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  • About calling an subclass' overriding method when casted to its superclass

    - by Omega
    #include <iostream> class Vehicle { public: void greet() { std::cout << "Hello, I'm a vehicle"; } }; class Car : public Vehicle { public: void greet() { std::cout << "Hello, I'm a car"; } }; class Bike : public Vehicle { public: void greet() { std::cout << "Hello, I'm a bike"; } }; void receiveVehicle(Vehicle vehicle) { vehicle.greet(); } int main() { receiveVehicle(Car()); return 0; } As you can see, I'm trying to send a parameter of type Vehicle to a function, which calls greet(). Car and Bike are subclasses of Vehicle. They overwrite greet(). However, I'm getting "Hello, I'm a vehicle". I suppose that this is because receiveVehicle receives a parameter of type Vehicle instead of a specific subclass like Car or Bike. But that's what I want: I want this function to work with any subclass of Vehicle. Why am I not getting the expected output?

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  • Clear listview content?

    - by Slash
    I have a little problem with listview. How do i clear a listview content, knowing that it has a custom adapter? edit : the custom adapter class extends BaseAdapter, it looks like this : import android.app.Activity; import android.content.Context; import android.view.LayoutInflater; import android.view.View; import android.view.ViewGroup; import android.widget.BaseAdapter; import android.widget.TextView; public class MyAdapter extends BaseAdapter { private Activity activity; private String[] data; private static LayoutInflater inflater=null; public MyAdapter(Activity _a, String[] _str) { activity = _a; data = _str; inflater = (LayoutInflater)activity.getSystemService(Context.LAYOUT_INFLATER_SERVICE); } public static class ViewHolder{ public TextView text; } @Override public int getCount() { return data.length; } @Override public Object getItem(int position) { return position; } @Override public long getItemId(int position) { return position; } @Override public View getView(int position, View view, ViewGroup parent) { View v = view; ViewHolder holder; if(v == null) { v = inflater.inflate(R.layout.rowa, null); holder=new ViewHolder(); holder.text=(TextView)v.findViewById(R.id.dexter); v.setTag(holder); }else{ holder=(ViewHolder)v.getTag(); } holder.text.setText(data[position]); return v; } }

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  • JQuery click anywhere except certain divs and issues with dynamically added html

    - by jCuga
    I want this webpage to highlight certain elements when you click on one of them, but if you click anywhere else on the page, then all of these elements should no longer be highlighted. I accomplished this task by the following, and it works just fine except for one thing (described below): $(document).click(function() { // Do stuff when clicking anywhere but on elements of class suggestion_box $(".suggestion_box").css('background-color', '#FFFFFF'); }); $(".suggestion_box").click(function() { // means you clicked on an object belonging to class suggestion_box return false; }); // the code for handling onclicks for each element function clickSuggestion() { // remove all highlighting $(".suggestion_box").css('background-color', '#FFFFFF'); // then highlight only a specific item $("div[name=" + arguments[0] + "]").css('background-color', '#CCFFCC'); } This way of enforcing the highlighting of elements works fine until I add more html to the page without having a new page load. This is done by .append() and .prepend() What I suspected from debugging was that the page is not "aware" of the new elements that were added to the page dynamically. Despite the new, dynamically added elements having the appropriate class names/IDs/names/onclicks ect, they never get highlighted like the rest of the elements (which continue to work fine the entire time). I was wondering if a possible reason for why my approach does not work for the dynamically added content is that the page is not able to recognize the elements that were not present during the pageload. And if this is a possibility, then is there a way to reconcile this without a pageload? If this line of reasoning is wrong, then the code I have above is probably not enough to show what's wrong with my webpage. But I'm really just interested in whether or not this line of thought is a possibility.

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  • Align child element to bottom with CSS

    - by alex
    I have a form input, and the label spans multiple lines, and I want the corresponding checkbox to appear at the bottom (last line of the label element). Here is what I was playing with CSS .standard-form { width: 500px; border: 1px solid red; } .standard-form .input-row { overflow: hidden; margin-bottom: 0.8em; } .standard-form label { width: 25%; float: left; } .standard-form .input-container { width: 70%; float: right; } .standard-form .checkbox .input-container { display: table-cell; height: 100%; vertical-align: text-bottom; } HTML <form class="standard-form"> <div class="input-row checkbox" id="permission"> <label for="input-permission"> Do I hereby grant you permission to do whatever tasks are neccessary to achieve an ideal outcome? </label> <div class="input-container"> <input type="checkbox" id="input-permission" name="permission" value="true" /> </div> </div> </form> It is also online at JSbin. Is there any way to do this? I notice that div.input-container isn't expanding, which is the old multi column problem with CSS. I thought I could get this going with display: table-cell and vertical-align: bottom but I haven't been able to do it yet. I don't mind that IE6/7 won't render it correctly.

