Creating a static class with no instances

Question

All of the tutorials I see online show how to create classes with   init   constructor methods so one can declare objects of that type  or instances of that class   How do I create a class  static in Java  so that I can access all methods and attributes of that class without having to create new instances objects   For example   class World       allElems           def addElem x              allElems append x   World addElem 6  print World allElems      EDIT  class World object        allAirports            staticmethod     def initialize             f   open os path expanduser    Desktop 1000airports csv            file reader   csv reader f           for col in file reader               allAirports append Airport col 0  col 2  col 3      error  name  allAirports  is  not defined

User · Accepted Answer

The Pythonic way to create a static class is simply to declare those methods outside of a class (Java uses classes both for objects and for grouping related functions, but Python modules are sufficient for grouping related functions that do not require any object instance). However, if you insist on making a method at the class level that doesn't require an instance (rather than simply making it a free-standing function in your module), you can do so by using the "@staticmethod" decorator.

That is, the Pythonic way would be:

# My module
elements = []

def add_element(x):
  elements.append(x)

But if you want to mirror the structure of Java, you can do:

# My module
class World(object):
  elements = []

  @staticmethod
  def add_element(x):
    World.elements.append(x)

You can also do this with @classmethod if you care to know the specific class (which can be handy if you want to allow the static method to be inherited by a class inheriting from this class):

# My module
class World(object):
  elements = []

  @classmethod
  def add_element(cls, x):
    cls.elements.append(x)

User · Answer

There are two ways to do that  Python 2 6     static method  class Klass object        staticmethod     def static method            print  Hello World   Klass static method     module  your module file  called klass py  def static method        print  Hello World    your code   import klass  klass static method

User · Answer

You could use a classmethod or staticmethod  class Paul object       elems            classmethod     def addelem cls  e           cls elems append e        staticmethod     def addelem2 e           Paul elems append e   Paul addelem 1  Paul addelem2 2   print Paul elems    classmethod has advantage that it would work with sub classes  if you really wanted that functionality   module is certainly best though

User · Answer

Seems that you need classmethod   class World object        allAirports            classmethod     def initialize cls            if not cls allAirports              f   open os path expanduser    Desktop 1000airports csv                file reader   csv reader f               for col in file reader                  cls allAirports append Airport col 0  col 2  col 3             return cls allAirports

[python] Creating a static class with no instances

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