René's URL Explorer Experiment

{"@context":"https://schema.org","@type":"DiscussionForumPosting","headline":"Improve the constructors of AST nodes","articleBody":"Currently, the constructors for AST nodes accept arbitrary keyword arguments and don't enforce any value:\r\n\r\n```pycon\r\n\u003e\u003e\u003e node=ast.FunctionDef(what=\"is this\")\r\n\u003e\u003e\u003e node.what\r\n'is this'\r\n\u003e\u003e\u003e node.name\r\nTraceback (most recent call last):\r\n  File \"\u003cstdin\u003e\", line 1, in \u003cmodule\u003e\r\nAttributeError: 'FunctionDef' object has no attribute 'name'\r\n```\r\n\r\nProblems with the current situation:\r\n- To make a correct AST node, you have to pass *every* attribute, including ones that could sensibly default to an empty list\r\n- You cannot rely on attributes like `name` being present\r\n- It's possible to create useless, broken AST nodes like the above\r\n- Introspection tools can't easily tell what the signature of the constructor is supposed to be\r\n- Adding new fields to an AST node causes various compatibility issues (#104799) \r\n\r\nProposed solution for 3.13:\r\n- Default all fields to some sensible value if they are not provided to the constructor: an empty list for list fields, and None for other fields.\r\n- Emit a DeprecationWarning if the constructor is passed arguments that it doesn't recognize (e.g., `what` above). In 3.15, this will raise an error.\r\n- Add a `__text_signature__` to the AST classes indicating the expected signature.\n\n\u003c!-- gh-linked-prs --\u003e\n### Linked PRs\n* gh-105880\n* gh-116025\n\u003c!-- /gh-linked-prs --\u003e\n","author":{"url":"https://github.com/JelleZijlstra","@type":"Person","name":"JelleZijlstra"},"datePublished":"2023-06-16T15:28:14.000Z","interactionStatistic":{"@type":"InteractionCounter","interactionType":"https://schema.org/CommentAction","userInteractionCount":6},"url":"https://github.com/105858/cpython/issues/105858"}