instance-methods

问题 module Country def location puts "location" end def self.included(base) def cities puts "cities" end end def self.extended(base) def animals puts "animals" end end end class Test include Country end class Test2 extend Country end As far as I understand, self.included will be invoked when the module is being included as instance method where as self.extended will be invoked when the module is being extended as static class method. But when I have two class in the same file, why it's not

问题 Quite new to this so I hope I have the terminology in the title right. I am trying to figure out how to create an instance method that will do the following: --An ID number is returned. --As each object is created from the class constructor(instantiated?), a unique integer ID number is assigned to it. The first ID number is 1, and as new objects are instantiated, successive numbers will be assigned. I am able to find examples of class/static methods that do the above however I am unable to

问题 Quite new to this so I hope I have the terminology in the title right. I am trying to figure out how to create an instance method that will do the following: --An ID number is returned. --As each object is created from the class constructor(instantiated?), a unique integer ID number is assigned to it. The first ID number is 1, and as new objects are instantiated, successive numbers will be assigned. I am able to find examples of class/static methods that do the above however I am unable to

问题 This question is similar to Why are methods in Ruby documentation preceded by a hash sign? I understand why in Ruby instance methods are proceeded with a pound sign, helping to differentiate talking about SomeClass#someMethod from SomeObject.someMethod and allowing rdoc to work. And I understand that the authors of PrototypeJS admire Ruby (with good reason) and so they use the hash mark convention in their documentation. My question is: is this a standard practice amongst JavaScript

问题 Instance methods can not automatically be pickled in both Python 2 or Python 3. I need to pickle instance methods with Python 3 and I ported example code of Steven Bethard to Python 3: import copyreg import types def _pickle_method(method): func_name = method.__func__.__name__ obj = method.__self__ cls = method.__self__.__class__ return _unpickle_method, (func_name, obj, cls) def _unpickle_method(func_name, obj, cls): for cls in cls.mro(): try: func = cls.__dict__[func_name] except KeyError:

问题 Let's say I have this program: class Foo { public: unsigned int bar () { static unsigned int counter = 0; return counter++; } }; int main () { Foo a; Foo b; } (Of course this example makes no sense since I'd obviously declare "counter" as a private attribute, but it's just to illustrate the problem). I'd like to know how C++ behaves in this kind of situation: will the variable "counter" in the bar() method be the same for every instance? 回答1: Yes, counter will be shared across all instances

问题 is it possible to call @selector methods from another class ? for example i make a method "bannerTapped:" and call it from "myViewController.m" class. myviewcontroller.m : anotherClass *ac= [[anotherClass alloc]init]; UITapGestureRecognizer *singleTap = [[UITapGestureRecognizer alloc]initWithTarget:ac action:@selector(bannerTapped:)]; singleTap.numberOfTapsRequired = 1; singleTap.numberOfTouchesRequired = 1; cell.conversationImageView.tag = indexPath.row; [cell.conversationImageView

问题 Is there a way to make len() work with instance methods without modifying the class? Example of my problem: >>> class A(object): ... pass ... >>> a = A() >>> a.__len__ = lambda: 2 >>> a.__len__() 2 >>> len(a) Traceback (most recent call last): File "<stdin>", line 1, in <module> TypeError: object of type 'A' has no len() Note: different instances of A will have different __len__ methods attached I cannot change the class A 回答1: It is actually possible without modifying the class based on this

问题 If I call a method on a rails active model method like so: class Foo < ActiveRecord::Base end Foo.first I'll get back the first active record. I don't have to instantiate the class. But if I create my own class and call a method, I get an exception: class Person < ActiveRecord::Base def greeting 'hello' end end Person.greeting #EXCEPTION: undefined method `greeting' for Person:Class How can I make that problem go away? 回答1: There are several kinds of methods. The two most important ones are:

问题 This question already has answers here : Can a method be used as either a staticmethod or instance method? (4 answers) Closed 6 years ago . Can I define a Python method to be both static and instance at the same time? Something like: class C(object): @staticmethod def a(self, arg1): if self: blah blah So that I can call it with both: C.a(arg1) C().a(arg1) The intent is to be able to run two sets of logics. If accessed as an instance method, it would make use of instance variables and do stuff