Python Patterns

Included with Lifetime

$97 forever

This skill should be used when the user asks about "Python best practices", "Pythonic code", "Python patterns", "Python idioms", "type hints", "dataclasses", "async Python", "Python decorators", "context managers"

General

What this skill does


# Python Patterns

Guidance for writing idiomatic, modern Python code.

## Modern Python Features (3.9+)

| Feature | Purpose | Key Concept |
|---------|---------|-------------|
| **Type hints** | Static analysis | `def func(x: str) -> int:` |
| **Dataclasses** | Structured data | Auto `__init__`, `__repr__`, etc. |
| **Context managers** | Resource cleanup | `with` statement guarantees cleanup |
| **Decorators** | Cross-cutting concerns | Wrap functions to add behavior |
| **Async/await** | Concurrent I/O | Non-blocking operations |

---

## Type Hints

**Modern syntax (3.10+)**: Use `|` for unions, built-in types for generics.

| Old | Modern |
|-----|--------|
| `Optional[str]` | `str \| None` |
| `Union[str, int]` | `str \| int` |
| `List[str]` | `list[str]` |
| `Dict[str, int]` | `dict[str, int]` |

**Key concept**: Type hints are for tooling (mypy, IDEs) - no runtime enforcement.

---

## Dataclasses vs Alternatives

| Use | For |
|-----|-----|
| `@dataclass` | Mutable data with methods |
| `@dataclass(frozen=True)` | Immutable, hashable |
| `NamedTuple` | Lightweight, tuple semantics |
| `TypedDict` | Dict with known keys |
| `Pydantic` | Validation, serialization |

---

## Context Managers

Use for any resource that needs cleanup: files, connections, locks, transactions.

**Pattern**: Acquire in `__enter__`, release in `__exit__` (or use `@contextmanager` with `yield`)

---

## Decorators

| Pattern | Use Case |
|---------|----------|
| Simple decorator | Logging, timing |
| Decorator with args | Configurable behavior |
| Class decorator | Modify class definition |
| `@functools.wraps` | Preserve function metadata |

---

## Async Python

**When to use**: I/O-bound operations (HTTP requests, DB queries, file I/O)

**When NOT to use**: CPU-bound operations (use `multiprocessing` instead)

| Concept | Purpose |
|---------|---------|
| `async def` | Define coroutine |
| `await` | Suspend until complete |
| `asyncio.gather()` | Run multiple concurrently |
| `async with` | Async context manager |
| `async for` | Async iteration |

---

## Pythonic Idioms

| Instead of | Use |
|------------|-----|
| `if len(x) > 0:` | `if x:` |
| `for i in range(len(x)):` | `for item in x:` or `enumerate()` |
| `d.has_key(k)` | `k in d` |
| `try/if exists` (LBYL) | `try/except` (EAFP) |
| Manual swap | `a, b = b, a` |

---

## Project Structure

```
my_project/
├── src/my_package/     # Source code
├── tests/              # Test files
├── pyproject.toml      # Project config
└── README.md
```

**Key concept**: Use `src/` layout to prevent import confusion.

---

## Tooling

| Tool | Purpose |
|------|---------|
| **ruff** | Fast linter + formatter |
| **mypy** | Type checking |
| **pytest** | Testing |
| **uv/pip** | Dependencies |

## Resources

- Python docs: <https://docs.python.org/3/>
- Real Python: <https://realpython.com/>

Files: 1

Size: 3.1 KB

Complexity: 12/100

Category: General

Source: https://github.com/eyadsibai/ltk/tree/main/plugins/ltk-engineering/skills/python/python-patterns

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