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  • How to initiate chatting between two clients and two clients only, using applets and servlets?

    - by mithun1538
    Hello everyone, I first need to apologize for my earlier questions. (You can check my profile for them)They seemed to ask more questions than give answers. Hence, I am laying down the actual question that started all them absurd questions. I am trying to design a chat applet. Till now, I have coded the applet, servlet and communication between the applet and the servlet. The code in the servlet side is such that I was able to establish chatting between clients using the applets, but the code was more like a broadcast all feature, i.e. all clients would be chatting with each other. That was my first objective when I started designing the chat applet. The second step is chatting between only two specific users, much like any other chat application we have. So this was my idea for it: I create an instance of the servlet that has the 'broadcast-all' code. I then pass the address of this instance to the respective clients. 2 client applets use the address to then chat. Technically the code is 'broadcast-all', but since only 2 clients are connected to it, it gives the chatting between two clients feature. Thus, groups of 2 clients have different instances of the same servlet, and each instance handles chatting between two clients at a max. However, as predicted, the idea didn't materialize! I tried to create an instance of the servlet but the only solution for that was using sessions on the servlet side, and I don't know how to use this session for later communications. I then tried to modify my broadcast-all code. In that code, I was using classes that implemented Observer and Observable interfaces. So the next idea that I got was: Create a new object of the Observable class(say class_1). This object be common to 2 clients. 2 clients that wish to chat will use same object of the class_1. 2 other clients will use a different object of class_1. But the problem here lies with the class that implements the Observer interface(say class_2). Since this has observers monitoring the same type of class, namely class_1, how do I establish an observer monitoring one object of class_1 and another observer monitoring another object of the same class class_1 (Because notifyObservers() would notify all the observers and I can't assign a particular observer to a particular object)? I first decided to ask individual problems, like how to create instances of servlets, using objects of observable and observer and so on in stackoverflow... but I got confused even more. Can anyone give me an idea how to establish chatting between two clients only?(I am using Http and not sockets or RMI). Regards, Mithun. P.S. Thanks to all who replied to my previous (absurd) queries. I should have stated the purpose earlier so that you guys could help me better.

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  • jQuery: tabs where the tab/content can be linked to

    - by Ricardo Zea
    My issue is simple. I have already implemented a tab system, and I'd probably spend more time implementing another one with the solution I need, than giving a shot at adapting the code I have, and learn something while asking :) My problem is that the tabs can't be linked to, I need to be able to link to a tab from another website or page, and have that tab get selected upon page load. ie: I have three tabs showing different products, by default tab 1 is active/selected when the page loads. From the home page I want to link to tab 2 but I can't link to tab 2 because it doesn't get selected. Not sure if that makes sense. Tabs: <ul> <li><a href="products.php">Product 1</a></li> <li><a href="products.php">Product 2</a></li> <li><a href="products.php">Product 3</a></li> </ul> <div class="tab_container"> <div id="tab1" class="tab_content">Product 1 info...</div> <div id="tab2" class="tab_content">Product 2 info...</div> <div id="tab3" class="tab_content">Product 3 info...</div> </div> my jQuery: $(document).ready(function() { //Default Action $(".tab_content").hide(); $("ul.tabs li:first").addClass("active").show(); $(".tab_content:first").show(); //On Click Event $("ul.tabs li").click(function() { $("ul.tabs li").removeClass("active"); $(this).addClass("active"); $(".tab_content").hide(); var activeTab = $(this).find("a").attr("href"); $(activeTab).fadeIn(); return false; }); }); Is there a way this code can be adapted to be able to link to any tab from anywhere and have that tab get selected when the page loads? Thanks in advance.

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  • Injecting Annotated Bean into Regular Bean

    - by jboyd
    AppContext.xml <bean id="myBean" class="com.myapp.MyClass"> <property ref="myService"/> </bean> MyService.java @Service public class MyService { ... } This will throw an exception stating that no bean can be found for property "myService", which I understand because it can't be found in the context files, but I can autowire that field in other spring managed beans, but I need to explicitly build the bean in my context because the POJO is not editable in the scope of my project.

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  • Should ActionResult perform other tasks too

    - by Ori
    In Asp.net MVC one is encouraged to derive custom ActionResults, however should these classes handle other tasks unrelated to views, perhaps a EmailActionResult would render a view then send an email. What is best practice for the class ActionResult, is it only view specific? I want to keep things DRY too. Should the sending of the email be factored into a service class? perhaps using a filter would work. what are your thoughts?

