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• How do I add multiple joins (Fetches) to a joined table using nhibernate and LINQ ?

  - by ooo

  i have these tables /entities VacationRequestDate table which has a VacationRequestId field that links with VacationRequest table VacationRequest has PersonId and RequestStatusId fields that links with Person and RequestStatus respectively. i have this query so far: IEnumerable<VacationRequestDate> dates = Session.Query<VacationRequestDate>().Fetch(r => r.VacationRequest).ThenFetch(p=>p.RequestStatus).ToList(); this works fine and joins with VacationRequest and then VacationRequest joins with RequestStatus but i can't figure out how to add an additional EAGER join to the VacationRequest table. If i add a Fetch at the end, it refers to the VacationRequestDate table If i add a ThenFetch at the end, it refers to the RequestStatus table I can't find any api that will refer to the VacationRequest table as the reference point. how would you add multiple joins to a joined table using nhibernate LINQ ?

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• How to coerce type of ActiveRecord attribute returned by :select phrase on joined table?

  - by tribalvibes

  Having trouble with AR 2.3.5, e.g.: users = User.all( :select => "u.id, c.user_id", :from => "users u, connections c", :conditions => ... ) Returns, e.g.: => [#<User id: 1000>] >> users.first.attributes => {"id"=>1000, "user_id"=>"1000"} Note that AR returns the id of the model searched as numeric but the selected user_id of the joined model as a String, although both are int(11) in the database schema. How could I better form this type of query to select columns of tables backing multiple models and retrieving their natural type rather than String ? Seems like AR is punting on this somewhere. How could I coerce the returned types at AR load time and not have to tack .to_i (etc.) onto every post-hoc access?

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• Create a UIView Subclass that calls a delegate function whenever it's parent viewController appears?

  - by Andrew Johnson

  UIViewControllers have viewWillAppear, viewDidDisappear, etc. delegate methods. I would like to create a UIView subclass that can be added to a viewController's view, and when that UIViewController apears or disappears, a delegate function is called. I could easily do this by putting function calls in the UIViewController viewWillAppear/viewWillDisappear delegate functions, but how can I encapsulate this behavior in the UIView?

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• Can't install "cedar trail drm driver in DKMS format" on Ubuntu 12.04

