Wednesday 10/11

Scope and Modules

Scope

What will be printed by the following python script?

name = "Herman"

def print_greeting(alias):
    name = alias
    print(name)

def print_hello():
    print("Hello", name)


print_greeting("Mary")
print_hello()
print(name)

How about this one?

names = ["Herman", "Alice"]

def print_greeting(alias):
    names.append(alias)
    print(names[0])

def print_hello():
    print("Hello", names[-1])


print_greeting("Mary")
print_greeting("Jane")
print_hello()
print(names)

Variables assigned inside function have local scope, variables declared outside of any function have global scope.

Modules

Consider the following two python files:

geometry.py

"""Useful geometry functions."""

origin = (0, 0)

def distance(point_a, point_b):
    return ( (point_a[0] - point_b[0])**2
           + (point_a[1] - point_b[1])**2)**.5


print("Let's calculate the distance from the origin!")
x = float(input("x: "))
y = float(input("y: "))
print(distance(origin, (x, y)))

finder.py

import geometry

def furthest(start, points):
    largest_distance = -1
    index_largest = -1

    for i, point in enumerate(points):
        dist = geometry.distance(start, point)
        if dist > largest_distance:
            largest_distance = dist
            index_largest = i

    return index_largest

locations = [(10, 10),
             (1, 1),
             (100, 100)]
print(furthest(geometry.origin, locations))

What will happen when we run finder.py?

Quiz Instructions

• Log into the desktop as student with no password.
• Log into Canvas.
• Wait until the instructor says to start before accessing Part 1.
• The quiz can be found in the "Modules" section of Canvas.
• The entire quiz has a 25 minute time limit.
• Part 1 (Conceptual):
  • You may not use Thonny (or any other resources) for Part 1.
• Part 2 (Coding):
  • You have unlimited submissions.
  • You do NOT need to provide docstrings.
  • The autograder will NOT check for PEP8 violations (though you should still use good style.)
  • You must use Thonny as your editor.
  • You may not access any external web pages or other resources.