Using Decorators for implementing Function Sentinels

func_sentinel.py

#!/usr/bin/python

#decorator function
def sentinel(lst,integer):
    def wrap(f):
        def wrapped_f(*args):
            if args[0].__class__ is list and args[1].__class__ is int:
                print 'Valid call to {0:s}'.format(f.func_name)
                f(args[0],args[1])
            else:
                print 'Invalid call to {0:s}'.format(f.func_name)
        return wrapped_f
    return wrap
    

@sentinel(['foo','bar'],5)
def fnc1(lst, integer):
    print lst, integer

@sentinel(['foo','bar'],5)
def fnc2(lst, integer):
    print lst, integer

#entry point
if __name__ == '__main__':
    fnc1([1,2],5)
    fnc1([1,2],'a')
    fnc2([1,2],'a')

# Sample output:

$ python func_sentinel.py 
Valid call to fnc1
[1, 2] 5
Invalid call to fnc1
Invalid call to fnc2