  - by Mychal Phillip Segala Sajulga

  Ubuntu 12.04 32bit ... Toshiba NB520 *side-note, this computer is so slow even with a 2gbram; far better than my emachine and neo laptop. I think this is the answer: driver. /var/log/jockey.log 2013-09-19 05:29:36,773 DEBUG: Comparing 3.8.0-29 with 2013-09-19 05:32:45,094 DEBUG: updating <jockey.detection.LocalKernelModulesDriverDB instance at 0x8427a0c> 2013-09-19 05:32:50,861 DEBUG: reading modalias file /lib/modules/3.8.0-29-generic/modules.alias 2013-09-19 05:32:56,240 DEBUG: reading modalias file /usr/share/jockey/modaliases/b43 2013-09-19 05:32:56,265 DEBUG: reading modalias file /usr/share/jockey/modaliases/disable-upstream-nvidia 2013-09-19 05:32:56,474 DEBUG: loading custom handler /usr/share/jockey/handlers/dvb_usb_firmware.py 2013-09-19 05:32:56,791 DEBUG: Instantiated Handler subclass __builtin__.DvbUsbFirmwareHandler from name DvbUsbFirmwareHandler 2013-09-19 05:32:56,792 DEBUG: Firmware for DVB cards not available 2013-09-19 05:32:56,793 DEBUG: loading custom handler /usr/share/jockey/handlers/cdv.py 2013-09-19 05:32:56,927 WARNING: modinfo for module cedarview_gfx failed: ERROR: modinfo: could not find module cedarview_gfx 2013-09-19 05:32:58,213 DEBUG: linux-lts-raring installed: True linux-lts-saucy installed: False linux minor version: 8 xserver ABI: 13 xserver-lts-quantal: False 2013-09-19 05:32:58,214 DEBUG: Instantiated Handler subclass __builtin__.CdvDriver from name CdvDriver 2013-09-19 05:32:58,214 DEBUG: cdv.available: falling back to default 2013-09-19 05:32:58,685 DEBUG: XorgDriverHandler(cedarview_gfx, cedarview-graphics-drivers, None): Disabling as package video ABI(s) xorg-video-abi-11 not compatible with X.org video ABI xorg-video-abi-13 2013-09-19 05:32:58,686 DEBUG: Intel Cedarview graphics driver not available 2013-09-19 05:32:58,687 DEBUG: loading custom handler /usr/share/jockey/handlers/vmware-client.py 2013-09-19 05:32:58,716 WARNING: modinfo for module vmxnet failed: ERROR: modinfo: could not find module vmxnet 2013-09-19 05:32:58,717 DEBUG: Instantiated Handler subclass __builtin__.VmwareClientHandler from name VmwareClientHandler 2013-09-19 05:32:58,758 DEBUG: VMWare Client Tools availability undetermined, adding to pool 2013-09-19 05:32:58,758 DEBUG: loading custom handler /usr/share/jockey/handlers/nvidia.py 2013-09-19 05:32:58,826 WARNING: modinfo for module nvidia_304 failed: ERROR: modinfo: could not find module nvidia_304 2013-09-19 05:32:58,836 DEBUG: Instantiated Handler subclass __builtin__.NvidiaDriver304 from name NvidiaDriver304 2013-09-19 05:32:58,837 DEBUG: nvidia.available: falling back to default 2013-09-19 05:33:11,682 DEBUG: NVIDIA accelerated graphics driver availability undetermined, adding to pool 2013-09-19 05:33:11,688 WARNING: modinfo for module nvidia_304_updates failed: ERROR: modinfo: could not find module nvidia_304_updates 2013-09-19 05:33:11,696 DEBUG: Instantiated Handler subclass __builtin__.NvidiaDriver304Updates from name NvidiaDriver304Updates 2013-09-19 05:33:11,696 DEBUG: nvidia.available: falling back to default 2013-09-19 05:33:24,326 DEBUG: NVIDIA accelerated graphics driver (post-release updates) availability undetermined, adding to pool 2013-09-19 05:33:24,332 WARNING: modinfo for module nvidia_current_updates failed: ERROR: modinfo: could not find module nvidia_current_updates 2013-09-19 05:33:24,339 DEBUG: Instantiated Handler subclass __builtin__.NvidiaDriverCurrentUpdates from name NvidiaDriverCurrentUpdates 2013-09-19 05:33:24,340 DEBUG: nvidia.available: falling back to default 2013-09-19 05:33:24,381 DEBUG: NVIDIA accelerated graphics driver (post-release updates) not available 2013-09-19 05:33:24,387 WARNING: modinfo for module nvidia_experimental_304 failed: ERROR: modinfo: could not find module nvidia_experimental_304 2013-09-19 05:33:24,427 DEBUG: Instantiated Handler subclass __builtin__.NvidiaDriverExperimental304 from name NvidiaDriverExperimental304 2013-09-19 05:33:24,427 DEBUG: nvidia.available: falling back to default 2013-09-19 05:33:24,461 DEBUG: NVIDIA accelerated graphics driver (**experimental** beta) not available 2013-09-19 05:33:24,467 WARNING: modinfo for module nvidia_current failed: ERROR: modinfo: could not find module nvidia_current

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• Is it possible to make a subclass of NSObject which support subnodes in IB for iPhone project?

  - by Eonil

  I'm making a custom UI element class for iPhone. It'll cool to edit my class on Interface Builder with hierarchy. Some of my class is management class like UINavigationController, but they're not one of them, subclasses from NSObject. Of course, I can place a NSObject instance on IB, but it cannot have a child node. Is there a way to enable adding child node to subclass of NSObject?

