Python Function Signatures and Calling Conventions

in

Today we’re going to talk about function signatures and calling conventions two of the most important concepts in programming that are often misunderstood or overlooked by beginners. Don’t Worry, because I’m here to make it fun and easy for you!

First things first: what is a function signature? It’s basically just a fancy way of saying “what goes into the function” (the arguments) and “what comes out” (the return value). For example, let’s take a look at this simple function called `add_numbers`:

# Defining a function called "add_numbers" with two parameters, x and y, both of type integer, and a return type of integer
def add_numbers(x: int, y: int) -> int:
    """Add two numbers together"""
    # Creating a variable called "result" and assigning it the value of x + y
    result = x + y
    # Returning the value of "result" as the output of the function
    return result

The signature for this function is `(int, int) -> int`. That means it takes in two integer arguments (`x` and `y`) and returns an integer. Pretty straightforward!

Now calling conventions how you actually call the function once you have its signature.In Python, there are a few different ways to do this depending on whether or not you want to pass in default arguments:

# Defining the function add_numbers with two integer arguments (x and y) and returning an integer
def add_numbers(x: int, y: int) -> int:
    return x + y

# Calling the function with all required arguments (no defaults)
result = add_numbers(5, 10)
print(result) # Output: 15

# Calling the function with only one argument (default for the other is used)
result2 = add_numbers(x=10, y=25) # Passing in both arguments explicitly
print(result2) # Output: 35

Notice that in the second example, we’re passing in a default value of `10` for the first argument using keyword arguments (i.e., `x=10`). This is because the function signature specifies that both `x` and `y` are required arguments, but it also allows you to pass them in as keyword arguments if you prefer.

Function signatures and calling conventions two important concepts for any Python programmer. Remember: always check the function signature before using a new library or module, and make sure your own functions are well-documented with clear and concise comments.

SICORPS