how to assert that method accepts specific types
Rhodri James
rhodri at wildebst.demon.co.uk
Sat Feb 21 01:25:08 EST 2009
On Sat, 21 Feb 2009 01:12:01 -0000, Darren Dale <dsdale24 at gmail.com> wrote:
> I would like to assert that a method accepts certain types. I have a
> short example that works:
>
> from functools import wraps
>
> def accepts(*types):
> def check_accepts(f):
> @wraps(f)
> def new_f(self, other):
> assert isinstance(other, types), \
> "arg %r does not match %s" % (other, types)
> return f(self, other)
> return new_f
> return check_accepts
>
> class Test(object):
>
> @accepts(int)
> def check(self, obj):
> print obj
>
> t = Test()
> t.check(1)
>
> but now I want Test.check to accept an instance of Test as well. Does
> anyone know how this can be accomplished? The following class
> definition for Test raises a NameError:
>
> class Test(object):
>
> @accepts(int, Test)
> def check(self, obj):
> print obj
An icky but relatively clear way to get around this is to gratuitously
subclass Test:
class AcceptableTest(object):
pass
class Test(AcceptableTest):
@accepts(int, AcceptableTest)
def check(self, obj):
print obj
--
Rhodri James *-* Wildebeeste Herder to the Masses
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