instance

问题 I want to create a new user in IAM, and allow him to be able to create new EC2 instances, but be able to view/administer only those instances that he creates. Is this possible with IAM? This is the group policy I tried: { "Statement": [ { "Effect": "Allow", "Action": [ "ec2:DescribeImages", "ec2:DescribeKeyPairs", "ec2:DescribeSecurityGroups", "ec2:DescribeAvailabilityZones" ], "Resource": "*" }, { "Effect": "Allow", "Action": [ "ec2:DescribeInstances","ec2:RunInstances", "ec2

问题 class MyClass: def myMethod(self): pass myInstance = MyClass() methodReference = myInstance.myMethod Now can you get a reference to myInstance if you now only have access to methodReference ? 回答1: methodReference.im_self and by a similar token, for the class: methodReference.im_class For this kind of code discovery you should install iPython and use tab, for instance, in your case myReference.+TAB would give: In [6]: methodReference. methodReference.im_class methodReference.im_func

问题 Heres some sample code, class Base { private int val; Base() { val = lookup(); } public int lookup() { //Perform some lookup // int num = someLookup(); return 5; } public int value() { return val; } } class Derived extends Base { private int num = 10; public int lookup() { return num; } } class Test { public static void main(String args[]) { Derived d = new Derived(); System.out.println("d.value() returns " + d.value()); } } output: d.value() returns 0 // I expected 10 as lookup() is

问题 I am trying to verify the difference between instance attributes and class attributes as laid out by the Python tutorial release 2.7.3 dated Nov 01, 2012, chapter 9: Classes, Page 66 last line (source): Valid method names of an instance object depend on its class. By definition, all attributes of a class that are function objects define corresponding methods of its instances. So in our example, x.f is a valid method reference, since MyClass.f is a function, but x.i is not, since MyClass.i is

问题 How is it possible to have an instance of a class which is an object , without the class being a subclass of object ? here is an example: >>> class OldStyle(): pass >>> issubclass(OldStyle, object) False >>> old_style = OldStyle() >>> isinstance(old_style, object) True 回答1: In Python 2, type and class are not the same thing, specifically, for old-style classes, type(obj) is not the same object as obj.__class__ . So it is possible because instances of old-style classes are actually of a

问题 Closed . This question needs to be more focused. It is not currently accepting answers. Want to improve this question? Update the question so it focuses on one problem only by editing this post. Closed 5 years ago . i would like to ask the question when it would be advantageous to use static variables/methods or in the other case instance variables/methods in Java? I know that it depends on the certain case (like programming util-classes as static methods), but can we declare something like a

问题 Currently, I am reading "JUnit in action" book. In this book I found text below: JUnit creates a new instance of the test class before invoking each @Test method. This helps provide independence between test methods and avoids unintentional side effects in the test code. Because each test method runs on a new test class instance, we can’t reuse instance variable values across test methods. Now I do not see much point in this approach: For example: public class CalculatorTest { @Test public

问题 I am a Java developer. In an interview I was asked a question about private constructors: Can you access a private constructor of a class and instantiate it? I answered 'No' but was wrong. Can you explain why I was wrong and give an example of instantiating an object with a private constructor? 回答1: One way to bypass the restriction is to use reflections: import java.lang.reflect.Constructor; public class Example { public static void main(final String[] args) throws Exception { Constructor

问题 Is it possible to get value without creating an instance ? I have this class: public class MyClass { public string Name{ get{ return "David"; } } public MyClass() { } } Now I need get the value "David", without creating instance of MyClass. 回答1: Real answer : no. It's an instance property, so you can only call it on an instance. You should either create an instance, or make the property static as shown in other answers. See MSDN for more information about the difference between static and

问题 I'm working on a project in C#. The previous programmer didn't know object oriented programming, so most of the code is in huge files (we're talking around 4-5000 lines) spread over tens and sometimes hundreds of methods, but only one class. Refactoring such a project is a huge undertaking, and so I've semi-learned to live with it for now. Whenever a method is used in one of the code files, the class is instantiated and then the method is called on the object instance. I'm wondering whether