28 lines
835 B
Python
28 lines
835 B
Python
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import functools
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def method_cache(fn):
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"""
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A decorator for instance based caching.
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Unlike lru_cache / memoization, this allows us to not have to have the
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instance itself be hashable - only the arguments must be so.
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The cache is stored as a dictionary in a private attribute on the instance
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with the name ``_cache_{func_name}``.
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"""
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cache_name = f'_cache_{fn.__name__}'
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@functools.wraps(fn)
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def cached_method(self, *args, **kwargs):
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cache = getattr(self, cache_name, None)
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if cache is None:
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cache = {}
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object.__setattr__(self, cache_name, cache)
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cache_key = hash(args + tuple(kwargs.items()))
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if cache_key not in cache:
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cache[cache_key] = fn(self, *args, **kwargs)
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return cache[cache_key]
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return cached_method
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