Sep 16: Variable Scope, Docstrings

Learning Objectives

After today's class, you should be able to:

• Explain the difference between global and local variables.
• Write a docstring for a function (following Google's Style).
• Use help() to explore modules and functions in a shell.

Announcements

• Feedback on Gradescope [5 min]
  • See Quiz1 (written + coding)
• Due tomorrow
  • Ch 4 on zyBooks
  • HW 4 on Gradescope
• Practice Quiz 2 on Wednesday
  • Based on HW 3 and HW 4
• This Friday: What is CS Research?

Return Examples

• Run in Python Tutor   [5 min]

# Example 1: No return statement

def greeting():
    print("Have a nice day!\n")


# Example 2: One return statement

def time_str(hour, minute):
    if hour < 12:
        ampm = "AM"
    else:
        ampm = "PM"
        hour -= 12
    if hour == 0:
        hour = 12
    return f"{hour}:{minute:02d} {ampm}"


# Example 3: Multiple return statements

def analyze(number):
    if number == 0:
        return "Zero!"
    if number > 0:
        return "Positive"
    return "Negative"


# Example 4: Multiple return values

def stats(grades):
    avg = sum(grades) / len(grades)
    return min(grades), avg, max(grades)


print("1:", greeting())
print("2:", time_str(12, 5))
print("3:", analyze(-1))
print("4:", stats([95, 71, 100, 88]))

Bank of JMU Lab

Slides   Code   [40 min]

Highlights:

• Thonny debugger's with functions
• Functions that modify parameters
• Writing docstrings for functions
• Using the built-in help() function