Finding a "safety syntax" for classes

Herby Vojčík herby at
Tue Mar 20 12:50:26 PDT 2012

David Herman wrote:
> I can mostly dig it -- I've been trying to encourage minimal classes for
> quite some time now.
> The part that I'm least happy about is that this doesn't allow for
> declarative private methods, because if we had the computed syntax like
> what we're adding to object literals, it would clash with hoisting:
> {
> let priv = new Name();
> class C {
> // oops, priv is still undefined!!
> [priv](x, y, z) {
> return x * y / z
> }
> }
> }

Maybe too brittle, but since (I see that) classes are sugar for creating 
a function with appropriate [[Prototype]] and .prototype _and_also_ 
populating the prototype, you can do hoisting the same way as you do for 
other elements (have a dead zone, hoist declaration, do not hoist 
prototype population), so that it would de-facto be:

   let priv;
   let /* function */ C; // sort-of
   priv = new Name;
   C = function (/*ctr_params*/) /*extends C_superclass*/ {/*ctr_body*/};
     [priv](x, y, z) {
       return x * y / z

which works.

> I do think that class declarations should be hoisted, both in the sense
> of being in scope for the whole containing block (as with let and
> function) and in the sense of being initialized before the block begins
> executing (as with function).
> Dave


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