Lexical Scoping in Python

• What is a closure?

  • why is it helpful?

• Python’s underyling memory structure for functions

  • build up enough of an explanation that a language beginner can understand pyObjects,
  • explain how in CPython, a PyFuncObject has a pointer to a PyObject of default values, keyword defaults, etc.
  • https://github.com/python/cpython/blob/3db0a21f731cec28a89f7495a82ee2670bce75fe/Include/cpython/funcobject.h

A closure is stored as a variable (tuple of cell objects)

• What would you expect to occur naively?

What about in another familiar language, like java script?

How can you make this work?

Default parameters, where you fill in a value

Why does this work?

• Functions are also python objects! So, when you pass a default parameter, a copy of it at runtime becomes associated with the function object.
• what if the object is a list of lists?
  • Does a default parameter make a deep copy?
    • to do: run this experiment.