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  • Getting all the classes in project and their packages from CodeRush extension

    - by drasto
    I've spent some time trying to find a way CodeRush could add using when it finds undeclared element that is in the fact class name with no using added. The solution suggested in this answer to my question (Refactor_resolve) does not work (bugged?). In a process I found out that writing plug-ins for CodeRush is easy, so I decided to code this functionality myself (and share it). I'd only implement a CodeProvider (like in this tutorial). The only thinks I need to do the job are answers to this questions: At the start up of my plugin I need to get a list (set, map, whatever) of all classes and their packages. This means all the classes(interfaces...) and their packages in project, and within all referenced libraries. And I also need to receive updated on this (when user adds reference, creates new class). Can I get this from some CodeRush classes or maybe VS interface available from CodeProvider class? How do I add created CodeProvider to the pop-up that is shown when user hovers over an Issue?

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  • AJAX Request Erroring

    - by 30secondstosam
    I can not figure out for the life of me why this is erroring - can someone please cast a second pair of eyes over this - it's probably something really stupid, thanks in advance for the help: EDIT Stupidly I was putting the wrong URL in - HOWEVER... Now I have put the correct URL in, the site just hangs and crashes. Any ideas please? HTML: <input id="pc" class="sfc" name="ProdCat[]" type="checkbox" value=""> <input id="psc" class="sfc" name="ProdSubCat[]" type="checkbox" value=""> <input id="bf" class="sfc" name="BrandFil[]" type="checkbox" value=""> JQuery: $('input[type="checkbox"]').change(function(){ var name = $(this).attr("name"); var ProdCatFil = []; var ProdSubCatFil = []; var BrandFil = []; // Loop through the checked checkboxes in the same group // and add their values to an array $('input[type="checkbox"]:checked').each(function(){ switch(name) { case 'ProdCatFil[]': ProdCatFil.push($(this).val()); break; case 'ProdSubCatFil[]': ProdSubCatFil.push($(this).val()); break; case 'BrandFil[]': BrandFil.push($(this).val()); break; } }); $("#loading").ajaxStart(function(){ $(this).show(); $('.content_area').hide(); }); $("#loading").ajaxStop(function(){ $(this).hide(); $('.content_area').show(); }); $.ajax({ type: "GET", url: '../ajax/ajax.php', data: 'ProdCatFil='+ProdCatFil+'&ProdSubCatFil='+ProdSubCatFil+'&BrandFil='+BrandFil, success: function(data) { $('.content_area').html(data); } }).error(function (event, jqXHR, ajaxSettings, thrownError) { $('.content_area').html("<h2>Could not retrieve data</h2>"); //alert('[event:' + event + '], [jqXHR:' + jqXHR + '], [ajaxSettings:' + ajaxSettings + '], [thrownError:' + thrownError + '])'); }); PHP (just to prove it's working): echo '<h1>TEST TEST TEST </h1>'; The errors from JQuery alert box: [event:[object Object]], [jqXHR:error], [ajaxSettings:Not Found], [thrownError:undefined])

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  • initialise a var in scala

    - by user unknown
    I have a class where I like to initialize my var by reading a configfile, which produces intermediate objects/vals, which I would like to group and hide in a method. Here is the bare minimum of the problem - I call the ctor with a param i, in reality a File to parse, and the init-method generates the String s, in reality more complicated than here, with a lot of intermediate objects being created: class Foo (val i: Int) { var s : String; def init () { s = "" + i } init () } This will produce the error: class Foo needs to be abstract, since variable s is not defined. In this example it is easy to solve by setting the String to "": var s = "";, but in reality the object is more complex than String, without an apropriate Null-implementation. I know, I can use an Option, which works for more complicated things than String too: var s : Option [String] = None def init () { s = Some ("" + i) } or I can dispense with my methodcall. Using an Option will force me to write Some over and over again, without much benefit, since there is no need for a None else than to initialize it that way I thought I could. Is there another way to achieve my goal?

