Python Tip #88 (of 365):
When assigning multiple variables to the same initial immutable value, use multiple assignment
Instead of this:
x = 0
y = 0
You can do this:
x = y = 0
That's safe as long as the value is immutable (numbers, strings, booleans, or None).
#Python #DailyPythonTip
Python Tip #87 (of 365):
Use tuple unpacking to swap references 🧵
You can use tuple unpacking to swap the values of 2 variables in #Python:
x, y = y, x
Outside of feeling clever in an interview, you may NEVER need to do that... but you MIGHT need to do something similar.
#DailyPythonTip
Python Tip #86 (of 365):
Acknowledge that containment is (sort of) a lie. 🧵
Data structures in Python don't contain data...
Well, at least data structures don't contain objects.
#Python #DailyPythonTip
Python Tip #85 (of 365):
Think of variables as pointers. 🧵
When explaining your code in Python, be sure to disambiguate between the 2 types of change (assignments and mutations).
#Python #DailyPythonTip
Python Tip #84 (of 365):
Use variables to improve code clarity. 🧵
Today's tip is the inverse of yesterday's tip.
Well-named variables CAN make your code more readable and they don't really make your code less efficient (after all, variables are just pointers).
#Python #DailyPythonTip
Python Tip #83 (of 365):
Don't overuse variables in Python. 🧵
Expressions are valid almost anywhere in Python.
If a variable isn't needed to refer to a value multiple times AND the variable isn't clearer than the expression it replaces, just use the expression instead.
#Python #DailyPythonTip
Python Tip #82 (of 365):
Don't assign 2 variables to the same mutable object. 🧵
An assignment of one variable to another ("x = y") is usually only a good idea for IMMUTABLE VALUES.
#Python #DailyPythonTip
Python Tip #81 (of 365):
Normalize cases with the string casefold method. 🧵
When normalizing the cases of strings for the sake of a comparison, consider using casefold instead of lower or upper.
#Python #DailyPythonTip
Python Tip #80 (of 365):
Concatenate iterables with the string join method. 🧵
Instead of this:
guests = ""
for name in names:
if guests:
guests += ", "
guests += name
Do this:
guests = ", ".join(names)
#Python #DailyPythonTip
Python Tip #79 (of 365):
Don't use strip if you just need to remove a single character 🧵
To remove a single trailing newline, instead of using rstrip:
line = line.rstrip("\n")
Consider using removesuffix:
line = line.removesuffix("\n")
#Python #DailyPythonTip
Python Tip #78 (of 365):
Don't remove string prefixes and suffixes manually. 🧵
Instead of this:
normalized = hex_value.lower()
if normalized.startswith("0x"):
normalized = normalized[2:]
Do this:
normalized = hex_value.lower().removeprefix("0x")
#Python #DailyPythonTip
Python Tip #77 (of 365):
Need to check for the presence of prefixes or suffixes? Use startswith or endswith. 🧵
Instead of this:
test_key = (API_KEY[:5] == "test-")
Do this:
test_key = API_KEY.startswith("test-")
#Python #DailyPythonTip
Python Tip #76 (of 365):
Don't call the string split() method with a space character 🧵
Instead of this:
words = some_string.split(" ")
Do this:
words = some_string.split()
#Python #DailyPythonTip
Python Tip #75 (of 365):
Don't use the string split() method for splitting lines.
Instead of this:
lines = poem.split("\n")
Do this:
lines = poem.splitlines()
The string splitlines method will:
• Trim a trailing newline (if there is one)
• Split by "\r\n", "\n", or "\r"
#Python #DailyPythonTip
Python Tip #74 (of 365):
Print blank lines with print()
Instead of this:
print("TITLE\n")
print("Descrption")
Consider this:
print("TITLE")
print()
print("Descrption")
It's easier to see there's meant to be a blank line when a separate print call is used.
#Python #DailyPythonTip
Python Tip #73 (of 365):
Use self-concatenation to make horizontal rules
To print 80 '=', '-', or '*' characters, you can multiply a single-character string by the number 80:
print("-" * 80)
#Python #DailyPythonTip
Python Tip #72 (of 365):
You can redirect all printed output in Python with contextlib.redirect_stdout 🧵
from contextlib import redirect_stdout
import io
with redirect_stdout(io.StringIO()) as output:
print("hello")
printed_text = output.getvalue()
#Python #DailyPythonTip
Python Tip #71 (of 365):
Print non-standard output to standard error 🧵
Python's print function writes to the "standard output" stream by default.
But terminals have a second output stream that also writes to the screen: standard error.
#Python #DailyPythonTip
Python Tip #70 (of 365):
Print partial lines by specifying end="" 🧵
Instead of writing to "sys.stdout" to avoid printing newlines:
sys.stdout.write(prefix)
sys.stdout.write(remainder + "\n")
Consider passing end to print():
print(prefix, end="")
print(remainder)
#Python #DailyPythonTip
Python Tip #69 (of 365):
Joining and then printing? Consider using print() to do your joining instead. 🧵
print() can often function as an alternative to the string join method.
#Python #DailyPythonTip
Python Tip #68 (of 365):
Instead of printing an f-string with a single space between values, consider passing 2 arguments to print.
Instead of this:
print(f"User: {name}")
You could do this:
print("User:", name)
Why?
Less syntax. That's all.
#Python #DailyPythonTip
Python Tip #67 (of 365):
When making a class that should support inheritance, don't hard-code references to your own class. 🧵
If your class is meant to be inherited from, instead of hard-coding references to it, use type(self) to dynamically look up the current class.
#Python #DailyPythonTip
Python Tip #66 (of 365):
Consider implementing __eq__ on every class you make 🧵
Tips 63 and 64 were about always implementing __init__ and __repr__ methods on your classes.
You don't ALWAYS need a __eq__ method, but you should seriously consider one.
#Python #DailyPythonTip
Python Tip #65 (of 365):
Rarely define a __str__ method 🧵
A __str__ method controls the human-readable string representation of your class instances.
You may think you need __str__, but most classes really don't need this method and your class probably doesn't either.
#Python #DailyPythonTip
Python Tip #64 (of 365):
Ensure your classes all have a sensible __repr__ method 🧵
A __repr__ method controls the default string representation of your class instances.
Pretty much every object should have a nice string representation.
#Python #DailyPythonTip
Python Tip #63 (of 365):
Every class should have an initializer 🧵
If your class doesn't have an initializer method, it could probably be a module instead of a class.
#Python #DailyPythonTip
Python Tip #62 (of 365):
Avoid conditionally present attributes 🧵
Python's "del" statement is pretty much ONLY used to delete dictionary keys (or list indexes).
You'll probably never see "del" used to delete an attribute. There's a reason for that.
#Python #DailyPythonTip
Python Tip #61 (of 365):
When passing the same object(s) to different functions, consider a class. 🧵
Consider this code:
server = get_connection(host, name, password)
messages = [
get_message(server, u)
for u in get_message_uids(server)
]
close_connection(server)
#Python #DailyPythonTip
Python Tip #60 (of 365):
Be cautious of "if" expressions in comprehensions 🧵
An "if" expression in a "for" loop can look confusing:
sanitized = [n if n > 0 else 0 for n in counts]
That "else" isn't part of the comprehension. It's just inline "if" expression.
#Python #DailyPythonTip
Python Tip #59 (of 365):
Don't use comprehensions to loop 🧵
List comprehensions are for creating new lists, not for looping.
This is a valid comprehension:
[print(n**2) for n in numbers]
But it's also a misuse of the comprehension syntax.
#Python #DailyPythonTip
