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• Composite pattern in C++ problem

  - by annouk

  Hello! I have to work with an application in C++ similar to a phone book: the class Agenda with an STL list of Contacts.Regarding the contacts hierarchy,there is a base-class named Contact(an abstract one),and the derived classes Friend and Acquaintance(the types of contact). These classes have,for instance, a virtual method called getName,which returns the name of the contact. Now I must implement the Composite pattern by adding another type of contact,Company(being derived from Contact),which also contains a collection of Contacts(an STL list as well),that can be either of the "leaf" type(Friends or Acquaintances),or they can be Companies as well. Therefore,Company is the Compound type. The question is: how and where can I implement an STL find_if to search the contact with a given name(via getName function or suggest me smth else) both among the "leaf"-type Contact and inside the Company collection? In other words,how do I traverse the tree in order to find possible matches there too,using an uniform function definition? I hope I was pretty clear...

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• Android sql creating database once

  - by semajhan

  One thing i'm not understanding is how to create the database and data just once in an android application. I extend SQLiteOpenHelper and use a DataHelper class that to manipulate data. Now, I have addEvent() and updateEvent() within the DataHelper class. I create an instance of DataHelper in my Activity and addEvent() a couple of times to insert data. Well, now I don't know how to just do that once. If I restart the app, its just going to "addEvent()" again and so the data is being reset every time. Sorry for the probably really REALLY noob question. The only solution I found was not using the DataHelper class and just adding data "manually" within the onCreate() method in SQLiteOpenHelper.

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• Can I add a custom method to Core Data-generated classes?

  - by Andy

  I've got a couple of Core Data-generated class files that I'd like to add custom methods to. I don't need to add any instance variables. How can I do this? I tried adding a category of methods: // ContactMethods.h (my category on Core Data-generated "Contact" class) #import "Contact.h" @interface Contact (ContactMethods) -(NSString*)displayName; @end ... // ContactMethods.m #import "ContactMethods.h" @implementation Contact (ContactMethods) -(NSString*)displayName { return @"Some Name"; // this is test code } @end This doesn't work, though. I get a compiler message that "-NSManagedObject may not respond to 'displayName' " and sure enough, when I run the app, I don't get "Some Name" where I should be seeing it.

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• Ubuntu Wired network(ethernet does not work)

  - by badnaam

  It was working just fine, until the other day I yanked it out. The wireless works just fine on the same router. If I login to a windows 7 instance on this dual boot laptop then the ehternet works just fine. So it's not a hardware, cable or router issue. The card even gets an ip, but I can't connect to the internet. Here are the details from route, iptables, ifconfig, ping etc. Any ideas? I have been struggling with this for day, none seems to have an answer. http://pastie.org/954816

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• c# - best way to initialize an array of reference type object

  - by lidong

  I wonder if there is better way to initialize an array of reference type object, like this. Queue<int>[] queues = new Queue<int>[10]; for (int i = 0; i < queues.Length; i++) { queues[i] = new Queue<int>(); } I tried Enumerable.Repeat, but all elements in the array refer to same instance, Queue<int>[] queues = Enumerable.Repeat(new Queue<int>(), 10).ToArray(); I also tried Array.ForEach, but it doesn't work without ref keyword: Queue<int>[] queues = Array.ForEach(queues, queue => queue = new Queue<int>()); any other idea?

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• Showing/Hiding the main form in C#

  - by DazSlayer

  I am working on a program where clicking on a button on form1 will open form2. I will then hide form1 until form2 is closed. The problem I have is that I cannot get form1 to show after form2 closes. Any ideas on how to fix this? try { Form1.ActiveForm.Hide(); AddGradeForm = new Form2(Form.NumberOfSelections); AddGradeForm.ShowDialog(); MessageBox.Show(AddGradeForm.Result.ToString()); } catch (Exception i) { Form1.ActiveForm.Hide(); AddGradeForm.Dispose(); AddGradeForm = new Form2(Form.NumberOfSelections); AddGradeForm.ShowDialog(); MessageBox.Show(AddGradeForm.Result.ToString()); } Form1.ActiveForm.Show(); ERROR: NullReferenceException was unhanded. Object reference not set to an instance of an object.

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• Why is this Python class copying another class contents?

