cannot convert type T to RFIDeas_Wrapper. EDIT private List<string> GetTagCollection<T>(T Reader) { TagCollection = new List<string>(); if (Reader.GetType() == typeof(RFIDeas_Wrapper)) { ((RFIDeas_Wrapper)Reader).OpenDevice(); // here Reader is of type RFIDeas_Wrapper //, but i m not able to convert Reader into its datatype. string Tag_Id = ((RFIDeas_Wrapper)Reader).TagID(); //Adds Valid Tag Ids into the collection if(Tag_Id!="0") TagCollection.Add(Tag_Id); } else if (Reader.GetType() == typeof(AlienReader)) TagCollection = ((AlienReader)Reader).TagCollection; return TagCollection; } ((RFIDeas_Wrapper)Reader).OpenDevice(); , ((AlienReader)Reader).TagCollection; I want this line to be executed without any issue. As Reader will always be of the type i m specifying. How to make compiler understand the same thing.

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  • properly format postal address with line breaks [google maps]

    - by munchybunch
    Using V3 of the google maps API, is there any reliable way to format addresses with the line break? By this, I mean something like 1600 Amphitheatre Parkway Mountain View, CA 94043 should be formatted as 1600 Amphitheatre Parkway Mountain View, CA 94043 Looking through the response object from geocoding, there is an address_components array that has, for the above address, 8 components (not all of the components are used for the address): 0: Object long_name: "1600" short_name: "1600" types: Array[1] 0: "street_number" length: 1 1: Object long_name: "Amphitheatre Pkwy" short_name: "Amphitheatre Pkwy" types: Array[1] 0: "route" length: 1 2: Object long_name: "Mountain View" short_name: "Mountain View" types: Array[2] 0: "locality" 1: "political" length: 2 3: Object long_name: "San Jose" short_name: "San Jose" types: Array[2] 0: "administrative_area_level_3" 1: "political" length: 2 4: Object long_name: "Santa Clara" short_name: "Santa Clara" types: Array[2] 0: "administrative_area_level_2" 1: "political" length: 2 5: Object long_name: "California" short_name: "CA" types: Array[2] 0: "administrative_area_level_1" 1: "political" length: 2 6: Object long_name: "United States" short_name: "US" types: Array[2] 0: "country" 1: "political" length: 2 7: Object long_name: "94043" short_name: "94043" types: Array[1] 0: "postal_code" length: 1 I was thinking that you could just combine parts that you want, like sprintf("%s %s<br />%s, %s %s", array[0].short_name, array[1].short_name, array[2].short_name, array[5].short_name, array[7].short_name) [edit]I just realized that sprintf isn't defined by default in JavaScript, so just a concatenation would do I guess.[/edit] But that seems awfully unreliable. Does anyone know the details on the structure of address_components, and if it's reliably similar like that for street addresses in the US? If I wanted to, I guess I could look for the proper types (street_number,route, etc) as well. I'd love it if anyone had a better way than what I"m doing here...

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  • Mapping enum with fluent nhibernate

    - by Puneet
    I am following the http://wiki.fluentnhibernate.org/Getting%5Fstarted tutorial to create my first NHibernate project with Fluent NHibernate I have 2 tables 1) Account with fields Id AccountHolderName AccountTypeId 2) AccountType with fields Id AccountTypeName Right now the account types can be Savings or Current So the table AccountTypes stores 2 rows 1 - Savings 2 - Current For AccoutType table I have defined enum public enum AccountType { Savings=1, Current=2 } For Account table I define the entity class public class Account { public virtual int Id {get; private set;} public virtual string AccountHolderName {get; set;} public virtual string AccountType {get; set;} } The fluent nhibernate mappings are: public AgencyMap() { Id(o => o.Id); Map(o => o.AccountHolderName); Map(o => o.AccountType); } When I try to run the solution, it gives an exception - InnerException = {"(XmlDocument)(2,4): XML validation error: The element 'class' in namespace 'urn:nhibernate-mapping-2.2' has incomplete content. List of possible elements expected: 'meta, subselect, cache, synchronize, comment, tuplizer, id, composite-id' in namespace 'ur... I guess that is because I have not speciofied any mapping for AccountType. The questions are: How can I use AccountType enum instead of a AccountType class? Maybe I am going on wrong track. Is there a better way to do this? Thanks!

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  • How can I control the height of a ListView in WPF, using a complex DataTemplate with DataTriggers?

