[Cuis-dev] [Ann] Serialization of BlockClosures

[Phil B]

Juan,

On Mon, Sep 30, 2019 at 11:43 PM Juan Vuletich via Cuis-dev <
cuis-dev at lists.cuis.st> wrote:

> Hi Nicolas,
>
> On 9/30/2019 8:36 PM, Nicolas Cellier via Cuis-dev wrote:
>
> Hi Juan,
> Something strikes me.
> Isn't this example a pathological case of inheritance? Is Color really
> kind of Collection? Wouldn't any object potentially be a collection of its
> instances variables in this case?
>
>
Well that kind of gets to a core issue (in an abstract way... I know, your
favorite ;-) in that there is nothing inherent about being a Color that one
should reasonably expect it to behave as a collection.  Sending #collect:
etc. on a Color from an outside object doesn't actually make a lot of sense
other than to abuse a leaked implementation detail (i.e. that it's actually
implemented as a collection.)

>
> It can be considered a space optimization. Just like Squeak's encoding of
> RGB in a SmallInteger. Other examples in Cuis packages include
> Float32Matrix3x3, Float32Vector3, Float64Matrix?x?, Float64Quaternion,
> Float64Vector?, GPSPosition, All these could use ivars, but dont, and
> inherit from FloatArray or Float64Array.
>

There are FFI reasons as well. (but that's an implementation detail)


> This makes sense especially on 64 bit images for objects whose parts can
> be 32bit or shorter immediates, and if we build many instances. In this
> cases, I think the space saving overwheights the inconvenience of not
> having real ivars.
>

One could argue (and I am) that whether it was implemented it that way for
space savings or other reasons that we shouldn't depend on it being a
collection because you could just as easily re-implement it as a direct
subclass of Object and it would still make sense.  The fact that it is
currently a collection seems irrelevant to being a Color.  The fact that it
would no longer responded to #collect: and friends wouldn't make it any
less a Color... so why encourage/support using these (essentially) leaked
methods externally?

> --
> Juan Vuletichwww.cuis-smalltalk.orghttps://github.com/Cuis-Smalltalk/Cuis-Smalltalk-Devhttps://github.com/jvuletichhttps://www.linkedin.com/in/juan-vuletich-75611b3
> @JuanVuletich
>
>
Thanks,
Phil
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