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• Cheese won't start

  - by Anthony Hohenheim

  I can't start Cheese Webcam Booth. It starts loading and there is a brief moment when the window shows up but then it disappears, like it shuts itself down and it's not in system monitor. My webcam works perfectly in Skype video call. I installed and run Camorama and it gave me an error: Could not connect to video device (/dev/video0) Please check connection When I run the lsusb I get this line for my webcam: Bus 002 Device 002: ID 04f2:b210 Chicony Electronics Co., Ltd And for my graphic card, running lspci: VGA compatible controller: Intel Corporation Mobile 4 Series Chipset Integrated Graphics Controller (rev 07) It's not a pressing matter, but it bugs my nerves, if it works on Skype, why does Cheese and other programs refuse to run. As I said, it's not a big deal but any help would be appreciated. Running Cheese in terminal: (cheese:11454): Gtk-WARNING **: Attempting to add a widget with type GtkImage to a GtkToggleButton, but as a GtkBin subclass a GtkToggleButton can only contain one widget at a time; it already contains a widget of type GtkLabel (cheese:11454): Gtk-WARNING **: Attempting to add a widget with type GtkImage to a GtkToggleButton, but as a GtkBin subclass a GtkToggleButton can only contain one widget at a time; it already contains a widget of type GtkLabel (cheese:11454): Gtk-WARNING **: Attempting to add a widget with type GtkImage to a GtkToggleButton, but as a GtkBin subclass a GtkToggleButton can only contain one widget at a time; it already contains a widget of type GtkLabel (cheese:11454): Gtk-WARNING **: Attempting to add a widget with type GtkHBox to a GtkButton, but as a GtkBin subclass a GtkButton can only contain one widget at a time; it already contains a widget of type GtkLabel (cheese:11454): Gtk-WARNING **: Attempting to add a widget with type GtkImage to a GtkButton, but as a GtkBin subclass a GtkButton can only contain one widget at a time; it already contains a widget of type GtkLabel (cheese:11454): Gtk-WARNING **: Attempting to add a widget with type GtkHBox to a GtkToggleButton, but as a GtkBin subclass a GtkToggleButton can only contain one widget at a time; it already contains a widget of type GtkLabel (cheese:11454): Gtk-WARNING **: Attempting to add a widget with type GtkImage to a GtkButton, but as a GtkBin subclass a GtkButton can only contain one widget at a time; it already contains a widget of type GtkLabel (cheese:11454): Gdk-WARNING **: The program 'cheese' received an X Window System error. This probably reflects a bug in the program. The error was 'BadDrawable (invalid Pixmap or Window parameter)'. (Details: serial 932 error_code 9 request_code 137 minor_code 9) (Note to programmers: normally, X errors are reported asynchronously; that is, you will receive the error a while after causing it. To debug your program, run it with the --sync command line option to change this behavior. You can then get a meaningful backtrace from your debugger if you break on the gdk_x_error() function.)

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• GHC.Generics and Type Families

  - by jberryman

  This is a question related to my module here, and is simplified a bit. It's also related to this previous question, in which I oversimplified my problem and didn't get the answer I was looking for. I hope this isn't too specific, and please change the title if you can think if a better one. Background My module uses a concurrent chan, split into a read side and write side. I use a special class with an associated type synonym to support polymorphic channel "joins": {-# LANGUAGE TypeFamilies #-} class Sources s where type Joined s newJoinedChan :: IO (s, Messages (Joined s)) -- NOT EXPORTED --output and input sides of channel: data Messages a -- NOT EXPORTED data Mailbox a instance Sources (Mailbox a) where type Joined (Mailbox a) = a newJoinedChan = undefined instance (Sources a, Sources b)=> Sources (a,b) where type Joined (a,b) = (Joined a, Joined b) newJoinedChan = undefined -- and so on for tuples of 3,4,5... The code above allows us to do this kind of thing: example = do (mb , msgsA) <- newJoinedChan ((mb1, mb2), msgsB) <- newJoinedChan --say that: msgsA, msgsB :: Messages (Int,Int) --and: mb :: Mailbox (Int,Int) -- mb1,mb2 :: Mailbox Int We have a recursive action called a Behavior that we can run on the messages we pull out of the "read" end of the channel: newtype Behavior a = Behavior (a -> IO (Behavior a)) runBehaviorOn :: Behavior a -> Messages a -> IO () -- NOT EXPORTED This would allow us to run a Behavior (Int,Int) on either of msgsA or msgsB, where in the second case both Ints in the tuple it receives actually came through separate Mailboxes. This is all tied together for the user in the exposed spawn function spawn :: (Sources s) => Behavior (Joined s) -> IO s ...which calls newJoinedChan and runBehaviorOn, and returns the input Sources. What I'd like to do I'd like users to be able to create a Behavior of arbitrary product type (not just tuples) , so for instance we could run a Behavior (Pair Int Int) on the example Messages above. I'd like to do this with GHC.Generics while still having a polymorphic Sources, but can't manage to make it work. spawn :: (Sources s, Generic (Joined s), Rep (Joined s) ~ ??) => Behavior (Joined s) -> IO s The parts of the above example that are actually exposed in the API are the fst of the newJoinedChan action, and Behaviors, so an acceptable solution can modify one or all of runBehaviorOn or the snd of newJoinedChan. I'll also be extending the API above to support sums (not implemented yet) like Behavior (Either a b) so I hoped GHC.Generics would work for me. Questions Is there a way I can extend the API above to support arbitrary Generic a=> Behavior a? If not using GHC's Generics, are there other ways I can get the API I want with minimal end-user pain (i.e. they just have to add a deriving clause to their type)?