    - by Rob Perkins
    I have a ListView element with a DataTemplate for each ListViewItem defined as follows. When run, the ListView's height is not collapsed onto the items in the view, which is undesirable behavior: <DataTemplate x:Key="LicenseItemTemplate"> <Grid> <Grid.RowDefinitions> <RowDefinition Height="Auto" /> <RowDefinition Height="Auto" /> </Grid.RowDefinitions> <TextBlock Grid.Row="0" Text="{Binding company}"></TextBlock> <Grid Grid.Row="1" Style="{StaticResource HiddenWhenNotSelectedStyle}"> <Grid.RowDefinitions> <RowDefinition /> </Grid.RowDefinitions> <Button Grid.Row="0">ClickIt</Button> </Grid> </Grid> </DataTemplate> The second row of the outer grid has a style applied which looks like this. The purpose of the style is to : <Style TargetType="{x:Type Grid}" x:Key="HiddenWhenNotSelectedStyle" > <Style.Triggers> <DataTrigger Binding="{Binding Path=IsSelected, RelativeSource={ RelativeSource Mode=FindAncestor, AncestorType={x:Type ListBoxItem} } }" Value="False"> <Setter Property="Grid.Visibility" Value="Collapsed" /> </DataTrigger> <DataTrigger Binding="{Binding Path=IsSelected, RelativeSource={ RelativeSource Mode=FindAncestor, AncestorType={x:Type ListBoxItem} } }" Value="True"> <Setter Property="Grid.Visibility" Value="Visible" /> </DataTrigger> </Style.Triggers> </Style> The ListView renders like this: The desired appearance is this, when none of the elements are selected: ...with, of course, the ListView's height adjusting to accommodate the additional content when the second grid is made visible by selection. What can I do to get the desired behavior?

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  • asp.net mvc ajax helper/post additional data w/o jquery.

    - by Jopache
    I would like to use the ajax helper to create ajax requests that send additional, dynamic data with the post (for example, get the last element with class = blogCommentDateTime and send the value of that last one to the controller which will return only blog comments after it). I have successfully done so with the help of jQuery Form plugin like so: $(document).ready(function () { $("#addCommentForm").submit(function () { var lastCommentDate = $(".CommentDateHidden:last").val(); var lastCommentData = { lastCommentDateTicks: lastCommentDate }; var formSubmitParams = { data: lastCommentData, success: AddCommentResponseHandler } $("#addCommentForm").ajaxSubmit(formSubmitParams); return false; }); This form was created with html.beginform() method. I am wondering if there is an easy way to do this using the ajax.beginform() helper? When I try to use the same code but replace html.beginform() with ajax.beginform(), when i try to submit the form, I am issuing 2 posts (which is understandable, one being taken care of by the helper, the other one by me with the JS above. I can't create 2 requests, so this option is out) I tried getting rid of the return false and changing ajaxSubmit() to ajaxForm() so that it would only "prepare" the form, and this leads in only one post, but it does not include the extra parameter that I defined, so this is worthless as well. I then tried keeping the ajaxForm() but calling that whenever the submit button on the form gets clicked rather than when the form gets submitted (I guess this is almost the same thing) and that results in 2 posts also. The biggest reason I am asking this question is that I have run in to some issues with the javascript above and using mvc validation provided by the mvc framework (which i will set up another question for) and would like to know this so I can dive further in to my validation issue.

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  • Create an instance of an exported C++ class from Delphi

    - by Alan G.
    I followed an excellent article by Rudy Velthuis about using C++ classes in DLL's. Everything was golden, except that I need access to some classes that do not have corresponding factories in the C++ DLL. How can I construct an instance of a class in the DLL? The classes in question are defined as class __declspec(dllexport) exampleClass { public: void foo(); }; Now without a factory, I have no clear way of instantiating the class, but I know it can be done, as I have seen SWIG scripts (.i files) that make these classes available to Python. If Python&SWIG can do it, then I presume/hope there is some way to make it happen in Delphi too. Now I don't know much about SWIG, but it seems like it generates some sort of map for C++ mangled names? Is that anywhere near right? Looking at the exports from the DLL, I suppose I could access functions & constructor/destructor by index or the mangled name directly, but that would be nasty; and would it even work? Even if I can call the constructor, how can I do the equivalent of "new CClass();" in Delphi?

