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  • Is it any loose coupling mechanism in Objective-C + Cocoa like C# delegates or C++Qt signals+slots?

    - by Eye of Hell
    Hello. For a large programs, the standard way to chalenge a complexity is to divide a program code into small objects. Most of the actual programming languages offer this functionality via classes, so is Objective-C. But after source code is separated into small object, the second challenge is to somehow connect them with each over. Standard approaches, supported by most languages are compositon (one object is a member field of another), inheritance, templates (generics) and callbacks. More cryptic techniques include method-level delagates (C#) and signals+slots (C++Qt). I like the delegates / signals idea, since while connecting two objects i can connect individual methods with each over, without objects knowing anything of each over. For C#, it will look like this: var object1 = new CObject1(); var object2 = new CObject2(); object1.SomethingHappened += object2.HandleSomething; In this code, is object1 calls it's SomethingHappened delegate (like a normal method call) the HandleSomething method of object2 will be called. For C++Qt, it will look like this: var object1 = new CObject1(); var object2 = new CObject2(); connect( object1, SIGNAL(SomethingHappened()), object2, SLOT(HandleSomething()) ); The result will be exactly the same. This technique has some advantages and disadvantages, but generally i like it more than interfaces since if program code base grows i can change connections and add new ones without creating tons of interfaces. After examination of Objective-C i havn't found any way to use this technique i like :(. It seems that Objective-C supports message passing perfectly well, but it requres for object1 to have a pointer to object2 in order to pass it a message. If some object needs to be connected to lots of other objects, in Objective-C i will be forced to give him pointers to each of the objects it must be connected. So, the question :). Is it any approach in Objective-C programming that will closely resemble delegate / signal+slot types of connection, not a 'give first object an entire pointer to second object so it can pass a message to it'. Method-level connections are a bit more preferable to me than object-level connection ^_^.

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  • How to reflect over T to build an expression tree for a query?

    - by Alex
    Hi all, I'm trying to build a generic class to work with entities from EF. This class talks to repositories, but it's this class that creates the expressions sent to the repositories. Anyway, I'm just trying to implement one virtual method that will act as a base for common querying. Specifically, it will accept a an int and it only needs to perform a query over the primary key of the entity in question. I've been screwing around with it and I've built a reflection which may or may not work. I say that because I get a NotSupportedException with a message of LINQ to Entities does not recognize the method 'System.Object GetValue(System.Object, System.Object[])' method, and this method cannot be translated into a store expression. So then I tried another approach and it produced the same exception but with the error of The LINQ expression node type 'ArrayIndex' is not supported in LINQ to Entities. I know it's because EF will not parse the expression the way L2S will. Anyway, I'm hopping someone with a bit more experience can point me into the right direction on this. I'm posting the entire class with both attempts I've made. public class Provider<T> where T : class { protected readonly Repository<T> Repository = null; private readonly string TEntityName = typeof(T).Name; [Inject] public Provider( Repository<T> Repository) { this.Repository = Repository; } public virtual void Add( T TEntity) { this.Repository.Insert(TEntity); } public virtual T Get( int PrimaryKey) { // The LINQ expression node type 'ArrayIndex' is not supported in // LINQ to Entities. return this.Repository.Select( t => (((int)(t as EntityObject).EntityKey.EntityKeyValues[0].Value) == PrimaryKey)).Single(); // LINQ to Entities does not recognize the method // 'System.Object GetValue(System.Object, System.Object[])' method, // and this method cannot be translated into a store expression. return this.Repository.Select( t => (((int)t.GetType().GetProperties().Single( p => (p.Name == (this.TEntityName + "Id"))).GetValue(t, null)) == PrimaryKey)).Single(); } public virtual IList<T> GetAll() { return this.Repository.Select().ToList(); } protected virtual void Save() { this.Repository.Update(); } }

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  • Grails populate params with XML from POST request

    - by othman
    I have a RestFull grails api that i expose through grails Controller. I need to automatically bind the xml data sent in a POST request. I don't think using groovy bindData(object,params) works as the params reference seems not having the xml elements. i use the parseRequest=true in the UrlMappings but yet the params Object does'nt have the xml elements. am i missing some other config so that my params object get automatically populated with the xml body elements?