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• Why would it be necessary to subclass from object in Python?

  - by rmh

  I've been using Python for quite a while now, and I'm still unsure as to why you would subclass from object. What is the difference between this: class MyClass(): pass And this: class MyClass(object): pass As far as I understand, object is the base class for all classes and the subclassing is implied. Do you get anything from explicitly subclassing from it? What is the most "Pythonic" thing to do?

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• Subclassing Cocoa means no subclass ivars in some cases?

  - by Michael

  The question is generally coming from self = [super init]. In case if I'm subclassing NSSomething and in my init's method self = [super init] returns object of different class, does it mean I am not able to have my very own ivars in my subclass, just because self will be pointing to different class? Appreciate if you could bring some examples if my statement is wrong.

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• AS3 - Can I know if a class implements an interface (or is a subclass of another class) ?

  - by lk

  With this code function someFunction(classParam:Class):Boolean { // how to know if classParam implements some interface? } i.e. Comparing classParam with IEventDispatcher interface: someFunction(EventDispatcher) // returns true someFunction(Object) // returns false I know it can't be done with is operator. But, is there a way to do it? Is there a way to know if a class implements some interface? (or is a subclass of another class?)

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• Can I set up Samba shares that are authenticated against a domain *without* being joined to a domain

  - by arathorn

  I'd like to create a Samba server with some shares that have access controlled via accounts on the domain, but without joining the machine to the domain? Is this possible?

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• Does query plan optimizer works well with joined/filtered table-valued functions?

  - by smoothdeveloper

  In SQLSERVER 2005, I'm using table-valued function as a convenient way to perform arbitrary aggregation on subset data from large table (passing date range or such parameters). I'm using theses inside larger queries as joined computations and I'm wondering if the query plan optimizer work well with them in every condition or if I'm better to unnest such computation in my larger queries. Does query plan optimizer unnest table-valued functions if it make sense? If it doesn't, what do you recommend to avoid code duplication that would occur by manually unnesting them? If it does, how do you identify that from the execution plan? code sample: create table dbo.customers ( [key] uniqueidentifier , constraint pk_dbo_customers primary key ([key]) ) go /* assume large amount of data */ create table dbo.point_of_sales ( [key] uniqueidentifier , customer_key uniqueidentifier , constraint pk_dbo_point_of_sales primary key ([key]) ) go create table dbo.product_ranges ( [key] uniqueidentifier , constraint pk_dbo_product_ranges primary key ([key]) ) go create table dbo.products ( [key] uniqueidentifier , product_range_key uniqueidentifier , release_date datetime , constraint pk_dbo_products primary key ([key]) , constraint fk_dbo_products_product_range_key foreign key (product_range_key) references dbo.product_ranges ([key]) ) go . /* assume large amount of data */ create table dbo.sales_history ( [key] uniqueidentifier , product_key uniqueidentifier , point_of_sale_key uniqueidentifier , accounting_date datetime , amount money , quantity int , constraint pk_dbo_sales_history primary key ([key]) , constraint fk_dbo_sales_history_product_key foreign key (product_key) references dbo.products ([key]) , constraint fk_dbo_sales_history_point_of_sale_key foreign key (point_of_sale_key) references dbo.point_of_sales ([key]) ) go create function dbo.f_sales_history_..snip.._date_range ( @accountingdatelowerbound datetime, @accountingdateupperbound datetime ) returns table as return ( select pos.customer_key , sh.product_key , sum(sh.amount) amount , sum(sh.quantity) quantity from dbo.point_of_sales pos inner join dbo.sales_history sh on sh.point_of_sale_key = pos.[key] where sh.accounting_date between @accountingdatelowerbound and @accountingdateupperbound group by pos.customer_key , sh.product_key ) go -- TODO: insert some data -- this is a table containing a selection of product ranges declare @selectedproductranges table([key] uniqueidentifier) -- this is a table containing a selection of customers declare @selectedcustomers table([key] uniqueidentifier) declare @low datetime , @up datetime -- TODO: set top query parameters . select saleshistory.customer_key , saleshistory.product_key , saleshistory.amount , saleshistory.quantity from dbo.products p inner join @selectedproductranges productrangeselection on p.product_range_key = productrangeselection.[key] inner join @selectedcustomers customerselection on 1 = 1 inner join dbo.f_sales_history_..snip.._date_range(@low, @up) saleshistory on saleshistory.product_key = p.[key] and saleshistory.customer_key = customerselection.[key] I hope the sample makes sense. Much thanks for your help!

