subclassing

问题 I'm building an iOS app in Swift and drawing on the Lister sample project Apple provides. Lister uses two model objects: List and ListItem. I found that both of them do not call super.init() in their initializers even though they subclass NSObject. However, in the Objective-C version of Lister, both model objects (AAPLList and AAPLListItem) do call [super init] . The Swift Programming Language clearly states that “designated initializers must call a designated initializer from their immediate

问题 I'm trying to subclass an unmanaged statusbar window from my managed COM server using a class inherited from NativeWindow, and am running into a wall trying to make sense of how to properly marshal the contents of an lParam. http://msdn.microsoft.com/en-us/library/bb760757%28VS.85%29.aspx says that the contents of this lParam is of type (LPARAM)(LPINT) aWidths , and that the contents of this variable is actually a "pointer to an integer array." I can't figure out a way to marshal this

问题 As we all know, there are multiple reasons of OutOfMEmoryError (see first answer). Why there is only one exception covering all these cases instead of multiple fine-grained ones inheriting from OutOfMEmoryError ? 回答1: I'd expect because you really can't do anything else when that happens: it almost doesn't matter WHY you ran out, since you're screwed regardless. Perhaps the additional info would be nice, but... I know tomcat tries to do this "Out Of Memory Parachute" thing, where they hold

问题 I'm currently building a tabbed iPhone application where each tab's view controller is an instance of UINavigationController , and where every subcontroller of every one of the UINavigationController instances is an instance of UITableViewController . Ideally, I'd like to subclass UINavigationController so that the controller for each tab is a subclass of UINavigationController that (in addition to having all the standard UINavigationController functionality, obviously) serves as the

问题 This question already has an answer here : Is it possible to overwrite str's % behaviour using __rmod__? (1 answer) Closed 2 years ago . >>> class MyInt(int): ... def __rmod__(self, other): ... return 42 ... >>> class MyStr(str): ... def __rmod__(self, other): ... return 'wat' ... >>> 0 % MyInt() 42 >>> '%r' % MyStr() "''" Why is the int subclass able to control this BinOp from the reflected side, but str can not? This seems to contradict the documented datamodel. I was hoping to use the

问题 I want to check if winproc of a window form was subclassed. Any winapi or spy++ trick to do this? 回答1: you can use next code for determinate is window subclassed by another module (different from module which register window class ) BOOL IsSubclassed(HWND hwnd) { LPARAM pfn = (IsWindowUnicode(hwnd) ? GetWindowLongPtrW : GetWindowLongPtrA) (hwnd, GWLP_WNDPROC); HMODULE hmod; //if (RtlPcToFileHeader(pfn, &hmod)) if (GetModuleHandleExW(GET_MODULE_HANDLE_EX_FLAG_FROM_ADDRESS| GET_MODULE_HANDLE_EX

问题 This question already has answers here : Why callback functions needs to be static when declared in class (6 answers) Closed 3 years ago . I am attempting to write a class to handle the creation of a button and it's messages internally. I wish to keep all of the code contained within the class itself. This may be simple or impossible as I am relatively new to Winapi and C++, having used vb.net much more extensively. I was unable to find an example that accomplished this seeming simple

问题 I've subclassed UIImage to create UIImageExtra. I have a method within UIImageExtra called adjustForResolution that adjusts the size of the UIImage. However I want it to return a UIImageExtra. I understand that I need to convert it but not exactly sure how. Basically, if I resize a UIImageExtra it becomes a UIImage. Here is my UIImageExtra class: #import "UIImageExtra.h" #import <objc/runtime.h> #import "UIApplication+AppDimensions.h" #define kOriginData @"originData" @implementation

问题 I need to make fixed point number class inherit from System.Type. class FixedPoint : Type { public bool Signed { get; set; } public int Width { get; set; } public int IntegerWidth { get; set; } public FixedPoint(Boolean signed = false, int width = 16, int integerWidth = 8) { Signed = signed; Width = width; IntegerWidth = integerWidth; } } When I tried to compile this code, I got error messages saying that I need to implement methods as Type is abstract class. userdef.cs(3,7): error CS0534:

问题 Have a class Car with a public method public Car myself() { return this; } Have a subclass Ferrari , and a variable foo that contains a Ferrari object. Finally, Ferrari bar = foo.myself(); This will warn you, because the method myself() returns a Car object, rather than the expected Ferrari . Note: I know that the example is stupid because you'd just do bar = foo . It's just an example. Solutions: Override the myself() method in Ferrari . Cast the Car object to a Ferrari object when assigning