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  • c++ "interface"-like classes similar to Java?

    - by William the Coderer
    In Java, you can define an interface as a class with no actual code implementation, but only to define the methods that a class must implement. Those types can be passed as parameters to methods and returned from methods. In C++, a pure virtual class can't be used as a parameter or return type, from what I can tell. Any way to mimic Java's interface classes? I have a string class in C++, and several subclasses for different encodings (like UTFxxx, ISOxxx, etc) that derive from the base string class. However, since there are so many different encodings, the base class has no meaningful implementation. But it would serve well as an interface if I could handle it as its own object and calls to that object would call on the correct subclass it was inherited to.

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  • What is the MVC version of this code?

    - by Ian Boyd
    i'm trying to wrap my head around how to enterprise up my code: taking a simple routine and splitting it up into 5 or 6 methods in 3 or 4 classes. i quickly came up three simple examples of code how i currently write it. Could someone please convert these into an MVC/MVP obfuscated version? Example 1: The last name is mandatory. Color the text box red if nothing is entered. Color it green if stuff is entered: private void txtLastname_TextChanged(object sender, EventArgs e) { //Lastname mandatory. //Color pinkish if nothing entered. Greenish if entered. if (txtLastname.Text.Trim() == "") { //Lastname is required, color pinkish txtLastname.BackColor = ControlBad; } else { //Lastname entered, remove the coloring txtLastname.BackColor = ControlGood; } } Example 2: The first name is optional, but try to get it. We'll add a bluish tint to this "try to get" field: private void txtFirstname_TextChanged(object sender, EventArgs e) { //Firstname can be blank. //Hint them that they should *try* to get it with a bluish color. //If they do enter stuff: it better be not all spaces. if (txtFirstname.Text == "") { //Nothing there, hint it blue txtFirstname.BackColor = ControlRequired; } else if (txtFirstname.Text.Trim() == "") { //They entered spaces - bad user! txtFirstname.BackColor = ControlBad; } else { //Entered stuff, remove coloring txtFirstname.BackColor = SystemColors.Window; } } Example 3 The age is totally optional. If an age is entered, it better be valid: private void txtAge_TextChanged(object sender, EventArgs e) { //Age is optional, but if entered it better be valid int nAge = 0; if (Int32.TryParse(txtAge.Text, out nAge)) { //Valid integer entered if (nAge < 0) { //Negative age? i don't think so txtAge.BackColor = ControlBad; } else { //Valid age entered, remove coloring txtAge.BackColor = SystemColors.Window; } } else { //Whatever is in there: it's *not* a valid integer, if (txtAge.Text == "") { //Blank is okay txtAge.BackColor = SystemColors.Window; } else { //Not a valid age, bad user txtAge.BackColor = ControlBad; } } } Every time i see MVC code, it looks almost like random splitting of code into different methods, classes, and files. i've not been able to determine a reason or pattern to their madness. Without any understanding of they why it's being one some way, it makes no sense. And using the words model, view, controller and presenter, like i'm supposed to know what that means, doesn't help. The model is your data. The view shows data on screen. The controller is used to carry out the users actions And oranges taste orangy. Here's my attempt at splitting things up in order to make the code more difficult to follow. Is this anywhere close to MVC? private void txtFirstname_TextChanged(object sender, EventArgs e) { FirstnameTextChangedHandler(sender, e); } private void FirstnameTextChangedHandler(sender, e) { string firstname = GetFirstname(); Color firstnameTextBoxColor = GetFirstnameTextBoxColor(firstname); SetFirstNameTextBoxColor(firstnameTextBoxColor); } private string GetFirstname() { return txtFirstname.Text; } private Color GetFirstnameTextBoxColor(string firstname) { //Firstname can be blank. //Hint them that they should *try* to get it with a bluish color. //If they do enter stuff: it better be not all spaces. if (firstname == "") { //Nothing there, hint it blue return GetControlRequiredColor(); } else if (firstname.Trim() == "") { //They entered spaces - bad user! return GetControlBadColor(); } else { //Entered stuff, remove coloring return GetControlDefaultColor(); } } private Color GetControlRequiredColor() { return ControlRequired; } private Color GetControlBadColor() { return ControlBad; } private Color GetControlGoodColor() { return ControlGood; } //am i doin it rite i've obfuscated the code, but it's still altogether. The next step in the MVC obfuscation, i gather, is to hide the code in 3 or 4 different files. It's that next step that i don't understand. What is the logical separation of which functions are moved into what other classes? Can someone translate my 3 simple examples above into full fledged MVC obfuscation? Edit: Not ASP/ASP.NET/Online. Pretend it's on a desktop, handheld, surface, kiosk. And pretend it's language agnostic.

