Skip to main content

Code Style Guide

Coding standards and conventions for Qarion ETL.

Python Style​

PEP 8 Compliance​

Follow PEP 8 style guidelines:

  • Use 4 spaces for indentation
  • Maximum line length: 100 characters
  • Use snake_case for functions and variables
  • Use PascalCase for classes

Type Hints​

Always use type hints for function signatures:

from typing import Dict, List, Optional, Any

def process_data(
    data: Dict[str, Any],
    keys: List[str],
    default: Optional[str] = None
) -> Dict[str, Any]:
    """Process data with given keys."""
    pass

Docstrings​

Document all public functions and classes:

def my_function(param1: str, param2: int) -> bool:
    """
    Brief description of the function.

    Args:
        param1: Description of param1
        param2: Description of param2

    Returns:
        Description of return value

    Raises:
        ValueError: When param1 is invalid
    """
    pass

Naming Conventions​

  • Classes: PascalCase (MyClass)
  • Functions: snake_case (my_function)
  • Constants: UPPER_SNAKE_CASE (MY_CONSTANT)
  • Private: Leading underscore (_private_method)

Code Organization​

Imports​

Organize imports:

  1. Standard library
  2. Third-party packages
  3. Local application imports
# Standard library
import os
from typing import Dict, List

# Third-party
import yaml

# Local
from .base import BaseClass
from ..utils import helper_function

Module Structure​

"""
Module docstring.
"""
# Imports
# Constants
# Classes
# Functions

Error Handling​

Use appropriate exception types:

if not value:
    raise ValueError("Value cannot be empty")

if not os.path.exists(path):
    raise FileNotFoundError(f"Path not found: {path}")

Testing​

  • Test files: test_*.py
  • Test functions: test_*
  • Use descriptive test names
def test_process_data_with_valid_input():
    """Test processing valid data."""
    pass