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  • Choosing a method for a webservice

    - by Wrikken
    I'm asked to set up a new webservice which should be easily usable in whatever language (php, .NET, Java, etc.) possible. Of course rolling my own can be done, accepting different content-types (xml / x-www-form-urlencoded (normal post) / json / etc.), but an existing method or mechanism would of course be prefered, cutting down time spent on development for the consumers of the service. The webservice does accept modifications / sets (it is not only simply data retrieval), but those will most likely be quite a lot less then gets (we estimate about 2.5% sets, 97.5 gets). The term webservice here indicates the protocol should go over HTTP, not being able to implement it totally client sided (javascript in the end-users browser etc.), as it needs specific user authentication. Both gets and sets are pretty light on the parameter count (usually 1 to 4). Methods like REST (which I'd prefer for only gets), XML-RPC & SOAP (might be a bit overkill, but has the advantage of explicitly defined methods and returns) are the usual suspects. What in your opinion / experience is the most widely 'spoken' and most easily implementable protocol in different languages (seen from the consumers' viewpoint) which could fullfill this need?

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  • Strings exported from a module have extra line breaks

    - by Jesse Millikan
    In a DrScheme project, I'm using a MrEd editor-canvas% with text% and inserting a string from a literal in a Scheme file. This results in an extra blank line in the editor for each line of text I'm trying to insert. I've tracked this down to the apparent fact that string literals from outside modules are getting extra line breaks. Here's a full example. The editor is irrelevant at this point, but it displays the result. ; test-literals.ss (module test-literals scheme (provide (all-defined-out)) (define exported-string "From another module with some more line breaks. ")) ; editor-test.ss (module editor-test scheme (require mred "test-literals.ss") (define w (instantiate frame% ("Editor Test" #f) )) (define c (instantiate editor-canvas% (w) (line-count 12) (min-width 400))) (define editor (instantiate text% ())) (send c set-editor editor) (send w show #t) (send editor erase) (send editor insert "Some text with some line breaks. ") (send editor insert exported-string)) And the result in the editor is Some text with some line breaks. From another module with some more line breaks.

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  • Is a call to the following method considered late binding?

    - by AspOnMyNet
    1) Assume: • B1 defines methods virtualM() and nonvirtualM(), where former method is virtual while the latter is non-virtual • B2 derives from B1 • B2 overrides virtualM() • B2 is defined inside assembly A • Application app doesn’t have a reference to assembly A In the following code application app dynamically loads an assembly A, creates an instance of a type B2 and calls methods virtualM() and nonvirtualM(): Assembly a=Assembly.Load(“A”); Type t= a.GetType(“B2”); B1 a = ( B1 ) Activator.CreateInstance ( “t” ); a.virtualM(); a.nonvirtualM(); a) Is call to a.virtualM() considered early binding or late binding? b) I assume a call to a.nonvirtualM() is resolved during compilation time? 2) Does the term late binding refer only to looking up the target method at run time or does it also refer to creating an instance of given type at runtime? thanx EDIT: 1) A a=new A(); a.M(); As far as I know, it is not known at compile time where on the heap (thus at which memory address ) will instance a be created during runtime. Now, with early binding the function calls are replaced with memory addresses during compilation process. But how can compiler replace function call with memory address, if it doesn’t know where on the heap will object a be created during runtime ( here I’m assuming the address of method a.M will also be at same memory location as a )? 2) The method slot is determined at compile time I assume that by method slot you’re referring to the entry point in V-table?

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  • Why does this extension method throw a NullReferenceException in VB.NET?

    - by Dan
    From previous experience I had been under the impression that it's perfectly legal (though perhaps not advisable) to call extension methods on a null instance. So in C#, this code compiles and runs: // code in static class static bool IsNull(this object obj) { return obj == null; } // code elsewhere object x = null; bool exists = !x.IsNull(); However, I was just putting together a little suite of example code for the other members of my development team (we just upgraded to .NET 3.5 and I've been assigned the task of getting the team up to speed on some of the new features available to us), and I wrote what I thought was the VB.NET equivalent of the above code, only to discover that it actually throws a NullReferenceException. The code I wrote was this: ' code in module ' <Extension()> _ Function IsNull(ByVal obj As Object) As Boolean Return obj Is Nothing End Function ' code elsewhere ' Dim exampleObject As Object = Nothing Dim exists As Boolean = Not exampleObject.IsNull() The debugger stops right there, as if I'd called an instance method. Am I doing something wrong (e.g., is there some subtle difference in the way I defined the extension method between C# and VB.NET)? Is it actually not legal to call an extension method on a null instance in VB.NET, though it's legal in C#? (I would have thought this was a .NET thing as opposed to a language-specific thing, but perhaps I was wrong.) Can anybody explain this one to me?

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  • Are function-local typedefs visible inside C++0x lambdas?

