Extended observer does not notify when the base attribute changes

[frmdstryr]

Consider the following:

from atom.api import Atom, Int, Typed, observe
class Pt(Atom):
    x = Int()
    y = Int()

class Item(Atom):
    pos = Typed(Pt, ())

    @observe('pos.x') # adding 'pos' here makes it change
    def on_change(self, change):
        print(change)

item = Item()
item.pos.x = 1 # This triggers on_change
item.pos = Pt(x=2, y=0) # This does not trigger on_change

When running the code above it prints:

{'type': 'create', 'object': <__main__.Pt object at 0x7527f06a6640>, 'name': 'x', 'value': 1}

But it seems like it should probably have also printed an update?

{'type': 'update', 'object': <some new Pt>, 'name': 'x', 'oldvalue': 1, 'value': 2}

I'm not sure if the current behavior is expected or not.

[sccolbert]

I can't remember what the intended logic was for that. I know that Enthought Traits, which Atom took inspiration from, had to do a lot of machinations to track extended dependencies. What happens if you change the `Pt` object, then change it's `.x` value? Does it fire a change notification? If it does, then we might have a bug since we are already tracking the swap-out of the nested object.

…

On Thu, Feb 27, 2025 at 11:19 AM frmdstryr ***@***.***> wrote: Consider the following: from atom.api import Atom, Int, Typed, observeclass Pt(Atom): x = Int() y = Int() class Item(Atom): pos = Typed(Pt, ()) @observe('pos.x') # adding 'pos' here makes it change def on_change(self, change): print(change) item = Item()item.pos.x = 1 # This triggers on_changeitem.pos = Pt(x=2, y=0) # This does not trigger on_change When running the code above it prints: {'type': 'create', 'object': <__main__.Pt object at 0x7527f06a6640>, 'name': 'x', 'value': 1} But it seems like it should probably have also printed an update? {'type': 'update', 'object': <some new Pt>, 'name': 'x', 'oldvalue': 1, 'value': 2} I'm not sure if the current behavior is expected or not. — Reply to this email directly, view it on GitHub <#245>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AABBQSPWX675375Q27H63CT2R5CLJAVCNFSM6AAAAABYAMAHTGVHI2DSMVQWIX3LMV43ASLTON2WKOZSHA4DKMJTGU4TIOI> . You are receiving this because you are subscribed to this thread.Message ID: ***@***.***> [image: frmdstryr]*frmdstryr* created an issue (nucleic/atom#245) <#245> Consider the following: from atom.api import Atom, Int, Typed, observeclass Pt(Atom): x = Int() y = Int() class Item(Atom): pos = Typed(Pt, ()) @observe('pos.x') # adding 'pos' here makes it change def on_change(self, change): print(change) item = Item()item.pos.x = 1 # This triggers on_changeitem.pos = Pt(x=2, y=0) # This does not trigger on_change When running the code above it prints: {'type': 'create', 'object': <__main__.Pt object at 0x7527f06a6640>, 'name': 'x', 'value': 1} But it seems like it should probably have also printed an update? {'type': 'update', 'object': <some new Pt>, 'name': 'x', 'oldvalue': 1, 'value': 2} I'm not sure if the current behavior is expected or not. — Reply to this email directly, view it on GitHub <#245>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AABBQSPWX675375Q27H63CT2R5CLJAVCNFSM6AAAAABYAMAHTGVHI2DSMVQWIX3LMV43ASLTON2WKOZSHA4DKMJTGU4TIOI> . You are receiving this because you are subscribed to this thread.Message ID: ***@***.***>