The Complete Guide to Python Switch

Python, unlike some other programming languages, lacks a built-in switch statement. Switch case statements enable a program to run various code blocks based on the value of a variable or expression.

Fortunately, there are many methods that allow you to reach the same effects with Python.

In this article, we will explore the new switch case feature in Python. We'll provide examples to make the process more intuitive and explain three unique methods for coding it out.

What is a switch statement in Python?

In Python, a switch statement helps ascertain which code block should be executed depending on the value of an expression or variable. However, this language does not have built-in support.

If you‘re seeking to replicate the switch’s behavior, one option is using multiple if/elif statements. Take the following example:

In this scenario, if/elif statements detect the value of the fruit variable and then execute its related code block.

Another way to enable switch-like behavior in Python is by using a dictionary. This can be applied to link possible values with their respective code blocks. You can see dictionary in action below.

By using a dictionary, it's easy to link the values of the fruit variable with their relevant functions. The get method acquires the correct function corresponding with each respective value of the fruit. Then, this retrieved function is executed.

When to Use Switch Statements in Python

Given its versatility and ability to reduce the amount of code needed, switch in Python is an excellent choice for performing operations based on multiple possible values of a variable.

In contrast to if/elif statements and dictionary methods, this feature provides a more straightforward syntax while reducing the chance of errors. Moreover, the switch statement offers better readability and increases code maintainability.

If you're looking to enhance your Python code's clarity, using a switch-like construct is an ideal solution. In scenarios where there are various routes of execution based on the value of a variable, this type of structure can make it more legible. Plus, opting for if/elif statements or a dictionary with function mappings ensures that all elements remain organized.

By implementing a switch-like construct, your code can become more efficient. When the code block is populated with multiple if/elif statements, every condition must be evaluated in sequence. This can be avoided with switch-like constructs, allowing the code to run faster.

How to Use Switch Statements in Python

Python does not natively support switch-like structures. However, the language does provide alternatives for replicating this functionality. We’ll explain how to do so below.

To use a switch statement in Python, you need to create a dictionary with each of your case statements mapped to their corresponding functions. This dictionary is then used in conjunction with the get() method to retrieve the relevant function based on the value of the expression. Here is example syntax:

In this example, the switch_dict dictionary is created with two key-value pairs that map each of the cases to their relevant functions. Then, the get() method retrieves and executes the function that corresponds with the value of the expression.

The get() method takes two parameters: the key to retrieve and an optional default argument that specifies which function should be called in case there is no match found for the specified key.

To ensure proper execution, it's important to include a lambda function as a default argument when using this approach — otherwise, an error will be thrown if no matching case is found.

By using a switch statement in Python, you can create efficient, intuitive code that is easy to read and comprehend. It's a great way to reduce the amount of code needed while ensuring maximum performance.

Python Switch in Action

Now that we’ve discussed switch statements in Python, let’s explore a few examples of this code in action. Check out three examples below.

1. Using a dictionary to define a switch in Python.

The above code defines three functions (apple(), banana(), and orange()) that each print a specific message about a fruit. It also defines a dictionary called fruit_dict that maps fruit names to their corresponding functions.

This code allows you to retrieve a fruit-related function from the fruit_dict dictionary based on the value of the fruit variable. The script then executes that function to print a specific message about the fruit. If the fruit value is not found in the dictionary, a default message is printed.

2. Using a variable to define a switch in Python.

This code defines three functions: do_1(), do_2(), and do_3(). Each function prints a specific message indicating the choice made. The last line of code retrieves a function from the switcher dictionary based on the value of the choice. If the value of choice does not match any of the keys in the dictionary, the get() method returns a default value.

In summary, this code implements a simple switch-case-like behavior in Python. Based on the value of the choice variable, a corresponding function is executed to print a specific message. If the choice is not found in the dictionary, an “Invalid choice” message is printed.

3. Using a class to define a switch in Python.

This code defines a class called FruitSwitch that encapsulates a fruit and provides methods to identify and print information about the fruit.

The code also creates a dictionary called “switcher.” This dictionary maps fruit names as strings to their corresponding methods (apple, banana, and orange). If the value of self.fruit matches one of the keys in the switcher dictionary, the corresponding method is returned by switcher.get().

If the value of self.fruit does not match any of the keys in the dictionary, the get() method returns a default value (“I'm not sure what fruit this is”).

In summary, this code defines a class that allows you to set a fruit and then retrieve a specific method associated with that fruit from the switcher dictionary. If the fruit is not found in the dictionary, a default message is printed.

Getting Started

You‘ve just learned how to use a Switch Case in Python programming. Now, it’s time to put that knowledge to use and create your own switch case. So go ahead and give it a shot!