Chapter Summary

This chapter introduced the core ideas behind function definition—the syntax and operation of the def and return statements, the behavior of function call expressions, and the notion and benefits of polymorphism in Python functions. As we saw, a def statement is executable code that creates a function object at runtime; when the function is later called, objects are passed into it by assignment (recall that assignment means object reference in Python, which, as we learned in Chapter 6, really means pointer internally), and computed values are sent back by return. We also began exploring the concepts of local variables and scopes in this chapter, but we’ll save all the details on those topics for Chapter 17. First, though, a quick quiz.