On Thu, Oct 17, 2013 at 11:21 PM, Jonathan S. Shapiro <[email protected]>wrote:

> So just to be clear, I'm talking about objects that are immutable, rather
> than objects that allegedly implement read-only semantics.
>

The list i posted were all  only data entered by the constructor  with no
change of state ..

I used RW  ( and RO ) because i suggested all functions default to shallow
const/immutable params for references  ( ro) and  mut is 3 characters rw is
2 (and probably easier for most progammers to grasp as it would be very
common).



> On Wed, Oct 16, 2013 at 8:29 PM, Bennie Kloosteman <[email protected]>wrote:
>
>> I dont think the pay off will cover the costs but it may  , there are
>> many other benefits to knowing objects will not changes.
>>
>
> For dynamically immutable objects (so RO here is a per-object property),
> the main cost is a bit in the object header. Those bits are precious, so it
> definitely needs an experiment.
>
> For objects that are immutable by virtue of their static type, the bit can
> be tucked in the vtable. Those bits are a lot cheaper.
>

If its only 20 objects at a time you dont need this at all just lookup the
type .. Obviosuly for URC when you do a whole nursery its a diffirent
 story..


>
> Hmm. For that matter, you could simply use VTable pairs for dynamically RO
> objects (one indicating RO, the other indicating RW).
>

I was thinking of this for DB objects as well.


Ben
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