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Introspection with Python

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scottcrespo

Presentation given to the Orlando Python Meetup. "Introspection is a feature of some programming languages that allows a running program to obtain information about its own implementation." - Free On-Line Dictionary of Computing Introspection is often the entry point to framework development and other advanced programming concepts.

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Introspection with Python “Know thy object…Know thyself” -Socrates
Introspection
Introspection (tech)
Python • Strong introspection support • Consistent object interface • Flexible typing allows for serious meta-programming
Lets Talk to Some Objects!
What can you tell me? >>> dir(isinstance) ['__call__', '__class__', '__cmp__', '__delattr__', '__doc__', '__eq__', '__format__', '__ge__', '__getattribute__', '__gt__', '__hash__', '__init__', '__le__', '__lt__', '__module__', '__name__', '__ne__', '__new__', '__reduce__', '__reduce_ex__', '__repr__', '__self__', '__setattr__', '__sizeof__', '__str__', '__subclasshook__'] >>>
Tell me about yourself? >>> isinstance.__doc__ "isinstance(object, class-or-type-or-tuple) -> boolnnReturn whether an object is an instance of a class or of a subclass thereof.nWith a type as second argument, return whether that is the object's type.nThe form using a tuple, isinstance(x, (A, B, ...)), is a shortcut fornisinstance(x, A) or isinstance(x, B) or ... (etc.)." >>>
What class do you belong to? >>> isinstance.__class__ <type 'builtin_function_or_method'> >>>
Let’s Make a Person >>> class Person(object): ... """represents a human""" ... def talk(self): ... print "Hello, I'm a person!" ... >>> p = Person() >>> p.talk() Hello, I'm a person! >>> dir(p) ['__class__', '__delattr__', '__dict__', '__doc__', '__format__', '__getattribute__', '__hash__', '__init__', '__module__', '__new__', '__reduce__', '__reduce_ex__', '__repr__', '__setattr__', '__sizeof__', '__str__', '__subclasshook__', '__weakref__', 'talk'] >>> p.__doc__ 'represents a human' >>> >>> p.__module__ '__main__' >>>
Do you have Something I’m Looking For? >>> hasattr(p, 'talk') True >>> hasattr(p, 'grunt') False >>>
The Inspect Module >>> inspect.getmodule(p) <module '__main__' (built-in)> >>> >>> inspect.ismethod(p.talk) True >>>
Framework Development Using Introspection
Program Structure • Import all modules in CWD that start with “test” • Import all class in modules that start with “Test” • Create instances of classes • Call all member functions that start with “test”
See Text Editor
Upcoming Events! Orlando Data Science January 26 Apache NiFi: Joe Witt of Hortonworks Meetup.com/orlandodata Orlando Golang Meetup February 11 Testing in Go Meetup.com/orlandogolang
Thank You! Scott Crespo SSE, The Topps Company • scott@orlandods.com • Linkedin.com/in/scottcrespo • Github.com/scottcrespo • ODev Slack: scottcrespo • Code Examples: github.com/scottcrespo/introspection_demo

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Introspection with Python

  • 1. Introspection with Python “Know thy object…Know thyself��� -Socrates
  • 4. Python • Strong introspection support • Consistent object interface • Flexible typing allows for serious meta-programming
  • 5. Lets Talk to Some Objects!
  • 6. What can you tell me? >>> dir(isinstance) ['__call__', '__class__', '__cmp__', '__delattr__', '__doc__', '__eq__', '__format__', '__ge__', '__getattribute__', '__gt__', '__hash__', '__init__', '__le__', '__lt__', '__module__', '__name__', '__ne__', '__new__', '__reduce__', '__reduce_ex__', '__repr__', '__self__', '__setattr__', '__sizeof__', '__str__', '__subclasshook__'] >>>
  • 7. Tell me about yourself? >>> isinstance.__doc__ "isinstance(object, class-or-type-or-tuple) -> boolnnReturn whether an object is an instance of a class or of a subclass thereof.nWith a type as second argument, return whether that is the object's type.nThe form using a tuple, isinstance(x, (A, B, ...)), is a shortcut fornisinstance(x, A) or isinstance(x, B) or ... (etc.)." >>>
  • 8. What class do you belong to? >>> isinstance.__class__ <type 'builtin_function_or_method'> >>>
  • 9. Let’s Make a Person >>> class Person(object): ... """represents a human""" ... def talk(self): ... print "Hello, I'm a person!" ... >>> p = Person() >>> p.talk() Hello, I'm a person! >>> dir(p) ['__class__', '__delattr__', '__dict__', '__doc__', '__format__', '__getattribute__', '__hash__', '__init__', '__module__', '__new__', '__reduce__', '__reduce_ex__', '__repr__', '__setattr__', '__sizeof__', '__str__', '__subclasshook__', '__weakref__', 'talk'] >>> p.__doc__ 'represents a human' >>> >>> p.__module__ '__main__' >>>
  • 10. Do you have Something I’m Looking For? >>> hasattr(p, 'talk') True >>> hasattr(p, 'grunt') False >>>
  • 11. The Inspect Module >>> inspect.getmodule(p) <module '__main__' (built-in)> >>> >>> inspect.ismethod(p.talk) True >>>
  • 13. Program Structure • Import all modules in CWD that start with “test” • Import all class in modules that start with “Test” • Create instances of classes • Call all member functions that start with “test”
  • 15. Upcoming Events! Orlando Data Science January 26 Apache NiFi: Joe Witt of Hortonworks Meetup.com/orlandodata Orlando Golang Meetup February 11 Testing in Go Meetup.com/orlandogolang
  • 16. Thank You! Scott Crespo SSE, The Topps Company • scott@orlandods.com • Linkedin.com/in/scottcrespo • Github.com/scottcrespo • ODev Slack: scottcrespo • Code Examples: github.com/scottcrespo/introspection_demo