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Basics

  • 1. Collection initialization
  • 2. Chained comparison operators
  • 3. Falsy and truthy
  • 4. Ternary operator
  • 5. Use any and all for boolean scans
  • 6. Use is None for None checks
  • 7. Use the walrus operator to avoid repeated work in conditions

Loops and Iteration

  • 1. Looping over a range of numbers
  • 2. Looping backward
  • 3. Looping over a collection
  • 4. Looping over a collection with indices
  • 5. Looping over two collections
  • 6. Use enumerate(start=…) for numbered loops
  • 7. Use next with a default for searches
  • 8. Use deque for queue operations
  • 9. Use heapq for top-N selection
  • 10. Combinations of a list
  • 11. Cycling through a list
  • 12. Product of lists

Lists and Comprehensions

  • 1. Use list comprehensions
  • 2. Filtering a list
  • 3. Count matching items without a temporary list
  • 4. Most frequent item in list
  • 5. Dictionary comprehension
  • 6. Set comprehension

Tuples and Strings

  • 1. Unpacking sequences and tuples
  • 2. Ignoring unpacked values from a tuple
  • 3. Avoid accessing tuple elements by index
  • 4. String concatenation
  • 5. String interpolation
  • 6. String debug
  • 7. Don’t repeat yourself (DRY)
  • 8. String reversal
  • 9. Use removeprefix and removesuffix

Functions and Context

  • 1. Clarify function calls with keyword arguments
  • 2. Lambdas
  • 3. Generator functions
  • 4. Use contextlib.suppress for narrow ignored exceptions
  • 5. Use nullcontext for optional context managers

Dictionaries and Data

  • 1. Default dictionary values: defaultdict
  • 2. Accessing a dictionary value with a default value
  • 3. Updating dictionaries
  • 4. Merging dictionaries
  • 5. Using a dictionary to store counts
  • 6. Transforming data with map, filter, reduce
  • 7. Flattening data
  • 8. Caching data and results

Files, Paths, and Exceptions

  • 1. Reading a file
  • 2. Deleting a file
  • 3. Filtering files
  • 4. Saving objects to file
  • 5. Prefer pathlib over os.path
  • 6. Re-raise exceptions deliberately

Classes and Misc

  • 1. Classes and dunders (double underscores)
  • 2. Enumerations
  • 3. Use default_factory for mutable dataclass defaults
  • 4. Simultaneous state updates
  • 5. Pandas apply and numpy vectorization

General Modern Python

  • 1. New vs old classes
  • 2. Use explicit namespaces with exec and eval

Python 3.9+

  • 1. Use functools.cache for unbounded memoization

Python 3.10+

  • 1. Use zip(strict=True) when equal lengths are required
  • 2. Use dataclass(slots=True) for simple records
  • 3. Use structural pattern matching for structural dispatch

Python 3.11+

  • 1. Use StrEnum for string enums
  • 2. Use Self for fluent instance return types
  • 3. Use tomllib for reading TOML
  • 4. Use asyncio.TaskGroup for related tasks
  • 5. Use add_note for extra exception context
  • 6. Use except* for exception groups

Python 3.12+

  • 1. Use Path.walk in pathlib code
  • 2. Use explicit case sensitivity in pathlib globbing
  • 3. Use the type statement for type aliases
  • 4. Use @override for overridden methods
  • 5. Use itertools.batched for chunking

Python 3.13+

  • 1. Use copy.replace for shallow field updates
  • 2. Use Queue.shutdown instead of sentinel values

Python 3.14+

  • 1. Use InterpreterPoolExecutor for isolated parallel workers
  • 2. Use concurrent.interpreters instead of custom wrappers
  • 3. Use compression.zstd for standard-library Zstandard
  • 4. Use template strings for structured interpolation
Python: Do This, Not That!
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