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• Rails nested attributes with a join model, where one of the models being joined is a new record

  - by gzuki

  I'm trying to build a grid, in rails, for entering data. It has rows and columns, and rows and columns are joined by cells. In my view, I need for the grid to be able to handle having 'new' rows and columns on the edge, so that if you type in them and then submit, they are automatically generated, and their shared cells are connected to them correctly. I want to be able to do this without JS. Rails nested attributes fail to handle being mapped to both a new record and a new column, they can only do one or the other. The reason is that they are a nested specifically in one of the two models, and whichever one they aren't nested in will have no id (since it doesn't exist yet), and when pushed through accepts_nested_attributes_for on the top level Grid model, they will only be bound to the new object created for whatever they were nested in. How can I handle this? Do I have to override rails handling of nested attributes? My models look like this, btw: class Grid < ActiveRecord::Base has_many :rows has_many :columns has_many :cells, :through => :rows accepts_nested_attributes_for :rows, :allow_destroy => true, :reject_if => lambda {|a| a[:description].blank? } accepts_nested_attributes_for :columns, :allow_destroy => true, :reject_if => lambda {|a| a[:description].blank? } end class Column < ActiveRecord::Base belongs_to :grid has_many :cells, :dependent => :destroy has_many :rows, :through => :grid end class Row < ActiveRecord::Base belongs_to :grid has_many :cells, :dependent => :destroy has_many :columns, :through => :grid accepts_nested_attributes_for :cells end class Cell < ActiveRecord::Base belongs_to :row belongs_to :column has_one :grid, :through => :row end

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• How to intercept UIScrollView contentOffset changes from UITableView subclass?

  - by mystify

  Actually, a UITableView is a UIScrollView (inherits from that). Now, I made a UITableView subclass and added this line of code to it: - (void)scrollViewDidScroll:(UIScrollView *)scrollView { NSLog(@"contentOffset: %@", NSStringFromCGPoint(self.contentOffset)); } For some reason this is never called when I scroll the table view. But since UITableView has a delegate property on it's own, I assume that it must implement UIScrollViewDelegate protocol and is the delegate for the scroll view itself. Isn't it? How could I intercept scroll position changes? I want to read them only. Probably I couldn't set them with contentOffset, right?

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• Why can I not receive touch events within my custom UIScrollView subclass?

  - by stefanosn

  i have an uiscrollview with a uiimageview inside. I subclass the uiscrollview but i can not get touches to work touchbegin does not called. What should i do to call uitouch event? what is wrong? .h #import <UIKit/UIKit.h> @interface myScrollView : UIScrollView { } @end .m #import "myScrollView.h" @implementation myScrollView - (void) touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event { UITouch *touch = [[event allTouches] anyObject]; CGPoint location = [touch locationInView:touch.view]; if (touch.view.tag > 0) { touch.view.center = location; } NSLog(@"tag=%@", [NSString stringWithFormat:@"%i", touch.view.tag]); }

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• How do I MOVE a circle drawn in a subclass of UIView by overwriting the method "drawRect"??