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  • C# Casting system.__comobject to class type

    - by ijrufus
    I have an Excel Add-In that I'm currently trying to set up a unit test framework for. For the unit tests I've followed this guide: http://blogs.msdn.com/b/varsha/archive/2010/08/17/writing-automated-test-cases-for-vsto-application.aspx It seems to work fine, until I want to return a class object from my interface. Specifying the class object as the return type throws a "return argument has an invalid type" exception when calling the method. Changing the return type from the class to an object allows me to call the method and get the object, but now I'm unable to cast it as the class and use it as intended, getting this exception message when I try: > Unable to cast COM object of type 'System.__ComObject' to class type > 'anaplan.Utility.XYCoordinates'. Instances of types that represent COM > components cannot be cast to types that do not represent COM > components; however they can be cast to interfaces as long as the > underlying COM component supports QueryInterface calls for the IID of > the interface. I've retrieved the Type name using VisualBasic.Information.TypeName and it's showing it as the class I expect. Is there any way to get the comobject cast back to the class? Or another way to access the properties it has? Or am I just being a bit stupid here?

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  • How to draw mutiple rectangles using c#

    - by Nivas
    I have drawn and saved the Rectangle on the image i loaded in the picture box. How i like to draw multiple rectangles for that i tried array in the rectangle but it gives error ("Object reference not set to an instance of an object." (Null reference Exception was unhandled). enter code here private void pictureBox1_MouseDown(object sender, MouseEventArgs e) { if (mybitmap == null) { mybitmap = new Bitmap(sz.Width, sz.Height); } rect = new Rectangle(e.X, e.Y, 0, 0); this.Invalidate(); } private void pictureBox1_MouseMove(object sender, MouseEventArgs e) { if (stayToolStripMenuItem.Checked == true) { switch (e.Button) { case MouseButtons.Left: { rect = new Rectangle(rect.Left, rect.Top, e.X - rect.Left, e.Y - rect.Top); pictureBox1.Invalidate(); break; } } } } private void pictureBox1_Paint(object sender, PaintEventArgs e) { if (stayToolStripMenuItem.Checked == true) { button1.Visible = true; button2.Visible = true; if (mybitmap == null) { return; } using (g = Graphics.FromImage(mybitmap)) { using (Pen pen = new Pen(Color.Red, 2)) { //g.Clear(Color.Transparent); e.Graphics.DrawRectangle(pen, rect); label1.Top = rect.Top; label1.Left = rect.Left; label1.Width = rect.Width; label1.Height = rect.Height; if (label1.TextAlign == ContentAlignment.TopLeft) { e.Graphics.DrawString(label1.Text, label1.Font, new SolidBrush(label1.ForeColor), rect); g.DrawString(label1.Text, label1.Font, new SolidBrush(label1.ForeColor), rect); g.DrawRectangle(pen, rect); } } } } } How can i do this.....

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  • Force deletion of slot in boost::signals2

