Steven D'Aprano <st...@remove-this-cybersource.com.au> writes:
> I have a class with a method meant to verify internal program logic (not
> data supplied by the caller). Because it is time-consuming but optional,
> I treat it as a complex assertion statement, and optimize it away if
> __debug__ is false:
>
> class Parrot:
> def __init__(self, *args):
> print "Initialising instance..."
> if __debug__:
> self.verify() # check internal program state, not args
> if __debug__:
> def verify(self):
> print "Verifying..."
>
>
> If I run Python normally, I can do this:
FWIW here is a way with a metaclass:
===== verify_init.py =====
from functools import wraps
def post_verify(method):
@wraps(method)
def decorated(self, *args):
result = method(self, *args)
self.verify()
return result
return decorated
class VerifyInit(type):
def __new__(meta, name, bases, attrs):
if __debug__:
attrs['__init__'] = post_verify(attrs['__init__'])
else:
del attrs['verify']
return type.__new__(meta, name, bases, attrs)
class Parrot:
__metaclass__ = VerifyInit
def __init__(self, *args):
print "Initialising instance..."
def verify(self):
print "Verifying..."
coco = Parrot()
==========
marigold:junk arno$ python verify_init.py
Initialising instance...
Verifying...
marigold:junk arno$ python -O verify_init.py
Initialising instance...
You could also not use the metaclass and use post_verify as a decorator:
class Parrot:
@post_verify
def __init__(self, *args):
print "Initialising instance..."
if __debug__:
def verify(self):
print "Verifying..."
--
Arnaud
--
http://mail.python.org/mailman/listinfo/python-list
