I know that this answer is 3 years late but I really think the current answers do not provide enough information about how prototypal inheritance is better than classical inheritance. First let’s see the most common arguments JavaScript programmers state in defence of prototypal inheritance (I’m taking these arguments from the current pool of answers): … Read more
My answer is correct? Yes, mostly, and certainly in the context you describe. This is not multiple inheritance: It’s what you said it is, single inheritance with multiple levels. This is multiple inheritance: Inheriting from two or more bases that don’t have any “is a” relationship with each other; that would be inheriting from unrelated … Read more
Strings do have a length method: __len__() The protocol in Python is to implement this method on objects which have a length and use the built-in len() function, which calls it for you, similar to the way you would implement __iter__() and use the built-in iter() function (or have the method called behind the scenes … Read more
Obsess over: Final fields – Marking fields as final forces them to be set by end of construction, making that field reference immutable. This allows safe publication of fields and can avoid the need for synchronization on later reads. (Note that for an object reference, only the field reference is immutable – things that object … Read more
Unnamed namespaces are a utility to make an identifier translation unit local. They behave as if you would choose a unique name per translation unit for a namespace: namespace unique { /* empty */ } using namespace unique; namespace unique { /* namespace body. stuff in here */ } The extra step using the empty … Read more
First off, remember that JavaScript is primarily a prototypal language, rather than a class-based language1. Foo isn’t a class, it’s a function, which is an object. You can instantiate an object from that function using the new keyword which will allow you to create something similar to a class in a standard OOP language. I’d … Read more
Anonymous class instance — is it a bad idea? Yes, a very bad one. Just as bad as new function() { … } was in ES5. This writing style leads to the creation of a new constructor function and prototype object every time the expression is evaluated. If you create multiple objects with this approach, … Read more
For preserving the context, the bind method is really useful, it’s now part of the recently released ECMAScript 5th Edition Specification, the implementation of this function is simple (only 8 lines long): // The .bind method from Prototype.js if (!Function.prototype.bind) { // check if native implementation available Function.prototype.bind = function(){ var fn = this, args … Read more
You can put it into the constructor like this: public function __construct() { $this->fullname = $this->firstname.’ ‘.$this->lastname; $this->totalBal = $this->balance+$this->newCredit; } Why can’t you do it the way you wanted? A quote from the manual explains it: This declaration may include an initialization, but this initialization must be a constant value–that is, it must be … Read more
I’ll try to clear up some confusion about classes and objects for you first. Lets look at this block of code: >>> class Bank(): # let’s create a bank, building ATMs … crisis = False … def create_atm(self) : … while not self.crisis : … yield “$100” The comment there is a bit deceptive. The … Read more