    - by villintehaspam
    Hi! I have found that boost::signals2 uses sort of a lazy deletion of connected slots, which makes it difficult to use connections as something that manages lifetimes of objects. I am looking for a way to force slots to be deleted directly when disconnected. Any ideas on how to work around the problem by designing my code differently are also appreciated! This is my scenario: I have a Command class responsible for doing something that takes time asynchronously, looking something like this (simplified): class ActualWorker { public: boost::signals2<void ()> OnWorkComplete; }; class Command : boost::enable_shared_from_this<Command> { public: ... void Execute() { m_WorkerConnection = m_MyWorker.OnWorkDone.connect(boost::bind(&Command::Handle_OnWorkComplete, shared_from_this()); // launch asynchronous work here and return } boost::signals2<void ()> OnComplete; private: void Handle_OnWorkComplete() { // get a shared_ptr to ourselves to make sure that we live through // this function but don't keep ourselves alive if an exception occurs. shared_ptr<Command> me = shared_from_this(); // Disconnect from the signal, ideally deleting the slot object m_WorkerConnection.disconnect(); OnComplete(); // the shared_ptr now goes out of scope, ideally deleting this } ActualWorker m_MyWorker; boost::signals2::connection m_WorkerConnection; }; The class is invoked about like this: ... boost::shared_ptr<Command> cmd(new Command); cmd->OnComplete.connect( foo ); cmd->Execute(); // now go do something else, forget all about the cmd variable etcetera. the Command class keeps itself alive by getting a shared_ptr to itself which is bound to the ActualWorker signal using boost::bind. When the worker completes, the handler in Command is invoked. Now, since I would like the Command object to be destroyed, I disconnect from the signal as can be seen in the code above. The problem is that the actual slot object is not deleted when disconnected, it is only marked as invalid and then deleted at a later time. This in turn appears to depend on the signal to fire again, which it doesn't do in my case, leading to the slot never expiring. The boost::bind object thus never goes out of scope, holding a shared_ptr to my object that will never get deleted. I can work around this by binding using the this pointer instead of a shared_ptr and then keeping my object alive using a member shared_ptr which I then release in the handler function, but it kind of makes the design feel a bit overcomplicated. Is there a way to force signals2 to delete the slot when disconnecting? Or is there something else I could do to simplify the design? Any comments are appreciated!

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  • StreamSocket to Stream in windows phone 8

    - by Abouzar Nouri
    I am trying to use Bluetooth in WP8 to send an image from my app on a device and show it in my app on another device. The receiver has a StreamSocket object to read the data from it like the code below await _dataReader.LoadAsync(4); uint messageLen = (uint)_dataReader.ReadInt32(); await _dataReader.LoadAsync(messageLen); string imageData _dataReader.ReadString(messageLen); Then I have to save all the received data (image) on the device and then create a Stream object from the stored data to give it to the BitmapSource.SetSource(Stream) function to be able to show this image on my app. var image = new BitmapImage(); image.SetSource(stream); All I want to do is not to skip this double work and directly convert the StreamSocket object (from Bluetooth connection) to a Stream object and make the BitmapSource image. Is there any way to do this?

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  • When to retain a "delegate"

    - by Jose
    I know that in Objective-C you should never retain your delegates because it may cause a retain-cycle, however, how do you know the difference between a delegate and a non-delegate object ? Can't it be said that just sending a message to any object is delegating work to that object ?

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  • LINQ to SQL - database relationships won't update after submit

    - by Quantic Programming
    I have a Database with the tables Users and Uploads. The important columns are: Users -> UserID Uploads -> UploadID, UserID The primary key in the relationship is Users -> UserID and the foreign key is Uploads -> UserID. In LINQ to SQL, I do the following operations: Retrieve files var upload = new Upload(); upload.UserID = user.UserID; upload.UploadID = XXX; db.Uploads.InsertOnSubmit(upload) db.SubmitChanges(); If I do that and rerun the application (and the db object is re-built, of course) - if do something like this: foreach(var upload in user.Uploads) I get all the uploads with that user's ID. (like added in the previous example) The problem is, that my application, after adding an upload an submitting changes, doesn't update the user.Uploads collection. i.e - I don't get the newly added uploads. The user object is stored in the Session object. At first, I though that the LINQ to SQL Framework doesn't update the reference of the object, therefore I should simply "reset" the user object from a new SQL request. I mean this: Session["user"] = db.Users.Where(u => u.UserID == user.UserID).SingleOrDefault(); (Where user is the previous user) But it didn't help. Please note: After rerunning the application, user.Uploads does have the new upload! Did anyone experience this type of problem, or is it normal behavior? I am a newbie to this framework. I would gladly take any advice. Thank you!

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  • C# == operator in Immediate window behaves differently than at run-time

    - by Damiano
    Try the following in the Immediate window: object a1 = "a"; object a2 = "a"; a1==a2 // outputs false and you'll see that a1 == a2 outputs false. However, at runtime in either a window app or console, you'll get true: object t1 = "a"; object t2 = "a"; MessageBox.Show((t1 == t2).ToString()); // outputs true The runtime behavior is consistent with the definition for the == operator and strings. Does anybody know if this a bug in the Immediate window?

