Python Crash Course

started from p.130

Functions

Docstring
Usually placed at top of function/program

"""Describe what the function does"""

Generated documentation also uses this docstring.

Write a function called display_message() that prints one sentence telling everyone what you are learning about in this chapter. Call the function, and make sure the message displays correctly.

I decide to modify it a little (like second lesson)

def display_message(subject):
    print(f"In this chapter I'm learning: {subject}")
 
display_message("Functions")

Mixing argument’s order when you call function, can produce unexpected behavior. Mixing keywords is fine.

Using default values can simplify your function calls and clarify the ways your functions are typically used.

When you use default values, any parameter with a default value needs to be listed after all the parameters that don’t have default values. This allows Python to continue interpreting positional arguments correctly.

1. Location of exception (file/function)
2. Exception type with additional details

This is another motivation for giving your variables and functions descriptive names. If you do, Python’s error messages will be more useful to you and anyone else who might use your code.

8-3. T-Shirt: Write a function called make_shirt() that accepts a size and the text of a message that should be printed on the shirt. The function should print a sentence summarizing the size of the shirt and the message printed on it. Call the function once using positional arguments to make a shirt. Call the function a second time using keyword arguments

Functions 137 8-4. Large Shirts: Modify the make_shirt() function so that shirts are large by default with a message that reads I love Python. Make a large shirt and a medium shirt with the default message, and a shirt of any size with a different message. 8-5. Cities: Write a function called describe_city() that accepts the name of a city and its country. The function should print a simple sentence, such as Reykjavik is in Iceland. Give the parameter for the country a default value. Call your function for three different cities, at least one of which is not in the default country.