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  • Rails 3 Nested Forms with datamapper

    - by jens freudenau
    i have two models: class MeetingPoint include DataMapper::Resource belongs_to :profile property :id, Serial property :lat, String end and class Profile include DataMapper::Resource has n, :meeting_points property :id, Serial property :distance, Text property :created_at, DateTime property :updated_at, DateTime end Now I create a form to edit the profile and the meeting_poing: = form_for @profile do |f| = f.text_field :distance = f.fields_for :meeting_points do |ff| = ff.text_field :lat = f.submit But when I want to save the values I get always the error: "undefined method `readonly?' for ["lat", "14.000"]:Array"

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  • Android - OPENGL cube is NOT in the display

    - by Marc Ortiz
    I'm trying to display a square on my display and i can't. Whats my problem? How can I display it on the screen (center of the screen)? I let my code below! Here's my render class: public class GLRenderEx implements Renderer { private GLCube cube; Context c; GLCube quad; // ( NEW ) // Constructor public GLRenderEx(Context context) { // Set up the data-array buffers for these shapes ( NEW ) quad = new GLCube(); // ( NEW ) } // Call back when the surface is first created or re-created. @Override public void onSurfaceCreated(GL10 gl, EGLConfig config) { // NO CHANGE - SKIP } // Call back after onSurfaceCreated() or whenever the window's size changes. @Override public void onSurfaceChanged(GL10 gl, int width, int height) { // NO CHANGE - SKIP } // Call back to draw the current frame. @Override public void onDrawFrame(GL10 gl) { // Clear color and depth buffers using clear-values set earlier gl.glClear(GL10.GL_COLOR_BUFFER_BIT | GL10.GL_DEPTH_BUFFER_BIT); gl.glLoadIdentity(); // Reset model-view matrix ( NEW ) gl.glTranslatef(-1.5f, 0.0f, -6.0f); // Translate left and into the // screen ( NEW ) // Translate right, relative to the previous translation ( NEW ) gl.glTranslatef(3.0f, 0.0f, 0.0f); quad.draw(gl); // Draw quad ( NEW ) } } And here is my square class: public class GLCube { private FloatBuffer vertexBuffer; // Buffer for vertex-array private float[] vertices = { // Vertices for the square -1.0f, -1.0f, 0.0f, // 0. left-bottom 1.0f, -1.0f, 0.0f, // 1. right-bottom -1.0f, 1.0f, 0.0f, // 2. left-top 1.0f, 1.0f, 0.0f // 3. right-top }; // Constructor - Setup the vertex buffer public GLCube() { // Setup vertex array buffer. Vertices in float. A float has 4 bytes ByteBuffer vbb = ByteBuffer.allocateDirect(vertices.length * 4); vbb.order(ByteOrder.nativeOrder()); // Use native byte order vertexBuffer = vbb.asFloatBuffer(); // Convert from byte to float vertexBuffer.put(vertices); // Copy data into buffer vertexBuffer.position(0); // Rewind } // Render the shape public void draw(GL10 gl) { // Enable vertex-array and define its buffer gl.glEnableClientState(GL10.GL_VERTEX_ARRAY); gl.glVertexPointer(3, GL10.GL_FLOAT, 0, vertexBuffer); // Draw the primitives from the vertex-array directly gl.glDrawArrays(GL10.GL_TRIANGLE_STRIP, 0, vertices.length / 3); gl.glDisableClientState(GL10.GL_VERTEX_ARRAY); } } Thanks!!

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  • Memory efficient int-int dict in Python

