Python Functions

Wrapping work in a name, with arguments that read at the call site.

Defining and calling

A function is a block with a name and a result. Naming arguments at the call site keeps the meaning visible without opening the definition.

def greet(name, greeting="Hello"):
    return f"{greeting}, {name}!"

print(greet("Grace"))
print(greet("Alan", greeting="Hi"))

Output:

Hello, Grace!
Hi, Alan!

Returning several things

A function returns one object; a tuple makes that one object several values, unpacked by the caller.

def split_name(full):
    first, _, last = full.partition(" ")
    return first, last

first, last = split_name("Ada Lovelace")
print(first, "|", last)

Output:

Ada | Lovelace

Next

Carry on to the next tutorial in the rail — it picks up where this one leaves off.