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{"@context":"https://schema.org","@type":"DiscussionForumPosting","headline":"Nested AttributeError improved messages don't work with properties","articleBody":"The Python 3.15 improved error message for nested attribute access doesn't seem to work on properties.\n\n### Rationale\n\nTake the example from the [What's new in Python 3.15](https://docs.python.org/3.15/whatsnew/3.15.html#whatsnew315-improved-error-messages) docs:\n\n```py\nfrom dataclasses import dataclass\n\n@dataclass\nclass Circle:\n   radius: float\n\n   @property\n   def area(self) -\u003e float:\n      return pi * self.radius**2\n\nclass Container:\n   def __init__(self, inner: Circle) -\u003e None:\n      self.inner = inner\n\ncircle = Circle(radius=4.0)\ncontainer = Container(circle)\nprint(container.area)\n```\n\nRunning it with the CPython main branch or Python 3.15.0a1 through Python 3.15.0a7 (with uv) produces the following error:\n\n```py\nTraceback (most recent call last):\n  File \"/Users/rodrigogs/Documents/cpython/../tmp/circle.py\", line 17, in \u003cmodule\u003e\n    print(container.area)\n          ^^^^^^^^^^^^^^\nAttributeError: 'Container' object has no attribute 'area'\n```\n\nIf you remove `@property` or if you try accessing `container.radius` instead, you get the respective improved messages:\n\n```py\n# After removing `@property` from `area`:\nTraceback (most recent call last):\n  File \"/Users/rodrigogs/Documents/cpython/../tmp/circle_no_prop.py\", line 16, in \u003cmodule\u003e\n    print(container.area)\n          ^^^^^^^^^^^^^^\nAttributeError: 'Container' object has no attribute 'area'. Did you mean: 'inner.area'?\n\n# ---\n\n# Accessing `radius` instead of the property `area`:\nTraceback (most recent call last):\n  File \"/Users/rodrigogs/Documents/cpython/../tmp/circle_radius.py\", line 17, in \u003cmodule\u003e\n    print(container.radius)\n          ^^^^^^^^^^^^^^^^\nAttributeError: 'Container' object has no attribute 'radius'. Did you mean: 'inner.radius'?\n```\n\n### Helper scripts for easier testing\n\n\u003cdetails\u003e\n\u003csummary\u003e\u003ccode\u003ecircle.py\u003c/code\u003e — original example that doesn't work\u003c/summary\u003e\n\n```py\nfrom dataclasses import dataclass\n\n@dataclass\nclass Circle:\n   radius: float\n\n   @property\n   def area(self) -\u003e float:\n      return pi * self.radius**2\n\nclass Container:\n   def __init__(self, inner: Circle) -\u003e None:\n      self.inner = inner\n\ncircle = Circle(radius=4.0)\ncontainer = Container(circle)\nprint(container.area)\n```\n\n\u003c/details\u003e\n\n\u003cdetails\u003e\n\u003csummary\u003e\u003ccode\u003ecircle_radius.py\u003c/code\u003e — accessing radius works\u003c/summary\u003e\n\n```py\nfrom dataclasses import dataclass\n\n@dataclass\nclass Circle:\n   radius: float\n\n   @property\n   def area(self) -\u003e float:\n      return pi * self.radius**2\n\nclass Container:\n   def __init__(self, inner: Circle) -\u003e None:\n      self.inner = inner\n\ncircle = Circle(radius=4.0)\ncontainer = Container(circle)\nprint(container.radius)\n```\n\n\u003c/details\u003e\n\n\u003cdetails\u003e\n\u003csummary\u003e\u003ccode\u003ecircle_no_prop.py\u003c/code\u003e — removing the property works\u003c/summary\u003e\n\n```py\nfrom dataclasses import dataclass\n\n@dataclass\nclass Circle:\n   radius: float\n\n   # @property\n   def area(self) -\u003e float:\n      return pi * self.radius**2\n\nclass Container:\n   def __init__(self, inner: Circle) -\u003e None:\n      self.inner = inner\n\ncircle = Circle(radius=4.0)\ncontainer = Container(circle)\nprint(container.area)\n```\n\n\u003c/details\u003e\n\n### CPython versions tested on:\n\n3.15, CPython main branch\n\n### Operating systems tested on:\n\nmacOS\n\n\u003c!-- gh-linked-prs --\u003e\n### Linked PRs\n* gh-146188\n\u003c!-- /gh-linked-prs --\u003e\n","author":{"url":"https://github.com/rodrigogiraoserrao","@type":"Person","name":"rodrigogiraoserrao"},"datePublished":"2026-03-19T14:28:37.000Z","interactionStatistic":{"@type":"InteractionCounter","interactionType":"https://schema.org/CommentAction","userInteractionCount":7},"url":"https://github.com/146171/cpython/issues/146171"}