Python functools.cache and lru_cache for memoization

import functools
import re
from typing import Callable

# functools.cache (Python 3.9+) — unlimited cache, equivalent to lru_cache(maxsize=None)
@functools.cache
def get_tag_pattern() -> re.Pattern:
    # Compiled once, cached forever
    return re.compile(r'^[a-z0-9][a-z0-9._-]{0,48}[a-z0-9]$|^[a-z0-9]$')

@functools.cache
def normalize_tag_cached(raw: str) -> str:
    return raw.strip().lower()[:50]

# lru_cache with max size (bounded memory)
@functools.lru_cache(maxsize=256)
def get_domain_for_tag(tag: str) -> str:
    # Expensive lookup — cached for last 256 unique tags
    return DOMAIN_MAPPING.get(tag, 'general')

# Cache with typed=True (treats int and float args as different)
@functools.lru_cache(maxsize=128, typed=True)
def wilson_score_cached(upvotes: int, total: int) -> float:
    if total == 0:
        return 0.0
    p = upvotes / total
    z = 1.9600
    n = total
    return (p + z*z/(2*n) - z * ((p*(1-p)+z*z/(4*n))/n)**0.5) / (1 + z*z/n)

# Method caching with cache_info
print(wilson_score_cached.cache_info())  # hits, misses, maxsize, currsize
wilson_score_cached.cache_clear()  # clear when needed

# For class methods — cache_info() works differently
class TagValidator:
    @functools.cached_property
    def pattern(self) -> re.Pattern:
        # Computed once per instance, on first access
        return re.compile(r'^[a-z0-9._-]+$')

    def validate(self, tag: str) -> bool:
        return bool(self.pattern.match(tag))