Deprecate Classic Classes

text/1117-deprecate-classic-classes.md

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+---
+stage: accepted
+start-date: 2025-06-20T00:00:00.000Z
+release-date:
+release-versions:
+teams: # delete teams that aren't relevant
+  - cli
+  - data
+  - framework
+  - learning
+  - steering
+  - typescript
+prs:
+  accepted: https://github.com/emberjs/rfcs/pull/1117
+project-link:
+---
+
+# Deprecate Classic Classes
+
+## Summary
+
+Deprecate the Classic Class system.
+
+## Motivation
+
+For quite a while now, Ember has recommended the use of Native Classes over the Classic Class
+system. The one remaining sticking point has been Mixins. If we
+[Deprecate Mixins](https://github.com/emberjs/rfcs/pull/1116), then we can deprecate the Classic Class system.
+
+## Transition Path
+
+All uses of Classic Classes should be converted to Native Classes. Anything that cannot be converted
+will be deprecated first such as [Mixins]((https://github.com/emberjs/rfcs/pull/1116) and the
+[`observer` helper function](https://github.com/emberjs/rfcs/pull/1115).
+
+## Exploration
+
+To validate this deprecation, I've tried removing all of the Classic Class system in this PR:
+https://github.com/emberjs/ember.js/pull/20923
+
+## How We Teach This
+
+We should remove all references from the guides.
+
+## Drawbacks
+
+Other than it being a lot of work, there are no drawbacks.
+
+## Alternatives
+
+None
+
+## Unresolved questions
+
+Should we keep `EmberObject` around as a home for some utility methods and sugar or remove it entirely?