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  • Extensions methods and forward compatibilty of source code.

    - by TcKs
    Hi, I would like solve the problem (now hypothetical but propably real in future) of using extension methods and maginification of class interface in future development. Example: /* the code written in 17. March 2010 */ public class MySpecialList : IList<MySpecialClass> { // ... implementation } // ... somewhere elsewhere ... MySpecialList list = GetMySpecialList(); // returns list of special classes var reversedList = list.Reverse().ToList(); // .Reverse() is extension method /* now the "list" is unchanged and "reveresedList" has same items in reversed order */ /* --- in future the interface of MySpecialList will be changed because of reason XYZ*/ /* the code written in some future */ public class MySpecialList : IList<MySpecialClass> { // ... implementation public MySpecialList Reverse() { // reverse order of items in this collection return this; } } // ... somewhere elsewhere ... MySpecialList list = GetMySpecialList(); // returns list of special classes var reversedList = list.Reverse().ToList(); // .Reverse() was extension method but now is instance method and do something else ! /* now the "list" is reversed order of items and "reveresedList" has same items lake in "list" */ My question is: Is there some way how to prevent this case (I didn't find them)? If is now way how to prevent it, is there some way how to find possible issues like this? If is now way how to find possible issues, should I forbid usage of extension methods? Thanks.

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  • Manual Linq to SQL entity framework mapping

    - by kprobst
    I've been playing with the O/R designer in VS and I was wondering if someone could shed come light on this. I'm used to OR mappers that are largely manual (homegrown and e.g., NHibernate). I don't mind encoding the entity classes myself, since they don't change all that often to begin with, and I have this irrational fear of designers and auto generated code as it is. I have noticed that the generated entity classes contain a lot of boilerplate extensibility methods, e.g. On[Property]Changed() and so on where [Property] is a mapped member of the class. These are placed in the setters of the property accessors. I assume it's OK if I don't include these when I do my hand coding, correct? They would be nice if I needed some sort of interception pattern but that's certainly not the case. I guess I just need to know if any of those methods are required by the entity framework to keep track of changes to the mapping types in order for things to work when updating the database. Thanks!

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  • Casting pointer to object to void * in C++

    - by JB
    I've been reading StackOverflow too much and started doubting all the code I've ever written, I keep thinking "Is that undefined behavour?" even in code that has been working for ages. So my question - Is it safe and well defined behavour to cast a pointer to an object (In this case abstract interface classes) to a void* and then later on cast them back to the original class and call method using them? I'm fully aware that the code that does this is probably awful. I wouldn't even consider writing it like this now (this is old code which I don't really want to change), so I'm not looking for a discussion of better ways to do this. I already know how to write it better if I ever did this again. But if it's actually broken to rely on this in C++ then I'll have to look at changing the code, if it's merely awful code then changing it won't be a priority. I would have had no doubts about something this simple a year or two ago but as my understanding of C++ increases I actually find I have more and more worries about code being safe under the standards even if it works perfectly well. Perhaps reading too much stack overflow is a bad thing for productivity sometimes :P

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  • "date_part('epoch', now() at time zone 'UTC')" not the same time as "now() at time zone 'UTC'" in po

    - by sirlark
    I'm writing a web based front end to a database (PHP/Postgresql) in which I need to store various dates/times. The times are meant to be always be entered on the client side in the local time, and displayed in the local time too. For storage purposes, I store all dates/times as integers (UNIX timestamps) and normalised to UTC. One particular field has a restriction that the timestamp filled in is not allowed to be in the future, so I tried this with a database constraint... CONSTRAINT not_future CHECK (timestamp-300 <= date_part('epoch', now() at time zone 'UTC')) The -300 is to give 5 minutes leeway in case of slightly desynchronised times between browser and server. The problem is, this constraint always fails when submitting the current time. I've done testing, and found the following. In PostgreSQL client: SELECT now() -- returns correct local time SELECT date_part('epoch', now()) -- returns a unix timestamp at UTC (tested by feeding the value into the date function in PHP correcting for its compensation to my time zone) SELECT date_part('epoch', now() at time zone 'UTC') -- returns a unix timestamp at two time zone offsets west, e.g. I am at GMT+2, I get a GMT-2 timestamp. I've figured out obviously that dropping the "at time zone 'UTC'" will solve my problem, but my question is if 'epoch' is meant to return a unix timestamp which AFAIK is always meant to be in UTC, why would the 'epoch' of a time already in UTC be corrected? Is this a bug, or I am I missing something about the defined/normal behaviour here.