    - by Bolo
    Hi, I need a memory efficient int-int dict in Python that would support the following operations in O(log n) time: d[k] = v # replace if present v = d[k] # None or a negative number if not present I need to hold ~250M pairs, so it really has to be tight. Do you happen to know a suitable implementation (Python 2.7)? EDIT Removed impossible requirement and other nonsense. Thanks, Craig and Kylotan! To rephrase. Here's a trivial int-int dictionary with 1M pairs: >>> import random, sys >>> from guppy import hpy >>> h = hpy() >>> h.setrelheap() >>> d = {} >>> for _ in xrange(1000000): ... d[random.randint(0, sys.maxint)] = random.randint(0, sys.maxint) ... >>> h.heap() Partition of a set of 1999530 objects. Total size = 49161112 bytes. Index Count % Size % Cumulative % Kind (class / dict of class) 0 1 0 25165960 51 25165960 51 dict (no owner) 1 1999521 100 23994252 49 49160212 100 int On average, a pair of integers uses 49 bytes. Here's an array of 2M integers: >>> import array, random, sys >>> from guppy import hpy >>> h = hpy() >>> h.setrelheap() >>> a = array.array('i') >>> for _ in xrange(2000000): ... a.append(random.randint(0, sys.maxint)) ... >>> h.heap() Partition of a set of 14 objects. Total size = 8001108 bytes. Index Count % Size % Cumulative % Kind (class / dict of class) 0 1 7 8000028 100 8000028 100 array.array On average, a pair of integers uses 8 bytes. I accept that 8 bytes/pair in a dictionary is rather hard to achieve in general. Rephrased question: is there a memory-efficient implementation of int-int dictionary that uses considerably less than 49 bytes/pair?

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  • Implementing a robust async stream reader for a console

    - by Jon
    I recently provided an answer to this question: C# - Realtime console output redirection. As often happens, explaining stuff (here "stuff" was how I tackled a similar problem) leads you to greater understanding and/or, as is the case here, "oops" moments. I realized that my solution, as implemented, has a bug. The bug has little practical importance, but it has an extremely large importance to me as a developer: I can't rest easy knowing that my code has the potential to blow up. Squashing the bug is the purpose of this question. I apologize for the long intro, so let's get dirty. I wanted to build a class that allows me to receive input from a Stream in an event-based manner. The stream, in my scenario, is guaranteed to be a FileStream and there is also an associated StreamReader already present to leverage. The public interface of the class is this: public class MyStreamManager { public event EventHandler<ConsoleOutputReadEventArgs> StandardOutputRead; public void StartSendingEvents(); public void StopSendingEvents(); } Obviously this specific scenario has to do with a console's standard output. StartSendingEvents and StopSendingEvents do what they advertise; for the purposes of this discussion, we can assume that events are always being sent without loss of generality. The class uses these two fields internally: protected readonly StringBuilder inputAccumulator = new StringBuilder(); protected readonly byte[] buffer = new byte[256]; The functionality of the class is implemented in the methods below. To get the ball rolling: public void StartSendingEvents(); { this.stopAutomation = false; this.BeginReadAsync(); } To read data out of the Stream without blocking, and also without requiring a carriage return char, BeginRead is called: protected void BeginReadAsync() { if (!this.stopAutomation) { this.StandardOutput.BaseStream.BeginRead( this.buffer, 0, this.buffer.Length, this.ReadHappened, null); } } The challenging part: BeginRead requires using a buffer. This means that when reading from the stream, it is possible that the bytes available to read ("incoming chunk") are larger than the buffer. Since we are only handing off data from the stream to a consumer, and that consumer may well have inside knowledge about the size and/or format of these chunks, I want to call event subscribers exactly once for each chunk. Otherwise the abstraction breaks down and the subscribers have to buffer the incoming data and reconstruct the chunks themselves using said knowledge. This is much less convenient to the calling code, and detracts from the usefulness of my class. Edit: There are comments below correctly stating that since the data is coming from a stream, there is absolutely nothing that the receiver can infer about the structure of the data unless it is fully prepared to parse it. What I am trying to do here is leverage the "flush the output" "structure" that the owner of the console imparts while writing on it. I am prepared to assume (better: allow my caller to have the option to assume) that the OS will pass me the data written between two flushes of the stream in exactly one piece. To this end, if the buffer is full after EndRead, we don't send its contents to subscribers immediately but instead append them to a StringBuilder. The contents of the StringBuilder are only sent back whenever there is no more to read from the stream (thus preserving the chunks). private void ReadHappened(IAsyncResult asyncResult) { var bytesRead = this.StandardOutput.BaseStream.EndRead(asyncResult); if (bytesRead == 0) { this.OnAutomationStopped(); return; } var input = this.StandardOutput.CurrentEncoding.GetString( this.buffer, 0, bytesRead); this.inputAccumulator.Append(input); if (bytesRead < this.buffer.Length) { this.OnInputRead(); // only send back if we 're sure we got it all } this.BeginReadAsync(); // continue "looping" with BeginRead } After any read which is not enough to fill the buffer, all accumulated data is sent to the subscribers: private void OnInputRead() { var handler = this.StandardOutputRead; if (handler == null) { return; } handler(this, new ConsoleOutputReadEventArgs(this.inputAccumulator.ToString())); this.inputAccumulator.Clear(); } (I know that as long as there are no subscribers the data gets accumulated forever. This is a deliberate decision). The good This scheme works almost perfectly: Async functionality without spawning any threads Very convenient to the calling code (just subscribe to an event) Maintains the "chunkiness" of the data; this allows the calling code to use inside knowledge of the data without doing any extra work Is almost agnostic to the buffer size (it will work correctly with any size buffer irrespective of the data being read) The bad That last almost is a very big one. Consider what happens when there is an incoming chunk with length exactly equal to the size of the buffer. The chunk will be read and buffered, but the event will not be triggered. This will be followed up by a BeginRead that expects to find more data belonging to the current chunk in order to send it back all in one piece, but... there will be no more data in the stream. In fact, as long as data is put into the stream in chunks with length exactly equal to the buffer size, the data will be buffered and the event will never be triggered. This scenario may be highly unlikely to occur in practice, especially since we can pick any number for the buffer size, but the problem is there. Solution? Unfortunately, after checking the available methods on FileStream and StreamReader, I can't find anything which lets me peek into the stream while also allowing async methods to be used on it. One "solution" would be to have a thread wait on a ManualResetEvent after the "buffer filled" condition is detected. If the event is not signaled (by the async callback) in a small amount of time, then more data from the stream will not be forthcoming and the data accumulated so far should be sent to subscribers. However, this introduces the need for another thread, requires thread synchronization, and is plain inelegant. Specifying a timeout for BeginRead would also suffice (call back into my code every now and then so I can check if there's data to be sent back; most of the time there will not be anything to do, so I expect the performance hit to be negligible). But it looks like timeouts are not supported in FileStream. Since I imagine that async calls with timeouts are an option in bare Win32, another approach might be to PInvoke the hell out of the problem. But this is also undesirable as it will introduce complexity and simply be a pain to code. Is there an elegant way to get around the problem? Thanks for being patient enough to read all of this.