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  • Properties.Settings.Default.Default.Save() does not work

    - by Akshay
    I have created code in WPF to let the window remember its last location like this: private void Window_Loaded(object sender, RoutedEventArgs e) { try { Rect storedLoc = Properties.Settings.Default.WindowSavedLocation; this.Top = storedLoc.Top; this.Left = storedLoc.Left; } catch { MessageBox.Show("No settings stored !"); } } private void Window_Closed(object sender, EventArgs e) { Properties.Settings.Default.WindowSavedLocation = RestoreBounds; Properties.Settings.Default.Save(); } When I build the application I can see that the app.exe.config file has the setting WindowSavedLocation but it just does not save and throws no exception. Everytime I run the application, it says "No settings stored !". It's scope is user.

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  • Backbone.js - Getting JSON back from url

    - by Brian
    While trying to learn Backbone.js, I've been trying to grab the content of a JSON file using the following code: (function($){ var MyModel = Backbone.Model.extend(); var MyCollection = Backbone.Collection.extend({ model : MyModel, url: '/backbone/data.json', parse: function(response) { console.log(response); return response; } }); var stuff = new MyCollection; console.log(stuff.fetch()); console.log(stuff.toJSON()); })(jQuery) 'stuff.fetch()' returns the entire object (with the data I'm after in responseText), 'stuff.toJSON' returns nothing ([]), but the console in the parse method is returning exactly what I want (the json object of my data). I feel like I'm missing something obvious here, but I just can't seem to figure it out why I can't get the right data out. Could someone point me in the right direction or show me what I'm doing wrong here? Am I using a model for the wrong thing?

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  • How do I specify a null relation in SQLAlchemy?

    - by Jesse
    Not sure what the correct title for this question should be. I have the following schema: Matters have a one-many relationship to WorkItems. WorkItems have a one-one (or one-zero) relationship to LineItems. I am trying to create the following relation between Matters and WorkItems Matter.unbilled_work_items = orm.relation(WorkItem, primaryjoin = (Matter.id == WorkItem.matter_id) and (WorkItem.line_item_id == None), foreign_keys = [WorkItem.matter_id, WorkItem.line_item_id], viewonly=True ) This throws: AttributeError: '_Null' object has no attribute 'table' That seems to be saying that the second clause in the primaryjoin returns an object of type _Null, but it seems to be expecting something with a "table" attribute. This seems like it should be pretty straightforward to me, am I missing something obvious?

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  • Should GSON ignore varying types if they're not used in a class?

    - by loeschg
    I'm making an API call that returns JSON which has a particular field which either returns false or a map depending on content. It's a field that I don't care about. I expected GSON to ignore this particular field, though it doesn't seem to be. The object generation fails with the following message: com.google.gson.JsonSyntaxException: java.lang.IllegalStateException: Expected a string but was BEGIN_OBJECT at line 1 column 403560 I've seen this particular question (Gson deserialize json with varying value types). I want to make sure I need to make a custom deserializer before doing so. I'm wondering if I may have another issue. edit: Example: "anonymous_flag": { } vs "anonymous_flag": "yes" Another Edit: I actually had the field in my model object... I was referencing the wrong class. Judge away :)

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  • when get pagecontent from URL the connect alway return nopermistion ?

    - by tiendv
    I have a methor to return pagecontent of link but when it run, alway return "Do not perrmisson ", plesea check it here is code to return string pagecontent public static String getPageContent(String targetURL) throws Exception { Hashtable contentHash = new Hashtable(); URL url; URLConnection conn; // The data streams used to read from and write to the URL connection. DataOutputStream out; DataInputStream in; // String returned as the result . String returnString = ""; // Create the URL object and make a connection to it. url = new URL(targetURL); conn = url.openConnection(); // check out permission of acess URL if (conn.getPermission() != null) { returnString = "Do not Permission access URL "; } else { // Set connection parameters. We need to perform input and output, // so set both as true. conn.setDoInput(true); conn.setDoOutput(true); // Disable use of caches. conn.setUseCaches(false); // Set the content type we are POSTing. We impersonate it as // encoded form data conn.setRequestProperty("Content-Type", "application/x-www-form-urlencoded"); // get the output stream . out = new DataOutputStream(conn.getOutputStream()); String content = ""; // Create a single String value pairs for all the keys // in the Hashtable passed to us. Enumeration e = contentHash.keys(); boolean first = true; while (e.hasMoreElements()) { // For each key and value pair in the hashtable Object key = e.nextElement(); Object value = contentHash.get(key); // If this is not the first key-value pair in the hashtable, // concantenate an "&" sign to the constructed String if (!first) content += "&"; // append to a single string. Encode the value portion content += (String) key + "=" + URLEncoder.encode((String) value); first = false; } // Write out the bytes of the content string to the stream. out.writeBytes(content); out.flush(); out.close(); // check if can't read from URL // Read input from the input stream. in = new DataInputStream(conn.getInputStream()); String str; while (null != ((str = in.readLine()))) { returnString += str + "\n"; } in.close(); } // return the string that was read. return returnString; }

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  • Server-side access to Client Browser's Latitude/Longitude using Django.

