Semicolons

Languages such as Java and C/C++ used a terminator to indicate the end of a line of code- most often the semicolon ( ; ). While this is not a mandatory feature for Python, you can still use semicolons as line separators. I personally use semicolons to make the most out of horizontal space in my code by combing initialization lines or similar expressions.

a = 1
b = 3.14
c = 'statement'
d = False

a = 1; b = 3.14 # numbers
c = 'statement' # strings
d = False # bools

Ternary Operator

Have you ever felt like some if-else cases appear to use too many lines?

x = 3; y = 4
if x < y:
    return 0
else:
    return 1

Enter the ternary operator, a one-line method of the form a if b else c, where b is your condition, a is your expression for the condition returning true, and c is the value passed is the condition returns false.

x = 3; y = 4
z = 0 if x < y else 1

Ternary operations can also be used as values inside other ternary operators!

x = 3; y = 4
s = "equal" if x == y else "less than" if x < y else "greater than"
print(s)

Type Hints and Annotations

def func(a: int, b: int = 1) -> int:
    return a + b - 5

def func(a: "fun value", b: "also a fun value" = 1) -> "sum of fun values":
    return a + b - 5

You can access the annotations by calling func.__annotations__, which returns the list of annotations in order.

Decorators

def decorator(func):
    def wrapper(*args, **kwargs):
        # decorator function code
        pass
return wrapper(*args, **kwargs)

@decorator
def func(x):
    return x + 1

Colon-Equals Operator (:=)

Similar to equals (=), Colon-Equals (:=) allows you to assign values to variables, with the added benefit of being able to do this in expressions! This is especially helpful when you would otherwise calculate a value twice, (once for use in the expression, and once in the post-condition).

def powers(x):
    # This list includes the value f(x) while assigning it to the variable y
    return [y := f(x), y**2, y**3, y**4]

The Integer Cache

Did you know that Python maintains a list of pre-defined objects for integers in the range [-5, 256]? To everyone’s surprise, this cache also comes with some quirks, especially if you do some comparisons at the edge of its range:

>>> a = 1
>>> b = 1
>>> a is b
True

>>> a = 257
>>> b = 257
>>> a is b
False

… unless you run the assignments and expression in-line with semi-colons, in which case the comparison works outside of the integer cache range.

>>> a = 257; b = 257; a is b
True

Zip and Enumerate

String multiplication

Strings in Python come with a lot of freedom compared to other programming langauges. There’s a lot of cool tricks that most programmers already take advantage of, (treating strings as list for indexing, string addition), but you can also perform string multiplication. This feature allows you to perform a large number of string additions more efficiently.

string_3 = 'string_' * 3
print(string_3) # -> 'string_string_string' 

Built-in Import Easter eggs

There’s a few built-in imports with fun Easter eggs for the truly curious…

import this -> prints 19 guiding principles for writing computer programs, by Tim Peters

import antigravity -> directly links to an XKCD comic.