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  • Cannot get MEDIA_URL from Django widget's template

    - by Eric
    Hi folks, I am a new Djangoer, and figuring out how to build custom widget, my problem is cannot get the MEDIA_URL in my widget's template, while the form use MySelectWidget able to get the MEDIA_URL itself. # #plus_sign.html # <a href="" class="" id="id_{{ field }}"> <img src="{{ MEDIA_URL }}images/plus_sign.gif" width="10" height="10" alt="Add"/> </a> *^ cannot load the {{ MEDIA_URL}} to this widget's template, and therefore I can't load the .gif image properly. :(* # #custom_widgets.py # from django import forms class MySelectMultiple(forms.SelectMultiple): def render(self, name, *args, **kwargs): html = super(MySelectMultiple, self).render(name, *args, **kwargs) plus = render_to_string("plus_sign.html", {'field': name}) return html+plus # #forms.py # from django import forms from myapp.custom_widgets.py import MySelectMultiple class MyForm(forms.ModelForm): contacts = forms.ModelMultipleChoiceField(Contact.objects, required=False, widget=MySelectMultiple) # #views.py # def AddContacts(request): if request.method == 'POST': form = MyForm(request.POST) if form.is_valid(): cd = form.cleaned_data new = form.save() return HttpResponseRedirect('/addedContact/') else: form = MyForm() return render_to_response('shop/my_form.html', {'form': form}, context_instance=RequestContext(request)) # #my_form.html # {% extends "base.html" %} {% block content %} {{ form.contacts }} {% endblock %} Please let me know how can I load the widget's image properly. Thank you so much for all responses.

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  • I need help solving a rather weird error in a WCF service.

    - by Moulde
    Hi.. I have a solution that contains three projects. A main project with my MVC app, a silverlight application and a (silverlight enabled) WCF service project. In my silverlight project i have made a Service Reference to my WCF service. And i pretty much got that working. In my WCF service i have a method that returns an Book object, which got some random fields like title, date etc. In the book class, i have a ICollection field that contains a list of events. The book class is generated using entity framework 4.0, and Lazy Loading is enabled. If i in my getBook(int id) method return a book with the events field not initialized, it works as a charm. But if i initialize the field, i'm getting this error. The server did not provide a meaningful reply; this might be caused by a contract mismatch, a premature session shutdown or an internal server error. I have a few ideas why that is happening, and while writing this i just got another one. The wcf service somehow threw away the reference to the event class. That would be very weird since i have a reference between my main mvc app (with the models) and my WCF service. Since i have enabled lazy loading in EF 4.0, i suspect that it may be the thing generating the error. But i'm not sure why that would be, because i'm not in any way accessing that field. I could understand that i may not be able to access the events field after i recive the object in my silverlight application since the connection between the book object and the entity framework is like broken. Did i mention that Lazy Loading is enabled on my EF instance? And there is no inner exception in the thrown exception. Thanks in advance. Malte Baden Hansen

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  • C++ Operator Ambiguity

    - by Scott
    Forgive me, for I am fairly new to C++, but I am having some trouble regarding operator ambiguity. I think it is compiler-specific, for the code compiled on my desktop. However, it fails to compile on my laptop. I think I know what's going wrong, but I don't see an elegant way around it. Please let me know if I am making an obvious mistake. Anyhow, here's what I'm trying to do: I have made my own vector class called Vector4 which looks something like this: class Vector4 { private: GLfloat vector[4]; ... } Then I have these operators, which are causing the problem: operator GLfloat* () { return vector; } operator const GLfloat* () const { return vector; } GLfloat& operator [] (const size_t i) { return vector[i]; } const GLfloat& operator [] (const size_t i) const { return vector[i]; } I have the conversion operator so that I can pass an instance of my Vector4 class to glVertex3fv, and I have subscripting for obvious reasons. However, calls that involve subscripting the Vector4 become ambiguous to the compiler: enum {x, y, z, w} Vector4 v(1.0, 2.0, 3.0, 4.0); glTranslatef(v[x], v[y], v[z]); Here are the candidates: candidate 1: const GLfloat& Vector4:: operator[](size_t) const candidate 2: operator[](const GLfloat*, int) <built-in> Why would it try to convert my Vector4 to a GLfloat* first when the subscript operator is already defined on Vector4? Is there a simple way around this that doesn't involve typecasting? Am I just making a silly mistake? Thanks for any help in advance.