  - by Christoph v

  hi, I'm trying to figure out what i'm doing wrong but i just don't get it. Here is what i want to do: I want to draw a circle somewhere on the screen of the iphone and then i want the circle always to be displayed at the position where the user currently taps on the screen. I started by creating a subclass of UIView and adding the following lines into the "drawRect" method: - (void)drawRect:(CGRect)rect { //Create the main view! CGContextRef mainscreen = UIGraphicsGetCurrentContext(); //Draw the dot //will be a circle cause rectangle is a square CGRect dotRect = CGRectMake(50, 80, 100, 100); [[UIColor blueColor] set]; CGContextStrokeEllipseInRect(mainscreen, dotRect); CGContextFillEllipseInRect(mainscreen, dotRect); } The appears just fine but now i have no idea how to make it move around on the screen i've tried serveral things and nothing worked pls help!

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• UIView subclass draws background despite completely empty drawRect: - why?

  - by Pascal

  So, I have a custom UIView subclass which enables drawing of rounded edges. The thing draws perfectly, however the background always fills the whole bounds, despite clipping to a path first. The border also draws above the rectangular background, despite the fact that I draw the border in drawRect: before the background. So I removed the whole content of drawRect:, which is now virtually empty - nevertheless the background gets drawn! Anybody an explanation for this? I set the backgroundColor in Interface Builder. Thanks!

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• How to retrieve stored reference to an NSManagedObject subclass?

  - by DavidDev

  Hi! I have a NSManagedObject subclass named Tour. I stored the reference to it using this code: prefs = [NSUserDefaults standardUserDefaults]; NSURL *myURL = [[myTour objectID] URIRepresentation]; NSData *uriData = [NSKeyedArchiver archivedDataWithRootObject:myURL]; [prefs setObject:uriData forKey:@"tour"]; Now I want to retrieve it. I tried using: NSData *myData = [prefs objectForKey:@"tour"]; NSURL *myURL = [NSKeyedUnarchiver unarchiveObjectWithData:myData]; TourAppDelegate *appDelegate = (TourAppDelegate *)[[UIApplication sharedApplication] delegate]; NSManagedObjectID *myID = [appDelegate.persistentStoreCoordinator managedObjectIDForURIRepresentation:myURL]; if (myID) { Tour *tempObject = [appDelegate.managedObjectContext objectWithID:myID]; //WARNING tour = tempObject; } if (tour) //instruction... But it's giving me this warning "Incompatible Objective-c types. Initializing 'struct NSManagedObject *', expected 'struct Tour *' Plus, when executing, it's giving me this: Terminating app due to uncaught exception 'NSObjectInaccessibleException', reason: 'CoreData could not fulfill a fault for '0x5001eb0 How can I solve this?

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• How do I refer to a view controller in a subclass?

  - by thekevinscott

  Hey all, I'm currently teaching myself Objective C and I'm kind of stuck. I'm building a backgammon game and I have a subclass, "Piece", which is being initialized, repeatedly, in BackGammonViewController. In BackGammonViewController, if I do this: UIImage *myImage = [ UIImage imageNamed: @"white-piece.png" ]; UIImageView *myImageView = [ [ UIImageView alloc ] initWithImage: myImage ]; [self.view addSubview:myImageView]; [myImageView release]; The image appears. However, I want to do this within my "piece" class. How do I refer to the "self.view" from within the piece class? Do I need to pass a reference to the view, into the "piece class" ? Or is there a global reference I can call from within the "piece class" ? Thanks for your help.

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• How can I access IEnumerable<T> extension methods on my custom subclass of BindingList<T>?

  - by Dan

  I have a custom subclass of BindingList<T> that I want to execute a LINQ query over using the handy extension methods. For example: public int GetSum(MyList<T> list) { return list.Sum(x => x.Value); } But the compiler complains that it can't resolve Sum because it doesn't recognize list as an IEnumerable<T>, which it obviously is, because this works: public int GetSum(MyList<T> list) { return ((IEnumerable<T>)list).Sum(x => x.Value); } Anyone have a clever way I can avoid the ugly and unecessary cast?

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• Is it good to subclass a class only to separate some functional parts?

  - by prostynick

  Suppose we have abstract class A (all examples in C#) public abstract class A { private Foo foo; public A() { } public void DoSomethingUsingFoo() { //stuff } public void DoSomethingElseUsingFoo() { //stuff } //a lot of other stuff... } But we are able to split it into two classes A and B: public abstract class A { public A() { } //a lot of stuff... } public abstract class B : A { private Foo foo; public B() : base() { } public void DoSomethingUsingFoo() { //stuff } public void DoSomethingElseUsingFoo() { //stuff } //nothing else or just some overrides of A stuff } That's good, but we are 99.99% sure, that no one will ever subclass A, because functionality in B is very important. Is it still good to have two separate classes only to split some code into two parts and to separate functional elements?

