subclass

问题 I am having a problem wrapping my brain around the reason for creating a subclass when using threading in python. I've read a number of websites including tutorialspoint. The docs say you need to define a new subclass of the Thread class. I have a basic understanding of classes but haven't played with subclasses at all. I haven't had to do anything like this yet with any other modules I've used like os & ftplib. Can anyone point me to a site that may explain this better for a newbie scripter?

问题 Other than by subclassing (from list for example) how do I make a python object implicitly convertable to ndarray ? Example: import numpy arg=[0,1,2] numpy.dot(arg,arg) # OK, arg is converted to ndarray #Looks somewhat array like, albeit without support for slices class A(object): def __init__(self, x=0,y=1,z=2): (self.x,self.y,self.z)=(x,y,z) def __getitem__(self, idx): if idx==0: return self.x elif idx==1: return self.y elif idx==2: return self.z else: raise IndexError() def __setitem__

问题 Which is generally considered the more preferred method when trying to add a constructor with an additional parameter? A subclass or a wrapper? That being, creating a subclass of the class and then just using that subclass' constructor? Or adding a wrapper method which will take the extra parameter and return an object with that parameter set? Thank you for your time! EDIT: I don't have access to the superclass's code. 回答1: The answer is language dependent. In C#/.NET, you would typically use

问题 I want to handle mouse click in a native MFC application from a C# application. To do so I'm trying to subclass the native application. I don't get any errors, but the wndproc are newer invoked. private const int GwlWndProc = -4; private delegate int Win32WndProc(IntPtr hWnd, int msg, int wParam, int lParam); [DllImport("user32")] private static extern IntPtr SetWindowLong(IntPtr hWnd, int nIndex, Win32WndProc newProc); Win32WndProc _newWndProc = MyWndProc; SetLastError(0); IntPtr oldWndProc

问题 How to get PreferenceScreen line height depend from xml in Preference subclass? public class MyPref extends Preference{ @Override protected void onBindView(View view) { super.onBindView(view); // Here getTop() & getBottom() is 0:0 } } EDIT & ANSWER from: Android: how to get value of "listPreferredItemHeight" attribute in code? value is in float listPreferredItemHeight public class MyPref extends Preference { private float listPreferredItemHeight; @Override protected View onCreateView

问题 I'm trying to build a program that has certain requirements, the main being I have a class, and then make a subclass that adds a feature. I create the class DVD, and then I create the subclass. I'm adding a method to add the year to the list, as well as a restocking fee which will be added to the final inventory value that prints. I built the subclass, created the overriding methods, but it is not being added to the output displayed. Not only that, but it is placing the input year in the

问题 This works: >> class Foo >> def xyz() >> Foo.subclasses >> end >> end => nil >> class Bar < Foo >> end => nil >> class Quux < Bar >> end => nil >> Foo.new.xyz() => ["Quux", "Bar"] But this doesn't. User is a class in my application. >> User.subclasses NoMethodError: protected method `subclasses' called for #<Class:0x20b5188> from [...]/vendor/rails/activerecord/lib/active_record/base.rb:1546:in `method_missing' from (irb):13 But this does! >> Foo.subclasses => ["Quux", "Bar"] What's going on

问题 Added a UIRefreshControl to one of my tableviews here, and just used respondsToSelector on the the tableview controller to see if it has the refreshControl property before configuring and adding the UIRefreshControl using NSClassFromString(). Works perfectly and I can continue supporting iOS 5.1 (just without them getting the new control). However… I want to override the beginRefreshing and endRefreshing methods to dynamically change the tint color of the control. And I figured subclassing

问题 I am trying to create an extremely simple Vector class as a subclass of Array in Smalltalk. My code to create the class looks like this: Array subclass: #Vector Vector comment: 'I represent a Vector of integers' Vector class extend [ new [ | r | <category: 'instance creation'> r := super new. r init. ^r ] ] Vector extend [ init [ <category: 'initialization'> ] ] Obviously I haven't written any methods yet, but I'm just trying to get this part working first. After the class is created as above

问题 I'm trying to subclass an inner class (defined in Java) in Rhino, and I can't seem to make it work. I've got some compiled Java code (which I essentially can't change) that has an inner abstract class: package mypackage; class MyClass { abstract static class MyInnerClass { abstract void print(String s); } } From Rhino, I can see it just fine: js> Packages.mypackage.MyClass.MyInnerClass [JavaClass mypackage.MyClass$MyInnerClass] But I can't figure out how to subclass it. I figured something