Elegant Solutions For Everyday Python Problems

Speaker

Nina Zaharenko (@nnja)

Material

• video
• slide

Note

Magic methods: __func__

• Custom iterator
  • __iter__: Make classes iterable
    • returns an iterator
  • __next__: Make class iterator
    • raises StopIteration when there is no more items to return
  • Use a generator when your iterator doesn't need to maintain a lot of state
• Method magic
  • getattr(object, name, default)
    • call function by name string
    • use case
      • cli tool with dynamic commands
  • functool.partial(func, *args, **kwargs)

Context manager

• perform an action before and/or after an operation
• use case
  • close a resource (e.g., file, network, database)
  • perform clean up before/after function call
  • feature flags: turn feature of your application on and off easily
    • A/B Testing
    • Rolling Releases
• from contextlib import contextmanager

Decorators

• Wrap a function in another function to do something
  • before the call
  • after the call
  • with provided arguments
• Problem: lost context using a decorator
  • Solution: from contextlib import wraps
• Use case
  • logging
  • timing
  • validation
  • rate limiting
  • mocking/patching

ConextDecorator

• By use it, you can write classes that can be used both as decorator and context managers
  • It's included if implemented through from contextlib import contextmanger.

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