switch-case.md

Select-Case Statement Workaround

Some languages (including VBA) call it a "Select-Case" statement, some languages call it a "Switch-Case" statement, but Python calls it pointless.

In general the idea is the same; have a keyword that begins the search through a series of options a variable might be, and return a value next to it. The idea is one that emphasizes clean formatting and keeping all the possibilities close to each other, but Python's solution to the problem is quite literally a series of if/elifs. The only other option is a combination of dictionaries and the get method which I will display here:

default_answer = "Invalid Month Number"
months = {
        1: "January",
        2: "February",
        3: "March",
        4: "April",
        5: "May",
        6: "June",
        7: "July",
        8: "August",
        9: "September",
        10: "October",
        11: "November",
        12: "December"
    }

looking_for = 2
result = months.get(looking_for, default_answer)
print(result)  # Will print "February"

looking_for = 13
result = months.get(looking_for, default_answer)
print(result)  # Will print "Invalid Month Number"

If you are looking for an actual function or something along those lines you can use the below code, which makes use of closures to give a more general solution:

def select_case_closure(dict_of_posibilities, default_answer):
    def select_case(looking_for):
        return dict_of_posibilities.get(looking_for, default_answer)
    return select_case

One thing to note in Python to understand what is going on in the above code is to understand the difference adding () makes. If you have a method or function named/labeled in your code, you call it by adding the () at the end, otherwise you are simply referring to it. See below:

>>> def add_2(a, b):
...    return a + b
>>> add_2(5, 10)
15
>>> add_2
<function add_2 at 0x03AC60C0>

With the parentheses, the result is returned, without the parentheses, the function itself is returned. So in the case of a closure, I am actually returning a function that you can then use over and over, like so:

default_answer = "Invalid Month Number"
months = {
        1: "January",
        2: "February",
        3: "March",
        4: "April",
        5: "May",
        6: "June",
        7: "July",
        8: "August",
        9: "September",
        10: "October",
        11: "November",
        12: "December"
    }

def select_case_closure(dict_of_posibilities, default):
    def select_case(looking_for):
        return dict_of_posibilities.get(looking_for, default)
    return select_case  # returning the 'select_case' function defined inside the 'select_case_closure' function

select_case_months = select_case_closure(months, default_answer)
print(select_case_months(6))  # Will print "June"
print(select_case_months(33))  # Will print "Invalid Month Number"

The beauty of this solution is you can reuse it over and over. Any time you need a new select-case statement, call the select_case_closure function and pass in a dictionary full of the possibilities and the default answer to return if one isn't found. You will be returned a unique select-case function that you can then call and pass in only what you're looking for and it will return a value from the dictionary of possibilities if it can be found or the default answer if it cannot. You can have as many variations of the returned select-case functions as you need.