On Tue, Jul 18, 2017 at 4:09 PM, Levente Uzonyi <leves@caesar.elte.hu> wrote:
On Tue, 18 Jul 2017, marcel.taeumel wrote:

Hi, there.

Why are there guards to prevent forward-becoming to immediates (chars, ints)
but not to symbols?

 The former is technically impossible due to different object representations, the latter is possible and not restricted at all. For example, true and false are not immediate objects, you can use #become*: on them to blow your image up.
So, there's no restriction at all if it's technically possible to use #become*:.
The responsibility model is the simplest here: use at your own risk.
Since this comes up every once in a while, I suggest a comment be added to those methods stating the responsibility model explicitly.

​+1

*Especially* a warning that becomeForward: does modify the target's hash.
​
I don't know how the VM handles immutability in this case, but it's possible that it wouldn't let #become*: affect immutable objects.

​I think that would be fine, you should​ be able to become an immutable object and vice versa.
 
On the other hand, I'm sure it would let you change fields of immutable objects via #become*:, but that's not an issue in your case.

​This is debatable ...​ I would rather have the VM raise an error when trying to become a field of an immutable object. Immutable should mean immutable, no?

​- Bert -​

 


Levente



This will break your image: "Object new becomeForward: #normal"

... because Cursor class MNU #normal ... :-) Either this is a bug or
forward-becoming to symbols is not intended at all.

Best,
Marcel