static variable in function python code example

Example: python static variable in function

#You can make static variables inside a function in many ways.
#____________________________________________________________#
"""1/You can add attributes to a function, and use it as a
static variable."""
def foo():
    foo.counter += 1
    print ("Counter is %d" % foo.counter)
foo.counter = 0 

#____________________________________________________________#
"""2/If you want the counter initialization code at the top
instead of the bottom, you can create a decorator:"""
def static_vars(**kwargs):
    def decorate(func):
        for k in kwargs:
            setattr(func, k, kwargs[k])
        return func
    return decorate
  
#Then use the code like this:
@static_vars(counter=0)
def foo():
    foo.counter += 1
    print ("Counter is %d" % foo.counter)

#____________________________________________________________#
"""3/Alternatively, if you don't want to setup the variable
outside the function, you can use hasattr() to avoid an
AttributeError exception:"""
def myfunc():
    if not hasattr(myfunc, "counter"):
        myfunc.counter = 0  # it doesn't exist yet, so initialize it
    myfunc.counter += 1
  
#____________________________________________________________#