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{"@context":"https://schema.org","@type":"DiscussionForumPosting","headline":"Problematic behavior of `locals()` inside a funtion","articleBody":"Use of `locals()` inside a function leads to unexpected behavior. For an example, the following code snippet\r\n\r\n```python\r\ndef make_tables():\r\n    schema = dj.schema('test', locals())\r\n    \r\n    @schema\r\n    class A():\r\n        definition = \"\"\"\r\n        id:  int     # id\r\n        \"\"\"\r\n    @schema\r\n    class B():\r\n        definition = \"\"\"\r\n         -\u003e A\r\n         \"\"\"\r\n```\r\nCalling the fucntion `make_tables()` will result in name resolution error for the foreign key reference `-\u003e A` inside the definition of `B` despite the fact that the following works just fine:\r\n\r\n```python\r\nschema = dj.schema('test', locals())\r\n    \r\n@schema\r\nclass A():\r\n    definition = \"\"\"\r\n    id:  int     # id\r\n    \"\"\"\r\n@schema\r\nclass B():\r\n    definition = \"\"\"\r\n     -\u003e A\r\n     \"\"\"\r\n```\r\n\r\nThe problem arise due to the fact that, for some reasons, the dictionary returned by the `locals()` do *not* stay updated when used inside a function. This can be demonstrated by the following code:\r\n\r\n```python\r\ndef test_locals():\r\n    names = locals()\r\n    print(names.keys())   # will print out []\r\n    # add new variables\r\n    a = 10\r\n    b = 5 \r\n    print(names.keys())   # still print out []!\r\n    print(locals().keys())  # ['names', 'a', 'b']\r\n    print(names.keys())   # ['names', 'a', 'b']\r\n```\r\n\r\nThis makes the use of `locals()` highly unreliable inside a function.","author":{"url":"https://github.com/eywalker","@type":"Person","name":"eywalker"},"datePublished":"2017-10-04T06:52:44.000Z","interactionStatistic":{"@type":"InteractionCounter","interactionType":"https://schema.org/CommentAction","userInteractionCount":5},"url":"https://github.com/368/datajoint-python/issues/368"}