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• How do I change the class of an object to a subclass of its current class in C++?

  - by Jared P

  I have an array of pointers to a base class, so that I can make those pointers point to (different) subclasses of the base class, but still interact with them. (really only a couple of methods which I made virtual and overloaded) I'm wondering if I can avoid using the pointers, and instead just make an array of the base class, but have some way to set the class to the subclass of my choosing. I know there must be something there specifying the class, as it needs to use that to look up the function pointer for virtual methods. By the way, the subclasses all have the same ivars and layout. Note: the design is actually based on using a template argument instead of a variable, due to performance increases, so really the abstract base class is just the interface for the subclasses, which are all the same except for their compiled code. Thanks

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• Storage model for various user setting and attributes in database?

  - by dvd

  I'm currently trying to upgrade a user management system for one web application. This web application is used to provide remote access to various networking equipment for educational purposes. All equipment is assigned to various pods, which users can book for periods of time. The current system is very simple - just 2 user types: administrators and students. All their security and other attributes are mostly hardcoded. I want to change this to something like the following model: user <-- (1..n)profile <--- (1..n) attributes. I.e. user can be assigned several profiles and each profile can have multiple attributes. At runtime all profiles and attributes are merged into single active profile. Some examples of attributes i'm planning to implement: EXPIRATION_DATE - single value, value type: date, specifies when user account will expire; ACCESS_POD - single value, value type: ref to object of Pod class, specifies which pod the user is allowed to book, user profile can have multiple such attributes with different values; TIME_QUOTA - single value, value type: integer, specifies maximum length of time for which student can reserve equipment. CREDIT_CHARGING - multi valued, specifies how much credits will be assigned to user over period of time. (Reservation of devices will cost credits, which will regenerate over time); Security permissions and user preferences can end up as profile or user attributes too: i.e CAN_CREATE_USERS, CAN_POST_NEWS, CAN_EDIT_DEVICES, FONT_SIZE, etc.. This way i could have, for example: students of course A will have profiles STUDENT (with basic attributes) and PROFILE A (wich grants acces to pod A). Students of course B will have profiles: STUDENT, PROFILE B(wich grants to pod B and have increased time quotas). I'm using Spring and Hibernate frameworks for this application and MySQL for database. For this web application i would like to stay within boundaries of these tools. The problem is, that i can't figure out how to best represent all these attributes in database. I also want to create some kind of unified way of retrieveing these attributes and their values. Here is the model i've come up with. Base classes. public abstract class Attribute{ private Long id; Attribute() {} abstract public String getName(); public Long getId() {return id; } void setId(Long id) {this.id = id;} } public abstract class SimpleAttribute extends Attribute{ public abstract Serializable getValue(); abstract void setValue(Serializable s); @Override public boolean equals(Object obj) { ... } @Override public int hashCode() { ... } } Simple attributes can have only one value of any type (including object and enum). Here are more specific attributes: public abstract class IntAttribute extends SimpleAttribute { private Integer value; public Integer getValue() { return value; } void setValue(Integer value) { this.value = value;} void setValue(Serializable s) { setValue((Integer)s); } } public class MaxOrdersAttribute extends IntAttribute { public String getName() { return "Maximum outstanding orders"; } } public final class CreditRateAttribute extends IntAttribute { public String getName() { return "Credit Regeneration Rate"; } } All attributes stored stored using Hibenate variant "table per class hierarchy". Mapping: <class name="ru.mirea.rea.model.abac.Attribute" table="ATTRIBUTES" abstract="true" > <id name="id" column="id"> <generator class="increment" /> </id> <discriminator column="attributeType" type="string"/> <subclass name="ru.mirea.rea.model.abac.SimpleAttribute" abstract="true"> <subclass name="ru.mirea.rea.model.abac.IntAttribute" abstract="true" > <property name="value" column="intVal" type="integer"/> <subclass name="ru.mirea.rea.model.abac.CreditRateAttribute" discriminator-value="CreditRate" /> <subclass name="ru.mirea.rea.model.abac.MaxOrdersAttribute" discriminator-value="MaxOrders" /> </subclass> <subclass name="ru.mirea.rea.model.abac.DateAttribute" abstract="true" > <property name="value" column="dateVal" type="timestamp"/> <subclass name="ru.mirea.rea.model.abac.ExpirationDateAttribute" discriminator-value="ExpirationDate" /> </subclass> <subclass name="ru.mirea.rea.model.abac.PodAttribute" abstract="true" > <many-to-one name="value" column="podVal" class="ru.mirea.rea.model.pods.Pod"/> <subclass name="ru.mirea.rea.model.abac.PodAccessAttribute" discriminator-value="PodAccess" lazy="false"/> </subclass> <subclass name="ru.mirea.rea.model.abac.SecurityPermissionAttribute" discriminator-value="SecurityPermission" lazy="false"> <property name="value" column="spVal" type="ru.mirea.rea.db.hibernate.customTypes.SecurityPermissionType"/> </subclass> </subclass> </class> SecurityPermissionAttribute uses enumeration of various permissions as it's value. Several types of attributes imlement GrantedAuthority interface and can be used with Spring Security for authentication and authorization. Attributes can be created like this: public final class AttributeManager { public <T extends SimpleAttribute> T createSimpleAttribute(Class<T> c, Serializable value) { Session session = HibernateUtil.getCurrentSession(); T att = null; ... att = c.newInstance(); att.setValue(value); session.save(att); session.flush(); ... return att; } public <T extends SimpleAttribute> List<T> findSimpleAttributes(Class<T> c) { List<T> result = new ArrayList<T>(); Session session = HibernateUtil.getCurrentSession(); List<T> temp = session.createCriteria(c).list(); result.addAll(temp); return result; } } And retrieved through User Profiles to which they are assigned. I do not expect that there would be very large amount of rows in the ATTRIBUTES table, but are there any serious drawbacks of such design?