    - by ZenGyro
    Hello, So i am writing a little app that compares a user's position against a database on web-based server written using Django and performs some functions with it. Accessing the browser's geolocation data (in supported browsers ) is fairly trivial using JavaScript. But what is the best way to allow the Django server to access the longitude and latitude variables? Is it best to wrap them up as a JSON object and send to the server via POST? Or is there some easier (Geo)Django-based way to access the Navigator.geolocation browser object. Please forgive a newbie a question like this, but my Google-Fuing only seems to find ways to insert variables into JavaScript via template tag, whereas I need it to work the other way! Any advice or code snippets greatly appreciated. Feel free to talk to me like I am an idiot.

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  • jquery trouble with getJSON call.

    - by Yo-L
    Hi guys. Got some basic problem again. I need to modify a function that previously returned a in code written object. Im now trying to get the object from json through $.getJSON function getEventData() { var result = ''; $.getJSON("ajax.php?cmd=getbydate&fromdate=&todate=", function(data){ result = data; }); return result; } Problem is that result isn't set in the callback function for obvious reasons. Do you guys have a solution for this?

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  • $.get sends prototype functions in request URL?

    - by pimvdb
    I have some prototype functions added to Object which in my opinion were practical in certain scenarios. However, I noticed that when I executed a $.get, the prototype functions are handled as data members and are sent like http://...?prototypefunc=false. This is rather useless as I don't supply these as data members, but they are added to the query string. To be exact, I have this code: Object.prototype.in = function() { for(var i=0; i<arguments.length; i++) if(arguments[i] == this) return true; return false; } $.get('http://localhost/test.php', {'test': 'foo'}, function(text) { }); The corresponding URL constructed is: http://localhost/test.php?test=foo&in=false How can I avoid this?

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  • Get an Entity in Save Method, What is correct form ?

    - by Felipe
    Hi everybody I'm begginer in asp.net mvc and i have some doubts. P.S: I'm using DDD to learn I have an ACtion in a Controller and it'll save an entity (from my model) by a repository (for a database). My doubts is, How can I get the informations from the View and save it by a repository in my Controller ? Is it correct to get an entity of my Model in Save method of controller, like this: public ActionResult Save(Product product) { // validate object // save data in repository return View("Success"); } Or Need I get an DTO (with a structure similar to my entity) and create an object passing property by property to an entity ? I didnt' like of FormCollection and I'd like to know, What is recommended architecturally ? Thanks a lot guys Cheers

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  • Class Property in for each

    - by KoolKabin
    Hi guys, I am running from a problem while iterating over class properties. I have my first class: class Item private _UIN as integer = 0 private _Name as string = "" private _Category as ItemCategory = new ItemCategory() public Property UIN() as integer public property Name() as string public property Category() as ItemCategory end class Now when i iterate over the class properties from following code Dim AllProps As System.Reflection.PropertyInfo() Dim PropA As System.Reflection.PropertyInfo dim ObjA as object AllProps = new Item().getType().getProperties() for each propA in AllProps ObjA = PropA.GetValue(myObj, New Object() {}) debug.write ObjA.GetType().Name next I get UIN, Name, ItemCategory but i expected UIN, Name and Category. I am a bit unclear about this and dun know why this is happening? What should i do to correct it?

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  • How do you override operator == when using interfaces instead of actual types?

    - by RickL
    I have some code like this: How should I implement the operator == so that it will be called when the variables are of interface IMyClass? public class MyClass : IMyClass { public static bool operator ==(MyClass a, MyClass b) { if (ReferenceEquals(a, b)) return true; if ((Object)a == null || (Object)b == null) return false; return false; } public static bool operator !=(MyClass a, MyClass b) { return !(a == b); } } class Program { static void Main(string[] args) { IMyClass m1 = new MyClass(); IMyClass m2 = new MyClass(); MyClass m3 = new MyClass(); MyClass m4 = new MyClass(); Console.WriteLine(m1 == m2); // does not go into custom == function. why not? Console.WriteLine(m3 == m4); // DOES go into custom == function } }

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  • Gridview adding row dynamically on RowDataBound with the same RowState (Alternate or Normal)

