Dagster Io Skills Skills

Dignified Python

Opinionated Python guidance for writing clean, maintainable, modern Python code (versions 3.10-3.13).

When to Use This Skill

Auto-invoke when users ask about:

• "make this pythonic" / "is this good python"
• "type hints" / "type annotations" / "typing"
• "LBYL vs EAFP" / "exception handling"
• "pathlib vs os.path" / "path operations"
• "CLI patterns" / "click usage"
• "code review" / "improve this code"
• Any Python code quality or standards question

Note: This skill is general-purpose Python style guidance, not Dagster-specific. It captures one explicit, LBYL-leaning set of conventions; project conventions can override it when needed.

When to Use This Skill vs. Others

Core Knowledge (ALWAYS Loaded)

@dignified-python-core.md

Version Detection

Identify the project's minimum Python version by checking (in order):

1. pyproject.toml - Look for requires-python field (e.g., requires-python = ">=3.12")
2. setup.py or setup.cfg - Look for python_requires
3. .python-version file - Contains version like 3.12 or 3.12.0
4. Default to Python 3.12 if no version specifier found

Once identified, load the appropriate version-specific file:

• Python 3.10: Load versions/python-3.10.md
• Python 3.11: Load versions/python-3.11.md
• Python 3.12: Load versions/python-3.12.md
• Python 3.13: Load versions/python-3.13.md

Conditional Loading (Load Based on Task Patterns)

Core files above cover 80%+ of Python code patterns. Only load these additional files when you detect specific patterns:

Pattern detection examples:

• If task mentions "click" or "CLI" -> Load cli-patterns.md
• If task mentions "subprocess" -> Load subprocess.md

Reference Documentation Structure

This skill's reference material is organized by topic:

Core References

• dignified-python-core.md - Essential standards (always loaded)
• cli-patterns.md - Command-line interface patterns (click, argparse)

Version-Specific References (versions/)

• python-3.10.md - Features available in Python 3.10+
• python-3.11.md - Features available in Python 3.11+
• python-3.12.md - Features available in Python 3.12+
• python-3.13.md - Features available in Python 3.13+

Advanced Topics (references/advanced/)

• exception-handling.md - LBYL patterns, error boundaries
• interfaces.md - ABC and Protocol patterns
• typing-advanced.md - Advanced typing patterns
• api-design.md - API design principles

When to Read Each Reference Document

references/advanced/exception-handling.md

Read when:

• Writing try/except blocks
• Wrapping third-party APIs that may raise
• Seeing or writing from e or from None
• Unsure if LBYL alternative exists

references/advanced/interfaces.md

Read when:

• Creating ABC or Protocol classes
• Writing @abstractmethod decorators
• Designing gateway layer interfaces
• Choosing between ABC and Protocol

references/advanced/typing-advanced.md

Read when:

• Using typing.cast()
• Creating Literal type aliases
• Narrowing types in conditional blocks

references/module-design.md

Read when:

• Creating new Python modules
• Adding module-level code (beyond simple constants)
• Using @cache decorator at module level
• Seeing Path() or computation at module level
• Considering inline imports

references/advanced/api-design.md

Read when:

• Adding default parameter values to functions
• Defining functions with 5 or more parameters
• Using ThreadPoolExecutor.submit()
• Reviewing function signatures

references/checklists.md

Read when:

• Final review before committing Python code
• Unsure if you've followed all rules
• Need a quick lookup of requirements

How to Use This Skill

1. Core knowledge is loaded automatically (defaults, pathlib, imports, anti-patterns)
2. Version detection happens once - identify the minimum Python version and load the appropriate version file
3. Reference documents are loaded on-demand based on the triggers above
4. Additional patterns may require extra loading (CLI patterns, subprocess)
5. Each file is self-contained with complete guidance for its domain

Source: dagster-io/skills — distributed by TomeVault.