Somehow, this did not get into the list, so I am resending it...
hopefully it won't get duplicated.
-------- Original Message --------
From: Herby Vojčík <he...@mailbox.sk>
Subject: Setting inheritance chains, <|, extends, class and all the stuff
Date: Wed, 21 Mar 2012 18:58:59 +0100
To: ECMAScript discussion <es-discuss@mozilla.org>
Hi,
as for setting the [[Prototype]] chains with constructor function, I see
there are three scenarios:
CP: aka 'classical inheritance'
SubCtr.[[Prototype]] is set to SuperObj
SubCtr.prototype.[[Prototype]] is set to SuperObj.prototype
C: aka 'constructor inheritance'
SubCtr.[[Prototype]] is set to SuperObj
SubCtr.prototype.[[Prototype]] is set to Object.prototype
P: aka 'prototype inheritance'
SubCtr.[[Prototype]] is set to Function.prototype
SubCtr.prototype.[[Prototype]] is set to SuperObj
I propose these should be covered syntactically this way:
CP:
class SubCtr extends SuperObj { ... }
// and if possible also, to have more basic construct without
// defining methods, just the constructor function:
function SubCtr (...) extends SuperObj { ... }
C:
SuperObj <| function SubCtr (...) { ... }
P:
SuperObj <| class SubCtr { ... }
Precondition:
class's extends keyword is agreed to create CP type inheritance
Rationale:
If extends represent the classish CP inheritance, and looking at all
other uses of <| you see that its spirit is to set only the
[[Prototype]] of thing described by RHS, we can use both and have them
unambiguously define what kind of [[Prototype]] they set only based on
which construct is used, not based on structure of LHS.
This plays with "explicit is better then implicit" card - you know
instantly when you read/write code, what type of chaining you want to
accomplish, so readability and hidden bugs from using variable LHS could
be prevented.
Comments?
Herby
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