    - by rob waminal
    I am adding rows dynamically on code behind depending on the Row currently bounded on RowDataBound event. I want that added row to be the same state (Alternate or Normal) of the currently bounded row is this possible? I'm doing something like this but it doesn't follow what I want. I'm expecting the added row dynamically would be the same as the current row. But it is not. protected void gv_RowDataBound(object sender, GridViewRowEventArgs e) { if(e.Row.RowType == DataControlRowType.DataRow) { GVData data = e.Row.DataItem as GVData; // not original object just for brevity if(data.AddHiddenRow) { // the row state here should be the same as the current GridViewRow tr = new GridViewRow(e.Row.RowIndex +1, e.Row.RowIndex + 1, DataControlRowType.DataRow, e.Row.RowState); TableCell newTableCell = new TableCell(); newTableCell.Style.Add("display", "none"); tr.Cells.Add(newTableCell); ((Table)e.Row.Parent).Rows.Add(tr); } } }

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  • DeleteObject method is missing in Entity Framework 4.1

    - by bobetko
    This is driving me crazy. I am getting error that object doesn't contain definition for DeleteObject. Here is my line of code that produces an error: ctx.Tanks.DeleteObject(Tank); I tried to reference another object from another edmx file that my friend has created and then everything is fine, DeleteObject exists. I don't think I miss any references in my project. And project itself contains edmx file and I used DBContext to create POCOs. Any ideas?

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  • Entity Framework projections

    - by David McClelland
    We are investigating the Entity Framework to see if it will meet our particular needs. Here is the scenario I am interested in: I have a large table (let's call it VeryWideRecord) which has many columns, and it has a corresponding business object (it's also called VeryWideRecord). I would like to be able to query my database for a VeryWideRecord business object, but only have values for certain columns returned by the underlying SQL. Can I do this with the Entity Framework? I am uncertain as to whether this could be done with the Entity Framework's table splitting feature, because the application needs to be able (at runtime) to change the columns that are requested. The reason for this is that we are trying to minimize the amount of information that is going across the wire. I see how this could be done using NHibernate (example), but how can I do this with the Entity Framework?

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  • Bad Design? Constructor of composition uses `this`

    - by tanascius
    Example: class MyClass { Composition m_Composition; void MyClass() { m_Composition = new Composition( this ); } } I am interested in using depenency-injection here. So I will have to refactor the constructor to something like: void MyClass( Composition composition ) { m_Composition = composition; } However I get a problem now, since the Composition-object relies on the object of type MyClass which is just created. Can a dependency container resolve this? Is it supposed to do so? Or is it just bad design from the beginning on?

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  • Java Swing - Problem in JSpinner

    - by Yatendra Goel
    I am developing a Java Desktop Application and designing the GUI with the help of Netbeans Swing GUI builder. I want to use a JSpinner in my app. I have dragged and dropped it to a JPanel. Now, I want to set its two properties: First, It should display numbers in the range of 1 to 50. Neither less than 1 nor greater than 50. How can I set that range? Second, when I try to get the value of it by spinner.getValue() it returns an Object. As my spinner's data type is Integer, would it be better to downcast the Object into Integer or Is there any other way to get that numeric value?

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  • How to dynamically change fields in an .NET ORM

    - by rsteckly
    I'm working in ASP.NET in an application where often users want to add fields or change field names. I'd like to be able to have an xml schema in place that is parsed and a dynamic object model created from it that can be accessed throughout the application. My initial reaction is that this is not realistic. I think there is flexibility about the dynamic nature of it. I think the people I'm trying to build this for wouldn't mind recompiling. Even if the app recompiled, I don't know how to abstract away enough in my code access the data to allow for users changing property names, etc. How can you write LINQ when the properties might change? In short, there's two questions here: 1) is there a way to dynamically generate an object model of the database and 2) is there a way to abstract away enough so that code accessing the database doesn't break when properties change?

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  • How to invoke static method in C#4.0 with dynamic type?

    - by Morgan Cheng
    In C#4.0, we have dynamic type, but how to invoke static method of dynamic type object? Below code will generate exception at run time. class Foo { public static int Sum(int x, int y) { return x + y; } } class Program { static void Main(string[] args) { dynamic d = new Foo(); Console.WriteLine(d.Sum(1, 3)); } } IMHO, dynamic is invented to bridge C# and other programming language. There is some other language (e.g. Java) allows to invoke static method through object instead of type. BTW, The introduction of C#4.0 is not so impressive compared to C#3.0.

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  • default model field attribute in Django

    - by Rosarch
    I have a Django model: @staticmethod def getdefault(): print "getdefault called" return cPickle.dumps(set()) _applies_to = models.TextField(db_index=True, default=getdefault) For some reason, getdefault() is never called, even as I construct instances of this model and save them to the database. This seems to contradict the Django documentation: Field.default The default value for the field. This can be a value or a callable object. If callable it will be called every time a new object is created. Am I doing something wrong? Update: Originally, I had this, but then I switched to the above version to debug: _applies_to = models.TextField(db_index=True, default=cPickle.dumps(set())) I'm not sure why that wouldn't work.

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