subclass

iPhone - Use of self = [super init] when [super init] fails

由 家住魔仙堡 提交于 2019-12-07 23:27:28
问题 What is the difference beetween : // 1 -(id) init { self = [super init]; if (self) { ... do init .... } return self; } // 2 - I guess it's exactly the same as previous -(id) init { if (self = [super init]) { ... do init .... } return self; } // 3 - is this one a really bad idea and if yes, Why ? -(id) init { self = [super init]; if (!self) return nil; ... do init .... return self; } // 4 - I think this one sounds OK, no ? But what is returned... nil ? -(id) init { self = [super init]; if (

How to create instances of all subclasses

由 ＊爱你＆永不变心＊ 提交于 2019-12-07 16:30:49
问题 I have over 250 subclasses that need instances made of them, and I can't sit there and coy and paste new Class(); 250 times. Is there anyway using Reflection to make an instnace of the classes? No constructor is needed when making the instance. Thanks. 回答1: I really don't undesrtand you, but I try to guess (not tested): public class Test { public static void main(String[] args) { Class[] classes = new Class[]{Class1.class, Class2.class, Class3.class}; for (Class cls : classes) { Object

Qt Subclassing and “No matching function for call to connect”

由 时光总嘲笑我的痴心妄想 提交于 2019-12-07 14:34:11
问题 I am trying to encapsulate table view behavior and am starting with connecting table view header signals to table view slots defined in the subclass. I can get the behavior I'm looking for without subclassing, but that defeats the purpose. When I do try to subclass, I get the dreaded "No matching function call to connect. All components are ultimately QObjects, so I don't think that's the problem. (But, then again, maybe that IS the problem.) Right now I'm connecting to 'hideColumn()', but I

how does jquery return an array of the selected elements

由 泪湿孤枕 提交于 2019-12-07 13:46:41
问题 I have just seen a google tech talk presented by John Resig where he said jQuery operates as an array. Following that advice I have been playing with a subclassed array and it works great but I have been looking through the jQuery source and can't see that they have used the same method of jQuery.prototype = new Array(); And I can't see it even taking the native Array.prototype.methods with call/apply or in the prototype chain in the window.$ object, so I am wondering how does the jQuery

Is there any reason why we don't use subclasses of UIImageView?

由 為{幸葍}努か 提交于 2019-12-07 13:25:35
问题 I'm currently trying to create a subclass of UIImageView in order to make it download its image from server asynchronously ;) I tried to do it by myself but I haven't gone very far yet :D Anyway, I looked around here and found this : AsyncImageDownload I had a look at the code and the first which springs to mind is : why subclassing a UIView and not a UIImageView ?!? Any thoughts ? Cheers mates, Gotye. 回答1: The reason it is subclassing UIView is so that you should, for example, display a

how do i subclass threading.Event?

由 北慕城南 提交于 2019-12-07 12:25:46
问题 In Python 2.7.5: from threading import Event class State(Event): def __init__(self, name): super(Event, self).__init__() self.name = name def __repr__(self): return self.name + ' / ' + self.is_set() I get: TypeError: Error when calling the metaclass bases function() argument 1 must be code, not str Why? Everything I know about threading.Event I learned from: http://docs.python.org/2/library/threading.html?highlight=threading#event-objects What does it mean when it says that threading.Event()

Custom UIControl subclass with RxSwift

由 那年仲夏 提交于 2019-12-07 11:58:59
问题 I am creating a custom subclass of UIControl (I need to override its draw method) and I want to add RxSwift to bind its isSelected property to my model. So far so good. This works fine. My problem is how can I do to change the value isSelected property in response of user touchUpInside event?. My first try was to use the addTarget method of UIControl, but changing the value of isSelected programmatically is not reported by the ControlProperty (as stated in the doc). But I can figure another

Objective C - Subclassing NSArray

由 心不动则不痛 提交于 2019-12-07 06:30:41
问题 I am trying to subclass NSArray , but it crashes the app when trying to access the count method. I know that NSArray is a class cluster . But what does this mean? Is there a work around to be able to subclass an NSArray? I know that I can simply subclass NSObject and have my array as an instance variable but I would rather subclass NSArray . EDIT: Reason: I am creating a card game, I have a class Deck which should subclass NSMutableArray to have a couple of extra methods ( -shuffle ,

How to add pointer to an NSObject custom subclass to an NSMutableArray?

由 余生颓废 提交于 2019-12-07 02:11:27
For the following code snippet from ViewController.m: - (IBAction)buttonAction:(id)sender { CustomButton *button = (CustomButton *)sender; button.associatedObject = [self.sourceOfObjects.objectArray lastObject]; [self.foo.arrayOfObjects addObject:button.associatedObject]; // this does not work? } • CustomButton is subclass of UIButton and has @property (nonatomic, strong) associatedObject that is a pointer to an object of type NSObject. • sourceOfObjects is a @property (nonatomic, strong) of self of type MyCustomObject, a subclass of NSObject. • objectArray is a @property (nonatomic, strong)

How to “hide” superclass methods in a subclass

由 Deadly 提交于 2019-12-07 01:53:46
问题 I basically want to create a subclass that "hides" methods on the superclass so that they don't show up in a dir() or hasattr() call and the users can't call them (at least not through any of the normal channels). I would also like to do this with the least amount of "magic" possible. Thanks. 回答1: Overriding the __dir__ and __getattribute__ method respectively should do the trick. This is the pretty much the canonical way to do this kind of stuff in Python. Although whether you should be
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