PY3.W1518
Method cache max size none
By decorating a method with lru_cache or cache the 'self' argument will be linked to the function and therefore never garbage collected. Unless your instance will never need to be garbage collected (singleton) it is recommended to refactor code to avoid this pattern or add a maxsize to the cache. The default value for maxsize is 128.
Noncompliant Code:
Copy
import functools
class Fibonnaci:
@functools.lru_cache(maxsize=None) # [method-cache-max-size-none]
def fibonacci(self, n):
if n in {0, 1}:
return n
return self.fibonacci(n - 1) + self.fibonacci(n - 2)
Compliant Code:
Copy
import functool
@functools.cache
def cached_fibonacci(n):
if n in {0, 1}:
return n
return cached_fibonacci(n - 1) + cached_fibonacci(n - 2)
class Fibonnaci:
def fibonacci(self, n):
return cached_fibonacci(n)