  - by fjfnaranjo

  Hello guys. I'm trying to understand an estrange behavior in Python. I have the next python code: class IntContainer: listOfInts = [] def __init__(self, initListOfInts): for i in initListOfInts: self.listOfInts.append(i) def printInts(self): print self.listOfInts if __name__ == "__main__": intsGroup1 = [1,2,3,4] intsGroup2 = [4,5,6,7] intsGroups = [intsGroup1,intsGroup2] intsContainers = [] for ig in intsGroups: newIntContainer = IntContainer(ig) intsContainers.append(newIntContainer) for ic in intsContainers: print ic.listOfInts I expect to get something like: [1, 2, 3, 4] [4, 5, 6, 7] But i get: [1, 2, 3, 4, 4, 5, 6, 7] [1, 2, 3, 4, 4, 5, 6, 7] I have check the next question: http://stackoverflow.com/questions/1876905/why-is-python-reusing-a-class-instance-inside-in-function And a lot of Python reference, but I can not understand what is happening. I think is related with the newIntContainer identifier reutilization, but I do not understand it deeply. Why Python appears to reused the last reference for the new object, even if I have added it to a permanent list? What can I do to resolve this behavior? Thanks ;)

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• SubSonic Change DropDown Value for Load Drops SUB

  - by GTJR

  I used the subsonic generator to create some aspx pages, It works fine. On some of the pages it automaticaly generated the dropdown boxes for foreign key values. How Can change that value in the load drops code? Or where I need to change it. For instance I have a workers table and a workersweek table. The workers table has a workerid,firstname and lastname field and the workersweek has a workerID field. The generator automatically set it up to show the firstname in the dropdown. I want to change the value to be both firstname and lastname. I am sure I will have to add code that does something like firstname + " " + Lastname. I am just not sure where to do it withing the code that was generated. I see the load drops sub, but it does not seem like that is the one I need to modify.

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• Can't modify XNA Vector components

  - by Matt H

  I have a class called Sprite, and ballSprite is an instance of that class. Sprite has a Vector2 property called Position. I'm trying to increment the Vector's X component like so: ballSprite.Position.X++; but it causes this error: Cannot modify the return value of 'WindowsGame1.Sprite.Position' because it is not a variable Is it not possible to set components like this? The tooltip for the X and Y fields says "Get or set ..." so I can't see why this isn't working.

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• How can I get a Dialog style activity window to fill the screen?

  - by Matthias

  I am using an activity with the dialog theme set, and I want it to be full screen. I tried all sorts of things, even going through the WindowManager to expand the window to full width and height manually, but nothing works. Apparently, a dialog window (or an activity with the dialog theme) will only expand according to its contents, but even that doesn't always work. For instance, I show a progress bar circle which has width and height set to FILL_PARENT (so does its layout container), but still, the dialog wraps around the much smaller progress bar instead of filling the screen. There must be a way of displaying something small inside a dialog window but have it expand to full screen size without its content resizing as well?

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• Initializing a value through a Session variable

  - by William Calleja

  I need to Initialize a value in a Javascript by using a c# literal that makes reference to a Session Variable. I am using the following code <script type="text/javascript" language="javascript" > var myIndex = <%= !((Session["myIndex"]).Equals(null)||(Session["myIndex"]).Equals("")) ? Session["backgroundIndex"] : "1" %>; However the code above is giving me a classic Object reference not set to an instance of an object. error. Why? Shouldn't (Session["myIndex"]).Equals(null) capture this particular error?

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• Creating Pages with unique PageMaps

  - by Michael Krauklis

  I have a wicket Application that has long lived Pages. I would like each instance of this Page to be created with a unique PageMap for reasons I won't get into here, but when I try to specify a PageMap on the constructor of my Page I end up getting OOM and StackOverflow errors. Here is the code: public <CTOR>() { super(Session.get().newPageMap("" + System.currentTimeMillis())); ... I'm using a custom BookmarkablePageLink (custom in that it does not pass on the current PageMap name to the new Page) to effectively abandon the old Page/PageMap and create a new one with a new PageMap. The errors seem to be coming from page serialization after only two or three pages have been created. Can anyone find issue with this approach?