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  • Access to bytes array of a Bitmap

    - by Deulis
    1- In Windows CE, I have a Bitmap object in C#. 2- I have a C function in an extern dll that expects as parameters the pointer to a bytes array that represents an image in RGB565 format, width and height. This function will draw on this array of bytes. So I need to pass the byte array pointer of the Bitmap object, but I can find a practical way to get this pointer. One way is convert this Bitmap into a bytes array using a memory stream or something else, but it will create a new bytes array, so I will keep in memory both object, the Bitmap and the bytes array, but I don’t want it because the few available memory, that’s why I need to access to the bytes array of the bitmap object, not create a new bytes array. Anyone can help me?

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  • How does one refer to the game1 class's variables in XNA

    - by user1149068
    I try to refer to an array in the Game1 class by creating an object of the Game1 class with its definition Game1 gameObject; , its declaration gameObject = new Game1(); in the constructor, and its usage gameObject.tileArray[xInt, yInt].treed = true;. The game1 class itself remains unchanged in its class code other than some methods and variables. When I try to use this code in the TreeRegion class it gives me "Object reference not set to an instance of an object," leading me to believe that the game1 class is null somehow. How might one change the class or object in order to refer to game1's variables? Mind you I am self-taught and still rather new to C#. The class that refers to game1: http://pastebin.com/0chEcKfq Game1 itself http://pastebin.com/zLDVzCca

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  • siverlight and windows workflow foundation

    - by wissem
    private void btnUpdate_Click(object sender, RoutedEventArgs e) { xxxxxxx.Workflow1_WebServiceSoapClient zer = new xxxxx.Workflow1_WebServiceSoapClient(); zer.demanderSubmitReportCompleted += new EventHandler<xxxxxxxxxxxxxxx.demanderSubmitReportCompletedEventArgs>(service2); zer.demanderSubmitReportAsync("zzz", 20000); } public void service2(object sender, xxxxx.demanderSubmitReportCompletedEventArgs e) { string a = e.Result; } I'm trying to call a windows workflow foundation published as a web service from a Silverlight project. When I call it from a console application it works fine because I can add a web reference then I just make an instance of that webservice then I invoke the method I want. The problem is in the silverlight project cause i can just add a service reference so I find myself working with soap stuff that doesn't work at all, and here is the code error: here is the code error:i change it a litle bit in english Error in exécution Microsoft JScript: Unhandled Error in Silverlight Application exception happened in the operation, résult not valide. Consult InnerException for more information. in System.ComponentModel.AsyncCompletedEventArgs.RaiseExceptionIfNecessary() in AEDSilverlightIntegrated.ServiceReference2.demanderSubmitReportCompletedEventArgs.get_Result() in AEDSilverlightIntegrated.SilverEntryAedHeaderNew.mmm_demanderSubmitReportCompleted(Object sender, demanderSubmitReportCompletedEventArgs e) in AEDSilverlightIntegrated.ServiceReference2.Workflow1_WebServiceSoapClient.OndemanderSubmitReportCompleted(Object state)

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  • Translate from c# to c++

    - by Xaver
    Help to translate from c# code to c++ code. Type tp = Type.GetTypeFromProgID("Shell.Application"); object o = Activator.CreateInstance(tp); Object[] arg = new Object[1]; arg[0] = "C:\\!!"; object b = o.GetType().InvokeMember(@"NameSpace", BindingFlags.Public | BindingFlags.InvokeMethod, null, o, arg); arg[0] = "ftp://anonymous:[email protected]/bussys/1394"; b.GetType().InvokeMember(@"CopyHere", BindingFlags.Public | BindingFlags.InvokeMethod, null, b, arg);

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  • How to reference a particular JSON in a function call.