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  • Terminating app due to uncaught exception 'NSInvalidArgumentException' in iPhnoe

    - by mayur birari
    i have view controller including image ,table and tab ,i want to fill the table thats why i written separate class for table as uitableviewcontroller and give mapping to that class in IB, but i have following exception Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '* -[AssetTableView superview]: unrecognized selector sent to instance 0x39322b0' please give me answer ,i am waiting, thANKS IN ADVANCE

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  • Should an installer run automatically with a setup project

    - by Tom Brown
    I have a windows app (app.exe) build with visual studio 2008, for which I have created a custom installer class. When I run installutil.exe on app.exe, the custom installer is executed OK. I then added a setup & deployment project to create the windows installer file app.msi - this works fine but it does not run the custom installer. How is my custom installer class supposed to get linked to the setup MSI file?

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  • Eclipse getResourceAsStream returning null

    - by Chris
    I cannot get getResourceAsStream to find a file. I have put the file in the top level dir, target dir, etc, etc and have tried it with a "/" in front as well. Everytime it returns null. Any suggestions ? Thanks. public class T { public static final void main(String[] args) { InputStream propertiesIS = T.class.getClassLoader().getResourceAsStream("test.txt"); System.out.println("Break"); } }

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  • jQuery: Setting 'style' attribute of element with object

    - by JamesBrownIsDead
    I saw this in our codebase the other day: link.attr('style', map({ color: '#9a4d9e', cursor: 'default' })); map is defined as: function map(map) { var cssValue = []; for (var o in map) { cssValue.push(o + ':' + map[o] + ';') } return cssValue.join(';'); } Is map necessarily? Is there a shorter way to do this? It's important to note that the "style" attribute overrides any styles set by a class added/defined in the "class" attribute.

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  • Why is my slot not being called?

    - by Jen
    I have this class: class CustomEdit : public QTextEdit { Q_GADGET public: CustomEdit(QWidget* parent); public slots: void onTextChanged (); }; CustomEdit::CustomEdit(QWidget* parent) : QTextEdit(parent) { connect( this, SIGNAL(textChanged()), this, SLOT(onTextChanged())); } void CustomEdit::onTextChanged () { // ... do stuff } The onTextChanged method is never called when I type text into the edit control. What am I missing?

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  • C# OOP File Structure?

