Javascript Getting Objects to Fallback to One Another
- by Ian
Here's a ugly bit of Javascript it would be nice to find a workaround.
Javascript has no classes, and that is a good thing. But it implements fallback between objects in a rather ugly way. The foundational construct should be to have one object that, when a property fails to be found, it falls back to another object.
So if we want a to fall back to b we would want to do something like:
a = {sun:1};
b = {dock:2};
a.__fallback__ = b;
then
a.dock == 2;
But, Javascript instead provides a new operator and prototypes. So we do the far less elegant:
function A(sun) {
this.sun = sun;
};
A.prototype.dock = 2;
a = new A(1);
a.dock == 2;
But aside from elegance, this is also strictly less powerful, because it means that anything created with A gets the same fallback object.
What I would like to do is liberate Javascript from this artificial limitation and have the ability to give any individual object any other individual object as its fallback. That way I could keep the current behavior when it makes sense, but use object-level inheritance when that makes sense.
My initial approach is to create a dummy constructor function:
function setFallback(from_obj, to_obj) {
from_obj.constructor = function () {};
from_obj.constructor.prototype = to_obj;
}
a = {sun:1};
b = {dock:2};
setFallback(a, b);
But unfortunately:
a.dock == undefined;
Any ideas why this doesn't work, or any solutions for an implementation of setFallback?
(I'm running on V8, via node.js, in case this is platform dependent)
