Preface
Acknowledgments
About the Author
1. Pythonic Thinking
Item 1: Know Which Version of Python You’re Using
Item 2: Follow the PEP 8 Style Guide
Item 3: Know the Differences Between bytes and str
Item 4: Prefer Interpolated F-Strings Over C-style Format Strings and str.format
Item 5: Write Helper Functions Instead of Complex Expressions
Item 6: Prefer Multiple Assignment Unpacking Over Indexing
Item 7: Prefer enumerate Over range
Item 8: Use zip to Process Iterators in Parallel
Item 9: Avoid else Blocks After for and while Loops
Item 10: Prevent Repetition with Assignment Expressions
2. Lists and Dictionaries
Item 11: Know How to Slice Sequences
Item 12: Avoid Striding and Slicing in a Single Expression
Item 13: Prefer Catch-All Unpacking Over Slicing
Item 14: Sort by Complex Criteria Using the key Parameter
Item 15: Be Cautious When Relying on dict Insertion Ordering
Item 16: Prefer get Over in and KeyError to Handle Missing Dictionary Keys
Item 17: Prefer defaultdict Over setdefault to Handle Missing Items in Internal State
Item 18: Know How to Construct Key-Dependent Default Values with __missing__
3. Functions
Item 19: Never Unpack More Than Three Variables When Functions Return Multiple Values
Item 20: Prefer Raising Exceptions to Returning None
Item 21: Know How Closures Interact with Variable Scope
Item 22: Reduce Visual Noise with Variable Positional Arguments
Item 23: Provide Optional Behavior with Keyword Arguments
Item 24: Use None and Docstrings to Specify Dynamic Default Arguments
Item 25: Enforce Clarity with Keyword-Only and Positional-Only Arguments
Item 26: Define Function Decorators with functools.wraps
4. Comprehensions and Generators
Item 27: Use Comprehensions Instead of map and filter
Item 28: Avoid More Than Two Control Subexpressions in Comprehensions
Item 29: Avoid Repeated Work in Comprehensions by Using Assignment Expressions
Item 30: Consider Generators Instead of Returning Lists
Item 31: Be Defensive When Iterating Over Arguments
Item 32: Consider Generator Expressions for Large List Comprehensions
Item 33: Compose Multiple Generators with yield from
Item 34: Avoid Injecting Data into Generators with send
Item 35: Avoid Causing State Transitions in Generators with throw
Item 36: Consider itertools for Working with Iterators and Generators
5. Classes and Interfaces
Item 37: Compose Classes Instead of Nesting Many Levels of Built-in Types
Item 38: Accept Functions Instead of Classes for Simple Interfaces
Item 39: Use @classmethod Polymorphism to Construct Objects Generically
Item 40: Initialize Parent Classes with super
Item 41: Consider Composing Functionality with Mix-in Classes
Item 42: Prefer Public Attributes Over Private Ones
Item 43: Inherit from collections.abc for Custom Container Types
6. Metaclasses and Attributes
Item 44: Use Plain Attributes Instead of Setter and Getter Methods
Item 45: Consider @property Instead of Refactoring Attributes
Item 46: Use Descriptors for Reusable @property Methods
Item 47: Use __getattr__, __getattribute__, and __setattr__ for Lazy Attributes
Item 48: Validate Subclasses with __init_subclass__
Item 49: Register Class Existence with __init_subclass__
Item 50: Annotate Class Attributes with __set_name__
Item 51: Prefer Class Decorators Over Metaclasses for Composable Class Extensions
7. Concurrency and Parallelism
Item 52: Use subprocess to Manage Child Processes
Item 53: Use Threads for Blocking I/O, Avoid for Parallelism
Item 54: Use Lock to Prevent Data Races in Threads
Item 55: Use Queue to Coordinate Work Between Threads
Item 56: Know How to Recognize When Concurrency Is Necessary
Item 57: Avoid Creating New Thread Instances for On-demand Fan-out
Item 58: Understand How Using Queue for Concurrency Requires Refactoring
Item 59: Consider ThreadPoolExecutor When Threads Are Necessary for Concurrency
Item 60: Achieve Highly Concurrent I/O with Coroutines
Item 61: Know How to Port Threaded I/O to asyncio
Item 62: Mix Threads and Coroutines to Ease the Transition to asyncio
Item 63: Avoid Blocking the asyncio Event Loop to Maximize Responsiveness
Item 64: Consider concurrent.futures for True Parallelism
8. Robustness and Performance
Item 65: Take Advantage of Each Block in try/except/else/finally
Item 66: Consider contextlib and with Statements for Reusable try/finally Behavior
Item 67: Use datetime Instead of time for Local Clocks
Item 68: Make pickle Reliable with copyreg
Item 69: Use decimal When Precision Is Paramount
Item 70: Profile Before Optimizing
Item 71: Prefer deque for Producer–Consumer Queues for Producer–Consumer Queues
Item 72: Consider Searching Sorted Sequences with bisect
Item 73: Know How to Use heapq for Priority Queues
Item 74: Consider memoryview and bytearray for Zero-Copy Interactions with bytes
9. Testing and Debugging
Item 75: Use repr Strings for Debugging Output
Item 76: Verify Related Behaviors in TestCase Subclasses
Item 77: Isolate Tests from Each Other with setUp, tearDown, setUpModule, and tearDownModule
Item 78: Use Mocks to Test Code with Complex Dependencies
Item 79: Encapsulate Dependencies to Facilitate Mocking and Testing
Item 80: Consider Interactive Debugging with pdb
Item 81: Use tracemalloc to Understand Memory Usage and Leaks
10. Collaboration
Item 82: Know Where to Find Community-Built Modules
Item 83: Use Virtual Environments for Isolated and Reproducible Dependencies
Item 84: Write Docstrings for Every Function, Class, and Module
Item 85: Use Packages to Organize Modules and Provide Stable APIs
Item 86: Consider Module-Scoped Code to Configure Deployment Environments
Item 87: Define a Root Exception to Insulate Callers from APIs
Item 88: Know How to Break Circular Dependencies
Item 89: Consider warnings to Refactor and Migrate Usage
Item 90: Consider Static Analysis via typing to Obviate Bugs