On Sep 30, 2011, at 11:53 AM, Brendan Eich wrote:
> On Sep 30, 2011, at 7:57 PM, Erik Arvidsson wrote:
>
>> One of the things I like about the object literal syntax is that it
>> doesn't seem like things might be in scope. Take this example (with
>> intentional error):
>>
>> class Point {
>> var x = 0;
>> var y = 0;
>> distance(other) {
>> return Math.sqrt(x * other.x + y * other.y);
>> }
>> }
>>
>> it is very tempting to think that var x and var y are in scope. If an
>> object literal is used at least we have the current behavior to steer
>> people into doing the right thing.
>
> Two thoughts:
>
> 1. Oliver and others do want x and y to be in scope somehow. They can't be
> via the |this| parameter object on the scope chain, though. That's dynamic
> scope (the prototype is extensible, or *a* prototype, possibly
> Object.prototype, is). But the desire to avoid this. prefixing is natural and
> predictable for people coming from C++, Java, etc. Should we consider
> supporting this expectation somehow, rather than steering people away from it
> with less natural syntax?
My recent proposals have not been placing member fields in scope (all my
examples use this.blah), they have merely been providing a declarative syntax
to define the shape of an instance of the object. Basically i've started
leaning towards python-esque classes, with optional declarative field syntax
(which also has the benefit of saving you from the setter on the prototype trap
that you suffer when not using object literals).
I also see the constructor(this.x, ..) stuff as syntactic sugar that is
unrelated to the actual class semantics -- that syntax could be added at a
later date and would not impact the behaviour of classes, and if it were added
i see no reason to restrict it solely "constructors". That said I don't like
the syntax at all :D
--Oliver
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