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  • How to create anonymous objects of type IQueryable using LINQ

    - by Soham Dasgupta
    Hi, I'm working in an ASP.NET MVC project where I have created a two LinqToSQL classes. I have also created a repository class for the models and I've implemented some methods like LIST, ADD, SAVE in that class which serves the controller with data. Now in one of the repository classes I have pulled some data with LINQ joins like this. private HerculesCompanyDataContext Company = new HerculesCompanyDataContext(); private HerculesMainDataContext MasterData = new HerculesMainDataContext(); public IQueryable TRFLIST() { var info = from trfTable in Company.TRFs join exusrTable in MasterData.ex_users on trfTable.P_ID equals exusrTable.EXUSER select new { trfTable.REQ_NO, trfTable.REQ_DATE, exusrTable.USER_NAME, exusrTable.USER_LNAME, trfTable.FROM_DT, trfTable.TO_DT, trfTable.DESTN, trfTable.TRAIN, trfTable.CAR, trfTable.AIRPLANE, trfTable.TAXI, trfTable.TPURPOSE, trfTable.STAT, trfTable.ROUTING }; return info; } Now when I call this method from my controller I'm unable to get a list. What I want to know is without creating a custom data model class how can I return an object of anonymous type like IQueryable. And because this does not belong to any one data model how can refer to this list in the view.

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  • The same property and procedure in different Classes. How they can be accessed ?

    - by lyborko
    Hi, I created several new objects TMyMemo = class (TMemo) private FYahoo = Integer; procedure SetYahoo(Value:integer) public procedure Google(A,B:integer; S:string); published property Yahoo:integer read FYahoo write SetYahoo; end; TMyPaintbox = class (TPaintbox) private FYahoo = Integer; procedure SetYahoo(Value:integer) public procedure Google(A,B:integer; S:string); published property Yahoo:integer read FYahoo write SetYahoo; end; TMyButton = class (TButton) private FYahoo = Integer; procedure SetYahoo(Value:integer) public procedure Google(A,B:integer; S:string); published property Yahoo:integer read FYahoo write SetYahoo; end; . . . These Controls are placed on Form1. Is there a way, how can I change the same property (Yahoo) and run the procedure (Google), which is declared in different objects (inheritance is not possible) ? procedure Form1.Button1Click(Sender:TObject); var i:integer; begin for i:=0 to Form1.ControlCount-1 do begin Controls[i].Google(4,5, 'Web'); // this should be changed somehow Controls[i].Yahoo:=6; // this should be changed somehow end; end; end; Thanks

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  • Can foreground threads be aborted on application shutdown in C#.Net?

    - by Cartman
    I inherited a c# winforms app (.NET 2.0) which creates a thread upon startup in a singleton class. This thread handles messages from a messaging topic (Tibco EMS). When the app is shutdown, the thread doesn't remain the the background? How is this possible? Is there something else happening that can abort this thread? Code snippet: public class Startup { public static void main(string [] args) { MySingletonClass.Instance.Init(); // do other things below Application.Run(new MainForm()); } public class MySingletonClass { // singleton code //.. //.. private Thread t; public void Init() { t = new Thread(new ThreadStart(poll)); } private void poll() { while(true} { // listen for messages and process but there is no break clause // exceptions are also handled within to ensure control doesnt go out } } Pls. don't write to tell me this is bad code. I know it and i was going to refactor it when i realised that the app actually shutdowns correctly inspite of this aberration. So i want to understand how this is possible. Thanks for your help

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  • How can I avoid encoding mixups of strings in a C/C++ API?