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• WPF: Menu items and combo boxes don't render in Windows 7 64-bit

  - by lilserf

  I'm trying to use an existing internal WPF application (I do have access to the source), but it was developed on XP and I'm using Windows7 64-bit. When I click (for instance) the File menu, 90% of the time I see no drop-down menu at all. The menu still exists - I can use the arrow keys to navigate up and down and choose an option if I happen to know the order of the options, but nothing renders at all. The other 10% of the time, the menu or some portion of it DOES render, but as I move the cursor up and down I get graphical corruption or disappearing options until I end up back at the "no menu is visible at all" state. This is also true of combo boxes within the application - they show no data when I drop them down, but I can arrow down and choose an entry. Microsoft has some advice about WPF rendering issues here but none of these steps has helped with my issue.

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• Factory Method Using Is/As Operator

  - by Swim

  I have factory that looks something like the following snippet. Foo is a wrapper class for Bar and in most cases (but not all), there is a 1:1 mapping. As a rule, Bar cannot know anything about Foo, yet Foo takes an instance of Bar. Is there a better/cleaner approach to doing this? public Foo Make( Bar obj ) { if( obj is Bar1 ) return new Foo1( obj as Bar1 ); if( obj is Bar2 ) return new Foo2( obj as Bar2 ); if( obj is Bar3 ) return new Foo3( obj as Bar3 ); if( obj is Bar4 ) return new Foo3( obj as Bar4 ); // same wrapper as Bar3 throw new ArgumentException(); } At first glance, this question might look like a duplicate (maybe it is), but I haven't seen one exactly like it. Here is one that is close, but not quite: http://stackoverflow.com/questions/242097/factory-based-on-typeof-or-is-a

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• Archiving rows dynamically

  - by Serge

  I was wondering what would be the best solution to dynamically archive rows. For instance when a user marks a task as completed, that task needs to be archived yet still accessible. What would be the best practices for achieving this? Should I just leave it all in the same table and leave out completed tasks from the queries? I'm afraid that over time the table will become huge (1,000,000 rows in a year or less). Or should I create another table ie task_archive and query that row whenever data is needed from it? I know similar questions have been asked before but most of them where about archiving thousands of rows simultaneously, I just need to know what would be the best method (and why) to archive 1 row at a time once it's been marked completed

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• What's the advantage of an Adobe AIR app over a traditional desktop app?

  - by John

  I'm pretty familiar with using Adobe Flex & AS3, and compared with writing apps in JS/HTML I think it's very cool. However, since AIR is essentially a non-browser version of Flex with benefits like local storage, it seems to be competing as a cross-platform desktop application platform... and in that space it's much less mature than more established desktop technologies. So what's the advantage of creating a desktop application using AIR compared to something like Java (or C++ using a cross-platform GUI library like wxWidgets)? Java's equally capable of communicating with the server for instance, I'm not quite sure what AIR adds when competing head-to-head in the desktop development world?

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• Copy one column over another in a delimited file

  - by user275455

  For instance, I needed to remove column 25 and replace it with a copy of column 22 in a simple csv file with no embedded delimiters. The best I could come up with was the awkward looking: awk -F, '{ for(x=1;x<25;x++){printf("%s,", $x)};printf("%s,",$22);for(x=26;x<59;x++){printf ("%s,", $x)};print $59}' I would expect something like cut -d, -f1-24,23,26-59 to work but cut doesn't seem to want to print the same column two times... Is there a more elegant way to do it using anything typicaly available in a linux shell environment?

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• C#: Get key and value types of non-generic IDictionary at runtime

  - by Yang Zou

  there. I am wondering how I can get the key and value types of a non-generic IDictionary at runtime. For generic IDictionary, we can use reflection to get the generic arguments, which has been answered here. But for non-generic IDictionary, for instance, HybridDictionary, how can I get the key and value types? Thanks. Edit: I may not describe my problem properly. For non-generic IDictionary, if I have HyBridDictionary, which is declared as HyBridDictionary dict = new HyBridDictionary(); dict.Add("foo" , 1); dict.Add("bar", 2); How can I find out the type of the key is string and type of the value is int? Did I make the question clear? Thanks.

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• htaccess rewrite; Should I change all relative links or not?

