If you are using the Modern Objective-C Runtime (that’s either iOS 3.x or greater, or 64-bit Snow Leopard or greater) then you do not need to define ivars for your properties in cases like this. When you @synthesize the property, the ivar will in effect be synthesized also for you. This gets around the “fragile-ivar” … Read more
Every object has a __dict__ variable containing all the variables and its values in it. Try this >>> hi_obj = hi() >>> hi_obj.__dict__.keys() Output dict_keys([‘ii’, ‘kk’])
Just say (current object) .attributes .attributes returns a hash of any object. And it’s much cleaner too.
A variable prefixed with @ is an instance variable, while one prefixed with @@ is a class variable. Check out the following example; its output is in the comments at the end of the puts lines: class Test @@shared = 1 def value @@shared end def value=(value) @@shared = value end end class AnotherTest < … Read more
Writing @age directly accesses the instance variable @age. Writing self.age tells the object to send itself the message age, which will usually return the instance variable @age — but could do any number of other things depending on how the age method is implemented in a given subclass. For example, you might have a MiddleAgedSocialite … Read more
Instance variable on a class: class Parent @things = [] def self.things @things end def things self.class.things end end class Child < Parent @things = [] end Parent.things << :car Child.things << :doll mom = Parent.new dad = Parent.new p Parent.things #=> [:car] p Child.things #=> [:doll] p mom.things #=> [:car] p dad.things #=> [:car] … Read more
There is no difference – the instance variable initialization is actually put in the constructor(s) by the compiler. The first variant is more readable. You can’t have exception handling with the first variant. There is additionally the initialization block, which is as well put in the constructor(s) by the compiler: { a = new A(); … Read more
ServletContext When the servlet container (like Apache Tomcat) starts up, it will deploy and load all its web applications. When a web application is loaded, the servlet container creates the ServletContext once and keeps it in the server’s memory. The web app’s web.xml and all of included web-fragment.xml files is parsed, and each <servlet>, <filter> … Read more