    - by Soo
    Hey SO, I just started programming with objects recently and am trying to learn good habits early on. The way I plan to structure my application is to have two files: 1: Program.cs - This file will contain the main logic for the application 2: Class.cs - This file will contain all of the class definitions Pretty simple. What I'm wondering if I should have any more files for ... well, you tell me. Any help would be appreciated.

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  • "Cannot find symbol" problem.

    - by joseph
    I'm getting the Cannot find symbol error from my code. Does anyone know what can cause this problem? // Register JDBC driver Class.forName("net.sourceforge.jtds.jdbc.Driver"); method forName(java.Lang.String) Class.forName("net.sourceforge.jtds.jdbc.Driver); ^

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  • why retain of delegate is wrong what are all alternatives...?

    - by jeeva
    Hi, I have one problem let assume A and B are 2 view controller from A user push to B view controller,In B user starts some download by creating object C(which is NSObject class) and sets B as delegate to C(assign),now user want go back to A then dealloc of B calls object releases, C delegate fails to give call back(crashes).I want to get call and allow user to move to other view controller thats way i am retain the delegate in C class but retain of delegate is wrong ... what are all solutions ... Thanks in Advance.

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  • Invoke does not exist in the current context?

    - by Pawan Kumar
    Invoke does not exist in the current context. The same method was not giving any error in Form.cs class but when I used in other class in same project it gives error. i am using threading on forms control. private void UpdateText(object fileName) { if (Textbox.InvokeRequired) { UpdateTextCallback back = new UpdateTextCallback(UpdateText); this.Invoke(back, new object[] { fileName }); } }

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  • deleted gen folder, eclipse isn't generating it now :(

    - by LuxuryMode
    I accidentally deleted my gen folder and now, predictably, my resources are all messed up. I just created a gen folder myself and tried to project clean - that didn't work. Tried right-clicking project and going to android tools fix project properties - didn't work. Tried unchecking build automatically...didn't work. cleaned, closed project, closed eclipse, restarted, etc, etc. Nothing is working and I keep seeing this error: gen already exists but is not a source folder. Convert to a source folder or rename it. EDIT - OK was able to generate R.java, but now I'm getting crazy stuff in the console: [2011-06-14 17:06:11 - fastapp] Conversion to Dalvik format failed with error 1 [2011-06-14 17:06:42 - fastapp] Dx trouble processing "java/awt/font/NumericShaper.class": Ill-advised or mistaken usage of a core class (java.* or javax.*) when not building a core library. This is often due to inadvertently including a core library file in your application's project, when using an IDE (such as Eclipse). If you are sure you're not intentionally defining a core class, then this is the most likely explanation of what's going on. However, you might actually be trying to define a class in a core namespace, the source of which you may have taken, for example, from a non-Android virtual machine project. This will most assuredly not work. At a minimum, it jeopardizes the compatibility of your app with future versions of the platform. It is also often of questionable legality. If you really intend to build a core library -- which is only appropriate as part of creating a full virtual machine distribution, as opposed to compiling an application -- then use the "--core-library" option to suppress this error message. If you go ahead and use "--core-library" but are in fact building an application, then be forewarned that your application will still fail to build or run, at some point. Please be prepared for angry customers who find, for example, that your application ceases to function once they upgrade their operating system. You will be to blame for this problem. If you are legitimately using some code that happens to be in a core package, then the easiest safe alternative you have is to repackage that code. That is, move the classes in question into your own package namespace. This means that they will never be in conflict with core system classes. JarJar is a tool that may help you in this endeavor. If you find that you cannot do this, then that is an indication that the path you are on will ultimately lead to pain, suffering, grief, and lamentation. [2011-06-14 17:06:42 - fastapp] Dx 1 error; aborting [2011-06-14 17:06:42 - fastapp] Conversion to Dalvik format failed with error 1 And eclipse can't resolve the import of my resources import com.me.fastapp.R;

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  • Jquery stop load function after too many clicks

    - by Sergio
    How can I stop loading function after user is clicked too many times on link? Jquery code looks like: $(document).ready(function(){ $(".menu_rfr").click(function() { $("#main").html('<img src="img/spin.gif" class="spin">'); location.replace($(this).attr('rel')); }); $(".menu_clickable").click(function() { $("#main").html('<img src="img/spin.gif" class="spin">'); $("#main").load($(this).attr('rel')); }); });

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  • NSMutableArray of NSString in CoreData(iPhone

    - by azia
    I have a class, which describe an object for parsing XML. This class contains NSStrings and NSMutableArrays of NSStrings.I want to store parsed data using CoreData. How should I write CoreData model to store such objects if there is no such data type like NSMutableArray? Is there any way?

