oop

问题 The instanceof operator should look at the prototype, no? Why does it not change its answer after the object's prototype has been changed? Example below: // The .prototype of objects created with 'new MyKlass' // is MyKlass.prototype var MyKlass = function(name, age) { this.name = name; this.age = age; } var xx = new MyKlass('xx', 20); console.log(xx instanceof MyKlass); // true, OK xx.prototype = new String('s'); console.log(xx instanceof MyKlass); // also true, WHY??? 回答1: This case is

问题 The instanceof operator should look at the prototype, no? Why does it not change its answer after the object's prototype has been changed? Example below: // The .prototype of objects created with 'new MyKlass' // is MyKlass.prototype var MyKlass = function(name, age) { this.name = name; this.age = age; } var xx = new MyKlass('xx', 20); console.log(xx instanceof MyKlass); // true, OK xx.prototype = new String('s'); console.log(xx instanceof MyKlass); // also true, WHY??? 回答1: This case is

问题 Closed . This question needs details or clarity. It is not currently accepting answers. Want to improve this question? Add details and clarify the problem by editing this post. Closed 5 days ago . Improve this question Recreating java.lang.String is not hard. See attached code. I'm really writing this to show how easy it is. If anybody wants to figure out how to get the native isBigEndian() and add it in the solutions, that'd be great. Other String methods would be great too. Just put this

问题 Closed . This question needs details or clarity. It is not currently accepting answers. Want to improve this question? Add details and clarify the problem by editing this post. Closed 5 days ago . Improve this question Recreating java.lang.String is not hard. See attached code. I'm really writing this to show how easy it is. If anybody wants to figure out how to get the native isBigEndian() and add it in the solutions, that'd be great. Other String methods would be great too. Just put this

问题 Look this code: class MyClass_1(): @staticmethod def method_1(func): return func(1, 2, 3) class MyClass_2(): my_func = lambda a,b,c : a*b*c # I need to call this method def method_2(self): result = MyClass_1.method_1(self.my_func) print(result) My error: TypeError: () takes 3 positional arguments but 4 were given I need to call the lambda function my_func in the same way as the code above, but a self is appearing from somewhere I don't know and causing this error. What am I missing? 回答1:

问题 I thought that I realized this relationship: In Python everything is an object, and every object has a type. But what about classes? A class is a blueprint of an object, and an object is instance of a class. But I have read in an article that in Python, classes are themselves objects. I thought that an object cannot exist without its blueprint - its class. But, if class is an object, how it can exist? >>> type.__bases__ (<class 'object'>,) >>> int.__bases__ (<class 'object'>,) >>> str.__bases

问题 I'm trying to create a GUI application using Tkinter . This interface is made of the following widgets: a button , an entry and a text. The image below shows it. The idea behind this app is: the user enters a word on the entry and on hit the Meaning button it's meaning is showed in the text widget. My code is splitted in two classes: one for GUI and another for the app itself. GUI (removed the imaged showed before to reduce coding): class Gui: def __init__(self, master=None): if master is

问题 Is it possible to change a base class field data type and value in the derived class and still call the base class method but use the derived class values? Sample Code: public class class1 { protected DBContext DB { get; set; } public A() { DB = new DBContext(); } public virtual DBRecord find(int id) { return DB.DBRecord.Find(id); } } public class class2 : class2 { protected DifferentDBContext DB { get; set; } public B() { DB = new DifferentDBContext(); } } And then i tried to call the method

问题 Is it possible to change a base class field data type and value in the derived class and still call the base class method but use the derived class values? Sample Code: public class class1 { protected DBContext DB { get; set; } public A() { DB = new DBContext(); } public virtual DBRecord find(int id) { return DB.DBRecord.Find(id); } } public class class2 : class2 { protected DifferentDBContext DB { get; set; } public B() { DB = new DifferentDBContext(); } } And then i tried to call the method

问题 Is it possible to change a base class field data type and value in the derived class and still call the base class method but use the derived class values? Sample Code: public class class1 { protected DBContext DB { get; set; } public A() { DB = new DBContext(); } public virtual DBRecord find(int id) { return DB.DBRecord.Find(id); } } public class class2 : class2 { protected DifferentDBContext DB { get; set; } public B() { DB = new DifferentDBContext(); } } And then i tried to call the method