Objects and classes in Python

Contents:

• Decorators
  • The decorator syntax
  • Bound methods
  • staticmethod()
  • classmethod()
  • The call() decorator
  • Nesting decorators
  • Class decorators before Python 2.6
• Constructing classes
  • The empty class
• dict_from_class()
  • The __dict__ of the empty class
  • Is the doc-string part of the body?
  • Definition of dict_from_class()
• property_from_class()
  • About properties
  • Definition of property_from_class()
  • Using property_from_class()
  • Unwanted keys
• Deconstructing classes
• type(name, bases, dict)
  • Constructing the empty class
  • Constructing any class
  • Specifying __doc__, __name__ and __module__
• Subclassing int
  • Mutable and immutable types
  • Enumerated integers and named tuples
  • The bool type
  • Emulating bool - the easy part
  • Emulating bool - what goes wrong
  • Emulating bool - using __new__
  • Understanding int.__new__
• Subclassing tuple
  • The desired properties of Point
  • Answer
• What happens when you call a class?
  • Creation and initialisation
  • The default __new__
  • Summary
• Metaclass
  • Every object has a type
  • The metaclass of an object
  • A trivial non-type metaclass
  • A non-trivial example
  • What’s the point?
• The __metaclass__ attribute
  • Automatic subclassing of object
  • Review of type(name, bases, body) and class statement
  • The basic principle of the __metaclass__
  • A very silly example
  • A less silly example
  • A __metaclass__ gotcha
  • A decorator example
• Decorators versus __metaclass__
  • Bunch using decorators
  • Bunch using __metaclass__
  • How __metaclass__ works
  • Discussion
• JavaScript objects
  • Like Python classes
  • Custom item methods
  • On metaclass
  • Never instantiated
  • Conclusion
• Exercise: A line from a file
• Exercise: Property from class decorator
• Exercise: Named integers
• Exercise: Subset of a set
• Exercise: Class to and from class data
• Exercise: Your own class to class decorator

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