[New-bugs-announce] [issue27933] functools.lru_cache seems to not work when renaming decorated functions

[Федор Лянгузов]

New submission from Федор Лянгузов:

Greetings,

I've encountered strange behavior when using functools.lru_cache as a function (not as a decorator): it is at least miscounting misses, but probably not work at all, when the result of functools.lru_cache()(func) is saved in variable other than 'func'. Consider this snippet:

def factorial(n):
    if n == 0:
        return 1
    else:
        return n * factorial(n-1)

f = functools.lru_cache()(factorial)
f(20)
print(f.cache_info())

Output should be: CacheInfo(hits=0, misses=21, maxsize=128, currsize=21)
Instead it is: CacheInfo(hits=0, misses=1, maxsize=128, currsize=1)

I'm using Python 3.5.2 64bit on Windows 7 Professional 64bit.
I've written 3 unittests (using built-in module), which are attached as a file. I don't know how to comment them (conceptually, not syntactically), sorry.

Fedor

----------
components: Library (Lib)
files: lru_cache_test.py
messages: 274149
nosy: Федор Лянгузов
priority: normal
severity: normal
status: open
title: functools.lru_cache seems to not work when renaming decorated functions
type: behavior
versions: Python 3.5
Added file: http://bugs.python.org/file44325/lru_cache_test.py

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<http://bugs.python.org/issue27933>
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