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• How to get NSFormatter subclass to work with NSTableColumn sort key and selector?

  - by Andrew

  My setup: I have a sqlite database from which I populate a NSMutableArray of NSDictionary objects this is the DataSource for my NSTableView. One of the columns holds "time", the time is a float that holds seconds. I would like to display the values in this column as minutes:seconds. For instance my data would be 123.4329387 I want to display 2:03 which I have no problem doing with a subclass of NSFormatter (or NSNumberFormatter) applied to my NSTextField in the column. I have sorting set up by using the Table Column Attributes in IB, I just have the sort key set to "time" and the selector set to "compare:" which works fine without the formatter. Currently this gives me something like this when I sort (descending) 1:37, 1:31, 0:10, 0:10, 0:09, 1:30, 1:30, 1:26, 0:09 and similar nonsense, it looks like something is going on but it's definitely not sorted. How do I get the sort to look at the underlying data instead of the formatted value? Alternately, how do I specify a custom sort method and where do I put the code for said method? I have searched around quite a bit and have not found anything to help me out with this problem, any help with this is most appreciated.

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• How to copy generically superclass instances to subclass instances?

  - by gerry

  Hi @all, I have a class hierarchy / inheritance like this: public class A { private String name; // with getters & setters public void doAWithName(){ ... } } public class B extends A { public void doBWithName(){ // a differnt implementation to what I do in class A } } public class C extends B { public void doCWithName(){ // a differnt implementation to what I do in class A and B } } So at one time there is a instance of class A with the initialized field "name". Later I want this instance of A get wrapped into instance of B or C. So the superclasses should be get wrapped with a subclass! How can I make this most efficent with respect to DRY? I've thought about a constructor that does some copying with the getters/setters. But in this case I have to repeat myself - and this doesn't respect anymore to my initial requirement of DRY! So, how can I warp A to B by just initializing B's new fields (with default values) and delegating the rest to a method in A (which knows more than B about which fields of A should be accessed...). In the same way: If A should be wrapped into C only a method in c should init C's 'new' fields, delegate to B's wrap method (which therefore inits B's 'new' fields in C) and at last B delegates to A which copies it's fields to the fields of C). So in the end I have a new instance of C which has the values of A wrapped (and some default init values to the fields which the inheritance hierarchy has added).

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