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  • What is the worst gotcha in WPF?

    - by David
    Hi, I've started to make myself a list of "WPF gotchas": things that bug me and that I had to write down to remember because I fall for them every time.... Now, I'm pretty sure you all stumbled upon similar situations at one point, and I would like you to share your experience on the subject: What is the gotcha that gets you all the time? the one you find the most annoying? (I have a few issues that seem to be without explanation, maybe your submissions will explain them) Here are a few of my "personnal" gotchas (randomly presented): For a MouseEvent to be fired even when the click is on the "transparent" background of a control (e.g. a label) and not just on the content (the Text in this case), the control's Background has to be set to "Brushes.Transparent" and not just "null" (default value for a label) A WPF DataGridCell's DataContext is the RowView to whom the cell belong, not the CellView When inside a ScrollViewer, a Scrollbar is managed by the scrollviewer itself (i.e. setting properties such as ScrollBar.Value is without effect) Key.F10 is not fired when you press "F10", instead you get Key.System and you have to go look for e.SystemKey to get the Key.F10 ... and now you're on.

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  • How to proxy calls to the instance of an object

    - by mr.b
    Edit: Changed question title from "Does C# allow method overloading, PHP style (__call)?" - figured out it doesn't have much to do with actual question. Also edited question text. What I want to accomplish is to proxy calls to a an instance of an object methods, so I could log calls to any of its methods. Right now, I have code similar to this: class ProxyClass { static logger; public AnotherClass inner { get; private set; } public ProxyClass() { inner = new AnotherClass(); } } class AnotherClass { public void A() {} public void B() {} public void C() {} // ... } // meanwhile, in happyCodeLandia... ProxyClass pc = new ProxyClass(); pc.inner.A(); // need to write log message like "method A called" pc.inner.B(); // need to write log message like "method B called" // ... So, how can I proxy calls to an object instance in extensible way? Method overloading would be most obvious solution (if it was supported in PHP way). By extensible, meaning that I don't have to modify ProxyClass whenever AnotherClass changes. In my case, AnotherClass can have any number of methods, so it wouldn't be appropriate to overload or wrap all methods to add logging. I am aware that this might not be the best approach for this kind of problem, so if anyone has idea what approach to use, shoot. Thanks!

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  • Handling nulls in Datawarehouse

    - by rrydman
    I'd like to ask your input on what the best practice is for handling null or empty data values when it pertains to data warehousing and SSIS/SSAS. I have several fact and dimension tables that contain null values in different rows. Specifics: 1) What is the best way to handle null date/times values? Should I make a 'default' row in my time or date dimensions and point SSIS to the default row when there is a null found? 2) What is the best way to handle nulls/empty values inside of dimension data. Ex: I have some rows in an 'Accounts' dimensions that have empty (not NULL) values in the Account Name column. Should I convert these empty or null values inside the column to a specific default value? 3) Similar to point 1 above - What should I do if I end up with a Facttable row that has no record in one of the dimension columns? Do I need default dimension records for each dimension in case this happens? 4) Any suggestion or tips in regards to how to handle these operation in Sql server integration services (SSIS)? Best data flow configurations or best transformation objects to use would be helpful. Thanks :-)

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  • Session in php are not enough clear to me

    - by Lulzim
    I find sessions in php kind of confusing, can anybody of you explain those to me. I have an example which is not working in my case: I register sessions this way, would you please tell me is this the right way of registering sessions //this is the page from where i register myusername in sessions if($count==1){ session_start(); $_SESSION['myusername'] = $_POST['myusername']; include("enterpincover.php"); } else { echo "Wrong Pin"; } here i check first whether the username is registered in sessions in oder to open his account , otherwise open again login. It works, if user is not loged in, it will show login page which is right, if user is loged it shows welcome message but not the Welcome the name of the user as I want. for ex: Welcome David <?php session_start(); if(isset($_SESSION['myusername'])) { echo 'Welcome '.$_SESSION['myusername']; } else { include("leftmodules.php"); include("rightmodules.php"); include("login.php"); } ?>

