Carl K wrote:
> Is there a more elegant way of coding this:
>
> x=o.p # save .p
> o.p=0
> o.m()
> o.p=x # restore .p
>
> seems very push/pop to me - like there should be a way that doesn't need
> a var (x) or the save/set lines should be done in one command.
With the appropriate context manger, you could write this as::
with setting(o, 'p', 2):
o.m()
Here's the code::
>>> from __future__ import with_statement
>>> @contextlib.contextmanager
... def setting(obj, name, value):
... old_value = getattr(obj, name)
... setattr(obj, name, value)
... try:
... yield obj
... finally:
... setattr(obj, name, old_value)
...
>>> class C(object):
... def __init__(self, x):
... self.x = x
... def m(self):
... print self.x
...
>>> c = C(1)
>>> with setting(c, 'x', 2):
... c.m()
...
2
>>> print c.x
1
Of course, that just wraps up the same push/pop behavior you're doing
into a context manager.
> (personally I think .m would better be implemented by passing in a
> parameter, but that isn't my choice.)
Yep, that's the right answer. You should complain to whoever created
this API.
STeVe
--
http://mail.python.org/mailman/listinfo/python-list
