Sobre tipos y lenguajes de scripting

import functools

ensure_types = True

def args_types(*args_types, **kwargs_types):
def wrapper(function):
@functools.wraps(function)
def replacement(*args, **kwargs):
for (count, (arg, arg_type)) in enumerate(zip(args, args_types)):
if type(arg) != arg_type:
raise ValueError('Invalid type for arg ' + str(count) +
' expected ' + str(arg_type) + ' got ' + str(type(arg)))

for name, ktype in kwargs_types.iteritems():
if name in kwargs:
if type(kwargs[name]) != ktype:
raise ValueError('Invalid type for karg "' + name +
'" expected ' + str(ktype) + ' got ' + str(type(kwargs[name])))

return function(*args, **kwargs)

if ensure_types:
replacement._is_wrapped = True
return replacement
else:
function._is_wrapped = False
return function

return wrapper

def return_type(return_type):
def wrapper(function):
@functools.wraps(function)
def replacement(*args, **kwargs):
result = function(*args, **kwargs)

if type(result) != return_type:
raise ValueError('Invalid return type expected ' +
str(return_type) + ' got ' + str(type(result)))

return result

if ensure_types:
replacement._is_wrapped = True
return replacement
else:
function._is_wrapped = False
return function

return wrapper

import ensure
# if ensure.ensure_types is set to False then the decorators
# return the same functions and don't make the type checking
# that an be done when development finished and you want to
# deliver the code (it remove the checks and make the code faster)
# ensure.ensure_types = False

@ensure.args_types(int, str, bool, float, sure=bool, price=float)

def do_something(number, name, sure=False, price=10.0):

print number, name, sure, price

@ensure.return_type(int)

def return_param(param):
return param

if do_something._is_wrapped:

print 'do_something contains type checks'
else:
print 'do_something doesn\'t contains type checks'

if return_param._is_wrapped:

print 'return_param contains type checks'
else:
print 'return_param doesn\'t contains type checks'

print do_something.__name__

print

do_something(1, "spongebob", True)
do_something(1, "spongebob", sure=False)

do_something(1, "spongebob", sure=False, price=2.0)

# Fail
try:
do_something(False, "spongebob")
except ValueError, error:

print error

try:
do_something(1, 12.3)

except ValueError, error:
print error

try:

do_something(1, "patricio", 10)
except ValueError, error:

print error

try:
do_something(1, "patricio", True, 10)

except ValueError, error:
print error

try:

do_something(1, "patricio", sure=None)
except ValueError, error:

print error

try:
do_something(1, "patricio", sure=True, price=None)

except ValueError, error:
print error

print 'returned', return_param(5)

try:
print 'returned', return_param("hi!")
except ValueError, error:

print error