Python naming conventions (PEP 8)

PEP 8 defines Python's naming conventions: variables and functions use snake_case (my_variable, calculate_total). Classes use PascalCase (MyClass, HttpResponse). Constants use UPPER_SNAKE_CASE (MAX_RETRIES, API_BASE_URL). Module names use lowercase (my_module.py). Private attributes use leading underscore (_internal_value). Name-mangled attributes use double underscore (__private). When working with APIs that use camelCase (JavaScript conventions), you need to convert between cases at the API boundary.

# Python — convert between naming conventions
import re

def to_snake_case(s):
    return re.sub(r"(?<=[a-z])(?=[A-Z])", "_", s).lower()

def to_camel_case(s):
    parts = re.split(r"[_\-\s]+", s)
    return parts[0].lower() + "".join(w.capitalize() for w in parts[1:])

def to_pascal_case(s):
    return "".join(w.capitalize() for w in re.split(r"[_\-\s]+", s))

def to_kebab_case(s):
    return re.sub(r"(?<=[a-z])(?=[A-Z])", "-", s).lower().replace("_", "-")

print(to_snake_case("myVariableName"))   # "my_variable_name"
print(to_camel_case("my_variable_name")) # "myVariableName"
print(to_pascal_case("my-var-name"))     # "MyVarName"
print(to_kebab_case("myVariableName"))   # "my-variable-name"

How to convert between cases in Python

Snake to camel: def to_camel(s): parts = s.split('_'); return parts[0] + ''.join(p.capitalize() for p in parts[1:]). Snake to Pascal: def to_pascal(s): return ''.join(p.capitalize() for p in s.split('_')). Camel/Pascal to snake: import re; def to_snake(s): return re.sub(r'(?<=[a-z0-9])(?=[A-Z])', '_', s).lower(). For production code, use the inflection library: pip install inflection; inflection.underscore('CamelCase') returns 'camel_case'; inflection.camelize('snake_case') returns 'SnakeCase'.

Converting API responses between Python and JavaScript conventions

When Python APIs interact with JavaScript frontends, you often need to convert dict keys between snake_case and camelCase. Recursive converter: def keys_to_camel(d): if isinstance(d, dict): return {to_camel(k): keys_to_camel(v) for k, v in d.items()}; if isinstance(d, list): return [keys_to_camel(i) for i in d]; return d. Libraries: pydantic's model_config = ConfigDict(alias_generator=to_camel, populate_by_name=True) handles this automatically. FastAPI + Pydantic make case conversion seamless between Python backend and React frontend.