pymake

A build system based on Build Systems à la Carte
git clone https://git.grace.moe/pymake
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once.py (812B)

      1 from typing import Any
      2 from asyncio import Future
      3 from functools import wraps
      4 from inspect import signature
      5 
      6 
      7 def once():
      8     def decorator(f):
      9         futs: dict[tuple[Any, ...], Future] = {}
     10         sig = signature(f)
     11 
     12         @wraps(f)
     13         async def wrapped(*args, **kwargs):
     14             bound_args = sig.bind(*args, **kwargs)
     15             bound_args.apply_defaults()
     16             key = tuple(bound_args.arguments.values())
     17             if key in futs:
     18                 return await futs[key]
     19             futs[key] = Future()
     20             try:
     21                 res = await f(*args, **kwargs)
     22                 futs[key].set_result(res)
     23                 return res
     24             except BaseException as e:
     25                 futs[key].set_exception(e)
     26                 raise
     27 
     28         return wrapped
     29 
     30     return decorator