DIY Switch statement tutorial in Python

switch.py

# This is an example of switch statements in Python
# Switch statements are not a part of libpython (my nickname for the python standard library) or the Python Language Standard
# But they are very easy to DIY, and they improve readability, and performance!!

# Lets say we want to return the age for a passed name
def get_age(name):
  # You might think to start writing if statements, and for something small, that is fine. But they can get real messy and hard to edit
  # Let's use a DIY switch statement instead!!!
  
  switch = {
     "John": 22,
     "Mark": 13,
     "Daniel": 16,
     "Bob": 19,
     "Julia":33
  }
  
  # What we just made is a dictionary, it's sorta like python's built in version of JSON.
  # Dictionaries allows us to set a key (the value to the left of the ':') and a pair (the value to the right of the ':')
  
  return switch.get(name, "Invalid name")

  # What we are now doing is getting the value of the key (the key is the name)
  # This means we dont have to check if a name has a age paired to it
  # We just try to get the age without checking if it exists
  
  # But what if it doesnt exist?
  # Well that is why we aren't just returning 'switch[name]' (which is valid python code!)
  # The 'get' method automatically handles if there is no key with the name we passed.
  # it just returns the second argument we passed if it can't find the key.
  # For us we just set the second argument to be "Invalid name"
  # That means if we pass a name that doesn't exist. It just returns "Invalid name"
  # This is very easy to implement yourself, but why not let the language do it for you?
 

# Here we finally try the code
john_age = get_age("John")
daniel_age = get_age("Daniel")
bob_age = get_age("Bob")
julia_age = get_age("Julia")

# If we were to use if + elif + else statement instead of our DIY switch statement, the further we got down the list of names
# The longer it would take to return the age!

# But with switch statements, we ignore all the other names and just return the age of the passed name]

unknown_age = get_age("ALIENS!!!")

print(john_age)
print(daniel_age)
print(bob_age)
print(julia_age)

print(unknown_age)

"""
Output:

22
16
19
33
Invalid name
"""