strawman for the := operator

Erik Corry erik.corry at gmail.com
Wed Aug 8 03:42:41 PDT 2012


>From the straw man:

class Point {
   constructor(x,y) {
      this := {x,y}  //define and initialize x and y properties of new object
   }
}

should this read:

this := {x: x, y: y}

?

On 7 August 2012 00:44, Allen Wirfs-Brock <allen at wirfs-brock.com> wrote:
> Based upon discussions last week in the "July 25, 2012 - TC39 Meeting Notes"
> thread, I've created a new strawman proposal for a := operator.  See
> http://wiki.ecmascript.org/doku.php?id=strawman:define_properties_operator
>
> := is a convient way to copy properties from one object to another or to
> extend an object with new properties.  It combines supports for many of the
> same use cases as the previously proposed "object extension literals" and
> the JSFixed Object.extend proposal.
>
> The most important characteristic of := is that it uses
> [[DefineOwnProperty]] semantics rather than [[Put]] semantics to define
> properties on its target object so it doesn't run into issues with
> assignment to accessor properties or over-riding inherited readonly
> properties. It is also smart about dealing with methods that reference
> super.
>
> Some basic examples:
>
>   target := src;  //define all own properties of src onto target
>
>    //add a method and an accessor to an existing prototype
>   Point.prototype := {
>    plus(aPoint) {return new
> this.comstructor(this.x+aPoint.x,this.y+aPoint.y},
>    get rho() {return Math.sqrt(this.x*this.x+this.y*this.y}
> };
>
>
> Have at it,
>
> Allen
>
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