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  • When using delegates, need better way to do sequential processing

    - by Padawan
    I have a class WebServiceCaller that uses NSURLConnection to make asynchronous calls to a web service. The class provides a delegate property and when the web service call is done, it calls a method webServiceDoneWithXXX on the delegate. There are several web service methods that can be called, two of which are say GetSummary and GetList. The classes that use WebServiceCaller initially need both the summary and list so they are written like this: -(void)getAllData { [webServiceCaller getSummary]; } -(void)webServiceDoneWithGetSummary { [webServiceCaller getList]; } -(void)webServiceDoneWithGetList { ... } This works but there are at least two problems: The calls are split across delegate methods so it's hard to see the sequence at a glance but more important it's hard to control or modify the sequence. Sometimes I want to call just GetSummary and not also GetList so I would then have to use an ugly class-level state variable that tells webServiceDoneWithGetSummary whether to call GetList or not. Assume that GetList cannot be done until GetSummary completes and returns some data which is used as input to GetList. Is there a better way to handle this and still get asynchronous calls? Update based on Matt Long's answer: Using notifications instead of a delegate, it looks like I can solve problem #2 by setting a different selector depending on whether I want the full sequence (GetSummary+GetList) or just GetSummary. Both observers would still use the same notification name when calling GetSummary. I would have to write two separate methods to handle GetSummaryDone instead of using a single delegate method (where I would have needed some class-level variable to tell whether to then call GetList). -(void)getAllData { [[NSNotificationCenter defaultCenter] addObserver:self              selector:@selector(getSummaryDoneAndCallGetList:)                  name:kGetSummaryDidFinish object:nil];     [webServiceCaller getSummary]; } -(void)getSummaryDoneAndCallGetList { [NSNotificationCenter removeObserver] //process summary data [[NSNotificationCenter defaultCenter] addObserver:self              selector:@selector(getListDone:)                  name:kGetListDidFinish object:nil];     [webServiceCaller getList]; } -(void)getListDone { [NSNotificationCenter removeObserver] //process list data } -(void)getJustSummaryData { [[NSNotificationCenter defaultCenter] addObserver:self              selector:@selector(getJustSummaryDone:) //different selector but                  name:kGetSummaryDidFinish object:nil]; //same notification name     [webServiceCaller getSummary]; } -(void)getJustSummaryDone { [NSNotificationCenter removeObserver] //process summary data } I haven't actually tried this yet. It seems better than having state variables and if-then statements but you have to write more methods. I still don't see a solution for problem 1.

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  • Constructor or Explicit cast

    - by Felan
    In working with Linq to Sql I create a seperate class to ferry data to a web page. To simplify creating these ferry objects I either use a specialized constructor or an explicit conversion operator. I have two questions. First which approach is better from a readibility perspective? Second while the clr code that is generated appeared to be the same to me, are there situations where one would be treated different than the other by the compiler (in lambda's or such). Example code (DatabaseFoo uses specialized constructor and BusinessFoo uses explicit operator): public class DatabaseFoo { private static int idCounter; // just to help with generating data public int Id { get; set; } public string Name { get; set; } public DatabaseFoo() { Id = idCounter++; Name = string.Format("Test{0}", Id); } public DatabaseFoo(BusinessFoo foo) { this.Id = foo.Id; this.Name = foo.Name; } } public class BusinessFoo { public int Id { get; set; } public string Name { get; set; } public static explicit operator BusinessFoo(DatabaseFoo foo) { return FromDatabaseFoo(foo); } public static BusinessFoo FromDatabaseFoo(DatabaseFoo foo) { return new BusinessFoo {Id = foo.Id, Name = foo.Name}; } } public class Program { static void Main(string[] args) { Console.WriteLine("Creating the initial list of DatabaseFoo"); IEnumerable<DatabaseFoo> dafoos = new List<DatabaseFoo>() { new DatabaseFoo(), new DatabaseFoo(), new DatabaseFoo(), new DatabaseFoo(), new DatabaseFoo(), new DatabaseFoo()}; foreach(DatabaseFoo dafoo in dafoos) Console.WriteLine(string.Format("{0}\t{1}", dafoo.Id, dafoo.Name)); Console.WriteLine("Casting the list of DatabaseFoo to a list of BusinessFoo"); IEnumerable<BusinessFoo> bufoos = from x in dafoos select (BusinessFoo) x; foreach (BusinessFoo bufoo in bufoos) Console.WriteLine(string.Format("{0}\t{1}", bufoo.Id, bufoo.Name)); Console.WriteLine("Creating a new list of DatabaseFoo by calling the constructor taking BusinessFoo"); IEnumerable<DatabaseFoo> fufoos = from x in bufoos select new DatabaseFoo(x); foreach(DatabaseFoo fufoo in fufoos) Console.WriteLine(string.Format("{0}\t{1}", fufoo.Id, fufoo.Name)); } }

