Repeating an idea from an earlier email, with a suggestion for a fix.
PROBLEM: The following constructor cannot be extended – once its instances are
frozen, sub-constructors cannot add their own properties.
function Point(x, y) {
this.x = x;
this.y = y;
Object.freeze(this);
}
SOLUTION:
if (!Function.prototype.sealMaybe) {
Object.prototype.freezeMaybe = function(inst) {
// Is `inst` a direct instance of `this`?
if (Object.getPrototypeOf(inst) === this.prototype) {
Object.freeze(inst);
}
};
}
EXAMPLE:
function Point(x, y) {
this.x = x;
this.y = y;
Point.freezeMaybe(this);
}
function ColorPoint(x, y, color) {
Point.call(this, x, y);
this.color = color;
ColorPoint.freezeMaybe(this);
}
Does that make sense? Suggestions for improvements welcome.
--
Dr. Axel Rauschmayer
[email protected]
home: rauschma.de
twitter: twitter.com/rauschma
blog: 2ality.com
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