Python: static variable decorator

Question

I\'d like to create a decorator like below, but I can\'t seem to think of an implementation that works. I\'m starting to think it\'s not possible, but thought I would ask yo

Answer 1

A slight tweak of another anwser:

def static(**kwargs):
    def decorator(func):
        return type(func)(func.func_code, dict(func.func_globals, **kwargs))
    return decorator

message = "goodbye, world!"
@static(message="hello, world!")
def hello(): print message

hello()

I found it icky to override a builtin name with a function argument name, so I changed **dict into the more canonical **kwargs. I also saved a few lines and IMO made the code cleaner by constructing a new dict with dict(the_original, **the_updates). Lastly I saved a few lines by accessing the function constructor via type(func) rather than an import---type and class objects are factory methods, so use them!

I also removed a global declaration. This works as long as you don't rebind the variable, i.e. removing global in effect makes the pointer (but not the object) read-only. If you use it this way, maybe let is a better name than static for the binding thus introduced.

Answer 2

Here's something that might be much clearer. It doesn't involve any decorators or hacking.

class F( object ):
    def __init__( self ):
        self.x= 0
    def __call__( self ):
        self.x += 1
        print self.x

f= F()

Now you have your function f with a static variable.

f() #prints 1
f() #prints 2