Python Naming

Python Naming Conventions

What I Do

Provide Python naming conventions for variables, functions, classes, constants, files, and directories.

Naming Rules

Variables and Functions

# Use snake_case for variables and functions
user_name = "alice"
input_data = get_input()

# Avoid single-letter names except for loop counters or math
for i in range(10):      # OK - loop counter
    x = coordinate[i]    # OK - mathematical variable

# Avoid generic names
# BAD: data, info, temp, x, y
# GOOD: user_data, config_info, temp_file, user_coordinates

# Avoid abbreviations unless widely recognized
# BAD: usr_nm, cfg, calc_val
# GOOD: user_name, config, calculated_value

Classes

# Use PascalCase for classes
class DataProcessor:
    pass

class ConfigurationError(Exception):
    pass

Constants

# Use UPPER_SNAKE_CASE for constants
MAX_BUFFER_SIZE = 1024
DEFAULT_TIMEOUT_SECONDS = 30

# Define magic numbers as constants
INPUT_FILE_ENCODING = "utf-8"
OUTPUT_DELIMITER = ","

Files and Directories

# Use _file suffix for filename variables
input_file: Path
output_file: Path

# Use _dir suffix for directory path variables
input_dir: Path
output_dir: Path

# NEVER mix these up
# BAD: input_file = Path("path/to/dir")       # Confusing
# BAD: output_dir = Path("file.txt")          # Confusing

# Use _path ONLY in rare exceptional cases when truly unclear
# Prefer _file or _dir instead

When to Use Me

Use this skill when:

• Naming variables, functions, or classes
• Defining constants
• Creating file/directory path parameters
• Reviewing code for naming consistency

Key Rules

1. Clarity over brevity - user_input_path > uip
2. Consistent conventions - Apply same pattern throughout
3. Avoid magic values - Use constants for repeated values
4. Type hints required - Always annotate types
5. Domain-appropriate names - Use context-relevant terminology

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