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  • How do I use accepts_nested_attributes_for? I cannot use the .build method (!)

    - by Angela
    Editing my question for conciseness and to update what I've done: How do I model having multiple Addresses for a Company and assign a single Address to a Contact, and be able to assign them when creating or editing a Contact? Here is my model for Contacts: class Contact < ActiveRecord::Base attr_accessible :first_name, :last_name, :title, :phone, :fax, :email, :company, :date_entered, :campaign_id, :company_name, :address_id, :address_attributes belongs_to :company belongs_to :address accepts_nested_attributes_for :address end Here is my model for Address: class Address < ActiveRecord::Base attr_accessible :street1, :street2, :city, :state, :zip has_many :contacts end I would like, when creating an new contact, access all the Addresses that belong to the other Contacts that belong to the Company. So here is how I represent Company: class Company < ActiveRecord::Base attr_accessible :name, :phone, :addresses has_many :contacts has_many :addresses, :through => :contacts end Here is how I am trying to create a field in the View for _form for Contact so that, when someone creates a new Contact, they pass the address to the Address model and associate that address to the Contact: <% f.fields_for :address, @contact.address do |builder| %> <p> <%= builder.label :street1, "Street 1" %> </br> <%= builder.text_field :street1 %> <p> <% end %> When I try to Edit, the field for Street 1 is blank. And I don't know how to display the value from show.html.erb. At the bottom is my error console -- can't seem to create values in the address table: My Contacts controller is as follows: def new @contact = Contact.new @contact.address.build # I GET AN ERROR HERE: says NIL CLASS @contact.date_entered = Date.today @campaigns = Campaign.find(:all, :order => "name") if params[:campaign_id].blank? else @campaign = Campaign.find(params[:campaign_id]) @contact.campaign_id = @campaign.id end if params[:company_id].blank? else @company = Company.find(params[:company_id]) @contact.company_name = @company.name end end def create @contact = Contact.new(params[:contact]) if @contact.save flash[:notice] = "Successfully created contact." redirect_to @contact else render :action => 'new' end end def edit @contact = Contact.find(params[:id]) @campaigns = Campaign.find(:all, :order => "name") end Here is a snippet of my error console: I am POSTING the attribute, but it is not CREATING in the Address table.... Processing ContactsController#create (for 127.0.0.1 at 2010-05-12 21:16:17) [POST] Parameters: {"commit"="Submit", "authenticity_token"="d8/gx0zy0Vgg6ghfcbAYL0YtGjYIUC2b1aG+dDKjuSs=", "contact"={"company_name"="Allyforce", "title"="", "campaign_id"="2", "address_attributes"={"street1"="abc"}, "fax"="", "phone"="", "last_name"="", "date_entered"="2010-05-12", "email"="", "first_name"="abc"}} Company Load (0.0ms)[0m [0mSELECT * FROM "companies" WHERE ("companies"."name" = 'Allyforce') LIMIT 1[0m Address Create (16.0ms)[0m [0;1mINSERT INTO "addresses" ("city", "zip", "created_at", "street1", "updated_at", "street2", "state") VALUES(NULL, NULL, '2010-05-13 04:16:18', NULL, '2010-05-13 04:16:18', NULL, NULL)[0m Contact Create (0.0ms)[0m [0mINSERT INTO "contacts" ("company", "created_at", "title", "updated_at", "campaign_id", "address_id", "last_name", "phone", "fax", "company_id", "date_entered", "first_name", "email") VALUES(NULL, '2010-05-13 04:16:18', '', '2010-05-13 04:16:18', 2, 2, '', '', '', 5, '2010-05-12', 'abc', '')[0m

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