    - by GMan - Save the Unicorns
    I've run into a strange problem. The following simplified code reproduces the problem in MSVC 2010 Beta 2: template <typename T> struct dummy { static T foo(void) { return T(); } }; int main(void) { typedef dummy<bool> dummy_type; auto x = [](void){ bool b = dummy_type::foo(); }; // auto x = [](void){ bool b = dummy<bool>::foo(); }; // works } The typedef I created locally in the function doesn't seem to be visible in the lambda. If I replace the typedef with the actual type, it works as expected. Here are some other test cases: // crashes the compiler, credit to Tarydon int main(void) { struct dummy {}; auto x = [](void){ dummy d; }; } // works as expected int main(void) { typedef int integer; auto x = [](void){ integer i = 0; }; } I don't have g++ 4.5 available to test it, right now. Is this some strange rule in C++0x, or just a bug in the compiler? From the results above, I'm leaning towards bug. Though the crash is definitely a bug. For now, I have filed two bug reports. All code snippets above should compile. The error has to do with using the scope resolution on locally defined scopes. (Spotted by dvide.) And the crash bug has to do with... who knows. :) Update According to the bug reports, they have both been fixed for the next release of Visual Studio 2010.

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  • What's with bad function call in view generated via scaffold?

    - by meta
    I've scaffolded Things element: script/generate scaffold wip/thing name:string and got some invalid function call in views, like: <td><%= link_to 'Edit', edit_thing_path(thing) %></td> Which raise this error: ActionView::TemplateError (undefined method `edit_thing_path' for #<ActionView::Base:0xb5c00944>) on line #11 of app/views/wip/things/index.html.erb: 8: <tr> 9: <td><%=h thing.name %></td> 10: <td><%= link_to 'Show', thing %></td> 11: <td><%= link_to 'Edit', edit_thing_path(thing) %></td> 12: <td><%= link_to 'Destroy', thing, :confirm => 'Are you sure?', :method => :delete %></td> 13: </tr> 14: <% end %> What's with that function? Where is it? Is it some kind of automagic stuff or do I need to implement it (if so - where should it go?) I have resource defined in routes with namespace: map.namespace :wip do |wip| wip.resources :things end rake routes gives me this: wip_things GET /wip/things(.:format) {:action=>"index", :controller=>"wip/things"} POST /wip/things(.:format) {:action=>"create", :controller=>"wip/things"} new_wip_thing GET /wip/things/new(.:format) {:action=>"new", :controller=>"wip/things"} edit_wip_thing GET /wip/things/:id/edit(.:format) {:action=>"edit", :controller=>"wip/things"} wip_thing GET /wip/things/:id(.:format) I assumed that those names (wip_thing, new_wip_thing) are the correct names, but it's still gives me that error Thanks.

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  • How to create closed areas (convex polygons) from set of line segments ?

    - by Marten
    The following problem is in 2D, so some simplifications can be made when suggesting answers. I need to create closed areas (defined either by line segments or just set of points - convex polygon) from a set of points/line segments. Basically I used Voronoi to generate "roads". Then I changed some of the data. Now I need a way to loop through that data (which is still line segments but doesn't comply with Voronoi anymore) and generate "neigbourhoods" that are bordered with the "roads". I looked at some graph diagrams and shortest path theories, but I could not figure it out. Logically it could be done by starting at left edge from one point, finding the way back to that point using the shortest path with available lines (using only clockwise directions). Then mark this line set down and remove from the data. Then you can repeat the same process and get all the areas like that. I tried to implement that but it did not get me anywhere as I could not figure out a way to write a C++ code that could do that. Problem was with choosing the most counterclockwise line from available lines from a specific point. All angle based math I did gave wrong answers because the way sin/cos are implemented in c++. So to summarize - if you can help me with a totally new approach to the problem its good, if not could you help me find a way to write the part of the code that finds the shortest clockwise path back to the beginning point using the line segment set as paths back. Thank you for your help!

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  • Recursive Maze in Java

    - by Api
    I have written a short Java code for solving a simple maze problem to go from S to G. I do not understand where the problem is going wrong. import java.util.Scanner; public class tester { static char [][] grid={ {'.','.'}, {'.','.'}, {'S','G'}, }; static int a=2; static int b=2; static boolean findpath(int x, int y) { if((x > grid.length-1) || (y > grid[0].length-1) || (x < 0 || y < 0)) { return false; } else if(x==a && y==b){ return true; } else if (findpath(x,y-1) == true){ return true; } else if (findpath(x+1,y) == true){ return true; } else if (findpath(x,y+1) == true) { return true; } else if (findpath(x-1,y) == true){ return true; } return false; } public static void main(String[] args){ boolean result=findpath(2,0); System.out.print(result); } } I am giving the starting position directly and goal is defined in a & b. Do help.

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