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Allen Wirfs-Brock (2013-07-01T17:25:13.000Z)
On Jul 1, 2013, at 10:00 AM, Axel Rauschmayer wrote:

>>> Similarly: @@create (which enables the subtyping of built-ins).
>>                                                                              ^^^^^^^^
>>                                                                            subclassing
> 
> 
> Curious: is that an important distinction? To me, a (sub)class is the implementation of a (sub)type.

In a dynamically typed language, a subclass typically isn't required to be a subtype (in most formal senses) of its superclass.  In languages like ES subclassing is an implementation technique that supports code sharing among the definitions of similar (a very informal term) objects.

Allen



> 
> Axel
> 
> -- 
> Dr. Axel Rauschmayer
> axel at rauschma.de
> 
> home: rauschma.de
> twitter: twitter.com/rauschma
> blog: 2ality.com
> 

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github at esdiscuss.org (2013-07-12T02:27:45.709Z)
On Jul 1, 2013, at 10:00 AM, Axel Rauschmayer wrote:

>>> Similarly: @@create (which enables the subtyping of built-ins).
>>
>> subclassing
>
> Curious: is that an important distinction? To me, a (sub)class is the implementation of a (sub)type.

In a dynamically typed language, a subclass typically isn't required to be a subtype (in most formal senses) of its superclass.  In languages like ES subclassing is an implementation technique that supports code sharing among the definitions of similar (a very informal term) objects.
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