Memoizer

API

A Memoizer can be used as a factory for creating objects of a certain class. It exposes a constructor and 2 methods

• memoizer = Memoizer(SomeClass)
• memoizer.get(*args, **kwargs)
  • If memoizer has never seen the given arguments, it creates SomeClass(*args, **kwargs) and returns it.
  • If memoizer has seen the given arguments before, it returns the same instance that it returned the last time.
• memoizer.forget(*args, **kwargs)
  • Makes memoizer forget that is has seen the given arguments.

Usage

The original application was for a MeasurementQueue class that processes incoming sensor data from many sensors, where the sensor ID's were not known ahead of time:

queue_manager = Memoizer(MeasurementQueue)

for sensor_id, data in event_stream():
    queue = queue_manager.get(sensor_id)
    queue.push(data)

When the first measurement comes in for a given sensor_id, a new MeasurementQueue will be created and returned for that sensor. On subsequent events with the same sensor ID, the same MeasurementQueue instance will be used to process the data.

Installation

pip install classmemo

The only dependencies are Python 3.6 and the frozendict package.

Contributing

• Ensure the tests pass: pytest .
• Format the code with black . -t py36