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50f76e58ce
We now instantiate NEXT_ID in sequencer.py, which avoids having multiple modules make multiple copies of a sequencer and possibly causing id collisions.
51 lines
1.1 KiB
Python
51 lines
1.1 KiB
Python
from typing import Callable, Dict
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'''
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This module helps you set up a bunch
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of sequences, similar to how database
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sequences work.
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You need to be a bit careful here, since
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you're dealing with a big singleton, but
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for data imports that's usually easy to
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manage. See hipchat.py for example usage.
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'''
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def _seq() -> Callable[[], int]:
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i = 0
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def next_one() -> int:
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nonlocal i
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i += 1
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return i
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return next_one
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def sequencer() -> Callable[[str], int]:
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'''
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Use like this:
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NEXT_ID = sequencer()
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message_id = NEXT_ID('message')
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'''
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seq_dict = dict() # type: Dict[str, Callable[[], int]]
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def next_one(name: str) -> int:
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if name not in seq_dict:
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seq_dict[name] = _seq()
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seq = seq_dict[name]
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return seq()
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return next_one
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'''
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NEXT_ID is a singleton used by an entire process, which is
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almost always reasonable. If you want to have two parallel
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sequences, just use different `name` values.
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This object gets created once and only once during the first
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import of the file.
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'''
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NEXT_ID = sequencer()
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