    - by Frerich Raabe
    I'm working on implementing different APIs in C and C++ and wondered what techniques are available for avoiding that clients get the encoding wrong when receiving strings from the framework or passing them back. For instance, imagine a simple plugin API in C++ which customers can implement to influence translations. It might feature a function like this: const char *getTranslatedWord( const char *englishWord ); Now, let's say that I'd like to enforce that all strings are passed as UTF-8. Of course I'd document this requirement, but I'd like the compiler to enforce the right encoding, maybe by using dedicated types. For instance, something like this: class Word { public: static Word fromUtf8( const char *data ) { return Word( data ); } const char *toUtf8() { return m_data; } private: Word( const char *data ) : m_data( data ) { } const char *m_data; }; I could now use this specialized type in the API: Word getTranslatedWord( const Word &englishWord ); Unfortunately, it's easy to make this very inefficient. The Word class lacks proper copy constructors, assignment operators etc.. and I'd like to avoid unnecessary copying of data as much as possible. Also, I see the danger that Word gets extended with more and more utility functions (like length or fromLatin1 or substr etc.) and I'd rather not write Yet Another String Class. I just want a little container which avoids accidental encoding mixups. I wonder whether anybody else has some experience with this and can share some useful techniques. EDIT: In my particular case, the API is used on Windows and Linux using MSVC 6 - MSVC 10 on Windows and gcc 3 & 4 on Linux.

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  • java: assigning object reference IDs for custom serialization

    - by Jason S
    For various reasons I have a custom serialization where I am dumping some fairly simple objects to a data file. There are maybe 5-10 classes, and the object graphs that result are acyclic and pretty simple (each serialized object has 1 or 2 references to another that are serialized). For example: class Foo { final private long id; public Foo(long id, /* other stuff */) { ... } } class Bar { final private long id; final private Foo foo; public Bar(long id, Foo foo, /* other stuff */) { ... } } class Baz { final private long id; final private List<Bar> barList; public Baz(long id, List<Bar> barList, /* other stuff */) { ... } } The id field is just for the serialization, so that when I am serializing to a file, I can write objects by keeping a record of which IDs have been serialized so far, then for each object checking whether its child objects have been serialized and writing the ones that haven't, finally writing the object itself by writing its data fields and the IDs corresponding to its child objects. What's puzzling me is how to assign id's. I thought about it, and it seems like there are three cases for assigning an ID: dynamically-created objects -- id is assigned from a counter that increments reading objects from disk -- id is assigned from the number stored in the disk file singleton objects -- object is created prior to any dynamically-created object, to represent a singleton object that is always present. How can I handle these properly? I feel like I'm reinventing the wheel and there must be a well-established technique for handling all the cases.

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  • Java Detect Variable Change Using PropertyChangeSupport and PropertyChangeListener

    - by Sam
    I'm trying to print out debug statements when some third party code changes a variable. For example, consider the following: public final class MysteryClass { private int secretCounter; public synchronized int getCounter() { return secretCounter; } public synchronized void incrementCounter() { secretCounter++; } } public class MyClass { public static void main(String[] args) { MysteryClass mysteryClass = new MysteryClass(); // add code here to detect calls to incrementCounter and print a debug message } I don't have the ability to change the 3rd party MysteryClass, so I thought that I could use PropertyChangeSupport and PropertyChangeListener to detect changes to the secretCounter: public class MyClass implements PropertyChangeListener { private PropertyChangeSupport propertySupport = new PropertyChangeSupport(this); public MyClass() { propertySupport.addPropertyChangeListener(this); } public void propertyChange(PropertyChangeEvent evt) { System.out.println("property changing: " + evt.getPropertyName()); } public static void main(String[] args) { MysteryClass mysteryClass = new MysteryClass(); // do logic which involves increment and getting the value of MysteryClass } } Unfortunately, this did not work and I have no debug messages printed out. Does anyone see what is wrong with my implementation of the PropertyChangeSupport and Listener interfaces? I want to print a debug statement whenever incrementCounter is called or the value of secretCounter changes.

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  • Mixing has_one and has_and_belongs_to_many associations

    - by Thomas
    I'm trying to build a database of urls(links). I have a Category model that has and belongs to many Links. Here's the migration I ran: class CreateLinksCategories < ActiveRecord::Migration def self.up create_table :links_categories, :id => false do |t| t.references :link t.references :category end end def self.down drop_table :links_categories end end Here's the Link model: class Link < ActiveRecord::Base validates :path, :presence => true, :format => { :with => /^(#{URI::regexp(%w(http https))})$|^$/ } validates :name, :presence => true has_one :category end Here's the category model: class Category < ActiveRecord::Base has_and_belongs_to_many :links end And here's the error the console kicked back when I tried to associate the first link with the first category: >>link = Link.first => #<Link id: 1, path: "http://www.yahoo.com", created_at: "2011-01-10... >>category = Category.first => #<category id : 1, name: "News Site", created_at: "2011-01-11... >>link.category << category => ActiveRecord::StatementInvalid: SQLite3::Exception: no such column : categories.link_id: Are my associations wrong or am I missing something in the database? I expected it to find the links_categories table. Any help is appreciated.

