Python Exceptions

When something goes wrong in a Python program, you will run into an exception. Exceptions are raised when your program attempts to perform an action that is not allowed. Examples would be diving by 0 or adding a str and an int.

Handling Exceptions

Handling exceptions requires using the try/except keywords. You surround some code that could fail and cause an exception to be raised with the keyword try. The except keyword surrounds what to do in the case of an exception.

try: 
    1 / 0 
except:
    print('Exception')    

# You can also access the specific exception raised in order to operate on it. 

try:
    'hello' + 1
except TypeError as e:
    print(f'TypeError: {e}')
# This type of output is good for logging.

Raising Exceptions

Sometimes you want to inform the caller of your code that something went wrong.

# We define our function to operate on two variables that can be added together
def my_add_function(x, y):
    if type(x) != type(y):
        raise Exception('Both arguments must be of the same type')
    return f'{x} + {y} = {x + y}'        

z = my_add_function(1, 1)
# 1 + 1 = 2

a = my_add_function(1, 'chicken')
# Exception: Both arguments must be of the same type