What is the naming convention in Python for variab

Question

Coming from a C# background the naming convention for variables and method names are usually either CamelCase or Pascal Case:

// C# example
string thisIsMyVariable = "a"
public void ThisIsMyMethod()

In Python, I have seen the above but I have also seen underscores being used:

# python example
this_is_my_variable = 'a'
def this_is_my_function():

Is there a more preferable, definitive coding style for Python?

Answer 1

Most python people prefer underscores, but even I am using python since more than 5 years right now, I still do not like them. They just look ugly to me, but maybe that's all the Java in my head.

I simply like CamelCase better since it fits better with the way classes are named, It feels more logical to have SomeClass.doSomething() than SomeClass.do_something(). If you look around in the global module index in python, you will find both, which is due to the fact that it's a collection of libraries from various sources that grew overtime and not something that was developed by one company like Sun with strict coding rules. I would say the bottom line is: Use whatever you like better, it's just a question of personal taste.

Answer 2

See Python PEP 8.

Function names should be lowercase, with words separated by underscores as necessary to improve readability.

mixedCase is allowed only in contexts where that's already the prevailing style

Variables...

Use the function naming rules: lowercase with words separated by underscores as necessary to improve readability.

Personally, I deviate from this because I also prefer mixedCase over lower_case for my own projects.

Answer 3

Google Python Style Guide has the following convention:

module_name, package_name, ClassName, method_name, ExceptionName, function_name, GLOBAL_CONSTANT_NAME, global_var_name, instance_var_name, function_parameter_name, local_var_name

A similar naming scheme should be applied to a CLASS_CONSTANT_NAME

Answer 4

As the Style Guide for Python Code admits,

The naming conventions of Python's library are a bit of a mess, so we'll never get this completely consistent

Note that this refers just to Python's standard library. If they can't get that consistent, then there hardly is much hope of having a generally-adhered-to convention for all Python code, is there?

From that, and the discussion here, I would deduce that it's not a horrible sin if one keeps using e.g. Java's or C#'s (clear and well-established) naming conventions for variables and functions when crossing over to Python. Keeping in mind, of course, that it is best to abide with whatever the prevailing style for a codebase / project / team happens to be. As the Python Style Guide points out, internal consistency matters most.

^{Feel free to dismiss me as a heretic. :-) Like the OP, I'm not a "Pythonista", not yet anyway.}

Answer 5

The coding style is usually part of an organization's internal policy/convention standards, but I think in general, the all_lower_case_underscore_separator style (also called snake_case) is most common in python.

Answer 6

There is a paper about this: http://www.cs.kent.edu/~jmaletic/papers/ICPC2010-CamelCaseUnderScoreClouds.pdf

TL;DR It says that snake_case is more readable than camelCase. That's why modern languages use (or should use) snake wherever they can.