CS61A-lecture7-Function-Abstraction

(Updated: )
note › CS61a

Function Abstractions

eg:

1
2
3
4
5
def square(x):
  return mul(x, x)

def sum_squares(x, y):
  return square(x) + square(y)

What dos sum_squares need to know about square?

  • square need to know square exactly take one argument
  • no need to know the intrinsic name square, it can be bonded to any name
  • need to know the behavior of the square
  • do not need to know square compute the square by calling mul

choosing name

name typically don’t matter fo correctness
but they matter a lot for composition

  • name should convey the meaning or purpose of the values to which they are bound.
  • the type of value bound to the name is best documented in a function’s docstring.
  • function names typically convey their effect , their behavior , or the value returned.

Error & tracebacks

error

  • syntax errors, caused by expression not formal
  • run time error, it can be see a traceback
  • logical error, write test to check code