python decorator arguments

Question

Do python decorator function support arguments a how is the implementation

def decorator(fn, decorArg):
    print "I'm decorating!"
    print decorArg
    return fn

class MyClass(object):
    def __init__(self):
        self.list = []

    @decorator
    def my_function(self, funcArg = None):
        print "Hi"
        print funcArg

on run I got this error

TypeError: decorator() takes exactly 2 arguments (1 given)

I've tried @decorator(arg) or @ decorator arg . it did not work as well. So far I wonder if this is possible

Yes, but your example seems to indicate that you don't understand how decorators work. Have you read, for instance, [this](http://www.python.org/dev/peps/pep-0318/#current-syntax)? What do you want your decorator to do? — BrenBarn, Mar 02 '13 at 06:36
You should read this post order to better understand how to use decorators: http://stackoverflow.com/questions/739654/understanding-python-decorators — Carlos, Mar 02 '13 at 06:41

Hyperboreus · Answer 1 · 2013-03-02T07:16:55.107

3

I think you might want something like this:

class decorator:
    def __init__ (self, decorArg):
        self.arg = decorArg

    def __call__ (self, fn):
        print "I'm decoratin!"
        print self.arg
        return fn

class MyClass (object):
    def __init__ (self):
        self.list = []

    @decorator ("foo")
    def my_function (self, funcArg = None):
        print "Hi"
        print funcArg

MyClass ().my_function ("bar")

Or with nested functions as BlackNight pointed out:

def decorator (decorArg):
    def f (fn):
        print "I'm decoratin!"
        print decorArg
        return fn
    return f

edited Mar 02 '13 at 07:16

answered Mar 02 '13 at 07:04

Hyperboreus

31,997
9
47
87

You can also do it with nested functions, rather than a decorator class. Alas, Python's indentation requirements don't let me type an example here in the comments. – Blckknght Mar 02 '13 at 07:14

python decorator arguments

1 Answers1