decomouse.py

# Filename: decomouse.py
# Description: Test all ways of creating python decorators.
# Author: Pushpendre Rastogi
# Created: Wed Apr 15 00:26:57 2015 (-0400)
# Last-Updated:
#           By:
#     Update #: 14
'''
A post by [Bruce Eckel at Artima]()
described all the ways of defining decorators.
I wrote this code to memorize those patterns.
After writing those files I believe that the post could
have been greatly simplified if Bruce just said that the
call mechanism changes when we have a decorator with arguments
from decorator(f) to decorator(args)(f).

USAGE: python decomouse.py
OUTPUT:
 import saf
 saf
 run_saf (1, 2) {'a': 1, 'b': 1}
 decosaf (1, 2) {'a': 1, 'b': 1}
 None

 import waf (10, 20) {'c': 10, 'd': 20}
 import waf2
 waf
 run_waf (1, 2) {'a': 1, 'b': 1}
 decowaf (1, 2) {'a': 1, 'b': 1}
 None

 import sac
 sac
 run_sac (1, 2) {'a': 1, 'b': 1}
 decosac (1, 2) {'a': 1, 'b': 1}
 None

 import wac (10, 20) {'c': 10, 'd': 20}
 import_wac again
 wac
 run_wac (1, 2) {'a': 1, 'b': 1}
 decowac (1, 2) {'a': 1, 'b': 1}
 None
'''

# Type 1: Decorators sans arguments (defined as function)
def saf(f):
    print "import saf"
    def wf(*args, **kwargs):
        print "run_saf", args, kwargs
        return f(*args, **kwargs)
    return wf

@saf
def decosaf(*args, **kwargs):
    print "decosaf", args, kwargs
    return
print "saf\n", decosaf(1, 2, a=1, b=1), "\n"

# Type 2 : Decorators with arguments (defined as function)
# A decorator with argument is executed as `deco(arg)(f)` that's all.
def waf(*dargs, **dkwargs):
    print "import waf", dargs, dkwargs
    def internal_wf(f):
        print "import waf2"
        def wf(*args, **kwargs):
            print "run_waf", args, kwargs
            return f(*args, **kwargs)
        return wf
    return internal_wf

@waf(10, 20, c=10, d=20)
def decowaf(*args, **kwargs):
    print "decowaf", args, kwargs
    return

print "waf\n", decowaf(1, 2, a=1, b=1), "\n"

# Type 3: Decorators sans arguments (defined as class)
class sac(object):
    def __init__(self, f):
        print "import sac"
        self.f = f
        return

    def __call__(self, *args, **kwargs):
        print "run_sac", args, kwargs
        return self.f(*args, **kwargs)

@sac
def decosac(*args, **kwargs):
    print "decosac", args, kwargs
    return

print "sac\n", decosac(1, 2, a=1, b=1), "\n"

# Type 4: Decorators with arguments (defined as class)
class wac(object):
    def __init__(self, *dargs, **dkwargs):
        print "import wac", dargs, dkwargs
        return

    def __call__(self, f):
        print "import_wac again"
        def wf(*args, **kwargs):
            print "run_wac", args, kwargs
            return f(*args, **kwargs)
        return wf

@wac(10, 20, c=10, d=20)
def decowac(*args, **kwargs):
    print "decowac", args, kwargs
    return

print "wac\n", decowac(1, 2, a=1, b=1), "\n"