On 11/23/2013 10:01 AM, Peter Otten wrote:
In Python 3 the following two classes should be equivalent:
Says who?
>$ cat foo.py
>class Foo:
> def foo():
> pass
> print(callable(foo))
>
>class Foo:
> @staticmethod
> def foo():
> pass
> print(callable(foo))
>
>But they do not:
>
>$ python3 foo.py
>True
>False
Your script is saying that a staticmethod instance is not a callable object.
It need not be because
Foo.foo()
Yes, you are right about Python 3. But in Python 2, if I am not going
wrong, there is not solution, and I need to define a function outside
the class. For instance:
$ cat config.py
class Configuration(object):
def positiveCheck(value):
if not value > 0:
raise AttributeError('Must be a positive number')
attributes = {
# Attribute name: (type, checkrule)
'myattr': (int, positiveCheck),
}
def __setattr__(self, name, value):
if not name in Configuration.attributes:
raise AttributeError("Attribute `%s` non allowed." %name)
expected_type, checkrule = Configuration.attributes[name]
if not isinstance(value, expected_type):
raise TypeError('The value %s is not of type %s' \
%(value, expected_type.__name__))
if callable(checkrule):
print('calling %s(%s)' %(checkrule.__name__, value))
checkrule(value)
super(Configuration, self).__setattr__(name, value)
The positive check works fine:
>>> from config import Configuration
>>> c = Configuration()
>>> c.myattr = -10
calling positiveCheck(-10)
Traceback (most recent call last):
...
AttributeError: Must be a positive number
But I cannot use the method as a function:
>>> Configuration.positiveCheck(-10)
Traceback (most recent call last):
...
Configuration instance as first argument (got int instance instead).
Furthemore, I cannot use the method as a staticmethod, becase otherwise
it will not be callable inside the class body.
--
Marco Buttu
--
https://mail.python.org/mailman/listinfo/python-list
