善用 lru_cache 對設定檔進行 cache

python 3 原生提供了一個簡易的 cache decorator 叫 lru_cache，可以把耗時的函數執行結果儲存起來，一段時間就刪掉

舉例來說下面這段 code

@lru_cache()
def say_hi(name: str):
    return f'Hello {name}'

的循序圖大概長這樣

sequenceDiagram
  code->>say_hi(): say_hi(name='test')
  say_hi()->>func: exec
  func-->>code: result
  code->>say_hi(): say_hi(name='test')
  say_hi()-->>code: result
  code->>say_hi(): say_hi(name='tom')
  say_hi()->>func: exec
  func-->>code: result
  code->>say_hi(): say_hi(name='tom')
  say_hi()-->>code: result
  code->>say_hi(): say_hi(name='test')
  say_hi()-->>code: result

搭配 magic method 可以對設定的東西做到簡單的 cache 功能