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  • C++ and Dependency Injection in unit testing

    - by lhumongous
    Suppose I have a C++ class like so: class A { public: A() { } void SetNewB( const B& _b ) { m_B = _b; } private: B m_B; } In order to unit test something like this, I would have to break A's dependency on B. Since class A holds onto an actual object and not a pointer, I would have to refactor this code to take a pointer. Additionally, I would need to create a parent interface class for B so I can pass in my own fake of B when I test SetNewB. In this case, doesn't unit testing with dependency injection further complicate the existing code? If I make B a pointer, I'm now introducing heap allocation, and some piece of code is now responsible for cleaning it up (unless I use ref counted pointers). Additionally, if B is a rather trivial class with only a couple of member variables and functions, why introduce a whole new interface for it instead of just testing with an instance of B? I suppose you could make the argument that it would be easier to refactor A by using an interface. But are there some cases where two classes might need to be tightly coupled?

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  • Web page for IPhone - Large fonts instead of scrolling?

    - by chris_l
    I'm planning the layout of my web page, which should also be usable on the IPhone. I don't really have much experience with the IPhone yet - I just installed the IPhone Simulator on my Mac. The page's contents are flexible, so I think it would be better to use this flexibility to avoid that the user has to scroll around the entire page. Especially I have A header and a sidebar that will be used all the time to perform several actions. A main content area with a number of elements (e.g. images). The UI would stay usable pretty well, if the number of elements shown at one time is reduced for a small screen (e.g. by JavaScript). It would also be okay to make the main content area scrollable (as opposed to the entire page). The problem: If I simply display the page on the IPhone, it uses an extremely small font size, so that users must zoom in first, and then scroll around - so that they can't see the header and sidebar all the time. What's the best way to deal with this situation? Just leave it this way (very small fonts), because users expect that behaviour on the IPhone? Increase the font size (by specifying it in em or px or with xx-large, or what would be the best way?), if I detect - somehow - that it's being displayed on the IPhone. Or is there some way to restrict the viewport size to the screen size, and make it zoom in automatically? I think that would be the easiest solution in my case. Or ...?

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  • Storing same type but still getting an ArrayStoreException

    - by Firefoxx Pwnass
    I have strange problem. I have three classes. Book ( abstract ), and two subclasses ( Fiction, Nonfiction). I have created array of Book references. That array can hold both subclasse's objects. I'have following code for Fiction class. public class Fiction extends Book{ public Fiction(String title) { super(title); setPrice(); } public void setPrice() { super.price = 24.99; } } And the "same" code for Nonfiction class public class Nonfiction extends Book{ public Nonfiction(String title) { super(title); setPrice(); } public void setPrice() { super.price = 37.99; } } And this is Main program. import javax.swing.JOptionPane; public class Main { public static void main(String[] args) { Book[] book = new Fiction[6]; for(int i = 0; i<book.length; i++) { if(i<4) { String title = JOptionPane.showInputDialog("Enter fiction book, no "+i); book[i] = new Fiction(title); } else { String title = JOptionPane.showInputDialog("Enter non fiction book, no "+i); book[i] = new Nonfiction(title); } } for(int x = 0; x<book.length; x++) { System.out.println("Book named "+book[x].getTitle()+" costs "+book[x].getPrice()); } } } For any reason i'm getting ArrayStoreException on this line.. book[i] = new Nonfiction(title); But same code works for Fiction class. I checked java documentation and it says that this exception is thrown when i'm trying to store different objects in array ( like String and Int ), but in this case they are all the same objects. Both classes are children of superclass, that means, they are of the same type. I'm confsued. A little help here please?

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  • How to style "form" field labels in Windows Phone 7?

