Matt said:
List is an interface.
You cannot create a "List" object.
Think of "myArray extends Array implements List", that helps ;-)
How about:
Just enhance Array and call it List then
Another fully viable option.
----------
Array.prototype.add = function(element,index) {
if (('number'!=typeof index)||(index>=this.length)) {
this.push(element);
}
else {
this.splice(index,0,element);
}
}
Array.prototype.remove = function(index) {
if (('number' != typeof index)||(index >= this.length)) {
return null;
}
else {
if (index<0) {index -= this.length;}
return this.splice(index,1)[0];
}
}
var List = Array;
----------
Now, what value does it add? None, really. Under the hood, you're still just
using Array methods. So why not just call it an Array? You're not adding any
value by creating this "List" object.
That is a question of the kind "Why do you need to create class Manager
if it has only one property more than Employee? Simply add that
property to an Employee instance."
Or more generally: "Why do you need OOP hassle? Your custom objects do
not do anything what their supers couldn't, so just augment supers".
Having the prototype way as totally correct option, I need (think I
need, want) a separate object type, not just Array with extra methods.
Array is hadled as a fixed continuum defined by 0 - (length-1) borders.
We can extend this continuum or make "holes" ("gaps") in this continuum
by delete'ing elements.
List (interface) is flexible continuum able to automatically expand and
collapse ("healing the holes") on elements adding/removal.
That seems as enough of behavioral difference for a will to have two
different objects from different constuctors: rather than all existing
and future Array's acting this way or that way depending on what
methods do you apply to them.
Once again: prototype augmentation is definitely and always an option.