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  • photo upload with codeigniter

    I know there are many tutorials online, but I could not make them work :( maybe something particularly wrong with my system :/ My Controller localpath is: /localhost/rl/applications/backend/controller/ Controller: function do_upload() { $config['upload_path'] = './uploads/'; $config['allowed_types'] = 'gif|jpg|png'; $config['max_size'] = '100'; $config['max_width'] = '1024'; $config['max_height'] = '768'; $this->load->library('upload', $config); if ( ! $this->upload->do_upload()) { $error = array('error' => $this->upload->display_errors()); $this->load->view('add_image', $error); } else { $data = array('upload_data' => $this->upload->data()); $data['id'] = $this->input->post['id_work']; $this->load->view('add_image', $data); } } My View localpath is: /localhost/rl/applications/backend/view/ View: echo form_open_multipart('do_upload'); <ul class="frm"> <li><label>File: *</label><input type="file" name="userfile" class="frmlmnt" size="50" /></li> <li><label></label><input type="submit" class="btn" value="Upload" /></li> </ul> </form> Maybe I do something wrong with path

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  • Passing objects across Appdomains

    - by MUSTAQ
    My issue is similar to the one posted in "http://stackoverflow.com/questions/981773/moving-objects-across-appdomains-in-net". In one of my application, I am creating a separate appdomain. I need to create an instance of a class (Note: this class is derived by MarshalByRefObject) in my parent domain and invoke a MethodA in that instance. This instance is created using "CreateInstanceAndUnwrap". The problem is that this MethodA takes objects of type class as an argument. These objects are not created in the MethodB where i created the appdomain. It was passed as an argument to the MethodB where i create the appdomain. So is it necessary to create a new instance of these objects using "CreateInstanceAndUnwrap" before passing it to the created domain. Not doing this gives me an error in the created domain mentioning that "MyClass object has no attribute foo" during some invocation. Please let me know how to pass the objects across appdomains and execute the method. My statements might be confusing, please let me know for any specific details required.

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  • Doesn't (didn't) Scala have automatically generated setters?

    - by Malvolio
    Google and my failing memory are both giving me hints that it does, but every attempt is coming up dry. class Y { var y = 0 } var m = new Y() m.y_(3) error: value y_ is not a member of Y Please tell me I am doing something wrong. (Also: please tell me what it is I am doing wrong.) EDIT The thing I am not doing wrong, or at least not the only thing I am doing wrong, is the way I am invoking the setter. The following things also fail, all with the same error message: m.y_ // should be a function valued expression m.y_ = (3) // suggested by Google and by Mchl f(m.y_) // where f takes Int => Unit as an argument f(m.y) // complains that I am passing in Int not a function I am doing this all through SimplyScala, because I'm too lazy and impatient to set up Scala on my tiny home machine. Hope it isn't that... And the winner is ... Fabian, who pointed out that I can't have a space between the _ and the =. I thought out why this should be and then it occurred to me: The name of the setter for y is not y_, it is y_= ! Observe: class Y { var y = 0 } var m = new Y() m.y_=(3) m.y res1: Int = 3 m.y_= error: missing arguments for method y_= in class Y; follow this method with `_` if you want to treat it as a partially applied function m.y_= ^ m.y_=_ res2: (Int) => Unit = def four(f : Int => Unit) = f(4) four(m.y_=) m.y res3: Int = 4 Another successful day on StackExchange.

