Sandra-24 <[EMAIL PROTECTED]> wrote:
> So thinking myself clever with python I thought I could change
> S3ResponseError to have a __new__ method which returns one of the 30
> new exceptions. That way none of the raise S3ResponseError code needs
> changing. No problem. The trouble comes with those exceptions being
> subclasses of S3ResponseError, because __new__ is called again and
> goofs everything up.
I think what you want for Bar is something more along the lines:
class Foo(object):
def __new__(cls, *args):
print 'Foo.__new__', len(args)
return super(Foo, cls).__new__(cls, *args)
def __init__(self, a, b, c):
print 'Foo.__init__', 3
self.a = a
self.b = b
self.c = c
class Bar(Foo):
def __new__(cls, a, b, c, *args):
print 'Bar.__new__', len(args)
target = cls
if not args:
cls = Zoo
obj = super(Bar, cls).__new__(cls, a, b, c, *args)
if args:
return obj
obj.__init__(a, b, c, 7)
class Zoo(Bar):
def __init__(self, a, b, c, d):
print 'Zoo.__init__', 4
Foo.__init__(self, a, b, c)
self.d = d
Bar(1,2,3)
Output from this is:
Bar.__new__ 0
Foo.__new__ 3
Zoo.__init__ 4
Foo.__init__ 3
Bar can instantiate a subclass, but to do that it wants to call the
constructor __new__ only for the base classes, and because it has
changed the type of the object being constructed it has to call __init__
explicitly.
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