What is the Python equivalent of static variables inside a function?

Question

What is the idiomatic Python equivalent of this C/C++ code?

void foo()
{
    static int counter = 0;
    counter++;
          


        

Answer 1

Python doesn't have static variables but you can fake it by defining a callable class object and then using it as a function. Also see this answer.

class Foo(object):
  # Class variable, shared by all instances of this class
  counter = 0

  def __call__(self):
    Foo.counter += 1
    print Foo.counter

# Create an object instance of class "Foo," called "foo"
foo = Foo()

# Make calls to the "__call__" method, via the object's name itself
foo() #prints 1
foo() #prints 2
foo() #prints 3

Note that __call__ makes an instance of a class (object) callable by its own name. That's why calling foo() above calls the class' __call__ method. From the documentation:

Instances of arbitrary classes can be made callable by defining a __call__() method in their class.