    - by Jeremy Bell
    Is there any standards guidance on how to style field labels next to form fields in windows phone 7 silverlight applications? For example, let's say I have a StackPanel with the TextBlock label and a TextBox for data entry. Currently I am using the default TextBlock Margin included in the PhoneTextSubtleStyle ("12,0,12,0"), and using a Margin of "0,-12,0,0" to push the TextBox up closer to the label: <StackPanel HorizontalAlignment="Left"> <TextBlock VerticalAlignment="Center" Text="Name" Style="{StaticResource PhoneTextSubtleStyle}" /> <TextBox Text="{Binding ItemName, Mode=TwoWay}" TextChanged="TextBox_TextChanged" VerticalAlignment="Center" Width="433" Margin="0,-12,0,0" /> </StackPanel> Note that the TextBox seems to have some internal padding of 12 pixels to the left and right, so that the TextBlock label and the TextBox control visually line up perfectly on the left. The problem is, I see existing apps with widely varying conventions for field label styling. Some do not do the negative margin adjustment, like I have above. Some don't. Some appear to override the label TextBlock Margin so that it is indented an additional 12 pixels on the left (i.e. "24,0,12,0" instead of the default "12,0,12,0"). Some apps put the labels to the left of the fields themselves (I hate that). Is there some standard design guidance on field labels in Windows Phone 7? I read through the design template PDF and could only determine that the field labels should be upper case on the first word (preferably only one word labels), and should NOT have a colon at the end. I didn't see anything with regards to margins or alignment between the label and the field.

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  • What do you call a generalized (non-GUI-related) "Model-View-Controller" architecture?

    - by dcuccia
    I am currently refactoring code that coordinates multiple hardware components for data acquisition, and feeling a bit like I'm recreating the wheel. In particular, an MVC-like pattern seems to be emerging. Except, this has nothing to do with a GUI and I'm worried that I'm forcing this particular pattern where another might be more appropriate. Here's my scenario: Individual hardware "component" classes obey interface contracts for each hardware type. Previously, component instances were orchestrated by a single monolithic InstrumentController class, which relied heavily on configuration + branching logic for executing a specific acquisition sequence. After an iteration, I have a separate controller for each component, with these controllers all managed by a small InstrumentControllerBase (or its derivatives). The composite system will receive "input" either programmatically or via inter-hardware component triggering - in either case these interactions are routed to, and handled by, the appropriate controller. So, I have something that feels MVC-esque, but I don't know if that's because I'm forcing the point. With little direct MVC experience in application development, it's hard to know if I'm just trying to make my scenario fit MVC, where another pattern might be a good alternative or complimentary. My problem is, search results and wiki documentation of these family of patterns seems to immediately drop me into GUI-specific discussions. I understand "M means Model data and the V means View" - but do you call the superset pattern? Component-Commander-Controller? Whence can I exhume examples exemplary?

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  • NSManagedObject How To Reload

    - by crissag
    I have a view that consists of a table of existing objects and an Add button, which allows the user to create a new object. When the user presses Add, the object is created in the list view controller, so that the object will be part of that managed object context (via the NSEntityDescription insertNewObjectForEntityForName: method). The Add view has a property for the managed object. In the list view controller, I create an Add view controller, set the property to the managed object I created, and then push the Add view on to the navigation stack. In the Add view, I have two buttons for save and cancel. In the save, I save the managed object and pass the managed object back to the list view controller via a delegate method. If the user cancels, then I delete the object and pass nil back to the list view controller. The complication I am having in the add view is related to a UIImagePickerController. In the Add view, I have a button which allows the user to take a photo of the object (or use an existing photo from the photo library). However, the process of transferring to the UIImagePickerController and having the user use the camera, is resulting in a didReceiveMemoryWarning in the add view controller. Further, the view was unloaded, which also caused my NSManagedObject to get clobbered. My question is, how to you go about reloading the NSManagedObject in the case where it was released because of the low memory situation?

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  • Need a Java based interruptible timer thread

    - by LambeauLeap
    I have a Main Program which is running a script on the target device(smart phone) and in a while loop waiting for stdout messages. However in this particular case, some of the heartbeat messages on the stdout could be spaced almost 45secs to a 1minute apart. something like: stream = device.runProgram(RESTORE_LOGS, new String[] {}); stream.flush(); String line = stream.readLine(); while (line.compareTo("") != 0) { reporter.commentOnJob(jobId, line); line = stream.readLine(); } So, I want to be a able to start a new interruptible thread after reading line from stdout with a required a sleep window. Upon being able to read a new line, I want to be able to interrupt/stop(having trouble killing the process), handle the newline of stdout text and restart a process. And it the event I am not able to read a line within the timer window(say 45secs) I want to a way to get out of my while loop either. I already tried the thread.run, thread.interrupt approach. But having trouble killing and starting a new thread. Is this the best way out or am I missing something obvious?

