Idioms in Python helps in performing a range of tasks. As a programmer, you shall learn this module. Learn more about this Python module in this guide.
Idioms in Python: Dictionary key initializations
Prefer dict.get method if you are not sure if the key is present. It allows you to return a default value if key is not found. The traditional method dict[key] would raise a KeyError exception.
Rather than doing
students['count'] += 1
students['count'] = 1
students[‘count’] = students.get(‘count’, 0) + 1
To switch the value of two variables you can use tuple unpacking.
x = True
y = False
x, y = y, x
Use truth value testing
Python will implicitly convert any object to a Boolean value for testing, so use it wherever possible.
Good examples, using implicit truth testing if attr:
if not attr:
Bad examples, using specific types if attr == 1:
if attr == True:
if attr != '':
If you are looking to specifically check for None, use 'is' or 'is not' if attr is None:
This generally produces more readable code, and is usually much safer when dealing with unexpected types.
Click here for a list of what will be evaluated to False.
Idioms in Python: Test for “main” to avoid unexpected code execution
It is good practice to test the calling program’s name variable before executing your code.
Your code starts here
Don't forget to provide a return code return 0
if name == "main":
Using this pattern ensures that your code is only executed when you expect it to be; for example, when you run your file explicitly:
The benefit, however, comes if you decide to import your file in another program (for example if you are writing it as part of a library). You can then import your file, and the main trap will ensure that no code is executed unexpectedly:
A new program file
import my_program # main() is not run
But you can run main() explicitly if you really want it to run: my_program.main()