    - by Jane Wilkie
    Hi guys! I have two javascript routines.. the first one declares some JSON and it contains a function that takes two arguments, the first argument being the json object that needs traversing and the second argument is the tab that the rendering is done in. The second routine merely passes the name of the JSON that needs traversing and tab to render in. The code is below.... <script language="JavaScript1.2" type="text/javascript"> var arr = [ {"id":"10", "class":"child-of-9", "useless":"donotneed"}, {"id":"11", "class":"child-of-10", "useless":"donotneed"}]; var arrtwo = [ {"id":"12", "class":"child-of-12", "useless":"donotneed"}, {"id":"13", "class":"child-of-13", "useless":"donotneed"}]; function render_help(json,tab){ var html=''; for(var i=0;i<json.length;i++){ var obj = json[i]; for(var key in obj){ var attrName = key; var attrValue = obj[key]; if (attrName == "id"){ html = html +'<B>'+attrValue+'</B>'+'<BR><BR>'; }else if (attrName == "class"){ html = html + attrValue + '<BR><BR>'; } } } document.getElementById(tab).innerHTML=(html); } </script> <script language="JavaScript1.2" type="text/javascript"> render_help(arr,"helptab"); </script> Various testing and strategically placed alert boxes indicate that the tab parameter is being passed and interpreted correctly. I know this because when I change .... document.getElementById(tab).innerHTML=(html); to document.getElementById(tab).innerHTML=("Howdy"); and it renders "Howdy" just fine. Putting an alert box (alert(json)) in to check the value of json yields.... [object.Object],[object.Object] The JSON object remains elusive. For the purposes of this scripting I need the JSON "arr" to be iterated over. I feel like the answer is fairly obvious so far no luck. Admittedly I am new with Javascript and I am apparently missing something. Does anyone have a clue as to what I'm overlooking here? Happy New Year to you all! Janie

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  • How to stop attributes from being pickled in Python

    - by Ries
    I am using gnosis.xml.pickle to convert an object of my own class to xml. The object is initialized so that: self.logger = MyLogger() But when I do dump the object to a string I get an exception stating that the pickler encountered an unpickleable type . Is there a way to 'tag' the logger attribute so that pickler will know not to try and pickle that attribute?

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  • How to make a link button visible after another button has been clicked in asp.net(vb) in button_c

    - by Parth
    How to make a link button visible after another button has been clicked in asp.net(vb) in button_click() it says error as "Object reference not set to an instance of an object." i've done this in my code Protected Sub InsertButton_Click(ByVal sender As Object, ByVal e As System.EventArgs) Dim receipt As LinkButton = FormView1.FindControl("LinkButton1") ' receipt.Enabled = "true" ' receipt.EnableTheming = "true" ' receipt.EnableViewState = "true" receipt.Visible = "true" End Sub

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  • Data access layer using Linq to SQL

    - by Andrei Tanasescu
    I am building a c# - linq - sql server winforms/asp.net application, accessing a database. I would like my business logic layer to be easily testable, and that means not littering it with Linq database queries everywhere. What design patterns/ best practices are available for the following use cases - inserting/updating a new object - searching for an object - loading a bunch of related data into a sort of "presentation" object that could be displayed by various views ?

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  • help me with typecasting problem ...

    - by Anil Namde
    I would like to create a function which can take two arguments object and type and then type cast the object to appropriate type using the type parameter. Is that possible ? how can i achieve it ? public class TEST { public int test; } object ot = new TEST(); Type type = typeof(TEST); TEST t = (type)ot; //Function will be something like this public string SearializeObject(Object obj, Type t) { //check if obj is of type t if(obj is of type t){ //cast obj to type t to read it ((Type t)obj).someMethod } }

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  • Using CompareTo() on different .NET types (e.g. int vs. double)

    - by Yossin
    Hi, I've got a static method that accepts two object type variables and runs the CompareTo() method: public static int Compare(Object objA, Object objB) { return (((IComparable)objA).CompareTo(objB)); } Problem is that CompareTo() throws an exception when trying to compare between different types (e.g. int and double). Does any one know of a better way in C#, to compare between two different types? Or a workaround to this problem? Thanks

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