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  • Aliasing `T*` with `char*` is allowed. Is it also allowed the other way around?

    - by StackedCrooked
    Note: This question has been renamed and reduced to make it more focused and readable. Most of the comments refer to the old text. According to the standard objects of different type may not share the same memory location. So this would not be legal: int i = 0; short * s = reinterpret_cast<short*>(&i); // BAD! The standard however allows an exception to this rule: any object may be accessed through a pointer to char or unsigned char: int i = 0; char * c = reinterpret_cast<char*>(&i); // OK However, it is not clear to me if this is also allowed the other way around. For example: char * c = read_socket(...); unsigned * u = reinterpret_cast<unsigned*>(c); // huh? Summary of the answers The answer is NO for two reasons: You an only access an existing object as char*. There is no object in my sample code, only a byte buffer. The pointer address may not have the right alignment for the target object. In that case dereferencing it would result in undefined behavior. On the Intel and AMD platforms it will result performance overhead. On ARM it will trigger a CPU trap and your program will be terminated! This is a simplified explanation. For more detailed information see answers by @Luc Danton, @Cheers and hth. - Alf and @David Rodríguez.

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  • Why do I get this exception? {An item with the same key has already been added."})

    - by Alan
    Aknittel NewSellerID is the result of a lookup on tblSellers. These tables (tblSellerListings and tblSellers) are not "officially" joined with a foreign key relationship, either in the model or in the database, but I want some referential integrity maintained for the future. So my issue remains. Why do I get the exception ({"An item with the same key has already been added."}) with this code, if I don't begin each iteration of the foreach loop with a new ObjectContext and end it with SaveChanges, which I think will affect performance. Also, could you tell me why ORCSolutionsDataService.tblSellerListings (An ADO.NET DataServices/WCF object is not IDisposable, like LINQ to Entities?? ============================================== // Add listings to previous seller int NewSellerID = 0; // Look up existing Seller key using SellerUniqueEBAYID var qryCurrentSeller = from s in service.tblSellers where s.SellerEBAYUserID == SellerUserID select s; foreach (var s in qryCurrentSeller) NewSellerID = s.SellerID; // Save the selected listings for this seller foreach (DataGridViewRow dgr in dgvRows) { ORCSolutionsDataService.tblSellerListings NewSellerListing = new ORCSolutionsDataService.tblSellerListings(); NewSellerListing.ItemID = dgr.Cells["txtSellerItemID"].Value.ToString(); NewSellerListing.Title = dgr.Cells["txtSellerItemTitle"].Value.ToString(); NewSellerListing.CurrentPrice = Convert.ToDecimal(dgr.Cells["txtSellerItemPrice"].Value); NewSellerListing.QuantitySold = Convert.ToInt32(dgr.Cells["txtSellerItemSold"].Value); NewSellerListing.EndTime = Convert.ToDateTime(dgr.Cells["txtSellerItemEnds"].Value); NewSellerListing.CategoryName = dgr.Cells["txtSellerItemCategory"].Value.ToString(); NewSellerListing.ExtendedPrice = Convert.ToDecimal(dgr.Cells["txtExtendedReceipts"].Value); NewSellerListing.RetrievedDtime = Convert.ToDateTime(dtSellerDataRetrieved.ToString()); NewSellerListing.SellerID = NewSellerID; service.AddTotblSellerListings(NewSellerListing); } service.SaveChanges(); } catch (Exception ex) { MessageBox.Show("Unable to add a new case. Exception: " + ex.Message); }

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  • MySQL Query - WHERE and IF?

