instance

问题 So lets say I have a class called Car as below: class Car(object): """Car example with weight and speed.""" def __init__(self): self.weight = None self.speed = None If I initialize a Car as an empty object: red_car = Car() And I add a speed and a weight : red_car.speed = 60 red_car.weight = 3500 That's all fine but what if I want to run a function when attempting to add those variables to the instance? Like this function: def change_weight(self, any_int): return (any_int - 10) The thing is

问题 So lets say I have a class called Car as below: class Car(object): """Car example with weight and speed.""" def __init__(self): self.weight = None self.speed = None If I initialize a Car as an empty object: red_car = Car() And I add a speed and a weight : red_car.speed = 60 red_car.weight = 3500 That's all fine but what if I want to run a function when attempting to add those variables to the instance? Like this function: def change_weight(self, any_int): return (any_int - 10) The thing is

问题 I have 2 lists of instances: list1 list2 each instance contains variables such as id, name, etc... I am iterating through list2, and I want to find entries that don't exist in list1. eg.. for entry in list2: if entry.id in list1: <do something> I'm hoping to find a way to do this without a douple for loop. Is there an easy way? 回答1: I might do something like: set1 = set((x.id,x.name,...) for x in list1) difference = [ x for x in list2 if (x.id,x.name,...) not in set1 ] where ... is additional

问题 Until now I used for this task the service called Pingdom, but yesterday I tried to sign up for a new application, but there is not the free plan anymore? Anyway, I took a look for an alternative and I found New Relic could do this as well, but there is (in my eyes) one issue - we can set up an URL which we would like to ping, but this URL is pinged periodically each 30 seconds (and each 15 seconds if was detected an error). Cannot this approach "overload" my app? There is also a way to set

问题 is there any way to get the Instance from a Field? Here's a sample code: public class Apple { // ... a bunch of stuffs.. } public class Person { @MyAnnotation(value=123) private Apple apple; } public class AppleList { public add(Apple apple) { //... } } public class Main { public static void main(String args[]) { Person person = new Person(); Field field = person.getClass().getDeclaredField("apple"); // Do some random stuffs with the annotation ... AppleList appleList = new AppleList(); //

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've been searching for an answer to this for a while to no avail. First a bit of background: I'm trying to create an AI for robocode using Weka. I'm first logging the required data from a manual robot to an ARFF file, this is working as it should. This data is then processed this using Weka and a model created, I'm then saving this file. I can successfully import the model and classify a dataset that has been imported from another arff file and use the results. What I want to do now is every

问题 I am looking for an algorithm that can get the object that called the method, within that method. For instance: public class Class1 { public void Method () { //the question object a = ...;//the object that called the method (in this case object1) //other instructions } } public class Class2 { public Class2 () { Class1 myClass1 = new Class1(); myClass1.Method(); } public static void Main () { Class2 object1 = new Class2(); //... } } Is there any way to do this? 回答1: Obviously i don't know the

问题 I'd like to create several instances of a class in CodeIgniter. I have created my class as a library, but cannot figure out the syntax to use to create more than one instance. 回答1: From the CodeIgniter users guide: CI Users Guide: Loader Class Assigning a Library to a different object name If the third (optional) parameter is blank, the library will usually be assigned to an object with the same name as the library. For example, if the library is named Session, it will be assigned to a

问题 I'm trying to track down an issue in our system and the following code worries me. The following occurs in our doPost() method in the primary servlet (names have been changed to protect the guilty): ... if(Single.getInstance().firstTime()){ doPreperations(); } normalResponse(); ... The singleton 'Single' looks like this: private static Single theInstance = new Single(); private Single() { ...load properties... } public static Single getInstance() { return theInstance; } With the way this is