• If you want to write a class or static method in Python, you can write an object (or dynamic) method and then call the classmethod function to make it into a method that can additionally run on the the class as a whole:

def counter(cls):
   # This is a 'dynamic' method
   return thing.count
# Which we'll wrap to make (in effect) static too.
ctr = classmethod(counter)

Note that the method takes an object parameter (which we have chosen to label "cls" rather than "self") but it hasn't been used in the code block.

• In more recent versions of Python, you can also use a decorator to achieve the same thing - in fact, it's just a change of the syntax and does the same thing underneath - a decorator is a wrapper:

@classmethod
def counter2(self):
   # "self" is the object or the class
   return thing.count

• You can also use a staticmethod decorator to define a static method - but in this case the static behavior replaces the object or dynamic behavior rather than being additional, and so you don't pass in an object reference:

@staticmethod
def counter():
   return thing.count

There are working examples of each of these in the source code which is [here], written on yesterday's public python class where I was teaching Python Programming.

(written 2010-03-25)

 Y112 - Python - Objects - Intermediate
  [3524] Metaclasses (Python) and Metatables (Lua) - (2011-11-17)
  [3472] Static variables in functions - and better ways using objects - (2011-10-10)
  [3442] A demonstration of how many Python facilities work together - (2011-09-16)
  [3002] A list of special method and attribute names in Python - (2010-10-17)
  [2994] Python - some common questions answered in code examples - (2010-10-10)
  [2905] Defining static methods in Python - (2010-08-05)
  [2889] Should Python classes each be in their own file? - (2010-07-27)
  [2785] The Light bulb moment when people see how Object Orientation works in real use - (2010-05-28)
  [2764] Python decorators - your own, staticmethod and classmethod - (2010-05-14)
  [2722] Mixins example in Python - (2010-04-14)
  [2720] Multiple inheritance in Python - complete working example - (2010-04-14)
  [2717] The Multiple Inheritance Conundrum, interfaces and mixins - (2010-04-11)
  [2485] How do I set up a constant in Python? - (2009-10-31)
  [2409] TypeError: super() argument 1 must be type, not classobj (Python) - (2009-09-18)
  [2368] Python - fresh examples of all the fundamentals - (2009-08-20)
  [1819] Calling base class constructors - (2008-10-03)
  [1661] Equality, sameness and identity - Python - (2008-05-31)
  [1644] Using a utility method to construct objects of different types - Python - (2008-05-17)
  [1517] Python - formatting objects - (2008-01-24)
  [1217] What are factory and singleton classes? - (2007-06-04)
  [1146] __new__ v __init__ - python constructor alternatives? - (2007-04-14)
  [964] Practical polymorphism in action - (2006-12-04)
  [903] Pieces of Python - (2006-10-23)
  [831] Comparison of Object Oriented Philosophy - Python, Java, C++, Perl - (2006-08-13)
  [656] Think about your design even if you don't use full UML - (2006-03-24)
  [477] Class, static and unbound variables - (2005-10-25)
  [383] Overloading of operators on standard objects in Python - (2005-07-19)
  [296] Using a Python dictionary as a holder of object attributes - (2005-04-30)

Back to Flexible search and replace in Python

Previous and next or Horse's mouth home

Forward to Multiple processes (forking) in Python

Email metrics and filtering
Garlic bread without garlic
TCP v UDP / Client v Server - Python examples
Multiple processes (forking) in Python
Methods that run on classes (static methods) in Python
Flexible search and replace in Python
New brochures for the Melksham area
The World Company Register - is it another scam?
Can my dog eat potatoes? Doggie Dietary Research, and political sleaze!
Security considerations in programming - what do we teach?