    - by Prash
    I'm not quite sure how to right this query. Basically, I'm going to have a table with two columns (OS and country_code) - more columns too, but those are the conditional ones. These will be either set to 0 for all, or specific ones, separated by commas. Now, what I'm trying achieve is pull data from the table if the OS and country_code = 0, or if they contain matching data (separated by commas). Then, I have a column for time. I want to select rows where the time is GREATER than the time column, unless the column time_t is set to false, in which case this shouldn't matter. I hope I explained it right? This is what I kind of have so far: $get = $db->prepare("SELECT * FROM commands WHERE country_code = 0 OR country_code LIKE :country_code AND OS = 0 OR OS LIKE :OS AND IF (time_t = 1, expiry > NOW()) "); $get->execute(array( ':country_code' => "%{$data['country_code']}%", ':OS' => "%{$data['OS']}%" ));

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  • Search and remove an element in mulit-dimentional array in php depending on a criteria

    - by Nadeem
    I've a simple question about multi-dim array, I want to remove any redundent element let's say in my case, [serviceMethod] => PL is coming 2 times, I want to search 'PL' with respect of [APIPriceTax] if an element has a lower price I want to keep it and remove the other one in array Array ( [0] => Array ( [carrierIDs] => 150 [serviceMethod] => CP [APIPriceTax] => 30.63 [APIPriceWithOutTax] 28.32 [APIServiceName] => Xpresspost USA [APIExpectedTransitDay] => 2 ) [1] => Array ( [carrierIDs] => 155 [serviceMethod] => PL [APIPriceTax] => 84.13 [APIPriceWithOutTax] => 73.8 [APIServiceName] => PurolatorExpressU.S. [APIExpectedTransitDay] => 1 ) [2] => Array ( [carrierIDs] => 164 [serviceMethod] => PL [APIPriceTax] => 25.48 [APIPriceWithOutTax] => 22.35 [APIServiceName] => PurolatorGroundU.S. [APIExpectedTransitDay] => 3 ) ) This is my pseudo code: Where $carrierAddedToList is the actual array $newCarrierAry = function($carrierAddedToList) { $newArray = array(); foreach($carrierAddedToList as $cV => $cK) { if( !in_array($cK['serviceMethod'],$newArray) ) { array_push($newArray, $cK['serviceMethod']); } } return $newArray; } ; print_r($newCarrierAry($carrierAddedToList));

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  • Android lifecycle: Fill in data in activity in onStart() or onResume()?

    - by pjv
    Should you get data via a cursor and fill in the data on the screen, such as setting the window title, in onStart() or onResume()? onStart() would seem the logical place because after onStart() the Activity can already be displayed, albeit in the background. Notably I was having a problem with a managed dialog that made me rethink this. If the user rotates the screen while the dialog is still open, onCreateDialog() and onPrepareDialog() are called between onStart() and onResume(). If the dialog needs to be based on the data you need to have the data before onResume(). If I'm correct about onStart() then why does the Notepad example give a bad example by doing it in onResume()? See http://developer.android.com/resources/samples/NotePad/src/com/example/android/notepad/NoteEditor.html NoteEditor.java line 176 (title = mCursor.getString...). Also, what if my Activity launches another Actvity/Dialog that changes the data my cursor is tracking. Even in the simplest case, does that mean that I have to manually update my previous screen (a listener for a dialog in the main activity), or alternatively that I have to register a ContentObserver, since I'm no longer updating the data in onResume() (though I could update it twice of course)? I know it's a basic question but the dialog only recently, to my surprise, made me realize this.

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  • Detecting scroll in Jquery Mobile

    - by noway
    I can't detect whether the page is scrolled or not with jquery mobile. Scrolltop always return 0 in any case. <script> var interval = setInterval(function() { alert($("#articlecontent").scrollTop()); //alert($(window).scrollTop()); //alert($("#maindiv").scrollTop()); } }, 3000); </script> <div data-role="page" id="maindiv"> <div class="ui-bar ui-bar-b"> </div> <div id='articlecontent' data-role="content" data-iscroll> sldfjlkjsl lksjd kls df hjks djkh sdjfkh sjkf jksd jkhsdf jkhsd hjwiuhhfg skd jkshd fkj fkjsg kjhsdkjf sldfjlkjsl lksjd kls df hjks djkh sdjfkh sjkf jksd jkhsdf jkhsd hjwiuhhfg skd jkshd fkj fkjsg kjhsdkjf sldfjlkjsl lksjd kls df hjks djkh sdjfkh sjkf jksd jkhsdf jkhsd hjwiuhhfg skd jkshd fkj fkjsg kjhsdkjf </div> <div data-role="footer" data-id="foo1"> </div> </div>

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  • Preserving the order of annotations

