methods

问题 Given a class C with a function or method f , I use inspect.ismethod(obj.f) (where obj is an instance of C ) to find out if f is bound method or not. Is there a way to do the same directly at the class level (without creating an object)? inspect.ismethod does not work as this: class C(object): @staticmethod def st(x): pass def me(self): pass obj = C() results in this (in Python 3): >>> inspect.ismethod(C.st) False >>> inspect.ismethod(C.me) False >>> inspect.ismethod(obj.st) False >>> inspect

问题 I would like to make the log function a generic so that I can alter it's behavior under some newclass . I have a minimal package with a DESCRIPTION file: Package: logmethod Type: Package Title: A new Log Method Version: 0.1 Date: 2017-03-23 Author: Me Maintainer: Who to complain to <yourfault@somewhere.net> Description: More about what it does (maybe more than one line) License: MIT LazyData: TRUE RoxygenNote: 5.0.1 And the R Code, based on what I've learned at Writing R Extensions and Is it

问题 Consider the snippet: def check_conditions(range_of_numbers): #method returns a list containing messages list1 = [] if condition1: list1.append("message1") if condition2: list1.append("message2") if condition3: list1.append("message3") try: for i in range_of_numbers: int(i) except ValueError: list1.append("message4") return message I want to have a list in the with messages only if the conditions were satisfied. I do not use multiple if's since it adds on to the code complexity and every time

问题 I'm looking for a way to 'chain class methods', for example the Range object can do things like "Range.Borders.Color", I guess that the Borders part is it's own class which is being accessed by the Range class but I have no idea how to implement something similar with my own classes - Nor do I even know what this is called and after hours of searching I think I might slowly be un-learning VBA. Can anybody either a) Provide code which I could look at to replicate or b) Tell me what this is

问题 This is quite difficult to phrase, but I need to be able to link a specific method to an object. More specifically, I'm making a graphics-oriented GUI, and I want to be able to assign an arbitrary method as the default "action" function for an element, such as a button. That is, I created these interfaced "graphics" objects that basically have the ability to draw themselves. I would like them to handle their own actions, so I can, for example, do something like this: GraphicObject b1 = new

问题 Here is an example which creates a point as p=Point(x, y) . Assume that I have some array ppp=(x, y) where x and y are numbers and I want to make it of class Point but in the way: p=Point(ppp) . I can do either one or another way but not both simultaneously. Is it possible to have both ways? 回答1: If you know that you have a tuple/list while creating the instance, you can do: p = Point(*ppp) , where ppp is the tuple. 回答2: There are two different ways to acquire the result, the first is to

问题 I'm a beginner at java and want to make a JFrame with tabs containing a seperate JPanel. One panel has a list where it displays things that you select in a different panel, so I want this panel to always display a list of stuff that you have selected in a different panel (I hope that makes sense). To do this, I need to make a method to refresh the JList. This is the Farthest that I've gotten on that: public class PanelClass extends JPanel { private JList list; private DefaultListModel

问题 I have been trying to figure out how calculate the area and volume based on the input obtain from the Scanner Class. The exercise consist of receiving multiple pair of radius and height at once. I have written the methods and tested them, so those should be working. The problem I am having is when I want to use inputs from 'Scanner' and use them to make the calculations. Here is my code (I did not include the methods): Scanner keyboard = new Scanner(System.in); int radius = 0; int height = 0;

问题 I'm working with the basics of Java reflection and observing information on methods of classes. I need to get a method that matches specifications as described by the getMethod() function. However, when I do this I get a NoSuchMethodException, and I was hoping you could tell me why my implementation is incorrect. static void methodInfo2(String className) throws ClassNotFoundException, NoSuchMethodException{ Class cls = null; try{ cls = Class.forName(className); } catch(ClassNotFoundException

问题 I have a method which is supposed to do something and the return value is a boolean (success/failure). If the method fails, there are a few reasons causing the failure which the caller (user interface layer) can use to show an appropriate message to the user (this way user can fix the problem). I was thinking of throwing exceptions with appropriate message but failure reasons are part of normal execution path (almost have 20% chance to occur in compare to method success). So exceptions don't