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  • Compile time type determination in C++

    - by dicroce
    A coworker recently showed me some code that he found online. It appears to allow compile time determination of whether a type has an "is a" relationship with another type. I think this is totally awesome, but I have to admit that I'm clueless as to how this actually works. Can anyone explain this to me? template<typename BaseT, typename DerivedT> inline bool isRelated(const DerivedT&) { DerivedT derived(); char test(const BaseT&); // sizeof(test()) == sizeof(char) char (&test(...))[2]; // sizeof(test()) == sizeof(char[2]) struct conversion { enum { exists = (sizeof(test(derived())) == sizeof(char)) }; }; return conversion::exists; } Once this function is defined, you can use it like this: #include <iostream> class base {}; class derived : public base {}; class unrelated {}; int main() { base b; derived d; unrelated u; if( isRelated<base>( b ) ) std::cout << "b is related to base" << std::endl; if( isRelated<base>( d ) ) std::cout << "d is related to base" << std::endl; if( !isRelated<base>( u ) ) std::cout << "u is not related to base" << std::endl; }

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  • auto div height

    - by Geln
    <html><head><title>Test</title> <style> .main{width:600px;border:1px solid red; } .main .left{background:lightblue; width:100px;clear:both; float:left;} .main .right{margin-left:100px;background:lightyellow; } </style> </head><body> <div class="main"> <div class="left"> title </div> <div class="right"> <div id="item">item</div> <div id="item">item</div> <div id="item">item</div> <div id="item">item</div> <div id="item">item</div> <div id="item">item</div> <div id="item">item</div> </div> </div> </body></html> How to change the CSS to make the page display like the dialog shows? PS,I think it's a way that to make the "left" div's height auto expend when the height of the "right" div or parent div expend, but I don't know how.

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  • Why Is the sender type null when dealing with events

    - by ChloeRadshaw
    From C# Via CLR: Note A lot of people wonder why the event pattern requires the sender parameter to always be of type Object After all, since the MailManager will be the only type raising an event with a NewMail EventArgs object, it makes more sense for the callback method to be prototyped like this: void MethodName(Mai l Manager sender, NewMail EventArgs e); The pattern requires the sender parameter to be of type Object mostly because of inheritance What if Mai lManager were used as a base class for SmtpMailManager? In this case, the callback method should have the sender parameter prototyped as SmtpMailManager instead of Mail Manager, but this can’t happen because SmtpMai lManager just inherited the NewMai l event So the code that was expecting SmtpMail Manager to raise the event must still have to cast the sender argument to SmtpMailManager In other words, the cast is still required, so the sender parameter might as well be typed as Obj ect The next reason for typing the sender parameter as Obj ect is just fexibility It allows the delegate to be used by multiple types that offer an event that passes a NewMail EventArgs object For example, a PopMai lManager class could use the delegate even if this class were not derived from Mail Manager I just simply cannot understand why the sender is an object - Why can it not be generified? so most of the time we do not need to do generic casts

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  • hibernate empty collection in component

    - by Jurgen H
    I have a component mapped using Hibernate. If all fields in the component in the database are null, the component itself is set to null by hibernate. This is the expected behavior and also what I need. The problem I have, is that when I add a bag to that component, the bag is initialized to an empty list. This means the component has a non null value... resulting in the component being created. Any idea how to fix this? <class name="foo.bar.Entity" table="Entity"> <id name="id" column="id"> <generator class="native" /> </id> <property name="departure" column="departure_time" /> <property name="arrival" column="arrival_time" /> <component name="statistics"> <bag name="linkStatistics" lazy="false" cascade="all" > <key column="entity_id" not-null="true" /> <one-to-many class="foo.bar.LinkStatistics" /> </bag> <property name="loggedTime" column="logged_time" /> ... </component> A criteria with Restirctions.isNull("statistics") does return the expected values.

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  • Active State Image Display

    - by fmz
    I have some images that need to change, based not only on hover, but also on active state. If you look at the page here: http://site427.mysite4now.net/tazthedog/site1/ There are some tabs with Screen Printing Quick Links, etc. The tab image is associated with the link and displays properly. The icon in tabs defaults to the gray and turns blue on mouse over, however, I also need it to be blue on the "active" state. Here is the css: .quick-links em:hover { background: transparent url(../images/quick-links.png) 10px 9px no-repeat ; display: block ; float: left; } Here is the html: <ul class="tabs"> <li class="quick-links"> <a href="#quickLinks" id=""> <em> <span>Screen Printing Quick Links</span> </em> </a> </li> <li class="distributor-ql"> <a href="#distributorQL" id=""> <em> <span>Dealer &amp; Distributor Quick Links</span> </em> </a> </li> </ul> I tried adding a .quick-links em:active... but that doesn't maintain it. I know there is a way to keep the icon blue while in the active state, I just need a little help to understand what that is. Thanks!

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