monty.design_patterns module¶
Some common design patterns such as singleton and cached classes.
- cached_class(klass: type[Klass]) type[Klass] [source]¶
Decorator to cache class instances by constructor arguments. This results in a class that behaves like a singleton for each set of constructor arguments, ensuring efficiency.
Note that this should be used for immutable classes only. Having a cached mutable class makes very little sense. For efficiency, avoid using this decorator for situations where there are many constructor arguments permutations.
The keywords argument dictionary is converted to a tuple because dicts are mutable; keywords themselves are strings and so are always hashable, but if any arguments (keyword or positional) are non-hashable, that set of arguments is not cached.