    - by Ragunath Jawahar
    When obtaining the list of fields using getFields() and getDeclaredFields(), the order of the fields in a Java class is undefined. I need this order in my validation library. Since the order is not preserved (though some claim that the order is preserved in JDK 6 and above but is not guaranteed across VMs). I cannot speculate on this because the order of annotations across fields is absolutely essential for the library. One way to get around this is to have an order or an index attribute in my Annotation. What worries me is that the code could become a bit cumbersome for maintaining in the following case. If the use wants to insert a new annotated field then, he might have to renumber all the other annotations in the class. I could have the order or index as a floating point number - float or double but , it wouldn't look good to have order such as 1, 1.5, 2, etc., What would be an elegant solution for this problem? Here is a example code so that you can get an idea about the problem: @Required @TextRule (minLength = 6, message = "You need at least 6 characters.") private EditText usernameEditText; @Password private EditText passwordEditText; @ConfirmPassword private EditText confirmPasswordEditText; @Email private EditText emailEditText;

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  • File IO with Streams - Best Memory Buffer Size

    - by AJ
    I am writing a small IO library to assist with a larger (hobby) project. A part of this library performs various functions on a file, which is read / written via the FileStream object. On each StreamReader.Read(...) pass, I fire off an event which will be used in the main app to display progress information. The processing that goes on in the loop is vaired, but is not too time consuming (it could just be a simple file copy, for example, or may involve encryption...). My main question is: What is the best memory buffer size to use? Thinking about physical disk layouts, I could pick 2k, which would cover a CD sector size and is a nice multiple of a 512 byte hard disk sector. Higher up the abstraction tree, you could go for a larger buffer which could read an entire FAT cluster at a time. I realise with today's PC's, I could go for a more memory hungry option (a couple of MiB, for example), but then I increase the time between UI updates and the user perceives a less responsive app. As an aside, I'm eventually hoping to provide a similar interface to files hosted on FTP / HTTP servers (over a local network / fastish DSL). What would be the best memory buffer size for those (again, a "best-case" tradeoff between perceived responsiveness vs. performance).

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  • Database/Object Mapping

    - by Eric
    Hello everyone, This is a beginner question, but it's been frustrating me... I am using C#, by the way. I'd like to make a few classes, each with their own properties and methods. I would also like to have a database to store certain instances of these classes in case I would ever need to look at them again. So, for example... class Polygon { String name; Double perimiter; int numSides; public Double GetArea() { // ... } } class Circle { String name; Double radius; public void PrintName() { // ... } } Say I've got these classes. I also want a database that has the TABLES "Polygon" and "Circle" with the COLUMNS "name" "perimeter" "radius" etc. And I want an easy way to save a class instance into the database, or pull a class instance out of the database. I have previously been using MS Access for my database stuff, which I don't mind using, but I would prefer if nothing other than .NET need to be installed. I've been researching online a bit, but I wanted to get some opinions on here. I have looked at Linq-to-Sql, but it seems you need Sql-Server. Is this true? If so, I'd really rather not use it because I don't want to have to have it installed everywhere. Anway, I'm just fishing for some ideas/insights/suggestions/etc. so please help me out if you can. Thanks.

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  • how can i make sure to get the server response correctly when i invoke the server with QNetworkReque

    - by noname
    I wrote the server site call in Qt, but i haven't get the server response for every server invoking. I have to use the server reply to continue the program flow. The request is correctly reached to server and server do reply.The server is also on my machine. Here is the code how i make the server site call; QNetworkAccessManager nam1 = new QNetworkAccessManager(this); qnetmg=nam1; QObject::connect(nam1, SIGNAL(finished(QNetworkReply*)),this,SLOT(finishedGettingMarker(QNetworkReply*))); QString strurl="http://localhost:8080/ServerWeb"; QUrl url(strurl); QNetworkRequest preq(url); QNetworkReply* reply = nam1->get(preq); qreply=reply; Inside finisedGettingMarker slot, i have already eliminate for QNetworkReply-error case and i used one global variable for QNetworkAccessManager;"qnetmg" and one global variable for QNetworkReply;"qreply". And also i make qnetmg.disconnect(this,0); and qreply.abort(); inside that slot method. But the problem is i haven't got the response for every server invoking time. If anyone who know the way to solve it , please reply me. This situation happened only in Opera. Thanks in advance.

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