Using decorators with argument in Python

Jigar Tanna poisonousrattle5 at gmail.com
Tue Jun 28 12:52:11 EDT 2011


I am new to Python and Django, was going through the concept of
decorators
where I came across a special case of using arguments with decorators
Below is the code for memoization where I was looking at the
concept...

cache = {}
def get_key(function, *args, **kw) :
    key = '%s. %s: ' % (function. __module__,function. __name__)
    hash_args = [ str(arg) for arg in args]
    hash_kw = [' %s: %s' % (k, hash(v) )
               for k, v in kw.items() ]
    return ' %s:: %s: : %s' % (key, hash_args, hash_kw)

def memoize(get_key=get_key, cache=cache) :
    def _memoize( function) :
        print function
        def __memoize(*args, **kw) :
            key = get_key(function, *args, **kw)
            try:
                return cache[key]
            except KeyError:
                cache[key] = function( *args, **kw)
                return cache[key]
        return __memoize
    return _memoize

@memoize()
def factory(n) :
    return n * n

# testcase
#print factory(3)
#
#

coming across to certain views from people, it is not a good practice
to use
decorators with arguments (i.e. @memoize() ) and instead it is good to
just
use @memoize. Can any of you guys explain me advantages and
disadvantages of
using each of them



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