subclass

问题 I'm trying to write a subclass a masked_array . What I've got so far is this: class gridded_array(ma.core.masked_array): def __init__(self, data, dimensions, mask=False, dtype=None, copy=False, subok=True, ndmin=0, fill_value=None, keep_mask=True, hard_mask=None, shrink=True): ma.core.masked_array.__init__(data, mask, dtype, copy, subok, ndmin, fill_value, keep_mask, hard_mask, shrink) self.dimensions = dimensions However, when now I create a gridded_array , I don't get what I expect: dims =

问题 I'm trying to subclass numpy.complex64 in order to make use of the way numpy stores the data, (contiguous, alternating real and imaginary part) but use my own __add__ , __sub__ , ... routines. My problem is that when I make a numpy.ndarray , setting dtype=mysubclass , I get a numpy.ndarray with dtype='numpy.complex64' in stead, which results in numpy not using my own functions for additions, subtractions and so on. Example: import numpy as np class mysubclass(np.complex64): pass a =

问题 I'm trying to subclass numpy.complex64 in order to make use of the way numpy stores the data, (contiguous, alternating real and imaginary part) but use my own __add__ , __sub__ , ... routines. My problem is that when I make a numpy.ndarray , setting dtype=mysubclass , I get a numpy.ndarray with dtype='numpy.complex64' in stead, which results in numpy not using my own functions for additions, subtractions and so on. Example: import numpy as np class mysubclass(np.complex64): pass a =

问题 I want to use a superclass sort which uses a subclass compare function. I've tried to distill the nature of the question in the following code. This isn't the "production" code, but is presented here for illustration. It's tested. #!/usr/bin/perl # $Id: foo,v 1.10 2019/02/23 14:14:33 bennett Exp bennett $ use strict; use warnings; package Fruit; use Scalar::Util 'blessed'; sub new { my $class = shift; my $self = bless({}, $class); $self->{itemList} = []; warn "Called with class ", blessed

问题 Like many others, I would like to perform an action when the 'back' button is used in a UINavigationController. I am aware of some alternative approaches to this, such as adding my own button and trying to spoof the look, using viewWillDisappear and setting tags on all non-back actions that will cause the view do disappear, etc. But the one that I would like to try is subclassing UINavigationController and injecting something in popViewControllerAnimated: But I can't get a simple test case to

问题 I am implementing a custom UIGestureRecognizer subclass. I would like to implement velocityInView: the same way that UIPanGestureRecognizer has done it. But I'm not sure how to go about doing it. How do I calculate the velocity in points / second? 回答1: Firstly, if you're using Swift, you're going to need to create a Bridging Header and #import <UIKit/UIGestureRecognizerSubclass.h> so you can override UIGestureRegoniser 's touches began/moved/cancelled/ended methods. If you're using Objective

问题 This question is in relation to posts at What does 'super' do in Python? , How do I initialize the base (super) class? , and Python: How do I make a subclass from a superclass? which describes two ways to initialize a SuperClass from within a SubClass as class SuperClass: def __init__(self): return def superMethod(self): return ## One version of Initiation class SubClass(SuperClass): def __init__(self): SuperClass.__init__(self) def subMethod(self): return or class SuperClass: def __init__

问题 This question is in relation to posts at What does 'super' do in Python? , How do I initialize the base (super) class? , and Python: How do I make a subclass from a superclass? which describes two ways to initialize a SuperClass from within a SubClass as class SuperClass: def __init__(self): return def superMethod(self): return ## One version of Initiation class SubClass(SuperClass): def __init__(self): SuperClass.__init__(self) def subMethod(self): return or class SuperClass: def __init__

问题 I have two classes: class Bar extends Foo { // Foo isn't relevant constructor(value) { if (!(value instanceof Foo)) throw "InvalidArgumentException: (...)"; super(); this.value = value; } } class Baz extends Bar { constructor(value) { super(value); } } The Bar constructor checks if value is an instance of Foo, it throws an error if it isn't. At least, that's what I wanted it to do. If you pass a Bar or a Baz as value, the if-statement returns true as well. The goal is to only let Foo s

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