[squeak-dev] immutability

Frank Shearar frank.shearar at angband.za.org
Thu Mar 18 09:47:10 UTC 2010

Randal L. Schwartz wrote:
>>>>>> "Michael" == Michael van der Gulik <mikevdg at gmail.com> writes:
> Michael> In SecureSqueak, direct invasive object access using basicAt:put:,
> Michael> at:put: and so forth will be disallowed.
> And that would require a VM change.
> Otherwise, I can just create a method that does the primitive.

So #basicAt:put: etc. is the reason why, as Ralph put it, immutability 
is a _language_ feature and not simply part of a library?

Or, to put it another way, if we want to _guarantee_ immutability we 
can't rely on ProtoObject/Object defining immutability because 
subclasses could override that behaviour? (Which would be breaking the 
programming-by-convention rule for immutability.)


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