What is the naming convention in Python for variable and function names

Question

Coming from a C  background the naming convention for variables and method names are usually either camelCase or PascalCase      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

User · Answer

further to what  JohnTESlade has answered  Google s python style guide has some pretty neat recommendations   Names to Avoid   single character names except for counters or iterators dashes  -  in any package module name    double leading and trailing underscore   names  reserved by Python    Naming Convention    Internal  means internal to a module or protected or private within a class  Prepending a single underscore     has some support for protecting module variables and functions  not included with import   from   Prepending a double underscore      to an instance variable or method effectively serves to make the variable or method private to its class  using name mangling   Place related classes and top-level functions together in a module  Unlike Java  there is no need to limit yourself to one class per module  Use CapWords for class names  but lower with under py for module names  Although there are many existing modules named CapWords py  this is now discouraged because it s confusing when the module happens to be named after a class    wait -- did I write import StringIO or from StringIO import StringIO      Guidelines derived from Guido s Recommendations

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David Goodger  in  Code Like a Pythonista  here   describes the PEP 8 recommendations as follows    joined lower for functions  methods  attributes  variables joined lower or ALL CAPS for constants StudlyCaps for classes camelCase only to conform to pre-existing conventions

User · Answer

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

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There is PEP 8  as other answers show  but PEP 8 is only the styleguide for the standard library  and it s only taken as gospel therein  One of the most frequent deviations of PEP 8 for other pieces of code is the variable naming  specifically for methods  There is no single predominate style  although considering the volume of code that uses mixedCase  if one were to make a strict census one would probably end up with a version of PEP 8 with mixedCase  There is little other deviation from PEP 8 that is quite as common

User · Answer

As mentioned  PEP 8 says to use lower case with underscores for variables  methods and functions   I prefer using lower case with underscores for variables and mixedCase for methods and functions makes the code more explicit and readable   Thus following the Zen of Python s  explicit is better than implicit  and  Readability counts

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I personally use Java s naming conventions when developing in other programming languages as it is consistent and easy to follow  That way I am not continuously struggling over what conventions to use which shouldn t be the hardest part of my project

User · Answer

Personally I try to use CamelCase for classes  mixedCase methods and functions  Variables are usually underscore separated  when I can remember   This way I can tell at a glance what exactly I m calling  rather than everything looking the same

User · Answer

Typically  one follow the conventions used in the language s standard library

User · Answer

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

User · Answer

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

User · Answer

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

User · Answer

See Python PEP 8  Function and Variable Names   Function names should be lowercase  with words separated by underscores as necessary to improve readability  Variable names follow the same convention as function names  mixedCase is allowed only in contexts where that s already the prevailing style  e g  threading py   to retain backwards compatibility

User · Answer

As mentioned  PEP 8 says to use lower case with underscores for variables  methods and functions   I prefer using lower case with underscores for variables and mixedCase for methods and functions makes the code more explicit and readable   Thus following the Zen of Python s  explicit is better than implicit  and  Readability counts

User · Answer

The 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

[python] What is the naming convention in Python for variable and function names?

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