  - by Camran

  I have a rewrite in htaccess which makes this: domain.com/ad.php?ad_id=bmw_m3_328942948 into this: domain.com/ads/bmw_m3_328942948 Problem is the links which are relative to the file wont work... for instance if a link is pointing at '/bin/edit.php' like this originally: domain.com/bin/edit.php // WORKS but after the rewrite the link wants to point here instead: domain.com/ads/bin/edit.php // NOT WORK - NOTE THE /ads/ DOESN'T EXIST IN REALITY Do you understand my issue? What is done about this? Do I have to make ALL links using the newer rewritten format? .htaccess: Options +FollowSymLinks Options +Indexes RewriteEngine On RewriteCond %{REQUEST_URI} !^/ad\.php RewriteRule ^annons/(.*)$ ad.php?ad_id=$1 [NC,L] Thanks

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• How to define a custom iterator in C++

  - by Robert Martin

  I've seen a number of posts on SO about how to define custom iterators, but nothing that seems to exactly answers my question, which is... How do I create an iterator that hides a nested for loop? For instance, I have a class Foo, inside of the Foo is a Bar, and inside of the Bar is a string. I could write for (const Foo& foo : foo_set) for (const Bar& bar : foo.bar_set) if (bar.my_string != "baz") cout << bar.my_string << endl; but instead I want to be able to do something like: for (const string& good : foo_set) cout << good << endl; How do I do something like this?

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• How to make an mutable C array for this data type?

  - by mystify

  There's this instance variable in my objective-c class: ALuint source; I need to have an mutable array of OpenAL Sources, so in this case probably I need a mutable C-array. But how would I create one? There are many questions regarding that: 1) How to create an mutable C-array? 2) How to add something to that mutable C-array? 3) How to remove something from that mutable C-array? 4) What memory management pitfalls must I be aware of? Must i free() it in my -dealloc method? And yes, I think this is something for the nice community wiki...

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• Continuously reading from a stream in C#?

  - by Damien Wildfire

  I have a Stream object that occasionally gets some data on it, but at unpredictable intervals. Messages that appear on the Stream are well-defined and declare the size of their payload in advance (the size is a 16-bit integer contained in the first two bytes of each message). I'd like to have a StreamWatcher class which detects when the Stream has some data on it. Once it does, I'd like an event to be raised so that a subscribed StreamProcessor instance can process the new message. Can this be done with C# events without using Threads directly? It seems like it should be straightforward, but I can't get quite get my head around the right way to design this.

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• need a virtual template member workaround

  - by yurib

  Hello, I need to write a program implementing the visitor design pattern. The problem is that the base visitor class is a template class. This means that BaseVisited::accept() takes a template class as a parameter and since it uses 'this' and i need 'this' to point to the correct runtime instance of the object, it also needs to be virtual. I'd like to know if there's any way around this problem. template <typename T> class BaseVisitor { public: BaseVisitor(); T visit(BaseVisited *visited); virtual ~BaseVisitor(); } class BaseVisited { BaseVisited(); template <typename T> virtual void accept(BaseVisitor<T> *visitor) { visitor->visit(this); }; // problem virtual ~BaseVisited(); }

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• jquery filtering content before specific string

  - by jeff

  Is is possible remove all content before a specific string with jquery? For instance say I wanted to strip all the text before the word "subcommittee" in this example below. How would I do that? With losses mounting among hoteliers, fishermen and others whose livelihoods have been curtailed by the spill, frustration is "rapidly escalating" along the Gulf Coast alive." Linn told a House Energy and Commerce subcommittee Monday that the amount of money BP has paid local residents for their losses has typically been about $5,000, a sum he dismissed as "a marketing ploy." Businesses such as his vacation rental company are borrowing money to pay their overhead costs, which he called "the only way we're going to keep our business alive."

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• MatLab plot part of surface

  - by Kristian

  Say I have the following script: u = -5:.2:5; [X,Y] = meshgrid(u, u); Z = cos(X).*cos(Y).*exp(-sqrt(X.^2 + Y.^2)/4); surf(X,Y,Z); Is there anyway that I can make MatLab plot only parts of the surface? Say, for instance, I just want to plot a single point, or a single grid, what can I do? I thought perhaps to plot a single point I could use: surf(X(1,1), Y(1,1), Z(1,1)) But then I get the error message: ??? Error using ==> surf at 78 Data dimensions must agree. I would really appreciate some input/help here. Thanks in advance :)

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